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Odeigah OO, Kwan ED, Garcia KM, Finsberg H, Valdez-Jasso D, Sundnes J. A computational study of right ventricular mechanics in a rat model of pulmonary arterial hypertension. Front Physiol 2024; 15:1360389. [PMID: 38529483 PMCID: PMC10961401 DOI: 10.3389/fphys.2024.1360389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Accepted: 02/23/2024] [Indexed: 03/27/2024] Open
Abstract
Pulmonary arterial hypertension (PAH) presents a significant challenge to right ventricular (RV) function due to progressive pressure overload, necessitating adaptive remodeling in the form of increased wall thickness, enhanced myocardial contractility and stiffness to maintain cardiac performance. However, the impact of these remodeling mechanisms on RV mechanics in not clearly understood. In addition, there is a lack of quantitative understanding of how each mechanism individually influences RV mechanics. Utilizing experimental data from a rat model of PAH at three distinct time points, we developed biventricular finite element models to investigate how RV stress and strain evolved with PAH progression. The finite element models were fitted to hemodynamic and morphological data to represent different disease stages and used to analyze the impact of RV remodeling as well as the altered RV pressure. Furthermore, we performed a number of theoretical simulation studies with different combinations of morphological and physiological remodeling, to assess and quantify their individual impact on overall RV load and function. Our findings revealed a substantial 4-fold increase in RV stiffness and a transient 2-fold rise in contractility, which returned to baseline by week 12. These changes in RV material properties in addition to the 2-fold increase in wall thickness significantly mitigated the increase in wall stress and strain caused by the progressive increase in RV afterload. Despite the PAH-induced cases showing increased wall stress and strain at end-diastole and end-systole compared to the control, our simulations suggest that without the observed remodeling mechanisms, the increase in stress and strain would have been much more pronounced. Our model analysis also indicated that while changes in the RV's material properties-particularly increased RV stiffness - have a notable effect on its mechanics, the primary compensatory factor limiting the stress and strain increase in the early stages of PAH was the significant increase in wall thickness. These findings underscore the importance of RV remodeling in managing the mechanical burden on the right ventricle due to pressure overload.
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Affiliation(s)
| | - Ethan D. Kwan
- Shu Chien-Gene Lay Department of Bioengineering, University of California San Diego, La Jolla, CA, United States
| | - Kristen M. Garcia
- Shu Chien-Gene Lay Department of Bioengineering, University of California San Diego, La Jolla, CA, United States
| | | | - Daniela Valdez-Jasso
- Shu Chien-Gene Lay Department of Bioengineering, University of California San Diego, La Jolla, CA, United States
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2
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Mendiola EA, Neelakantan S, Xiang Q, Xia S, Zhang J, Serpooshan V, Vanderslice P, Avazmohammadi R. An image-driven micromechanical approach to characterize multiscale remodeling in infarcted myocardium. Acta Biomater 2024; 173:109-122. [PMID: 37925122 PMCID: PMC10924194 DOI: 10.1016/j.actbio.2023.10.027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Revised: 10/19/2023] [Accepted: 10/24/2023] [Indexed: 11/06/2023]
Abstract
Myocardial infarction (MI) is accompanied by the formation of a fibrotic scar in the left ventricle (LV) and initiates significant alterations in the architecture and constituents of the LV free wall (LVFW). Previous studies have shown that LV adaptation is highly individual, indicating that the identification of remodeling mechanisms post-MI demands a fully subject-specific approach that can integrate a host of structural alterations at the fiber-level to changes in bulk biomechanical adaptation at the tissue-level. We present an image-driven micromechanical approach to characterize remodeling, assimilating new biaxial mechanical data, histological studies, and digital image correlation data within an in-silico framework to elucidate the fiber-level remodeling mechanisms that drive tissue-level adaptation for each subject. We found that a progressively diffused collagen fiber structure combined with similarly disorganized myofiber architecture in the healthy region leads to the loss of LVFW anisotropy post-MI, offering an important tissue-level hallmark for LV maladaptation. In contrast, our results suggest that reductions in collagen undulation are an adaptive mechanism competing against LVFW thinning. Additionally, we show that the inclusion of subject-specific geometry when modeling myocardial tissue is essential for accurate prediction of tissue kinematics. Our approach serves as an essential step toward identifying fiber-level remodeling indices that govern the transition of MI to systolic heart failure. These indices complement the traditional, organ-level measures of LV anatomy and function that often fall short of early prognostication of heart failure in MI. In addition, our approach offers an integrated methodology to advance the design of personalized interventions, such as hydrogel injection, to reinforce and suppress native adaptive and maladaptive mechanisms, respectively, to prevent the transition of MI to heart failure. STATEMENT OF SIGNIFICANCE: Biomechanical and architectural adaptation of the LVFW remains a central, yet overlooked, remodeling process post-MI. Our study indicates the biomechanical adaptation of the LVFW post-MI is highly individual and driven by altered fiber network architecture and collective changes in collagen fiber content, undulation, and stiffness. Our findings demonstrate the possibility of using cardiac strains to infer such fiber-level remodeling events through in-silico modeling, paving the way for in-vivo characterization of multiscale biomechanical indices in humans. Such indices will complement the traditional, organ-level measures of LV anatomy and function that often fall short of early prognostication of heart failure in MI.
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Affiliation(s)
- Emilio A Mendiola
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, USA
| | - Sunder Neelakantan
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, USA
| | - Qian Xiang
- Department of Molecular Cardiology, Texas Heart Institute, Houston, Texas, USA
| | - Shuda Xia
- Oden Institute for Computational Engineering and Sciences, Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX, USA
| | - Jianyi Zhang
- Department of Biomedical Engineering, The University of Alabama at Birmingham, Birmingham, AL, United States
| | - Vahid Serpooshan
- Wallace H. Coulter Department of Biomedical Engineering, Emory University School of Medicine and Georgia Institute of Technology, Atlanta, GA, United States; Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, United States; Children's Healthcare of Atlanta, Atlanta, GA, United States
| | - Peter Vanderslice
- Department of Molecular Cardiology, Texas Heart Institute, Houston, Texas, USA.
| | - Reza Avazmohammadi
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, USA; J. Mike Walker '66 Department of Mechanical Engineering, Texas A&M University, College Station, TX, USA; Department of Cardiovascular Sciences, Houston Methodist Academic Institute, Houston, TX, USA.
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3
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Valle C, Ujvari A, Elia E, Lu M, Gauthier N, Hoganson D, Marx G, Powell AJ, Ferraro A, Lakatos B, Tősér Z, Merkely B, Kovacs A, Harrild DM. Right ventricular contraction patterns in healthy children using three-dimensional echocardiography. Front Cardiovasc Med 2023; 10:1141027. [PMID: 37600046 PMCID: PMC10435279 DOI: 10.3389/fcvm.2023.1141027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Accepted: 07/04/2023] [Indexed: 08/22/2023] Open
Abstract
Background The right ventricle (RV) has complex geometry and function, with motion along three separate axes-longitudinal, radial, and anteroposterior. Quantitative assessment of RV function by two-dimension echocardiography (2DE) has been limited as a consequence of this complexity, whereas newer three dimensional (3D) analysis offers the potential for more comprehensive assessment of the contributors to RV function. The aims of this study were to quantify the longitudinal, radial and anteroposterior components of global RV function using 3D echocardiography in a cohort of healthy children and to examine maturational changes in these parameters. Methods Three-dimensional contours of the RV were generated from a cohort of healthy pediatric patients with structurally normal hearts at two centers. Traditional 2D and 3D echo characteristics were recorded. Using offline analysis of 3D datasets, RV motion was decomposed into three components, and ejection fractions (EF) were calculated (longitudinal-LEF; radial-REF; and anteroposterior-AEF). The individual decomposed EF values were indexed against the global RVEF. Strain values were calculated as well. Results Data from 166 subjects were included in the analysis; median age was 13.5 years (range 0 to 17.4 years). Overall, AEF was greater than REF and LEF (29.2 ± 6.2% vs. 25.1 ± 7.2% and 25.7 ± 6.0%, respectively; p < 0.001). This remained true when indexed to overall EF (49.8 ± 8.7% vs. 43.3 ± 11.6% and 44.4 ± 10%, respectively; p < 0.001). Age-related differences were present for global RVEF, REF, and all components of RV strain. Conclusions In healthy children, anteroposterior shortening is the dominant component of RV contraction. Evaluation of 3D parameters of the RV in children is feasible and enhances the overall understanding of RV function, which may allow improvements in recognition of dysfunction and assessment of treatment effects in the future.
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Affiliation(s)
- Christopher Valle
- Department of Cardiology, Boston Children’s Hospital, Boston, MA, United States
- Department of Pediatrics, Harvard Medical School, Boston, MA, United States
| | - Adrienn Ujvari
- Heart and Vascular Center, Semmelweis University, Budapest, Hungary
| | - Eleni Elia
- Department of Cardiology, Boston Children’s Hospital, Boston, MA, United States
- Department of Pediatrics, Harvard Medical School, Boston, MA, United States
- School of Engineering, Computing and Mathematics, Oxford Brookes University, Oxford, United Kingdom
| | - Minmin Lu
- Department of Cardiology, Boston Children’s Hospital, Boston, MA, United States
- Department of Pediatrics, Harvard Medical School, Boston, MA, United States
| | - Naomi Gauthier
- Department of Cardiology, Boston Children’s Hospital, Boston, MA, United States
- Department of Pediatrics, Harvard Medical School, Boston, MA, United States
| | - David Hoganson
- Department of Cardiac Surgery, Boston Children’s Hospital, Boston, MA, United States
| | - Gerald Marx
- Department of Cardiology, Boston Children’s Hospital, Boston, MA, United States
- Department of Pediatrics, Harvard Medical School, Boston, MA, United States
| | - Andrew J. Powell
- Department of Cardiology, Boston Children’s Hospital, Boston, MA, United States
- Department of Pediatrics, Harvard Medical School, Boston, MA, United States
| | - Alessandra Ferraro
- Department of Cardiology, Boston Children’s Hospital, Boston, MA, United States
- Department of Pediatrics, Harvard Medical School, Boston, MA, United States
| | - Bálint Lakatos
- Heart and Vascular Center, Semmelweis University, Budapest, Hungary
| | - Zoltán Tősér
- Argus Cognitive, Inc., Lebanon, NH, United States
| | - Béla Merkely
- Heart and Vascular Center, Semmelweis University, Budapest, Hungary
| | - Attila Kovacs
- Heart and Vascular Center, Semmelweis University, Budapest, Hungary
- Argus Cognitive, Inc., Lebanon, NH, United States
| | - David M. Harrild
- Department of Cardiology, Boston Children’s Hospital, Boston, MA, United States
- Department of Pediatrics, Harvard Medical School, Boston, MA, United States
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Tous C, Jodoin A, Grabs D, Van Houten E, Bureau NJ. Intersession Repeatability of
Diffusion‐Tensor
Imaging in the Supraspinatus and the Infraspinatus Muscles of Volunteers. J Magn Reson Imaging 2022; 57:1414-1422. [PMID: 36305562 DOI: 10.1002/jmri.28424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 08/19/2022] [Accepted: 08/22/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Quantifying the rotator cuff (RC) muscles' viscoelasticity could provide outcome relevant information in patients with RC tears. MR-elastography requires robust diffusion-tensor imaging (DTI) to account for tissue anisotropy in muscles stiffness computation. PURPOSE To assess the repeatability of DTI parameters in the supraspinatus and infraspinatus muscles and to explore DTI tractography conformity with the muscles' anatomy. STUDY TYPE Prospective. SUBJECTS Six healthy volunteers underwent three consecutive shoulder MRI sessions about 10 minutes apart. FIELD STRENGTH/SEQUENCE 3T/T1-vibe Dixon and Spin echo EPI DTI (12 gradient encoding directions, b-values 500 and 800 sec/mm2 ). ASSESSMENT Supraspinatus and infraspinatus muscles were segmented on the T1-vibe Dixon sequence. DTI image quality was assessed using a quantitative threshold based on the signal-to-noise ratio (SNR). The eigenvalues ( λ 1 , λ 2 , λ 3 ), fractional anisotropy (FA) and mean diffusivity were calculated. DTI tractography was visually assessed. STATISTICAL TESTS DTI parameters within-subject intersession repeatability was assessed with Bland-Altman analysis and the coefficient of variation (CV). Repeatability was considered good for CV < 10%. RESULTS The SNR between diffusion-weighted and non-diffusion-weighted images was greater than 3, which aligns with standards for estimating DTI parameters. The FA showed the lowest mean bias (-0.007; 95% confidence interval [CI] -0.031 to 0.018) whereas the λ1 had the highest mean bias (0.146 × 10-3 mm2 /sec; CI -0.034 to 0.326 × 10-3 mm2 /sec). CVs of the DTI parameters varied between 3.5% (FA) and 8.4% (λ3 ) for the supraspinatus and between 3.2% (λ1 ) and 6.8% (λ3 ) for the infraspinatus. Tractography provided muscle fiber representations in three-dimensional space concordant with RC anatomy. DATA CONCLUSION DTI of the supraspinatus and infraspinatus muscles achieved an adequate SNR, allowing the measurement of the DTI metrics with good repeatability, and thus can be used for optimizing stiffness estimation in these anisotropic tissues. EVIDENCE LEVEL 2 TECHNICAL EFFICACY: Stage 2.
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Affiliation(s)
- Cyril Tous
- Research Center, Centre hospitalier de l'Université de Montréal (CRCHUM) Montreal Quebec Canada
| | - Alexandre Jodoin
- Department of Radiology Centre hospitalier de l'Université de Montréal (CHUM) Montreal Quebec Canada
| | - Detlev Grabs
- Department of Anatomy Université du Québec à Trois‐Rivières Trois‐Rivières Quebec Canada
| | - Elijah Van Houten
- Department of Mechanical Engineering Université de Sherbrooke Sherbrooke Quebec Canada
| | - Nathalie J. Bureau
- Research Center, Centre hospitalier de l'Université de Montréal (CRCHUM) Montreal Quebec Canada
- Department of Radiology Centre hospitalier de l'Université de Montréal (CHUM) Montreal Quebec Canada
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Aimo A, Huang L, Tyler A, Barison A, Martini N, Saccaro LF, Roujol S, Masci PG. Quantitative susceptibility mapping (QSM) of the cardiovascular system: challenges and perspectives. J Cardiovasc Magn Reson 2022; 24:48. [PMID: 35978351 PMCID: PMC9387036 DOI: 10.1186/s12968-022-00883-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 08/05/2022] [Indexed: 11/10/2022] Open
Abstract
Quantitative susceptibility mapping (QSM) is a powerful, non-invasive, magnetic resonance imaging (MRI) technique that relies on measurement of magnetic susceptibility. So far, QSM has been employed mostly to study neurological disorders characterized by iron accumulation, such as Parkinson's and Alzheimer's diseases. Nonetheless, QSM allows mapping key indicators of cardiac disease such as blood oxygenation and myocardial iron content. For this reason, the application of QSM offers an unprecedented opportunity to gain a better understanding of the pathophysiological changes associated with cardiovascular disease and to monitor their evolution and response to treatment. Recent studies on cardiovascular QSM have shown the feasibility of a non-invasive assessment of blood oxygenation, myocardial iron content and myocardial fibre orientation, as well as carotid plaque composition. Significant technical challenges remain, the most evident of which are related to cardiac and respiratory motion, blood flow, chemical shift effects and susceptibility artefacts. Significant work is ongoing to overcome these challenges and integrate the QSM technique into clinical practice in the cardiovascular field.
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Affiliation(s)
- Alberto Aimo
- Scuola Superiore Sant'Anna, Pisa, Italy
- Fondazione Toscana Gabriele Monasterio, Pisa, Italy
| | - Li Huang
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, UK
| | - Andrew Tyler
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, UK
| | - Andrea Barison
- Scuola Superiore Sant'Anna, Pisa, Italy
- Fondazione Toscana Gabriele Monasterio, Pisa, Italy
| | | | | | - Sébastien Roujol
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, UK.
- Department of Biomedical Engineering, School of Imaging Sciences & Biomedical Engineering, King's College London, St Thomas' Hospital, 4th Floor Lambeth Wing, London, SE1 7EH, UK.
| | - Pier-Giorgio Masci
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, UK
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Wilson AJ, Sands GB, LeGrice IJ, Young AA, Ennis DB. Myocardial mesostructure and mesofunction. Am J Physiol Heart Circ Physiol 2022; 323:H257-H275. [PMID: 35657613 PMCID: PMC9273275 DOI: 10.1152/ajpheart.00059.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 05/23/2022] [Accepted: 05/23/2022] [Indexed: 11/22/2022]
Abstract
The complex and highly organized structural arrangement of some five billion cardiomyocytes directs the coordinated electrical activity and mechanical contraction of the human heart. The characteristic transmural change in cardiomyocyte orientation underlies base-to-apex shortening, circumferential shortening, and left ventricular torsion during contraction. Individual cardiomyocytes shorten ∼15% and increase in diameter ∼8%. Remarkably, however, the left ventricular wall thickens by up to 30-40%. To accommodate this, the myocardium must undergo significant structural rearrangement during contraction. At the mesoscale, collections of cardiomyocytes are organized into sheetlets, and sheetlet shear is the fundamental mechanism of rearrangement that produces wall thickening. Herein, we review the histological and physiological studies of myocardial mesostructure that have established the sheetlet shear model of wall thickening. Recent developments in tissue clearing techniques allow for imaging of whole hearts at the cellular scale, whereas magnetic resonance imaging (MRI) and computed tomography (CT) can image the myocardium at the mesoscale (100 µm to 1 mm) to resolve cardiomyocyte orientation and organization. Through histology, cardiac diffusion tensor imaging (DTI), and other modalities, mesostructural sheetlets have been confirmed in both animal and human hearts. Recent in vivo cardiac DTI methods have measured reorientation of sheetlets during the cardiac cycle. We also examine the role of pathological cardiac remodeling on sheetlet organization and reorientation, and the impact this has on ventricular function and dysfunction. We also review the unresolved mesostructural questions and challenges that may direct future work in the field.
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Affiliation(s)
- Alexander J Wilson
- Department of Radiology, Stanford University, Stanford, California
- Stanford Cardiovascular Institute, Stanford University, Stanford, California
| | - Gregory B Sands
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Ian J LeGrice
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
- Department of Physiology, University of Auckland, Auckland, New Zealand
| | - Alistair A Young
- Department of Anatomy and Medical Imaging, University of Auckland, Auckland, New Zealand
- Department of Biomedical Engineering, King's College London, London, United Kingdom
| | - Daniel B Ennis
- Department of Radiology, Stanford University, Stanford, California
- Veterans Administration Palo Alto Health Care System, Palo Alto, California
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7
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The Dynamic Characteristics of Myocardial Contractility and Extracellular Volume in Type 2 Diabetes Mellitus Mice Investigated by 7.0T Cardiac Magnetic Resonance. J Clin Med 2022; 11:jcm11154262. [PMID: 35893355 PMCID: PMC9332454 DOI: 10.3390/jcm11154262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 07/15/2022] [Accepted: 07/19/2022] [Indexed: 01/27/2023] Open
Abstract
Type 2 diabetes mellitus (T2DM) is associated with a high prevalence of diastolic dysfunction and congestive heart failure. A potential contributing factor is the accelerated accumulation of diffuse myocardial fibrosis and stiffness. Novel cardiac magnetic resonance (CMR) imaging techniques can identify both myocardial fibrosis and contractility quantitatively. This study aimed to investigate the dynamic characteristics of the myocardial strain and altered extracellular volume (ECV) fraction as determined by 7.0 T CMR in T2DM mice. C57Bl/6J mice were randomly divided into T2DM (fed a high-fat diet) and control (fed a normal diet) groups. They were scanned on 7.0 T MRI every 4 weeks until the end of week 24. The CMR protocol included multi-slice cine imaging to assess left ventricle strain and strain rate, and pre- and post-contrast T1 mapping images to quantify ECV. The ECV in the T2DM mice was significantly higher (p < 0.05) than that in the control group since week 12 with significantly impaired myocardial strain (p < 0.05). A significant linear correlation was established between myocardial strain and ECV (p < 0.001) and left ventricular-ejection fraction and ECV (p = 0.003). The results suggested that CMR feature tracking-derived myocardial strain analysis can assess functional abnormalities that may be associated with ECM alterations in diabetic cardiomyopathy, contributing to the study of diabetic therapy effects.
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Pérez JJ, Berjano E, González-Suárez A. In-Silico Modeling to Compare Radiofrequency-Induced Thermal Lesions Created on Myocardium and Thigh Muscle. Bioengineering (Basel) 2022; 9:bioengineering9070329. [PMID: 35877380 PMCID: PMC9312255 DOI: 10.3390/bioengineering9070329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Revised: 07/11/2022] [Accepted: 07/18/2022] [Indexed: 11/16/2022] Open
Abstract
Beating heart (BH) and thigh muscle (TM) are two pre-clinical models aimed at studying the lesion sizes created by radiofrequency (RF) catheters in cardiac ablation. Previous experimental results have shown that thermal lesions created in the TM are slightly bigger than in the BH. Our objective was to use in-silico modeling to elucidate some of the causes of this difference. In-silico RF ablation models were created using the Arrhenius function to estimate lesion size under different energy settings (25 W/20 s, 50 W/6 s and 90 W/4 s) and parallel, 45° and perpendicular catheter positions. The models consisted of homogeneous tissue: myocardium in the BH model and striated muscle in the TM model. The computer results showed that the lesion sizes were generally bigger in the TM model and the differences depended on the energy setting, with hardly any differences at 90 W/4 s but with differences of 1 mm in depth and 1.5 m in width at 25 W/20 s. The higher electrical conductivity of striated muscle (0.446 S/m) than that of the myocardium (0.281 S/m) is possibly one of the causes of the higher percentage of RF energy delivered to the tissue in the TM model, with differences between models of 2–5% at 90 W/4 s, ~9% at 50 W/6 s and ~10% at 25 W/20 s. Proximity to the air–blood interface (just 2 cm from the tissue surface) artificially created in the TM model to emulate the cardiac cavity had little effect on lesion size. In conclusion, the TM-based experimental model creates fairly similar-sized lesions to the BH model, especially in high-power short-duration ablations (50 W/6 s and 90 W/4 s). Our computer results suggest that the higher electrical conductivity of striated muscle could be one of the causes of the slightly larger lesions in the TM model.
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Affiliation(s)
- Juan J. Pérez
- BioMIT, Department of Electronic Engineering, Universitat Politècnica de València, 46022 Valencia, Spain; (J.J.P.); (E.B.)
| | - Enrique Berjano
- BioMIT, Department of Electronic Engineering, Universitat Politècnica de València, 46022 Valencia, Spain; (J.J.P.); (E.B.)
| | - Ana González-Suárez
- Electrical and Electronic Engineering, Translational Medical Device Lab, National University of Ireland Galway, H91 TK33 Galway, Ireland
- Correspondence:
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Dou W, Malhi M, Zhao Q, Wang L, Huang Z, Law J, Liu N, Simmons CA, Maynes JT, Sun Y. Microengineered platforms for characterizing the contractile function of in vitro cardiac models. MICROSYSTEMS & NANOENGINEERING 2022; 8:26. [PMID: 35299653 PMCID: PMC8882466 DOI: 10.1038/s41378-021-00344-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 11/12/2021] [Accepted: 12/03/2021] [Indexed: 05/08/2023]
Abstract
Emerging heart-on-a-chip platforms are promising approaches to establish cardiac cell/tissue models in vitro for research on cardiac physiology, disease modeling and drug cardiotoxicity as well as for therapeutic discovery. Challenges still exist in obtaining the complete capability of in situ sensing to fully evaluate the complex functional properties of cardiac cell/tissue models. Changes to contractile strength (contractility) and beating regularity (rhythm) are particularly important to generate accurate, predictive models. Developing new platforms and technologies to assess the contractile functions of in vitro cardiac models is essential to provide information on cell/tissue physiologies, drug-induced inotropic responses, and the mechanisms of cardiac diseases. In this review, we discuss recent advances in biosensing platforms for the measurement of contractile functions of in vitro cardiac models, including single cardiomyocytes, 2D monolayers of cardiomyocytes, and 3D cardiac tissues. The characteristics and performance of current platforms are reviewed in terms of sensing principles, measured parameters, performance, cell sources, cell/tissue model configurations, advantages, and limitations. In addition, we highlight applications of these platforms and relevant discoveries in fundamental investigations, drug testing, and disease modeling. Furthermore, challenges and future outlooks of heart-on-a-chip platforms for in vitro measurement of cardiac functional properties are discussed.
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Affiliation(s)
- Wenkun Dou
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, ON M5S 3G8 Canada
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, ON M5G 1X8 Canada
| | - Manpreet Malhi
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, ON M5G 1X8 Canada
- Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8 Canada
| | - Qili Zhao
- Institute of Robotics and Automatic Information System and the Tianjin Key Laboratory of Intelligent Robotics, Nankai University, Tianjin, 300350 China
| | - Li Wang
- School of Mechanical & Automotive Engineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan, 250353 China
| | - Zongjie Huang
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, ON M5S 3G8 Canada
| | - Junhui Law
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, ON M5S 3G8 Canada
| | - Na Liu
- School of Mechatronics Engineering and Automation, Shanghai University, Shanghai, 200444 China
| | - Craig A. Simmons
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, ON M5S 3G8 Canada
- Institute of Biomedical Engineering, University of Toronto, Toronto, ON M5S 3G9 Canada
- Translational Biology & Engineering Program, Ted Rogers Centre for Heart Research, Toronto, ON M5G 1M1 Canada
| | - Jason T. Maynes
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, ON M5G 1X8 Canada
- Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8 Canada
- Department of Anesthesiology and Pain Medicine, University of Toronto, Toronto, ON M5S 1A8 Canada
- Department of Anesthesia and Pain Medicine, The Hospital for Sick Children, Toronto, ON M5G 1X8 Canada
| | - Yu Sun
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, ON M5S 3G8 Canada
- Institute of Biomedical Engineering, University of Toronto, Toronto, ON M5S 3G9 Canada
- Department of Electrical and Computer Engineering, University of Toronto, Toronto, ON M5S 3G4 Canada
- Department of Computer Science, University of Toronto, Toronto, ON M5T 3A1 Canada
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10
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Ex Vivo Evaluation of Mechanical Anisotropic Tissues with High-Frequency Ultrasound Shear Wave Elastography. SENSORS 2022; 22:s22030978. [PMID: 35161728 PMCID: PMC8838528 DOI: 10.3390/s22030978] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/11/2021] [Revised: 01/21/2022] [Accepted: 01/23/2022] [Indexed: 01/01/2023]
Abstract
The use of imaging devices to assess directional mechanics of tissues is highly desirable. This is because the directional mechanics depend on fiber orientation, and altered directional mechanics are closely related to the pathological status of tissues. However, measuring directional mechanics in tissues with high-stiffness is challenging due to the difficulty of generating localized displacement in these tissues using acoustic radiation force, a general method for generating displacement in ultrasound-based elastography. In addition, common ultrasound probes do not provide rotational function, which makes the measurement of directional mechanics inaccurate and unreliable. Therefore, we developed a high-frequency ultrasound mechanical wave elastography system that can accommodate a wide range of tissue stiffness and is also equipped with a motorized rotation stage for precise imaging of directional mechanics. A mechanical shaker was applied to the elastography system to measure tissues with high-stiffness. Phantom and ex vivo experiments were performed. In the phantom experiments, the lateral and axial resolution of the system were determined to be 144 μm and 168 μm, respectively. In the ex vivo experiments, we used swine heart and cartilage, both of which are considered stiff. The elastography system allows us to acquire the directional mechanics with high angular resolution in the heart and cartilage. The results demonstrate that the developed elastography system is capable of imaging a wide range of tissues and has high angular resolution. Therefore, this system might be useful for the diagnostics of mechanically anisotropic tissues via ex vivo tests.
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11
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Hayashi H, Oda S, Kidoh M, Nakaura T, Morita K, Nagayama Y, Yoneda T, Takashio S, Misumi Y, Ueda M, Tsujita K, Hirai T. Can myocardial susceptibility quantification be an imaging biomarker for cardiac amyloidosis? Jpn J Radiol 2021; 40:500-507. [PMID: 34841460 PMCID: PMC9068634 DOI: 10.1007/s11604-021-01228-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Accepted: 11/22/2021] [Indexed: 11/17/2022]
Abstract
Purpose This study aimed to evaluate whether quantification of myocardial susceptibility by cardiac magnetic resonance imaging (CMR) can be an imaging biomarker for cardiac amyloidosis (CA). Materials and methods Twenty-six patients with CA underwent CMR, including magnetic phase imaging with a 3.0-T magnetic resonance imaging scanner. Myocardial susceptibility was quantified as a phase shift slope value by magnetic phase analysis. Those values from patients with CA were compared with corresponding values from 18 controls and 15 healthy volunteers. A univariate logistic regression analysis was conducted to identify significant parameters related to CA. Results The phase shift slope, a quantitative parameter of myocardial susceptibility, was significantly lower in the CA group compared with the control group and compared with healthy volunteers (p < 0.01). From a total of 17 tested variables, 6 were considered to be significant predictors of CA (p ≤ 0.05) during the univariate analysis. The phase shift slope yielded the best AUC of 0.89 (95% CI = 0.79–0.98) for the prediction of CA (p < 0.01). The phase shift slope was significantly correlated with the end-diastolic thickness of the interventricular septum (r = − 0.39, p < 0.01) and posterior wall of the left ventricle (r = − 0.35, p = 0.02). Conclusion Myocardial susceptibility analysis by CMR helps in the diagnosis of patients with CA and can be a new quantitative imaging biomarker for CA.
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Affiliation(s)
- Hidetaka Hayashi
- Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, 1-1-1 Honjyo, Chuo-ku, Kumamoto, 860-8556, Japan
| | - Seitaro Oda
- Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, 1-1-1 Honjyo, Chuo-ku, Kumamoto, 860-8556, Japan.
| | - Masafumi Kidoh
- Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, 1-1-1 Honjyo, Chuo-ku, Kumamoto, 860-8556, Japan
| | - Takeshi Nakaura
- Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, 1-1-1 Honjyo, Chuo-ku, Kumamoto, 860-8556, Japan
| | - Kosuke Morita
- Department of Central Radiology, Kumamoto University Hospital, Kumamoto, Japan
| | - Yasunori Nagayama
- Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, 1-1-1 Honjyo, Chuo-ku, Kumamoto, 860-8556, Japan
| | - Tetsuya Yoneda
- Department of Medical Physics in Advanced Biomedical Sciences, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Seiji Takashio
- Department of Cardiovascular Medicine, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Yohei Misumi
- Department of Neurology, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Mitsuharu Ueda
- Department of Neurology, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Kenichi Tsujita
- Department of Cardiovascular Medicine, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Toshinori Hirai
- Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, 1-1-1 Honjyo, Chuo-ku, Kumamoto, 860-8556, Japan
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12
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Finocchiaro G, Sheikh N, Leone O, Westaby J, Mazzarotto F, Pantazis A, Ferrantini C, Sacconi L, Papadakis M, Sharma S, Sheppard MN, Olivotto I. Arrhythmogenic potential of myocardial disarray in hypertrophic cardiomyopathy: genetic basis, functional consequences and relation to sudden cardiac death. Europace 2021; 23:985-995. [PMID: 33447843 DOI: 10.1093/europace/euaa348] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2020] [Accepted: 10/28/2020] [Indexed: 12/19/2022] Open
Abstract
Myocardial disarray is defined as disorganized cardiomyocyte spatial distribution, with loss of physiological fibre alignment and orientation. Since the first pathological descriptions of hypertrophic cardiomyopathy (HCM), disarray appeared as a typical feature of this condition and sparked vivid debate regarding its specificity to the disease and clinical significance as a diagnostic marker and a risk factor for sudden death. Although much of the controversy surrounding its diagnostic value in HCM persists, it is increasingly recognized that myocardial disarray may be found in physiological contexts and in cardiac conditions different from HCM, raising the possibility that central focus should be placed on its quantity and distribution, rather than a mere presence. While further studies are needed to establish what amount of disarray should be considered as a hallmark of the disease, novel experimental approaches and emerging imaging techniques for the first time allow ex vivo and in vivo characterization of the myocardium to a molecular level. Such advances hold the promise of filling major gaps in our understanding of the functional consequences of myocardial disarray in HCM and specifically on arrhythmogenic propensity and as a risk factor for sudden death. Ultimately, these studies will clarify whether disarray represents a major determinant of the HCM clinical profile, and a potential therapeutic target, as opposed to an intriguing but largely innocent bystander.
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Affiliation(s)
- Gherardo Finocchiaro
- Cardiothoracic Centre, Guy's and St Thomas' Hospital, London, UK.,King's College London
| | - Nabeel Sheikh
- Cardiothoracic Centre, Guy's and St Thomas' Hospital, London, UK.,King's College London
| | - Ornella Leone
- Cardiovascular and Cardiac Transplant Pathology Unit, Department of Pathology, Sant'Orsola-Malpighi University Hospital, Bologna, Italy
| | - Joe Westaby
- Cardiovascular Pathology Unit and Cardiology Clinical and Academic Group. St George's, University of London, London and St George's University Hospital NHS Foundation Trust, UK
| | - Francesco Mazzarotto
- Cardiomyopathy Unit, Careggi University Hospital, Florence, Italy.,Department of Experimental and Clinical Medicine, University of Florence, Italy.,National Heart and Lung Institute, Imperial College London, UK.,Cardiovascular Research Centre, Royal Brompton and Harefield National Health Service Foundation Trust, London, UK
| | - Antonis Pantazis
- Cardiovascular Research Centre, Royal Brompton and Harefield National Health Service Foundation Trust, London, UK
| | - Cecilia Ferrantini
- University of Florence, Florence, Italy.,European Laboratory for Non-Linear Spectroscopy, Florence, Italy
| | - Leonardo Sacconi
- European Laboratory for Non-Linear Spectroscopy, Florence, Italy.,Institute for Experimental Cardiovascular Medicine, University of Freiburg, Freiburg, Germany
| | - Michael Papadakis
- Cardiovascular Pathology Unit and Cardiology Clinical and Academic Group. St George's, University of London, London and St George's University Hospital NHS Foundation Trust, UK
| | - Sanjay Sharma
- Cardiovascular Pathology Unit and Cardiology Clinical and Academic Group. St George's, University of London, London and St George's University Hospital NHS Foundation Trust, UK
| | - Mary N Sheppard
- Cardiovascular Pathology Unit and Cardiology Clinical and Academic Group. St George's, University of London, London and St George's University Hospital NHS Foundation Trust, UK
| | - Iacopo Olivotto
- Cardiomyopathy Unit, Careggi University Hospital, Florence, Italy
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13
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Paddock S, Tsampasian V, Assadi H, Mota BC, Swift AJ, Chowdhary A, Swoboda P, Levelt E, Sammut E, Dastidar A, Broncano Cabrero J, Del Val JR, Malcolm P, Sun J, Ryding A, Sawh C, Greenwood R, Hewson D, Vassiliou V, Garg P. Clinical Translation of Three-Dimensional Scar, Diffusion Tensor Imaging, Four-Dimensional Flow, and Quantitative Perfusion in Cardiac MRI: A Comprehensive Review. Front Cardiovasc Med 2021; 8:682027. [PMID: 34307496 PMCID: PMC8292630 DOI: 10.3389/fcvm.2021.682027] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 06/04/2021] [Indexed: 01/05/2023] Open
Abstract
Cardiovascular magnetic resonance (CMR) imaging is a versatile tool that has established itself as the reference method for functional assessment and tissue characterisation. CMR helps to diagnose, monitor disease course and sub-phenotype disease states. Several emerging CMR methods have the potential to offer a personalised medicine approach to treatment. CMR tissue characterisation is used to assess myocardial oedema, inflammation or thrombus in various disease conditions. CMR derived scar maps have the potential to inform ablation therapy—both in atrial and ventricular arrhythmias. Quantitative CMR is pushing boundaries with motion corrections in tissue characterisation and first-pass perfusion. Advanced tissue characterisation by imaging the myocardial fibre orientation using diffusion tensor imaging (DTI), has also demonstrated novel insights in patients with cardiomyopathies. Enhanced flow assessment using four-dimensional flow (4D flow) CMR, where time is the fourth dimension, allows quantification of transvalvular flow to a high degree of accuracy for all four-valves within the same cardiac cycle. This review discusses these emerging methods and others in detail and gives the reader a foresight of how CMR will evolve into a powerful clinical tool in offering a precision medicine approach to treatment, diagnosis, and detection of disease.
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Affiliation(s)
- Sophie Paddock
- Department of Cardiovascular and Metabolic Health, Norwich Medical School, University of East Anglia, Norwich, United Kingdom.,Department of Cardiology, Norfolk and Norwich University Hospital, Norwich, United Kingdom
| | - Vasiliki Tsampasian
- Department of Cardiovascular and Metabolic Health, Norwich Medical School, University of East Anglia, Norwich, United Kingdom
| | - Hosamadin Assadi
- Department of Infection, Immunity and Cardiovascular Disease, University of Sheffield, Sheffield, United Kingdom
| | - Bruno Calife Mota
- Department of Cardiology, Norfolk and Norwich University Hospital, Norwich, United Kingdom
| | - Andrew J Swift
- Department of Infection, Immunity and Cardiovascular Disease, University of Sheffield, Sheffield, United Kingdom
| | - Amrit Chowdhary
- Multidisciplinary Cardiovascular Research Centre & Division of Biomedical Imaging, Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, United Kingdom
| | - Peter Swoboda
- Multidisciplinary Cardiovascular Research Centre & Division of Biomedical Imaging, Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, United Kingdom
| | - Eylem Levelt
- Multidisciplinary Cardiovascular Research Centre & Division of Biomedical Imaging, Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, United Kingdom
| | - Eva Sammut
- Bristol Heart Institute and Translational Biomedical Research Centre, Faculty of Health Science, University of Bristol, Bristol, United Kingdom
| | - Amardeep Dastidar
- Bristol Heart Institute and Translational Biomedical Research Centre, Faculty of Health Science, University of Bristol, Bristol, United Kingdom
| | - Jordi Broncano Cabrero
- Cardiothoracic Imaging Unit, Hospital San Juan De Dios, Ressalta, HT Medica, Córdoba, Spain
| | - Javier Royuela Del Val
- Cardiothoracic Imaging Unit, Hospital San Juan De Dios, Ressalta, HT Medica, Córdoba, Spain
| | - Paul Malcolm
- Department of Cardiovascular and Metabolic Health, Norwich Medical School, University of East Anglia, Norwich, United Kingdom
| | - Julia Sun
- Department of Cardiology, Norfolk and Norwich University Hospital, Norwich, United Kingdom
| | - Alisdair Ryding
- Department of Cardiology, Norfolk and Norwich University Hospital, Norwich, United Kingdom
| | - Chris Sawh
- Department of Cardiology, Norfolk and Norwich University Hospital, Norwich, United Kingdom
| | - Richard Greenwood
- Department of Cardiology, Norfolk and Norwich University Hospital, Norwich, United Kingdom
| | - David Hewson
- Department of Cardiology, Norfolk and Norwich University Hospital, Norwich, United Kingdom
| | - Vassilios Vassiliou
- Department of Cardiovascular and Metabolic Health, Norwich Medical School, University of East Anglia, Norwich, United Kingdom
| | - Pankaj Garg
- Department of Cardiovascular and Metabolic Health, Norwich Medical School, University of East Anglia, Norwich, United Kingdom.,Department of Infection, Immunity and Cardiovascular Disease, University of Sheffield, Sheffield, United Kingdom
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14
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Evaluation of isolated left ventricular noncompaction using cardiac magnetic resonance tissue tracking in global, regional and layer-specific strains. Sci Rep 2021; 11:7183. [PMID: 33785853 PMCID: PMC8010120 DOI: 10.1038/s41598-021-86695-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2019] [Accepted: 03/17/2021] [Indexed: 11/25/2022] Open
Abstract
We used cardiac magnetic resonance tissue tracking (CMR-TT) to quantitatively analyze the global, regional and layer-specific strain of isolated left ventricular noncompaction (ILVNC). Combined with late gadolinium enhancement (LGE), we initially explored the effect of focal myocardial fibrosis on myocardial strain. CMR was performed in 63 patients with ILVNC and 52 patients without ILVNC (i.e., the control group). The ILVNC group was divided into an LGE(+) group (29 patients) and an LGE(−) group (34 patients) according to the presence or absence of late gadalinum enhancement (LGE). CVI42 software was used to measure global and regional (basal, middle, apical) radial strain (RS), circumferential strain (CS), longitudinal strain (LS), subendocardial LS and subepicardial LS. The basal–apical strain gradient was defined as the apical mean strain minus the basal mean strain. We then compared differences between these strain parameters. The subendocardial-subepicardial LS gradient was defined as the maximum subendocardial LS minus the subepicardial LS. Compared with the control group, the global and regional RS, CS, LS and the subendocardial, subepicardial LS of the ILVNC group were significantly diminished (P < 0.01). Compared with the LGE(−) group, the global and regional RS, CS, LS and the subendocardial, subepicardial LS of the LGE(+) group were significantly diminished (P < 0.05). In the ILVNC group, the basal–apical CS and LS gradient, and the subendocardial-subepicardial LS gradient were significantly lower than those in the control group (P < 0.01). There were significant differences in myocardial strain between patients with and without ILVNC. ILVNC revealed a specific pattern in terms of strain change. The myocardial strain of the cardiac apex and endocardium was significantly lower than that of the cardiac base and epicardium, respectively. Myocardial strain reduction was more significant in ILVNC patients with focal myocardial fibrosis.
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15
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Stein D, Assaf Y, Dar G, Cohen H, Slon V, Kedar E, Medlej B, Abbas J, Hay O, Barazany D, Hershkovitz I. 3D virtual reconstruction and quantitative assessment of the human intervertebral disc's annulus fibrosus: a DTI tractography study. Sci Rep 2021; 11:6815. [PMID: 33767347 PMCID: PMC7994907 DOI: 10.1038/s41598-021-86334-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Accepted: 03/05/2021] [Indexed: 01/04/2023] Open
Abstract
The intervertebral disc’s (IVD) annulus fibrosus (AF) retains the hydrostatic pressure of the nucleus pulposus (NP), controls the range of motion, and maintains the integrity of the motion segment. The microstructure of the AF is not yet fully understood and quantitative characterization is lacking, leaving a caveat in modern medicine’s ability to prevent and treat disc failure (e.g., disc herniation). In this study, we show a reconstruction of the 3D microstructure of the fibers that constitute the AF via MRI diffusion tensor imaging (DTI) followed by fiber tracking. A quantitative analysis presents an anisotropic structure with significant architectural differences among the annuli along the width of the fibrous belt. These findings indicate that the outer annuli's construction reinforces the IVD while providing a sufficient degree of motion. Our findings also suggest an increased role of the outer annuli in IVD nourishment.
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Affiliation(s)
- Dan Stein
- Department of Anatomy and Anthropology, Sackler Faculty of Medicine, Tel Aviv University, 69978, Tel Aviv, Israel.,The Shmunis Family Anthropology Institute, Dan David Center for Human Evolution and Biohistory Research, Tel Aviv University, 69978, Tel Aviv, Israel
| | - Yaniv Assaf
- Department of Neurobiochemistry, Faculty of Life Sciences, Tel Aviv University, 69978, Tel Aviv, Israel
| | - Gali Dar
- Department of Physical Therapy, Faculty of Social Welfare and Health Studies, Haifa University, Mount Carmel, 31905, Haifa, Israel
| | - Haim Cohen
- Adelson School of Medicine, Ariel University, Kiryat Hamada 3, 40700, Ariel, Israel
| | - Viviane Slon
- Department of Anatomy and Anthropology, Sackler Faculty of Medicine, Tel Aviv University, 69978, Tel Aviv, Israel.,The Shmunis Family Anthropology Institute, Dan David Center for Human Evolution and Biohistory Research, Tel Aviv University, 69978, Tel Aviv, Israel
| | - Einat Kedar
- Department of Anatomy and Anthropology, Sackler Faculty of Medicine, Tel Aviv University, 69978, Tel Aviv, Israel.,The Shmunis Family Anthropology Institute, Dan David Center for Human Evolution and Biohistory Research, Tel Aviv University, 69978, Tel Aviv, Israel
| | - Bahaa Medlej
- Department of Anatomy and Anthropology, Sackler Faculty of Medicine, Tel Aviv University, 69978, Tel Aviv, Israel.,The Shmunis Family Anthropology Institute, Dan David Center for Human Evolution and Biohistory Research, Tel Aviv University, 69978, Tel Aviv, Israel
| | - Janan Abbas
- Department of Anatomy and Anthropology, Sackler Faculty of Medicine, Tel Aviv University, 69978, Tel Aviv, Israel
| | - Ori Hay
- Department of Anatomy and Anthropology, Sackler Faculty of Medicine, Tel Aviv University, 69978, Tel Aviv, Israel
| | - Daniel Barazany
- Department of Neurobiochemistry, Faculty of Life Sciences, Tel Aviv University, 69978, Tel Aviv, Israel
| | - Israel Hershkovitz
- Department of Anatomy and Anthropology, Sackler Faculty of Medicine, Tel Aviv University, 69978, Tel Aviv, Israel. .,The Shmunis Family Anthropology Institute, Dan David Center for Human Evolution and Biohistory Research, Tel Aviv University, 69978, Tel Aviv, Israel.
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16
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3D MRI of explanted sheep hearts with submillimeter isotropic spatial resolution: comparison between diffusion tensor and structure tensor imaging. MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2021; 34:741-755. [PMID: 33638739 PMCID: PMC8421292 DOI: 10.1007/s10334-021-00913-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Revised: 01/29/2021] [Accepted: 02/02/2021] [Indexed: 11/04/2022]
Abstract
Objective The aim of the study is to compare structure tensor imaging (STI) with diffusion tensor imaging (DTI) of the sheep heart (approximately the same size as the human heart). Materials and methods MRI acquisition on three sheep ex vivo hearts was performed at 9.4 T/30 cm with a seven-element RF coil. 3D FLASH with an isotropic resolution of 150 µm and 3D spin-echo DTI at 600 µm were performed. Tensor analysis, angles extraction and segments divisions were performed on both volumes. Results A 3D FLASH allows for visualization of the detailed structure of the left and right ventricles. The helix angle determined using DTI and STI exhibited a smooth transmural change from the endocardium to the epicardium. Both the helix and transverse angles were similar between techniques. Sheetlet organization exhibited the same pattern in both acquisitions, but local angle differences were seen and identified in 17 segments representation. Discussion This study demonstrated the feasibility of high-resolution MRI for studying the myocyte and myolaminar architecture of sheep hearts. We presented the results of STI on three whole sheep ex vivo hearts and demonstrated a good correspondence between DTI and STI. Supplementary Information The online version contains supplementary material available at 10.1007/s10334-021-00913-4.
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17
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Agger P, Stephenson RS. Assessing Myocardial Architecture: The Challenges and Controversies. J Cardiovasc Dev Dis 2020; 7:jcdd7040047. [PMID: 33137874 PMCID: PMC7711767 DOI: 10.3390/jcdd7040047] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 10/04/2020] [Accepted: 10/08/2020] [Indexed: 12/16/2022] Open
Abstract
In recent decades, investigators have strived to describe and quantify the orientation of the cardiac myocytes in an attempt to classify their arrangement in healthy and diseased hearts. There are, however, striking differences between the investigations from both a technical and methodological standpoint, thus limiting their comparability and impeding the drawing of appropriate physiological conclusions from the structural assessments. This review aims to elucidate these differences, and to propose guidance to establish methodological consensus in the field. The review outlines the theory behind myocyte orientation analysis, and importantly has identified pronounced differences in the definitions of otherwise widely accepted concepts of myocytic orientation. Based on the findings, recommendations are made for the future design of studies in the field of myocardial morphology. It is emphasised that projection of myocyte orientations, before quantification of their angulation, introduces considerable bias, and that angles should be assessed relative to the epicardial curvature. The transmural orientation of the cardiomyocytes should also not be neglected, as it is an important determinant of cardiac function. Finally, there is considerable disagreement in the literature as to how the orientation of myocardial aggregates should be assessed, but to do so in a mathematically meaningful way, the normal vector of the aggregate plane should be utilised.
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Affiliation(s)
- Peter Agger
- Comparative Medicine Lab, Department of Clinical Medicine, Aarhus University, 8220 Aarhus N, Denmark
- Department of Pediatrics, Randers Regional Hospital, Skovlyvej 15, 8930 Randers NE, Denmark
- Correspondence:
| | - Robert S. Stephenson
- Institute of Clinical Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham B15 2TT, UK;
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18
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Abstract
Classification of heart failure is based on the left ventricular ejection fraction (EF): preserved EF, midrange EF, and reduced EF. There remains an unmet need for further heart failure phenotyping of ventricular structure-function relationships. Because of high spatiotemporal resolution, cardiac magnetic resonance (CMR) remains the reference modality for quantification of ventricular contractile function. The authors aim to highlight novel frameworks, including theranostic use of ferumoxytol, to enable more efficient evaluation of ventricular function in heart failure patients who are also frequently anemic, and to discuss emerging quantitative CMR approaches for evaluation of ventricular structure-function relationships in heart failure.
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19
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Tous C, Gentles TL, Young AA, Pontré BP. Ex vivo cardiovascular magnetic resonance diffusion weighted imaging in congenital heart disease, an insight into the microstructures of tetralogy of Fallot, biventricular and univentricular systemic right ventricle. J Cardiovasc Magn Reson 2020; 22:69. [PMID: 32951605 PMCID: PMC7504600 DOI: 10.1186/s12968-020-00662-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2020] [Accepted: 08/11/2020] [Indexed: 11/10/2022] Open
Abstract
PURPOSE Common types of congenital heart disease exhibit a variety of structural and functional variations which may be accompanied by changes in the myocardial microstructure. We aimed to compare myocardial architecture from magnetic resonance diffusion tensor imaging (DTI) in preserved pathology specimens. MATERIALS AND METHODS Pathology specimens (n = 24) formalin-fixed for 40.8 ± 7.9 years comprised tetralogy of Fallot (TOF, n = 10), dextro-transposition of great arteries (D-TGA, n = 8) five with ventricular septal defect (VSD), systemic right ventricle (n = 4), situs inversus totalis (SIT, n = 1) and levo-TGA (L-TGA, n = 1). Specimens were imaged using a custom spin-echo sequence and segmented automatically according to tissue volume fraction. In each specimen T1, T2, fractional anisotropy, mean diffusivity, helix angle (HA) and sheet angle (E2A) were quantified. Pathologies were compared according to their HA gradient, HA asymmetry and E2A mean value in each myocardial segment (anterior, posterior, septal and lateral walls). RESULTS TOF and D-TGA with VSD had decreased helix angle gradient by - 0.34°/% and remained symmetric in the septum in comparison to D-TGA without VSD. Helix angle range was decreased by 45°. It was associated with a decreased HA gradient in the right ventricular (RV) wall, i.e. predominant circumferential myocytes. The sheet angle in the septum of TOF was opposing those of the left ventricular (LV) free wall. Univentricular systemic RV had the lowest HA gradient (- 0.43°/%) and the highest HA asymmetry (75%). HA in SIT was linear, asymmetric, and reversed with a sign change at about 70% of the depth at mid-ventricle. In L-TGA with VSD, HA was asymmetric (90%) and its gradients were decreased in the septum, anterior and lateral wall. CONCLUSION The organization of the myocytes as determined by DTI differs between TOF, D-TGA, L-TGA, systemic RV and SIT specimens. These differences in cardiac structure may further enlighten our understanding of cardiac function in these diverse congenital heart diseases.
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Affiliation(s)
- Cyril Tous
- Department of Anatomy and Medical Imaging, University of Auckland, Auckland, New Zealand
- Laboratory of Clinical Image Processing Le Centre de Recherche du Centre Hospitalier de l'Université de Montréal, Montréal, Canada
| | - Thomas L Gentles
- Green Lane Paediatric and Congenital Cardiac Service, Starship Children's Hospital, Auckland, New Zealand
| | - Alistair A Young
- Department of Anatomy and Medical Imaging, University of Auckland, Auckland, New Zealand
- Department of Biomedical Engineering, King's College London, London, UK
| | - Beau P Pontré
- Department of Anatomy and Medical Imaging, University of Auckland, Auckland, New Zealand.
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20
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Lohr D, Terekhov M, Veit F, Schreiber LM. Longitudinal assessment of tissue properties and cardiac diffusion metrics of the ex vivo porcine heart at 7 T: Impact of continuous tissue fixation using formalin. NMR IN BIOMEDICINE 2020; 33:e4298. [PMID: 32207190 DOI: 10.1002/nbm.4298] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Revised: 02/18/2020] [Accepted: 03/05/2020] [Indexed: 05/12/2023]
Abstract
In this study we aimed to assess the effects of continuous formalin fixation on diffusion and relaxation metrics of the ex vivo porcine heart at 7 T. Magnetic resonance imaging was performed on eight piglet hearts using a 7 T whole body system. Hearts were measured fresh within 3 hours of cardiac arrest followed by immersion in 10% neutral buffered formalin. T2* and T2 were assessed using a gradient multi-echo and multi-echo spin echo sequence, respectively. A spin echo and a custom stimulated echo sequence were employed to assess diffusion time-dependent changes in metrics of cardiac diffusion tensor imaging. SNR was determined for b = 0 images. Scans were performed for 5 mm thick apical, midcavity and basal slices (in-plane resolution: 1 mm) and repeated 7, 15, 50, 100 and 200 days postfixation. Eigenvalues of the apparent diffusion coefficient (ADC) and fractional anisotropy (FA) decreased significantly (P < 0.05) following fixation. Relative to fresh hearts, FA values 7 and 200 days postfixation were 90% and 80%, while respective relative ADC values at those fixation stages were 78% and 92%. Statistical helix and sheetlet angle distributions as well as respective mean and median values showed no systematic influence of continuous formalin fixation. Similar to changes in the ADC, values for T2 , T2* and SNR dropped initially postfixation. Respective relative values compared with fresh hearts at day 7 were 64%, 79% and 68%, whereas continuous fixation restored T2 , T2* and SNR leading to relative values of 74%, 100%, and 81% at day 200, respectively. Relaxation parameters and diffusion metrics are significantly altered by continuous formalin fixation. The preservation of microstructure metrics following prolonged fixation is a key finding that may enable future studies of ventricular remodeling in cardiac pathologies.
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Affiliation(s)
- David Lohr
- Cellular and Molecular Imaging, Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany
| | - Maxim Terekhov
- Cellular and Molecular Imaging, Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany
| | - Franziska Veit
- Tissue Engineering and Regenerative Medicine (TERM), University Hospital Wuerzburg, Wuerzburg, Germany
| | - Laura Maria Schreiber
- Cellular and Molecular Imaging, Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany
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21
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Khalique Z, Ferreira PF, Scott AD, Nielles-Vallespin S, Firmin DN, Pennell DJ. Diffusion Tensor Cardiovascular Magnetic Resonance Imaging. JACC Cardiovasc Imaging 2020; 13:1235-1255. [DOI: 10.1016/j.jcmg.2019.07.016] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Revised: 07/09/2019] [Accepted: 07/11/2019] [Indexed: 12/15/2022]
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22
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Carruth ED, Teh I, Schneider JE, McCulloch AD, Omens JH, Frank LR. Regional variations in ex-vivo diffusion tensor anisotropy are associated with cardiomyocyte remodeling in rats after left ventricular pressure overload. J Cardiovasc Magn Reson 2020; 22:21. [PMID: 32241289 PMCID: PMC7114814 DOI: 10.1186/s12968-020-00615-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Accepted: 03/05/2020] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Pressure overload left ventricular (LV) hypertrophy is characterized by increased cardiomyocyte width and ventricle wall thickness, however the regional variation of this remodeling is unclear. Cardiovascular magnetic resonance (CMR) diffusion tensor imaging (DTI) may provide a non-invasive, comprehensive, and geometrically accurate method to detect regional differences in structural remodeling in hypertrophy. We hypothesized that DTI parameters, such as fractional and planar anisotropy, would reflect myocyte remodeling due to pressure overload in a regionally-dependent manner. METHODS We investigated the regional distributions of myocyte remodeling in rats with or without transverse aortic constriction (TAC) via direct measurement of myocyte dimensions with confocal imaging of thick tissue sections, and correlated myocyte cross-sectional area and other geometric features with parameters of diffusivity from ex-vivo DTI in the same regions of the same hearts. RESULTS We observed regional differences in several parameters from DTI between TAC hearts and SHAM controls. Consistent with previous studies, helix angles from DTI correlated strongly with those measured directly from histological sections (p < 0.001, R2 = 0.71). There was a transmural gradient in myocyte cross-sectional area in SHAM hearts that was diminished in the TAC group. We also found several regions of significantly altered DTI parameters in TAC LV compared to SHAM, especially in myocyte sheet angle dispersion and planar anisotropy. Among others, these parameters correlated significantly with directly measured myocyte aspect ratios. CONCLUSIONS These results show that structural remodeling in pressure overload LV hypertrophy is regionally heterogeneous, especially transmurally, with a greater degree of remodeling in the sub-endocardium compared to the sub-epicardium. Additionally, several parameters derived from DTI correlated significantly with measurements of myocyte geometry from direct measurement in histological sections. We suggest that DTI may provide a non-invasive, comprehensive method to detect regional structural myocyte LV remodeling during disease.
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Affiliation(s)
- Eric D Carruth
- Department of Bioengineering, University of California San Diego, La Jolla, California, USA
| | - Irvin Teh
- Leeds Institute of Cardiovascular & Metabolic Medicine, University of Leeds, Leeds, UK
| | - Jurgen E Schneider
- Leeds Institute of Cardiovascular & Metabolic Medicine, University of Leeds, Leeds, UK
| | - Andrew D McCulloch
- Department of Bioengineering, University of California San Diego, La Jolla, California, USA
| | - Jeffrey H Omens
- Department of Bioengineering, University of California San Diego, La Jolla, California, USA.
- Department of Medicine, University of California San Diego, La Jolla, California, USA.
| | - Lawrence R Frank
- Department of Radiology, University of California San Diego, La Jolla, California, USA
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23
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Mojica M, Pop M, Sermesant M, Ebrahimi M. Novel atlas of fiber directions built from ex-vivo diffusion tensor images of porcine hearts. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2020; 187:105200. [PMID: 31830700 DOI: 10.1016/j.cmpb.2019.105200] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 09/07/2019] [Accepted: 11/11/2019] [Indexed: 06/10/2023]
Abstract
Cardiac MR image-based predictive models integrating statistical atlases of heart anatomy and fiber orientations can aid in better diagnosis of cardiovascular disease, a major cause of death worldwide. Such atlases have been built from diffusion tensor (DT) images and can be used in anisotropic models for personalized computational electro-mechanical simulations when the fiber directions from DTI are not available. In this paper, we propose a framework for building the first statistical fiber atlas from high-resolution ex-vivo DT images of porcine hearts. A mean geometry that represents the average cardiac morphology of the dataset was first generated via groupwise registration. Then, the associated average cardiac fiber architecture was mapped out by computing the mean of the transformed DT fields of the subjects. To evaluate the stability of the atlas, we performed leave-one-out cross-validation. The resulting tensor statistics indicate that the fiber atlas could accurately describe the fiber architecture of a healthy pig heart.
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Affiliation(s)
- Mia Mojica
- Faculty of Science, University of Ontario Institute of Technology, ON, Canada.
| | - Mihaela Pop
- Department of Medical Biophysics, University of Toronto, Sunnybrook Research Institute, ON, Canada.
| | | | - Mehran Ebrahimi
- Faculty of Science, University of Ontario Institute of Technology, ON, Canada.
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24
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Ariga R, Tunnicliffe EM, Manohar SG, Mahmod M, Raman B, Piechnik SK, Francis JM, Robson MD, Neubauer S, Watkins H. Identification of Myocardial Disarray in Patients With Hypertrophic Cardiomyopathy and Ventricular Arrhythmias. J Am Coll Cardiol 2020; 73:2493-2502. [PMID: 31118142 PMCID: PMC6548973 DOI: 10.1016/j.jacc.2019.02.065] [Citation(s) in RCA: 74] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/21/2018] [Revised: 02/07/2019] [Accepted: 02/26/2019] [Indexed: 01/26/2023]
Abstract
Background Myocardial disarray is a likely focus for fatal arrhythmia in hypertrophic cardiomyopathy (HCM). This microstructural abnormality can be inferred by mapping the preferential diffusion of water along cardiac muscle fibers using diffusion tensor cardiac magnetic resonance (DT-CMR) imaging. Fractional anisotropy (FA) quantifies directionality of diffusion in 3 dimensions. The authors hypothesized that FA would be reduced in HCM due to disarray and fibrosis that may represent the anatomic substrate for ventricular arrhythmia. Objectives This study sought to assess FA as a noninvasive in vivo biomarker of HCM myoarchitecture and its association with ventricular arrhythmia. Methods A total of 50 HCM patients (47 ± 15 years of age, 77% male) and 30 healthy control subjects (46 ± 16 years of age, 70% male) underwent DT-CMR in diastole, cine, late gadolinium enhancement (LGE), and extracellular volume (ECV) imaging at 3-T. Results Diastolic FA was reduced in HCM compared with control subjects (0.49 ± 0.05 vs. 0.52 ± 0.03; p = 0.0005). Control subjects had a mid-wall ring of high FA. In HCM, this ring was disrupted by reduced FA, consistent with published histology demonstrating that disarray and fibrosis invade circumferentially aligned mid-wall myocytes. LGE and ECV were significant predictors of FA, in line with fibrosis contributing to low FA. Yet FA adjusted for LGE and ECV remained reduced in HCM (p = 0.028). FA in the hypertrophied segment was reduced in HCM patients with ventricular arrhythmia compared to patients without (n = 15; 0.41 ± 0.03 vs. 0.46 ± 0.06; p = 0.007). A decrease in FA of 0.05 increased odds of ventricular arrhythmia by 2.5 (95% confidence interval: 1.2 to 5.3; p = 0.015) in HCM and remained significant even after correcting for LGE, ECV, and wall thickness (p = 0.036). Conclusions DT-CMR assessment of left ventricular myoarchitecture matched patterns reported previously on histology. Low diastolic FA in HCM was associated with ventricular arrhythmia and is likely to represent disarray after accounting for fibrosis. The authors propose that diastolic FA could be the first in vivo marker of disarray in HCM and a potential independent risk factor.
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Affiliation(s)
- Rina Ariga
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Elizabeth M Tunnicliffe
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Sanjay G Manohar
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
| | - Masliza Mahmod
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Betty Raman
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Stefan K Piechnik
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Jane M Francis
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Matthew D Robson
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Stefan Neubauer
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Hugh Watkins
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom.
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25
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Giannakidis A, Gullberg GT. Transmural Remodeling of Cardiac Microstructure in Aged Spontaneously Hypertensive Rats by Diffusion Tensor MRI. Front Physiol 2020; 11:265. [PMID: 32296341 PMCID: PMC7136532 DOI: 10.3389/fphys.2020.00265] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Accepted: 03/09/2020] [Indexed: 11/16/2022] Open
Abstract
The long-standing high blood pressure (also known as hypertension) overworks the heart. Microstructural remodeling is a key factor of hypertensive heart disease progression. Diffusion tensor magnetic resonance imaging (DT-MRI) is a powerful tool for the rapid noninvasive nondestructive delineation of the cardiomyocyte organization. The spontaneously hypertensive rat (SHR) is a well-established model of genetic hypertension. The goal of this study was to employ high-resolution DT-MRI and the SHR animal model to assess the transmural layer-specific remodeling of myocardial microstructure associated with hypertension. Ex vivo experiments were performed on excised formalin-fixed hearts of aged SHRs (n = 4) and age-matched controls (n = 4). The DT-MRI-derived fractional anisotropy (FA), longitudinal diffusivity (λL), transversal diffusivity (λT), and mean diffusivity (MD) served as the readout parameters investigated at three transmural zones (i.e., endocardium, mesocardium, and epicardium). The helix angles (HAs) of the aggregated cardiomyocytes and the orientation of laminar sheetlets were also studied. Compared with controls, the SHRs exhibited decreased epicardial FA, while FA changes in the other two transmural regions were insignificant. No substantial differences were observed in the diffusivity parameters and the transmural course of HAs between the two groups. A consistent distribution pattern of laminar sheetlet orientation was not identified for either group. Our findings are in line with the known cellular microstructure from early painstaking histological studies. Biophysical explanations of the study outcomes are provided. In conclusion, our experimental findings indicate that the epicardial microstructure is more vulnerable to high blood pressure leading to more pronounced changes in this region during remodeling. DT-MRI is well-suited for elucidating these alterations. The revealed transmural nonuniformity of myocardial reorganization may shed light on the mechanisms of the microstructure-function relationship in hypertension progression. Our results provide insights into the management of patients with systemic arterial hypertension, thus prevent the progression toward heart failure. The findings of this study should be acknowledged by electromechanical models of the heart that simulate the specific cardiac pathology.
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Affiliation(s)
- Archontis Giannakidis
- School of Science and Technology, Nottingham Trent University, Nottingham, United Kingdom.,Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, United States.,National Heart & Lung Institute, Imperial College London, London, United Kingdom
| | - Grant T Gullberg
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, United States.,Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA, United States
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26
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Nielles-Vallespin S, Scott A, Ferreira P, Khalique Z, Pennell D, Firmin D. Cardiac Diffusion: Technique and Practical Applications. J Magn Reson Imaging 2019; 52:348-368. [PMID: 31482620 DOI: 10.1002/jmri.26912] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 08/13/2019] [Accepted: 08/14/2019] [Indexed: 12/12/2022] Open
Abstract
The 3D microarchitecture of the cardiac muscle underlies the mechanical and electrical properties of the heart. Cardiomyocytes are arranged helically through the depth of the wall, and their shortening leads to macroscopic torsion, twist, and shortening during cardiac contraction. Furthermore, cardiomyocytes are organized in sheetlets separated by shear layers, which reorientate, slip, and shear during macroscopic left ventricle (LV) wall thickening. Cardiac diffusion provides a means for noninvasive interrogation of the 3D microarchitecture of the myocardium. The fundamental principle of MR diffusion is that an MRI signal is attenuated by the self-diffusion of water in the presence of large diffusion-encoding gradients. Since water molecules are constrained by the boundaries in biological tissue (cell membranes, collagen layers, etc.), depicting their diffusion behavior elucidates the shape of the myocardial microarchitecture they are embedded in. Cardiac diffusion therefore provides a noninvasive means to understand not only the dynamic changes in cardiac microstructure of healthy myocardium during cardiac contraction but also the pathophysiological changes in the presence of disease. This unique and innovative technology offers tremendous potential to enable improved clinical diagnosis through novel microstructural and functional assessment. in vivo cardiac diffusion methods are immediately translatable to patients, opening new avenues for diagnostic investigation and treatment evaluation in a range of clinically important cardiac pathologies. This review article describes the 3D microstructure of the LV, explains in vivo and ex vivo cardiac MR diffusion acquisition and postprocessing techniques, as well as clinical applications to date. Level of Evidence: 1 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2019. J. Magn. Reson. Imaging 2020;52:348-368.
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Affiliation(s)
- Sonia Nielles-Vallespin
- Cardiovascular MR Unit, Royal Brompton And Harefield NHS Foundation Trust, London, UK.,NHLI, Imperial College of Science, Technology and Medicine, London, UK
| | - Andrew Scott
- Cardiovascular MR Unit, Royal Brompton And Harefield NHS Foundation Trust, London, UK.,NHLI, Imperial College of Science, Technology and Medicine, London, UK
| | - Pedro Ferreira
- Cardiovascular MR Unit, Royal Brompton And Harefield NHS Foundation Trust, London, UK.,NHLI, Imperial College of Science, Technology and Medicine, London, UK
| | - Zohya Khalique
- Cardiovascular MR Unit, Royal Brompton And Harefield NHS Foundation Trust, London, UK.,NHLI, Imperial College of Science, Technology and Medicine, London, UK
| | - Dudley Pennell
- Cardiovascular MR Unit, Royal Brompton And Harefield NHS Foundation Trust, London, UK.,NHLI, Imperial College of Science, Technology and Medicine, London, UK
| | - David Firmin
- Cardiovascular MR Unit, Royal Brompton And Harefield NHS Foundation Trust, London, UK.,NHLI, Imperial College of Science, Technology and Medicine, London, UK
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27
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Hoermann JM, Pfaller MR, Avena L, Bertoglio C, Wall WA. Automatic mapping of atrial fiber orientations for patient-specific modeling of cardiac electromechanics using image registration. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2019; 35:e3190. [PMID: 30829001 PMCID: PMC6619047 DOI: 10.1002/cnm.3190] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Revised: 02/06/2019] [Accepted: 02/18/2019] [Indexed: 05/06/2023]
Abstract
Knowledge of appropriate local fiber architecture is necessary to simulate patient-specific electromechanics in the human heart. However, it is not yet possible to reliably measure in vivo fiber directions especially in human atria. Thus, we present a method that defines the fiber architecture in arbitrarily shaped atria using image registration and reorientation methods based on atlas atria with fibers predefined from detailed histological observations. Thereby, it is possible to generate detailed fiber families in every new patient-specific geometry in an automated, time-efficient process. We demonstrate the good performance of the image registration and fiber definition on 10 differently shaped human atria. Additionally, we show that characteristics of the electrophysiological activation pattern that appear in the atlas atria also appear in the patients' atria. We arrive to analogous conclusions for coupled electro-mechano-hemodynamical computations.
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Affiliation(s)
- Julia M. Hoermann
- Institute of Computational MechanicsTechnical University of MunichGarching bei MünchenGermany
| | - Martin R. Pfaller
- Institute of Computational MechanicsTechnical University of MunichGarching bei MünchenGermany
| | - Linda Avena
- Department of Electrophysiology, German Heart Center MunichTechnical University of MunichMünchenGermany
| | - Cristóbal Bertoglio
- Bernoulli InstituteUniversity of GroningenGroningenNetherlands
- Center for Mathematical ModelingUniversidad de ChileSantiagoChile
| | - Wolfgang A. Wall
- Institute of Computational MechanicsTechnical University of MunichGarching bei MünchenGermany
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28
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Lopez-Perez A, Sebastian R, Izquierdo M, Ruiz R, Bishop M, Ferrero JM. Personalized Cardiac Computational Models: From Clinical Data to Simulation of Infarct-Related Ventricular Tachycardia. Front Physiol 2019; 10:580. [PMID: 31156460 PMCID: PMC6531915 DOI: 10.3389/fphys.2019.00580] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Accepted: 04/25/2019] [Indexed: 12/20/2022] Open
Abstract
In the chronic stage of myocardial infarction, a significant number of patients develop life-threatening ventricular tachycardias (VT) due to the arrhythmogenic nature of the remodeled myocardium. Radiofrequency ablation (RFA) is a common procedure to isolate reentry pathways across the infarct scar that are responsible for VT. Unfortunately, this strategy show relatively low success rates; up to 50% of patients experience recurrent VT after the procedure. In the last decade, intensive research in the field of computational cardiac electrophysiology (EP) has demonstrated the ability of three-dimensional (3D) cardiac computational models to perform in-silico EP studies. However, the personalization and modeling of certain key components remain challenging, particularly in the case of the infarct border zone (BZ). In this study, we used a clinical dataset from a patient with a history of infarct-related VT to build an image-based 3D ventricular model aimed at computational simulation of cardiac EP, including detailed patient-specific cardiac anatomy and infarct scar geometry. We modeled the BZ in eight different ways by combining the presence or absence of electrical remodeling with four different levels of image-based patchy fibrosis (0, 10, 20, and 30%). A 3D torso model was also constructed to compute the ECG. Patient-specific sinus activation patterns were simulated and validated against the patient's ECG. Subsequently, the pacing protocol used to induce reentrant VTs in the EP laboratory was reproduced in-silico. The clinical VT was induced with different versions of the model and from different pacing points, thus identifying the slow conducting channel responsible for such VT. Finally, the real patient's ECG recorded during VT episodes was used to validate our simulation results and to assess different strategies to model the BZ. Our study showed that reduced conduction velocities and heterogeneity in action potential duration in the BZ are the main factors in promoting reentrant activity. Either electrical remodeling or fibrosis in a degree of at least 30% in the BZ were required to initiate VT. Moreover, this proof-of-concept study confirms the feasibility of developing 3D computational models for cardiac EP able to reproduce cardiac activation in sinus rhythm and during VT, using exclusively non-invasive clinical data.
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Affiliation(s)
- Alejandro Lopez-Perez
- Center for Research and Innovation in Bioengineering (Ci2B), Universitat Politècnica de València, Valencia, Spain
| | - Rafael Sebastian
- Computational Multiscale Simulation Lab (CoMMLab), Universitat de València, Valencia, Spain
| | - M Izquierdo
- INCLIVA Health Research Institute, Valencia, Spain.,Arrhythmia Unit, Cardiology Department, Hospital Clínico Universitario de Valencia, Valencia, Spain
| | - Ricardo Ruiz
- INCLIVA Health Research Institute, Valencia, Spain.,Arrhythmia Unit, Cardiology Department, Hospital Clínico Universitario de Valencia, Valencia, Spain
| | - Martin Bishop
- Division of Imaging Sciences & Biomedical Engineering, Department of Biomedical Engineering, King's College London, London, United Kingdom
| | - Jose M Ferrero
- Center for Research and Innovation in Bioengineering (Ci2B), Universitat Politècnica de València, Valencia, Spain
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29
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Rodríguez‐Cantano R, Sundnes J, Rognes ME. Uncertainty in cardiac myofiber orientation and stiffnesses dominate the variability of left ventricle deformation response. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2019; 35:e3178. [PMID: 30632711 PMCID: PMC6618163 DOI: 10.1002/cnm.3178] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Accepted: 12/15/2018] [Indexed: 05/26/2023]
Abstract
Computational cardiac modelling is a mature area of biomedical computing and is currently evolving from a pure research tool to aiding in clinical decision making. Assessing the reliability of computational model predictions is a key factor for clinical use, and uncertainty quantification (UQ) and sensitivity analysis are important parts of such an assessment. In this study, we apply UQ in computational heart mechanics to study uncertainty both in material parameters characterizing global myocardial stiffness and in the local muscle fiber orientation that governs tissue anisotropy. The uncertainty analysis is performed using the polynomial chaos expansion (PCE) method, which is a nonintrusive meta-modeling technique that surrogates the original computational model with a series of orthonormal polynomials over the random input parameter space. In addition, in order to study variability in the muscle fiber architecture, we model the uncertainty in orientation of the fiber field as an approximated random field using a truncated Karhunen-Loéve expansion. The results from the UQ and sensitivity analysis identify clear differences in the impact of various material parameters on global output quantities. Furthermore, our analysis of random field variations in the fiber architecture demonstrate a substantial impact of fiber angle variations on the selected outputs, highlighting the need for accurate assignment of fiber orientation in computational heart mechanics models.
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Affiliation(s)
- Rocío Rodríguez‐Cantano
- Department of Numerical Analysis and Scientific ComputingSimula Research Laboratory ASBærumNorway
| | - Joakim Sundnes
- Center for Cardiological InnovationSimula Research LaboratoryBærumNorway
| | - Marie E. Rognes
- Department of Numerical Analysis and Scientific ComputingSimula Research Laboratory ASBærumNorway
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30
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Lohr D, Terekhov M, Weng AM, Schroeder A, Walles H, Schreiber LM. Spin echo based cardiac diffusion imaging at 7T: An ex vivo study of the porcine heart at 7T and 3T. PLoS One 2019; 14:e0213994. [PMID: 30908510 PMCID: PMC6433440 DOI: 10.1371/journal.pone.0213994] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Accepted: 03/05/2019] [Indexed: 02/03/2023] Open
Abstract
Purpose of this work was to assess feasibility of cardiac diffusion tensor imaging (cDTI) at 7 T in a set of healthy, unfixed, porcine hearts using various parallel imaging acceleration factors and to compare SNR and derived cDTI metrics to a reference measured at 3 T. Magnetic resonance imaging was performed on 7T and 3T whole body systems using a spin echo diffusion encoding sequence with echo planar imaging readout. Five reference (b = 0 s/mm2) images and 30 diffusion directions (b = 700 s/mm2) were acquired at both 7 T and 3 T using a GRAPPA acceleration factor R = 1. Scans at 7 T were repeated using R = 2, R = 3, and R = 4. SNR evaluation was based on 30 reference (b = 0 s/mm2) images of 30 slices of the left ventricle and cardiac DTI metrics were compared within AHA segmentation. The number of hearts scanned at 7 T and 3 T was n = 11. No statistically significant differences were found for evaluated helix angle, secondary eigenvector angle, fractional anisotropy and apparent diffusion coefficient at the different field strengths, given sufficiently high SNR and geometrically undistorted images. R≥3 was needed to reduce susceptibility induced geometric distortions to an acceptable amount. On average SNR in myocardium of the left ventricle was increased from 29±3 to 44±6 in the reference image (b = 0 s/mm2) when switching from 3 T to 7 T. Our study demonstrates that high resolution, ex vivo cDTI is feasible at 7 T using commercial hardware.
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Affiliation(s)
- David Lohr
- Chair of Cellular and Molecular Imaging, Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany
- * E-mail:
| | - Maxim Terekhov
- Chair of Cellular and Molecular Imaging, Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany
| | - Andreas Max Weng
- Department of Diagnostic and Interventional Radiology, University of Wuerzburg, Wuerzburg, Germany
| | - Anja Schroeder
- Chair Tissue Engineering and Regenerative Medicine (TERM), University Hospital Wuerzburg, Wuerzburg, Germany
| | - Heike Walles
- Translational Center Regenerative Therapies (TLC-RT), Fraunhofer Institute for Silicate Research (ISC), Wuerzburg, Germany
| | - Laura Maria Schreiber
- Chair of Cellular and Molecular Imaging, Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany
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31
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Abstract
There has been an increasing interest in studying cardiac fibers in order to improve the current knowledge regarding the mechanical and physiological properties of the heart during heart failure (HF), particularly early HF. Having a thorough understanding of the changes in cardiac fiber orientation may provide new insight into the mechanisms behind the progression of left ventricular (LV) remodeling and HF. We conducted a systematic review on various technologies for imaging cardiac fibers and its link to HF. This review covers literature reports from 1900 to 2017. PubMed and Google Scholar databases were searched using the keywords "cardiac fiber" and "heart failure" or "myofiber" and "heart failure." This review highlights imaging methodologies, including magnetic resonance diffusion tensor imaging (MR-DTI), ultrasound, and other imaging technologies as well as their potential applications in basic and translational research on the development and progression of HF. MR-DTI and ultrasound have been most useful and significant in evaluating cardiac fibers and HF. New imaging technologies that have the ability to measure cardiac fiber orientations and identify structural and functional information of the heart will advance basic research and clinical diagnoses of HF.
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Affiliation(s)
- Shana R Watson
- Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, GA, USA
| | - James D Dormer
- Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, GA, USA
| | - Baowei Fei
- Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, GA, USA. .,Winship Cancer Institute of Emory University, Atlanta, GA, USA. .,Department of Mathematics and Computer Science, Emory University, Atlanta, GA, USA. .,Department of Biomedical Engineering, Emory University and Georgia Institute of Technology, Atlanta, GA, USA. .,Quantitative Bioimaging Laboratory, Department of Radiology and Imaging Sciences, School of Medicine, Emory University, Atlanta, United States.
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32
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Burton BM, Aras KK, Good WW, Tate JD, Zenger B, MacLeod RS. Image-based modeling of acute myocardial ischemia using experimentally derived ischemic zone source representations. J Electrocardiol 2018; 51:725-733. [PMID: 29997022 PMCID: PMC6050031 DOI: 10.1016/j.jelectrocard.2018.05.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Revised: 04/22/2018] [Accepted: 05/10/2018] [Indexed: 11/15/2022]
Abstract
BACKGROUND Computational models of myocardial ischemia often use oversimplified ischemic source representations to simulate epicardial potentials. The purpose of this study was to explore the influence of biophysically justified, subject-specific ischemic zone representations on epicardial potentials. METHODS We developed and implemented an image-based simulation pipeline, using intramural recordings from a canine experimental model to define subject-specific ischemic regions within the heart. Static epicardial potential distributions, reflective of ST segment deviations, were simulated and validated against measured epicardial recordings. RESULTS Simulated epicardial potential distributions showed strong statistical correlation and visual agreement with measured epicardial potentials. Additionally, we identified and described in what way border zone parameters influence epicardial potential distributions during the ST segment. CONCLUSION From image-based simulations of myocardial ischemia, we generated subject-specific ischemic sources that accurately replicated epicardial potential distributions. Such models are essential in understanding the underlying mechanisms of the bioelectric fields that arise during ischemia and are the basis for more sophisticated simulations of body surface ECGs.
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Affiliation(s)
- B M Burton
- University of Utah, Department of Bioengineering, Salt Lake City, UT, USA; Scientific Computing and Imaging Institute (SCI), Salt Lake City, UT, USA; Cardiovascular Research & Training Institute (CVRTI), Salt Lake City, UT, USA.
| | - K K Aras
- University of Utah, Department of Bioengineering, Salt Lake City, UT, USA; Scientific Computing and Imaging Institute (SCI), Salt Lake City, UT, USA; Cardiovascular Research & Training Institute (CVRTI), Salt Lake City, UT, USA
| | - W W Good
- University of Utah, Department of Bioengineering, Salt Lake City, UT, USA; Scientific Computing and Imaging Institute (SCI), Salt Lake City, UT, USA; Cardiovascular Research & Training Institute (CVRTI), Salt Lake City, UT, USA
| | - J D Tate
- University of Utah, Department of Bioengineering, Salt Lake City, UT, USA; Scientific Computing and Imaging Institute (SCI), Salt Lake City, UT, USA; Cardiovascular Research & Training Institute (CVRTI), Salt Lake City, UT, USA
| | - B Zenger
- University of Utah, Department of Bioengineering, Salt Lake City, UT, USA; Scientific Computing and Imaging Institute (SCI), Salt Lake City, UT, USA; Cardiovascular Research & Training Institute (CVRTI), Salt Lake City, UT, USA
| | - R S MacLeod
- University of Utah, Department of Bioengineering, Salt Lake City, UT, USA; Scientific Computing and Imaging Institute (SCI), Salt Lake City, UT, USA; Cardiovascular Research & Training Institute (CVRTI), Salt Lake City, UT, USA
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Hoffman JIE. Will the real ventricular architecture please stand up? Physiol Rep 2018; 5:5/18/e13404. [PMID: 28947592 PMCID: PMC5617926 DOI: 10.14814/phy2.13404] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Accepted: 07/23/2017] [Indexed: 12/28/2022] Open
Abstract
Ventricular twisting, essential for cardiac function, is attributed to the contraction of myocardial helical fibers. The exact relationship between ventricular anatomy and function remains to be determined, but one commonly used explanatory model is the helical ventricular myocardial band (HVMB) model of Torrent‐Guasp. This model has been successful in explaining many aspects of ventricular function, (Torrent‐Guasp et al. Eur. J. Cardiothorac. Surg., 25, 376, 2004; Buckberg et al. Eur. J. Cardiothorac. Surg., 47, 587, 2015; Buckberg et al. Eur. J. Cardiothorac. Surg. 47, 778, 2015) but the model ignores important aspects of ventricular anatomy and should probably be replaced. The purpose of this review is to compare the HVMB model with a different model (nested layers). A complication when interpreting experimental observations that relate anatomy to function is that, in the myocardium, shortening does not always imply activation and lengthening does not always imply inactivation.
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Affiliation(s)
- Julien I E Hoffman
- Department of Pediatrics, University of California, San Francisco, California
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Caenen A, Pernot M, Peirlinck M, Mertens L, Swillens A, Segers P. An in silico framework to analyze the anisotropic shear wave mechanics in cardiac shear wave elastography. Phys Med Biol 2018; 63:075005. [PMID: 29451120 DOI: 10.1088/1361-6560/aaaffe] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Shear wave elastography (SWE) is a potential tool to non-invasively assess cardiac muscle stiffness. This study focused on the effect of the orthotropic material properties and mechanical loading on the performance of cardiac SWE, as it is known that these factors contribute to complex 3D anisotropic shear wave propagation. To investigate the specific impact of these complexities, we constructed a finite element model with an orthotropic material law subjected to different uniaxial stretches to simulate SWE in the stressed cardiac wall. Group and phase speed were analyzed in function of tissue thickness and virtual probe rotation angle. Tissue stretching increased the group and phase speed of the simulated shear wave, especially in the direction of the muscle fiber. As the model provided access to the true fiber orientation and material properties, we assessed the accuracy of two fiber orientation extraction methods based on SWE. We found a higher accuracy (but lower robustness) when extracting fiber orientations based on the location of maximal shear wave speed instead of the angle of the major axis of the ellipsoidal group speed surface. Both methods had a comparable performance for the center region of the cardiac wall, and performed less well towards the edges. Lastly, we also assessed the (theoretical) impact of pathology on shear wave physics and characterization in the model. It was found that SWE was able to detect changes in fiber orientation and material characteristics, potentially associated with cardiac pathologies such as myocardial fibrosis. Furthermore, the model showed clearly altered shear wave patterns for the fibrotic myocardium compared to the healthy myocardium, which forms an initial but promising outcome of this modeling study.
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Affiliation(s)
- Annette Caenen
- IBiTech-bioMMeda, Ghent University, Ghent, Belgium. Author to whom any correspondence should be addressed
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Scharrenbroich J, Hamada S, Keszei A, Schröder J, Napp A, Almalla M, Becker M, Altiok E. Use of two-dimensional speckle tracking echocardiography to predict cardiac events: Comparison of patients with acute myocardial infarction and chronic coronary artery disease. Clin Cardiol 2018; 41:111-118. [PMID: 29359809 DOI: 10.1002/clc.22860] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Revised: 11/13/2017] [Accepted: 11/21/2017] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Two-dimensional speckle strain (2D STE) echocardiography can aid in the prognosis of acute myocardial infarction (AMI) and chronic coronary artery disease (CAD). HYPOTHESIS Differences occur in the prediction of cardiac events using 2D STE in AMI vs CAD patients. METHODS In this prospective study, 94 patients with a first AMI and successful revascularization, and 137 patients with stable CAD after complete revascularization were included. In all patients, we performed echocardiography and myocardial deformation analysis for layer-specific global circumferential strain (GCS) and longitudinal strain. Receiver operating characteristic (ROC) curve analysis was used to predict the presence of a cardiac event using strain values and baseline characteristics in different regression models. RESULTS Patients were followed for 3.6 ± 0.8 years. Strain parameters in AMI and CAD patients were significantly different with respect to the occurrence of a cardiac event. Frequency of diabetes and hypertension was associated with the presence of a cardiac event in CAD patients. Furthermore, in CAD patients, ROC analysis demonstrated that the addition of endocardial GCS to baseline characteristics and ejection fraction to a regression model significantly improved the prediction of cardiac events (area under curve = 0.86, cutoff value: 20%, sensitivity: 79%, specificity: 84%). In contrast, the addition of strain parameters in AMI patients did not increase the prediction power for cardiac events. CONCLUSIONS Global strain parameters by 2D STE may be useful for the prediction of cardiac events in patients with CAD but add no supplemental information to baseline characteristic and ejection fraction in patients with AMI.
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Affiliation(s)
- Jörg Scharrenbroich
- Department of Cardiology, University Hospital Aachen, Rhenish-Westphalian Technical University, Aachen, Germany
| | - Sandra Hamada
- Department of Cardiology, University Hospital Aachen, Rhenish-Westphalian Technical University, Aachen, Germany
| | - Andras Keszei
- Department of Medical Statistics, University Hospital Aachen, Rhenish-Westphalian Technical University, Aachen, Germany
| | - Jörg Schröder
- Department of Cardiology, University Hospital Aachen, Rhenish-Westphalian Technical University, Aachen, Germany
| | - Andreas Napp
- Department of Cardiology, University Hospital Aachen, Rhenish-Westphalian Technical University, Aachen, Germany
| | - Mohammad Almalla
- Department of Cardiology, University Hospital Aachen, Rhenish-Westphalian Technical University, Aachen, Germany
| | - Michael Becker
- Department of Cardiology, University Hospital Aachen, Rhenish-Westphalian Technical University, Aachen, Germany
| | - Ertunc Altiok
- Department of Cardiology, University Hospital Aachen, Rhenish-Westphalian Technical University, Aachen, Germany
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36
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Agger P, Ilkjær C, Laustsen C, Smerup M, Frandsen JR, Ringgaard S, Pedersen M, Partridge JB, Anderson RH, Hjortdal V. Changes in overall ventricular myocardial architecture in the setting of a porcine animal model of right ventricular dilation. J Cardiovasc Magn Reson 2017; 19:93. [PMID: 29178894 PMCID: PMC5702974 DOI: 10.1186/s12968-017-0404-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Accepted: 10/18/2017] [Indexed: 12/01/2022] Open
Abstract
BACKGROUND Chronic pulmonary regurgitation often leads to myocardial dysfunction and heart failure. It is not fully known why secondary hypertrophy cannot fully protect against the increase in wall stress brought about by the increased end-diastolic volume in ventricular dilation. It has been assumed that mural architecture is not deranged in this situation, but we hypothesised that there might be a change in the pattern of orientation of the aggregations of cardiomyocytes, which would contribute to contractile impairment. METHODS We created pulmonary valvular regurgitation by open chest, surgical suturing of its leaflets in seven piglets, performing sham operations in seven control animals. Using cardiovascular magnetic resonance imaging after 12 weeks of recovery, we demonstrated significantly increased right ventricular volumes in the test group. After sacrifice, diffusion tensor imaging of their hearts permitted measurement of the orientation of the cardiomyocytes. RESULTS The helical angles in the right ventricle approached a more circumferential orientation in the setting of right ventricular RV dilation (p = 0.007), with an increased proportion of surface-parallel cardiomyocytes. In contrast, this proportion decreased in the left ventricle. Also in the left ventricle a higher proportion of E3 angles with a value around zero was found, and conversely a lower proportion of angles was found with a numerical higher value. In the dilated right ventricle the proportion of E3 angles around -90° is increased, while the proportion around 90° is decreased. CONCLUSION Contrary to traditional views, there is a change in the orientation of both the left ventricular and right ventricular cardiomyocytes subsequent to right ventricular dilation. This will change their direction of contraction and hinder the achievement of normalisation of cardiomyocytic strain, affecting overall contractility. We suggest that the aetiology of the cardiac failure induced by right vetricular dilation may be partly explained by morphological changes in the myocardium itself.
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Affiliation(s)
- Peter Agger
- Department of Cardiothoracic & Vascular Surgery, Aarhus University Hospital, Skejby, Aarhus, Denmark
- Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Christine Ilkjær
- Department of Cardiothoracic & Vascular Surgery, Aarhus University Hospital, Skejby, Aarhus, Denmark
- Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Christoffer Laustsen
- MR Research Center, Aarhus University Hospital, Aarhus, Denmark
- Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Morten Smerup
- Department of Cardiothoracic Surgery, Rigshospitalet, Copenhagen, Denmark
| | - Jesper R. Frandsen
- Center for Functionally Integrative Neuroscience, Aarhus University Hospital, Aarhus, Denmark
| | - Steffen Ringgaard
- MR Research Center, Aarhus University Hospital, Aarhus, Denmark
- Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Michael Pedersen
- Comparative Medicine Lab, Aarhus University Hospital, Aarhus, Denmark
- Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - John B. Partridge
- Eurobodalla Unit, Rural Clinical School of the ANU College of Medicine, Biology & Environment, Batemans Bay, NSW Australia
| | - Robert H. Anderson
- Institute of Genetic Medicine, Newcastle University, Newcastle-upon-Tyne, UK
| | - Vibeke Hjortdal
- Department of Cardiothoracic & Vascular Surgery, Aarhus University Hospital, Skejby, Aarhus, Denmark
- Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
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Pervolaraki E, Dachtler J, Anderson RA, Holden AV. Ventricular myocardium development and the role of connexins in the human fetal heart. Sci Rep 2017; 7:12272. [PMID: 28947768 PMCID: PMC5612926 DOI: 10.1038/s41598-017-11129-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Accepted: 08/18/2017] [Indexed: 11/08/2022] Open
Abstract
The developmental timeline of the human heart remains elusive. The heart takes on its characteristic four chambered appearance by ~56 days gestational age (DGA). However, owing to the complexities (both technical and logistical) of exploring development in utero, we understand little of how the ventricular walls develop. To address this, we employed diffusion tensor magnetic resonance imaging to explore the architecture and tissue organization of the developing heart aged 95-143 DGA. We show that fractional anisotropy increases (from ~0.1 to ~0.5), diffusion coefficients decrease (from ~1 × 10-3mm2/sec to ~0.4 × 10-3mm2/sec), and fiber paths, extracted by tractography, increase linearly with gestation, indicative of the increasing organization of the ventricular myocytes. By 143 DGA, the developing heart has the classical helical organization observed in mature mammalian tissue. This was accompanied by an increase in connexin 43 and connexin 40 expression levels, suggesting their role in the development of the ventricular conduction system and that electrical propagation across the heart is facilitated in later gestation. Our findings highlight a key developmental window for the structural organization of the fetal heart.
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Affiliation(s)
| | - James Dachtler
- Department of Psychology, Durham University, Durham, DH1 3LE, UK
| | - Richard A Anderson
- MRC Centre for Reproductive Health, University of Edinburgh, Edinburgh, EH16 4TJ, UK
| | - Arun V Holden
- School of Biomedical Sciences, University of Leeds, Leeds, LS2 9JT, UK
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Ghonim S, Voges I, Gatehouse PD, Keegan J, Gatzoulis MA, Kilner PJ, Babu-Narayan SV. Myocardial Architecture, Mechanics, and Fibrosis in Congenital Heart Disease. Front Cardiovasc Med 2017; 4:30. [PMID: 28589126 PMCID: PMC5440586 DOI: 10.3389/fcvm.2017.00030] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Accepted: 04/28/2017] [Indexed: 01/15/2023] Open
Abstract
Congenital heart disease (CHD) is the most common category of birth defect, affecting 1% of the population and requiring cardiovascular surgery in the first months of life in many patients. Due to advances in congenital cardiovascular surgery and patient management, most children with CHD now survive into adulthood. However, residual and postoperative defects are common resulting in abnormal hemodynamics, which may interact further with scar formation related to surgical procedures. Cardiovascular magnetic resonance (CMR) has become an important diagnostic imaging modality in the long-term management of CHD patients. It is the gold standard technique to assess ventricular volumes and systolic function. Besides this, advanced CMR techniques allow the acquisition of more detailed information about myocardial architecture, ventricular mechanics, and fibrosis. The left ventricle (LV) and right ventricle have unique myocardial architecture that underpins their mechanics; however, this becomes disorganized under conditions of volume and pressure overload. CMR diffusion tensor imaging is able to interrogate non-invasively the principal alignments of microstructures in the left ventricular wall. Myocardial tissue tagging (displacement encoding using stimulated echoes) and feature tracking are CMR techniques that can be used to examine the deformation and strain of the myocardium in CHD, whereas 3D feature tracking can assess the twisting motion of the LV chamber. Late gadolinium enhancement imaging and more recently T1 mapping can help in detecting fibrotic myocardial changes and evolve our understanding of the pathophysiology of CHD patients. This review not only gives an overview about available or emerging CMR techniques for assessing myocardial mechanics and fibrosis but it also describes their clinical value and how they can be used to detect abnormalities in myocardial architecture and mechanics in CHD patients.
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Affiliation(s)
- Sarah Ghonim
- Adult Congenital Heart Unit, Royal Brompton Hospital, London, UK
- Cardiovascular Magnetic Resonance Unit, Royal Brompton Hospital, London, UK
- National Heart and Lung Institute, Imperial College, London, UK
| | - Inga Voges
- Adult Congenital Heart Unit, Royal Brompton Hospital, London, UK
- Cardiovascular Magnetic Resonance Unit, Royal Brompton Hospital, London, UK
| | - Peter D. Gatehouse
- Cardiovascular Magnetic Resonance Unit, Royal Brompton Hospital, London, UK
| | - Jennifer Keegan
- Cardiovascular Magnetic Resonance Unit, Royal Brompton Hospital, London, UK
| | - Michael A. Gatzoulis
- Adult Congenital Heart Unit, Royal Brompton Hospital, London, UK
- National Heart and Lung Institute, Imperial College, London, UK
| | - Philip J. Kilner
- Cardiovascular Magnetic Resonance Unit, Royal Brompton Hospital, London, UK
| | - Sonya V. Babu-Narayan
- Adult Congenital Heart Unit, Royal Brompton Hospital, London, UK
- Cardiovascular Magnetic Resonance Unit, Royal Brompton Hospital, London, UK
- National Heart and Lung Institute, Imperial College, London, UK
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Imaging the dynamics of cardiac fiber orientation in vivo using 3D Ultrasound Backscatter Tensor Imaging. Sci Rep 2017; 7:830. [PMID: 28400606 PMCID: PMC5429761 DOI: 10.1038/s41598-017-00946-7] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 03/20/2017] [Indexed: 01/23/2023] Open
Abstract
The assessment of myocardial fiber disarray is of major interest for the study of the progression of myocardial disease. However, time-resolved imaging of the myocardial structure remains unavailable in clinical practice. In this study, we introduce 3D Backscatter Tensor Imaging (3D-BTI), an entirely novel ultrasound-based imaging technique that can map the myocardial fibers orientation and its dynamics with a temporal resolution of 10 ms during a single cardiac cycle, non-invasively and in vivo in entire volumes. 3D-BTI is based on ultrafast volumetric ultrasound acquisitions, which are used to quantify the spatial coherence of backscattered echoes at each point of the volume. The capability of 3D-BTI to map the fibers orientation was evaluated in vitro in 5 myocardial samples. The helicoidal transmural variation of fiber angles was in good agreement with the one obtained by histological analysis. 3D-BTI was then performed to map the fiber orientation dynamics in vivo in the beating heart of an open-chest sheep at a volume rate of 90 volumes/s. Finally, the clinical feasibility of 3D-BTI was shown on a healthy volunteer. These initial results indicate that 3D-BTI could become a fully non-invasive technique to assess myocardial disarray at the bedside of patients.
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Intra-procedural determination of viability by myocardial deformation imaging: a randomized prospective study in the cardiac catheter laboratory. Clin Res Cardiol 2017; 106:629-644. [PMID: 28321497 DOI: 10.1007/s00392-017-1099-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Accepted: 03/01/2017] [Indexed: 10/19/2022]
Abstract
BACKGROUND The benefit of revascularization for functional recovery depends on the presence of viable myocardial tissue. OBJECTIVE Myocardial deformation imaging allows determination of myocardial viability. METHODS In a first approach, we assessed the optimal cutoff value to determine preserved viability by layer-specific echocardiographic myocardial deformation imaging at rest and low-dose dobutamine (DSE) echocardiography: regional endocardial circumferential strain (eCS) <-19% at rest was as accurate as eCS at DSE. In a main study, 123 patients (66% men, age 59 ± 6 years) with relevant coronary stenoses and corresponding severe regional myocardial dysfunction were included and randomized in 2 groups after coronary angiography: group A: intra-procedural myocardial deformation imaging in the cardiac catheter laboratory (CLab), determination of myocardial viability by regional eCS <-19%, in case of positive viability immediate coronary intervention in the same session. Group B: two-step determination of myocardial viability by cardiovascular magnetic resonance (CMR), in case of positive viability coronary intervention. After 18 months follow-up an analysis of the endpoints regarding cardiovascular events, left ventricular (LV) function, and comparison of cost was performed. RESULTS Group A (N = 61) and group B (N = 62) showed no differences concerning localization of the coronary stenosis, comorbidities, or medical therapy. Cardiovascular events at 18-month follow-up were as follows: group A 13% (N = 10) vs. group B 14% (N = 9, p = 0.288); improvement of LV function: group A: +7 ± 2% vs. group B: +7 ± 3%, p = 0.963; costs: group A: 3096 Dollar vs. group B: 6043 Dollar, p < 0.001. CONCLUSION Intra-procedural determination of myocardial viability by myocardial deformation imaging in the CLab is feasible, safe, and cost effective and may become an emerging alternative to the current practice of two-stage viability diagnostics.
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Teh I, McClymont D, Zdora MC, Whittington HJ, Davidoiu V, Lee J, Lygate CA, Rau C, Zanette I, Schneider JE. Validation of diffusion tensor MRI measurements of cardiac microstructure with structure tensor synchrotron radiation imaging. J Cardiovasc Magn Reson 2017; 19:31. [PMID: 28279178 PMCID: PMC5345150 DOI: 10.1186/s12968-017-0342-x] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2016] [Accepted: 02/16/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Diffusion tensor imaging (DTI) is widely used to assess tissue microstructure non-invasively. Cardiac DTI enables inference of cell and sheetlet orientations, which are altered under pathological conditions. However, DTI is affected by many factors, therefore robust validation is critical. Existing histological validation is intrinsically flawed, since it requires further tissue processing leading to sample distortion, is routinely limited in field-of-view and requires reconstruction of three-dimensional volumes from two-dimensional images. In contrast, synchrotron radiation imaging (SRI) data enables imaging of the heart in 3D without further preparation following DTI. The objective of the study was to validate DTI measurements based on structure tensor analysis of SRI data. METHODS One isolated, fixed rat heart was imaged ex vivo with DTI and X-ray phase contrast SRI, and reconstructed at 100 μm and 3.6 μm isotropic resolution respectively. Structure tensors were determined from the SRI data and registered to the DTI data. RESULTS Excellent agreement in helix angles (HA) and transverse angles (TA) was observed between the DTI and structure tensor synchrotron radiation imaging (STSRI) data, where HADTI-STSRI = -1.4° ± 23.2° and TADTI-STSRI = -1.4° ± 35.0° (mean ± 1.96 standard deviation across all voxels in the left ventricle). STSRI confirmed that the primary eigenvector of the diffusion tensor corresponds with the cardiomyocyte long-axis across the whole myocardium. CONCLUSIONS We have used STSRI as a novel and high-resolution gold standard for the validation of DTI, allowing like-with-like comparison of three-dimensional tissue structures in the same intact heart free of distortion. This represents a critical step forward in independently verifying the structural basis and informing the interpretation of cardiac DTI data, thereby supporting the further development and adoption of DTI in structure-based electro-mechanical modelling and routine clinical applications.
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Affiliation(s)
- Irvin Teh
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
- Leeds Institute of Cardiovascular & Metabolic Medicine, University of Leeds, Leeds, UK
| | - Darryl McClymont
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Marie-Christine Zdora
- Diamond Light Source, Didcot, UK
- Department of Physics and Astronomy, University College London, London, UK
| | - Hannah J. Whittington
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Valentina Davidoiu
- Division of Imaging Sciences and Biomedical Engineering, King’s College London, London, UK
| | - Jack Lee
- Division of Imaging Sciences and Biomedical Engineering, King’s College London, London, UK
| | - Craig A. Lygate
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Christoph Rau
- Diamond Light Source, Didcot, UK
- University of Manchester, Manchester, UK
- Feinberg School of Medicine, Northwestern University, Chicago, USA
| | | | - Jürgen E. Schneider
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
- Leeds Institute of Cardiovascular & Metabolic Medicine, University of Leeds, Leeds, UK
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Wu CH, Chen YJ, Wang MH, Chiou LL, Tseng WYI, Lee HS. Diffusion tensor tractography reveals muscle reconnection during axolotl limb regeneration. PLoS One 2017; 12:e0173425. [PMID: 28253344 PMCID: PMC5333890 DOI: 10.1371/journal.pone.0173425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Accepted: 02/19/2017] [Indexed: 11/19/2022] Open
Abstract
Axolotls have amazing ability to regenerate their lost limbs. Our previous works showed that after amputation the remnant muscle ends remained at their original location whilst sending satellite cells into the regenerating parts to develop into early muscle fibers in the late differentiation stage. The parental and the newly formed muscle fibers were not connected until very late stage. The present study used non-invasive diffusion tensor imaging (DTI) to monitor weekly axolotl upper arm muscles after amputation of their upper arms. DTI tractography showed that the regenerating muscle fibers became visible at 9-wpa (weeks post amputation), but a gap was observed between the regenerating and parental muscles. The gap was filled at 10-wpa, indicating reconnection of the fibers of both muscles. This was confirmed by histology. The DTI results indicate that 23% of the muscle fibers were reconnected at 10-wpa. In conclusion, DTI can be used to visualize axolotls' skeletal muscles and the results of muscle reconnection were in accordance with our previous findings. This non-invasive technique will allow researchers to identify the timeframe in which muscle fiber reconnection takes place and thus enable the study of the mechanisms underlying this reconnection.
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Affiliation(s)
- Cheng-Han Wu
- Institute of Biotechnology, National Taiwan University, Taipei, Taiwan
| | - Yu-Jen Chen
- Institute of Medical Device and Imaging, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Mu-Hui Wang
- Institute of Biotechnology, National Taiwan University, Taipei, Taiwan
| | - Ling-Ling Chiou
- Liver Disease Prevention and Treatment Research Foundation, Taipei, Taiwan
| | - Wen-Yih Isaac Tseng
- Institute of Medical Device and Imaging, National Taiwan University College of Medicine, Taipei, Taiwan
- * E-mail: (WYIT); (HSL)
| | - Hsuan-Shu Lee
- Institute of Biotechnology, National Taiwan University, Taipei, Taiwan
- Department of Internal Medicine, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei, Taiwan
- * E-mail: (WYIT); (HSL)
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Robini MC, Ozon M, Frindel C, Yang F, Zhu Y. Global Diffusion Tractography by Simulated Annealing. IEEE Trans Biomed Eng 2017; 64:649-660. [PMID: 28113211 DOI: 10.1109/tbme.2016.2570900] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
OBJECTIVE Our goal is to develop a robust global tractography method for cardiac diffusion imaging. METHODS A graph is stretched over the whole myocardium to represent the fiber structure, and the solutions are minima of a graph energy measuring the fidelity to the data along with the fiber density and curvature. The optimization is performed by a variant of simulated annealing that offers increased design freedom without sacrificing theoretical convergence guarantees. RESULTS Numerical experiments on synthetic and real data demonstrate the capability of our tractography algorithm to deal with low angular resolution, highly noisy data. In particular, our algorithm outperforms the Bayesian model-based algorithm of Reisert et al. (NeuroImage, vol. 54, no. 2, 2011) and the graph-based algorithm of Frindel et al. (Magn. Reson. Med., vol. 64, no. 4, 2010) at the noise levels typical of in vivo imaging. CONCLUSION The proposed algorithm avoids the drawbacks of local techniques and is very robust to noise, which makes it a promising tool for in vivo diffusion imaging of moving organs. SIGNIFICANCE Our approach is global in terms of both the fiber structure representation and the minimization problem. It also allows us to adjust the trajectory density by simply changing the vertex-lattice spacing in the graph model, a desirable feature for multiresolution tractography analysis.
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Pashakhanloo F, Herzka DA, Mori S, Zviman M, Halperin H, Gai N, Bluemke DA, Trayanova NA, McVeigh ER. Submillimeter diffusion tensor imaging and late gadolinium enhancement cardiovascular magnetic resonance of chronic myocardial infarction. J Cardiovasc Magn Reson 2017; 19:9. [PMID: 28122618 PMCID: PMC5264305 DOI: 10.1186/s12968-016-0317-3] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Accepted: 12/20/2016] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Knowledge of the three-dimensional (3D) infarct structure and fiber orientation remodeling is essential for complete understanding of infarct pathophysiology and post-infarction electromechanical functioning of the heart. Accurate imaging of infarct microstructure necessitates imaging techniques that produce high image spatial resolution and high signal-to-noise ratio (SNR). The aim of this study is to provide detailed reconstruction of 3D chronic infarcts in order to characterize the infarct microstructural remodeling in porcine and human hearts. METHODS We employed a customized diffusion tensor imaging (DTI) technique in conjunction with late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) on a 3T clinical scanner to image, at submillimeter resolution, myofiber orientation and scar structure in eight chronically infarcted porcine hearts ex vivo. Systematic quantification of local microstructure was performed and the chronic infarct remodeling was characterized at different levels of wall thickness and scar transmurality. Further, a human heart with myocardial infarction was imaged using the same DTI sequence. RESULTS The SNR of non-diffusion-weighted images was >100 in the infarcted and control hearts. Mean diffusivity and fractional anisotropy (FA) demonstrated a 43% increase, and a 35% decrease respectively, inside the scar tissue. Despite this, the majority of the scar showed anisotropic structure with FA higher than an isotropic liquid. The analysis revealed that the primary eigenvector orientation at the infarcted wall on average followed the pattern of original fiber orientation (imbrication angle mean: 1.96 ± 11.03° vs. 0.84 ± 1.47°, p = 0.61, and inclination angle range: 111.0 ± 10.7° vs. 112.5 ± 6.8°, p = 0.61, infarcted/control wall), but at a higher transmural gradient of inclination angle that increased with scar transmurality (r = 0.36) and the inverse of wall thickness (r = 0.59). Further, the infarcted wall exhibited a significant increase in both the proportion of left-handed epicardial eigenvectors, and in the angle incoherency. The infarcted human heart demonstrated preservation of primary eigenvector orientation at the thinned region of infarct, consistent with the findings in the porcine hearts. CONCLUSIONS The application of high-resolution DTI and LGE-CMR revealed the detailed organization of anisotropic infarct structure at a chronic state. This information enhances our understanding of chronic post-infarction remodeling in large animal and human hearts.
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Affiliation(s)
- Farhad Pashakhanloo
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD USA
| | - Daniel A. Herzka
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD USA
| | - Susumu Mori
- Department of Radiology, Johns Hopkins University, Baltimore, MD USA
| | - Muz Zviman
- Department of Medicine, Johns Hopkins University, Baltimore, MD USA
| | - Henry Halperin
- Department of Medicine, Johns Hopkins University, Baltimore, MD USA
| | - Neville Gai
- Radiology and Imaging Sciences, National Institutes of Health Clinical Center, Bethesda, MD USA
| | - David A. Bluemke
- Radiology and Imaging Sciences, National Institutes of Health Clinical Center, Bethesda, MD USA
| | - Natalia A. Trayanova
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD USA
| | - Elliot R. McVeigh
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD USA
- Department of Medicine, Johns Hopkins University, Baltimore, MD USA
- Departments of Bioengineering, Medicine, Radiology, University of California, 9500 Gilman Drive-MC0412,La Jolla, San Diego, 92093-0412 CA USA
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Carruth ED, McCulloch AD, Omens JH. Transmural gradients of myocardial structure and mechanics: Implications for fiber stress and strain in pressure overload. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2016; 122:215-226. [PMID: 27845176 DOI: 10.1016/j.pbiomolbio.2016.11.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Although a truly complete understanding of whole heart activation, contraction, and deformation is well beyond our current reach, a significant amount of effort has been devoted to discovering and understanding the mechanisms by which myocardial structure determines cardiac function to better treat patients with cardiac disease. Several experimental studies have shown that transmural fiber strain is relatively uniform in both diastole and systole, in contrast to predictions from traditional mechanical theory. Similarly, mathematical models have largely predicted uniform fiber stress across the wall. The development of this uniform pattern of fiber stress and strain during filling and ejection is due to heterogeneous transmural distributions of several myocardial structures. This review summarizes these transmural gradients, their contributions to fiber mechanics, and the potential functional effects of their remodeling during pressure overload hypertrophy.
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Affiliation(s)
- Eric D Carruth
- Department of Bioengineering, University of California San Diego, La Jolla, CA, USA.
| | - Andrew D McCulloch
- Department of Bioengineering, University of California San Diego, La Jolla, CA, USA.
| | - Jeffrey H Omens
- Department of Bioengineering, University of California San Diego, La Jolla, CA, USA; Department of Medicine, University of California San Diego, La Jolla, CA, USA.
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46
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Tran N, Giannakidis A, Gullberg GT, Seo Y. Quantitative analysis of hypertrophic myocardium using diffusion tensor magnetic resonance imaging. J Med Imaging (Bellingham) 2016; 3:046001. [PMID: 27872872 DOI: 10.1117/1.jmi.3.4.046001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 09/28/2016] [Indexed: 11/14/2022] Open
Abstract
Systemic hypertension is a causative factor in left ventricular hypertrophy (LVH). This study is motivated by the potential to reverse or manage the dysfunction associated with structural remodeling of the myocardium in this pathology. Using diffusion tensor magnetic resonance imaging, we present an analysis of myocardial fiber and laminar sheet orientation in ex vivo hypertrophic (6 SHR) and normal (5 WKY) rat hearts using the covariance of the diffusion tensor. First, an atlas of normal cardiac microstructure was formed using the WKY b0 images. Then, the SHR and WKY b0 hearts were registered to the atlas. The acquired deformation fields were applied to the SHR and WKY heart tensor fields followed by the preservation of principal direction (PPD) reorientation strategy. A mean tensor field was then formed from the registered WKY tensor images. Calculating the covariance of the registered tensor images about this mean for each heart, the hypertrophic myocardium exhibited significantly increased myocardial fiber derangement ([Formula: see text]) with a mean dispersion of 38.7 deg, and an increased dispersion of the laminar sheet normal ([Formula: see text]) of 54.8 deg compared with 34.8 deg and 51.8 deg, respectively, in the normal hearts. Results demonstrate significantly altered myocardial fiber and laminar sheet structure in rats with hypertensive LVH.
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Affiliation(s)
- Nicholas Tran
- University of California , Department of Radiology and Biomedical Imaging, Physics Research Laboratory, 185 Berry Street, Ste 350, San Francisco, United States
| | - Archontis Giannakidis
- Royal Brompton Hospital, Cardiovascular Biomedical Research Unit, Sydney Street, London SW3 6NP, United Kingdom; National Heart and Lung Institute, Imperial College London, Sydney Street, London SW3 6NP, United Kingdom; Lawrence Berkeley National Laboratory, Structural Biology and Imaging Department, One Cyclotron Road, Berkeley, California, United States
| | - Grant T Gullberg
- University of California, Department of Radiology and Biomedical Imaging, Physics Research Laboratory, 185 Berry Street, Ste 350, San Francisco, United States; Lawrence Berkeley National Laboratory, Structural Biology and Imaging Department, One Cyclotron Road, Berkeley, California, United States; University of California, Joint Graduate Group in Bioengineering, 1700 4th Street, San Francisco, United States
| | - Youngho Seo
- University of California, Department of Radiology and Biomedical Imaging, Physics Research Laboratory, 185 Berry Street, Ste 350, San Francisco, United States; Lawrence Berkeley National Laboratory, Structural Biology and Imaging Department, One Cyclotron Road, Berkeley, California, United States; University of California, Joint Graduate Group in Bioengineering, 1700 4th Street, San Francisco, United States; University of California, Department of Radiation Oncology, 1600 Divisadero Street, San Francisco, United States
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47
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Giannakidis A, Melkus G, Yang G, Gullberg GT. On the averaging of cardiac diffusion tensor MRI data: the effect of distance function selection. Phys Med Biol 2016; 61:7765-7786. [PMID: 27754986 DOI: 10.1088/0031-9155/61/21/7765] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Diffusion tensor magnetic resonance imaging (DT-MRI) allows a unique insight into the microstructure of highly-directional tissues. The selection of the most proper distance function for the space of diffusion tensors is crucial in enhancing the clinical application of this imaging modality. Both linear and nonlinear metrics have been proposed in the literature over the years. The debate on the most appropriate DT-MRI distance function is still ongoing. In this paper, we presented a framework to compare the Euclidean, affine-invariant Riemannian and log-Euclidean metrics using actual high-resolution DT-MRI rat heart data. We employed temporal averaging at the diffusion tensor level of three consecutive and identically-acquired DT-MRI datasets from each of five rat hearts as a means to rectify the background noise-induced loss of myocyte directional regularity. This procedure is applied here for the first time in the context of tensor distance function selection. When compared with previous studies that used a different concrete application to juxtapose the various DT-MRI distance functions, this work is unique in that it combined the following: (i) metrics were judged by quantitative-rather than qualitative-criteria, (ii) the comparison tools were non-biased, (iii) a longitudinal comparison operation was used on a same-voxel basis. The statistical analyses of the comparison showed that the three DT-MRI distance functions tend to provide equivalent results. Hence, we came to the conclusion that the tensor manifold for cardiac DT-MRI studies is a curved space of almost zero curvature. The signal to noise ratio dependence of the operations was investigated through simulations. Finally, the 'swelling effect' occurrence following Euclidean averaging was found to be too unimportant to be worth consideration.
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Affiliation(s)
- Archontis Giannakidis
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA. Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, London, SW3 6NP, UK. National Heart & Lung Institute, Imperial College London, London, SW3 6NP, UK
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Abdullah OM, Seidel T, Dahl M, Gomez AD, Yiep G, Cortino J, Sachse FB, Albertine KH, Hsu EW. Diffusion tensor imaging and histology of developing hearts. NMR IN BIOMEDICINE 2016; 29:1338-1349. [PMID: 27485033 PMCID: PMC5160010 DOI: 10.1002/nbm.3576] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 05/24/2016] [Accepted: 06/03/2016] [Indexed: 06/06/2023]
Abstract
Diffusion tensor imaging (DTI) has emerged as a promising method for noninvasive quantification of myocardial microstructure. However, the origin and behavior of DTI measurements during myocardial normal development and remodeling remain poorly understood. In this work, conventional and bicompartmental DTI in addition to three-dimensional histological correlation were performed in a sheep model of myocardial development from third trimester to postnatal 5 months of age. Comparing the earliest time points in the third trimester with the postnatal 5 month group, the scalar transverse diffusivities preferentially increased in both left ventricle (LV) and right ventricle (RV): secondary eigenvalues D2 increased by 54% (LV) and 36% (RV), whereas tertiary eigenvalues D3 increased by 85% (LV) and 67% (RV). The longitudinal diffusivity D1 changes were small, which led to a decrease in fractional anisotropy by 41% (LV) and 33% (RV) in 5 month versus fetal hearts. Histological analysis suggested that myocardial development is associated with hyperplasia in the early stages of the third trimester followed by myocyte growth in the later stages up to 5 months of age (increased average myocyte width by 198%, myocyte length by 128%, and decreased nucleus density by 70% between preterm and postnatal 5 month hearts.) In a few histological samples (N = 6), correlations were observed between DTI longitudinal diffusivity and myocyte length (r = 0.86, P < 0.05), and transverse diffusivity and myocyte width (r = 0.96, P < 0.01). Linear regression analysis showed that transverse diffusivities are more affected by changes in myocyte size and nucleus density changes than longitudinal diffusivities, which is consistent with predictions of classical models of diffusion in porous media. Furthermore, primary and secondary DTI eigenvectors during development changed significantly. Collectively, the findings demonstrate a role for DTI to monitor and quantify myocardial development, and potentially cardiac disease. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Osama M Abdullah
- Department of Bioengineering, University of Utah, Salt Lake City, UT, USA.
| | - Thomas Seidel
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT, USA
| | - MarJanna Dahl
- Department of Pediatrics, University of Utah, Salt Lake City, UT, USA
| | - Arnold David Gomez
- Department of Electrical Computer Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Gavin Yiep
- Department of Bioengineering, University of Utah, Salt Lake City, UT, USA
| | - Julia Cortino
- Department of Bioengineering, University of Utah, Salt Lake City, UT, USA
| | - Frank B Sachse
- Department of Bioengineering, University of Utah, Salt Lake City, UT, USA
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT, USA
| | - Kurt H Albertine
- Department of Pediatrics, University of Utah, Salt Lake City, UT, USA
| | - Edward W Hsu
- Department of Bioengineering, University of Utah, Salt Lake City, UT, USA
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Rodriguez B, Carusi A, Abi-Gerges N, Ariga R, Britton O, Bub G, Bueno-Orovio A, Burton RAB, Carapella V, Cardone-Noott L, Daniels MJ, Davies MR, Dutta S, Ghetti A, Grau V, Harmer S, Kopljar I, Lambiase P, Lu HR, Lyon A, Minchole A, Muszkiewicz A, Oster J, Paci M, Passini E, Severi S, Taggart P, Tinker A, Valentin JP, Varro A, Wallman M, Zhou X. Human-based approaches to pharmacology and cardiology: an interdisciplinary and intersectorial workshop. Europace 2016; 18:1287-98. [PMID: 26622055 PMCID: PMC5006958 DOI: 10.1093/europace/euv320] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Accepted: 08/20/2015] [Indexed: 12/12/2022] Open
Abstract
Both biomedical research and clinical practice rely on complex datasets for the physiological and genetic characterization of human hearts in health and disease. Given the complexity and variety of approaches and recordings, there is now growing recognition of the need to embed computational methods in cardiovascular medicine and science for analysis, integration and prediction. This paper describes a Workshop on Computational Cardiovascular Science that created an international, interdisciplinary and inter-sectorial forum to define the next steps for a human-based approach to disease supported by computational methodologies. The main ideas highlighted were (i) a shift towards human-based methodologies, spurred by advances in new in silico, in vivo, in vitro, and ex vivo techniques and the increasing acknowledgement of the limitations of animal models. (ii) Computational approaches complement, expand, bridge, and integrate in vitro, in vivo, and ex vivo experimental and clinical data and methods, and as such they are an integral part of human-based methodologies in pharmacology and medicine. (iii) The effective implementation of multi- and interdisciplinary approaches, teams, and training combining and integrating computational methods with experimental and clinical approaches across academia, industry, and healthcare settings is a priority. (iv) The human-based cross-disciplinary approach requires experts in specific methodologies and domains, who also have the capacity to communicate and collaborate across disciplines and cross-sector environments. (v) This new translational domain for human-based cardiology and pharmacology requires new partnerships supported financially and institutionally across sectors. Institutional, organizational, and social barriers must be identified, understood and overcome in each specific setting.
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Affiliation(s)
- Blanca Rodriguez
- Department of Computer Science, University of Oxford, Oxford, UK
| | | | - Najah Abi-Gerges
- AnaBios Corporation, San Diego Science Center, San Diego, CA 92109, USA
| | - Rina Ariga
- Radcliffe Department of Medicine, University of Oxford, John Radcliffe Hospital, Oxford, UK
| | - Oliver Britton
- Department of Computer Science, University of Oxford, Oxford, UK
| | - Gil Bub
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | | | - Rebecca A B Burton
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | | | | | - Matthew J Daniels
- Radcliffe Department of Medicine, University of Oxford, John Radcliffe Hospital, Oxford, UK
| | | | - Sara Dutta
- Department of Computer Science, University of Oxford, Oxford, UK
| | - Andre Ghetti
- AnaBios Corporation, San Diego Science Center, San Diego, CA 92109, USA
| | - Vicente Grau
- Department of Engineering Science, University of Oxford, Oxford, UK
| | - Stephen Harmer
- William Harvey Heart Centre, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, Charterhouse Square, London, UK
| | - Ivan Kopljar
- Discovery Sciences, Dis&Dev Research, Janssen Pharmaceutical NV, Beerse, Belgium
| | - Pier Lambiase
- Institute of Cardiovascular Science, University College London, Bars Heart Centre, London, UK
| | - Hua Rong Lu
- Discovery Sciences, Dis&Dev Research, Janssen Pharmaceutical NV, Beerse, Belgium
| | - Aurore Lyon
- Department of Computer Science, University of Oxford, Oxford, UK
| | - Ana Minchole
- Department of Computer Science, University of Oxford, Oxford, UK
| | - Anna Muszkiewicz
- Department of Computer Science, University of Oxford, Oxford, UK
| | - Julien Oster
- Department of Engineering Science, University of Oxford, Oxford, UK
| | - Michelangelo Paci
- Department of Electronics and Communications Engineering, Tampere University of Technology, BioMediTech, Tampere, Finland
| | - Elisa Passini
- Department of Computer Science, University of Oxford, Oxford, UK
| | - Stefano Severi
- Department of Electrical, Electronic and Information Engineering, University of Bologna, Cesena 47521, Italy
| | - Peter Taggart
- Institute of Cardiovascular Science, University College London, Bars Heart Centre, London, UK
| | - Andy Tinker
- William Harvey Heart Centre, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, Charterhouse Square, London, UK
| | | | | | | | - Xin Zhou
- Department of Computer Science, University of Oxford, Oxford, UK
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50
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Determinants of biventricular cardiac function: a mathematical model study on geometry and myofiber orientation. Biomech Model Mechanobiol 2016; 16:721-729. [PMID: 27581324 PMCID: PMC5350259 DOI: 10.1007/s10237-016-0825-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Accepted: 08/24/2016] [Indexed: 11/19/2022]
Abstract
In patient-specific mathematical models of cardiac electromechanics, usually a patient-specific geometry and a generic myofiber orientation field are used as input, upon which myocardial tissue properties are tuned to clinical data. It remains unclear to what extent deviations in myofiber orientation and geometry between model and patient influence model predictions on cardiac function. Therefore, we evaluated the sensitivity of cardiac function for geometry and myofiber orientation in a biventricular (BiV) finite element model of cardiac mechanics. Starting out from a reference geometry in which myofiber orientation had no transmural component, two new geometries were defined with either a 27 % decrease in LV short- to long-axis ratio, or a 16 % decrease of RV length, but identical LV and RV cavity and wall volumes. These variations in geometry caused differences in both local myofiber and global pump work below 6 %. Variation of fiber orientation was induced through adaptive myofiber reorientation that caused an average change in fiber orientation of \documentclass[12pt]{minimal}
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\begin{document}$${\sim }8^\circ $$\end{document}∼8∘ predominantly through the formation of a component in transmural direction. Reorientation caused a considerable increase in local myofiber work \documentclass[12pt]{minimal}
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\begin{document}$$({\sim }18\,\%)$$\end{document}(∼18%) and in global pump work \documentclass[12pt]{minimal}
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\begin{document}$$({\sim }17\,\%)$$\end{document}(∼17%) in all three geometries, while differences between geometries were below 5 %. The findings suggest that implementing a realistic myofiber orientation is at least as important as defining a patient-specific geometry. The model for remodeling of myofiber orientation seems a useful approach to estimate myofiber orientation in the absence of accurate patient-specific information.
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