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von Deuster C, Sammut E, Asner L, Nordsletten D, Lamata P, Stoeck CT, Kozerke S, Razavi R. Studying Dynamic Myofiber Aggregate Reorientation in Dilated Cardiomyopathy Using In Vivo Magnetic Resonance Diffusion Tensor Imaging. Circ Cardiovasc Imaging 2017; 9:CIRCIMAGING.116.005018. [PMID: 27729361 PMCID: PMC5068188 DOI: 10.1161/circimaging.116.005018] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Accepted: 08/26/2016] [Indexed: 11/30/2022]
Abstract
Supplemental Digital Content is available in the text. Background— The objective of this study is to assess the dynamic alterations of myocardial microstructure and strain between diastole and systole in patients with dilated cardiomyopathy relative to healthy controls using the magnetic resonance diffusion tensor imaging, myocardial tagging, and biomechanical modeling. Methods and Results— Dual heart-phase diffusion tensor imaging was successfully performed in 9 patients and 9 controls. Tagging data were acquired for the diffusion tensor strain correction and cardiac motion analysis. Mean diffusivity, fractional anisotropy, and myocyte aggregate orientations were compared between both cohorts. Cardiac function was assessed by left ventricular ejection fraction, torsion, and strain. Computational modeling was used to study the impact of cardiac shape on fiber reorientation and how fiber orientations affect strain. In patients with dilated cardiomyopathy, a more longitudinal orientation of diastolic myofiber aggregates was measured compared with controls. Although a significant steepening of helix angles (HAs) during contraction was found in the controls, consistent change in HAs during contraction was absent in patients. Left ventricular ejection fraction, cardiac torsion, and strain were significantly lower in the patients compared with controls. Computational modeling revealed that the dilated heart results in reduced HA changes compared with a normal heart. Reduced torsion was found to be exacerbated by steeper HAs. Conclusions— Diffusion tensor imaging revealed reduced reorientation of myofiber aggregates during cardiac contraction in patients with dilated cardiomyopathy relative to controls. Left ventricular remodeling seems to be an important factor in the changes to myocyte orientation. Steeper HAs are coupled with a worsening in strain and torsion. Overall, the findings provide new insights into the structural alterations in patients with dilated cardiomyopathy.
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Affiliation(s)
- Constantin von Deuster
- From the Department for Biomedical Engineering, Division of Imaging Sciences and Biomedical Engineering, King's College London, United Kingdom (C.v.D., E.S., L.A., D.N., P.L., C.T.S, S.K., R.R.); and Department of Information Technology and Electrical Engineering, Institute for Biomedical Engineering, University and ETH Zurich, Switzerland (C.v.D., C.T.S., S.K.)
| | - Eva Sammut
- From the Department for Biomedical Engineering, Division of Imaging Sciences and Biomedical Engineering, King's College London, United Kingdom (C.v.D., E.S., L.A., D.N., P.L., C.T.S, S.K., R.R.); and Department of Information Technology and Electrical Engineering, Institute for Biomedical Engineering, University and ETH Zurich, Switzerland (C.v.D., C.T.S., S.K.)
| | - Liya Asner
- From the Department for Biomedical Engineering, Division of Imaging Sciences and Biomedical Engineering, King's College London, United Kingdom (C.v.D., E.S., L.A., D.N., P.L., C.T.S, S.K., R.R.); and Department of Information Technology and Electrical Engineering, Institute for Biomedical Engineering, University and ETH Zurich, Switzerland (C.v.D., C.T.S., S.K.)
| | - David Nordsletten
- From the Department for Biomedical Engineering, Division of Imaging Sciences and Biomedical Engineering, King's College London, United Kingdom (C.v.D., E.S., L.A., D.N., P.L., C.T.S, S.K., R.R.); and Department of Information Technology and Electrical Engineering, Institute for Biomedical Engineering, University and ETH Zurich, Switzerland (C.v.D., C.T.S., S.K.)
| | - Pablo Lamata
- From the Department for Biomedical Engineering, Division of Imaging Sciences and Biomedical Engineering, King's College London, United Kingdom (C.v.D., E.S., L.A., D.N., P.L., C.T.S, S.K., R.R.); and Department of Information Technology and Electrical Engineering, Institute for Biomedical Engineering, University and ETH Zurich, Switzerland (C.v.D., C.T.S., S.K.)
| | - Christian T Stoeck
- From the Department for Biomedical Engineering, Division of Imaging Sciences and Biomedical Engineering, King's College London, United Kingdom (C.v.D., E.S., L.A., D.N., P.L., C.T.S, S.K., R.R.); and Department of Information Technology and Electrical Engineering, Institute for Biomedical Engineering, University and ETH Zurich, Switzerland (C.v.D., C.T.S., S.K.)
| | - Sebastian Kozerke
- From the Department for Biomedical Engineering, Division of Imaging Sciences and Biomedical Engineering, King's College London, United Kingdom (C.v.D., E.S., L.A., D.N., P.L., C.T.S, S.K., R.R.); and Department of Information Technology and Electrical Engineering, Institute for Biomedical Engineering, University and ETH Zurich, Switzerland (C.v.D., C.T.S., S.K.).
| | - Reza Razavi
- From the Department for Biomedical Engineering, Division of Imaging Sciences and Biomedical Engineering, King's College London, United Kingdom (C.v.D., E.S., L.A., D.N., P.L., C.T.S, S.K., R.R.); and Department of Information Technology and Electrical Engineering, Institute for Biomedical Engineering, University and ETH Zurich, Switzerland (C.v.D., C.T.S., S.K.)
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Heterogeneity of Fractional Anisotropy and Mean Diffusivity Measurements by In Vivo Diffusion Tensor Imaging in Normal Human Hearts. PLoS One 2015; 10:e0132360. [PMID: 26177211 PMCID: PMC4503691 DOI: 10.1371/journal.pone.0132360] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Accepted: 06/14/2015] [Indexed: 11/19/2022] Open
Abstract
Background Cardiac diffusion tensor imaging (cDTI) by cardiovascular magnetic resonance has the potential to assess microstructural changes through measures of fractional anisotropy (FA) and mean diffusivity (MD). However, normal variation in regional and transmural FA and MD is not well described. Methods Twenty normal subjects were scanned using an optimised cDTI sequence at 3T in systole. FA and MD were quantified in 3 transmural layers and 4 regional myocardial walls. Results FA was higher in the mesocardium (0.46 ±0.04) than the endocardium (0.40 ±0.04, p≤0.001) and epicardium (0.39 ±0.04, p≤0.001). On regional analysis, the FA in the septum was greater than the lateral wall (0.44 ±0.03 vs 0.40 ±0.05 p = 0.04). There was a transmural gradient in MD increasing towards the endocardium (epicardium 0.87 ±0.07 vs endocardium 0.91 ±0.08×10-3 mm2/s, p = 0.04). With the lateral wall (0.87 ± 0.08×10-3 mm2/s) as the reference, the MD was higher in the anterior wall (0.92 ±0.08×10-3 mm2/s, p = 0.016) and septum (0.92 ±0.07×10-3 mm2/s, p = 0.028). Transmurally the signal to noise ratio (SNR) was greatest in the mesocardium (14.5 ±2.5 vs endocardium 13.1 ±2.2, p<0.001; vs epicardium 12.0 ± 2.4, p<0.001) and regionally in the septum (16.0 ±3.4 vs lateral wall 11.5 ± 1.5, p<0.001). Transmural analysis suggested a relative reduction in the rate of change in helical angle (HA) within the mesocardium. Conclusions In vivo FA and MD measurements in normal human heart are heterogeneous, varying significantly transmurally and regionally. Contributors to this heterogeneity are many, complex and interactive, but include SNR, variations in cardiac microstructure, partial volume effects and strain. These data indicate that the potential clinical use of FA and MD would require measurement standardisation by myocardial region and layer, unless pathological changes substantially exceed the normal variation identified.
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Stoeck CT, Kalinowska A, von Deuster C, Harmer J, Chan RW, Niemann M, Manka R, Atkinson D, Sosnovik DE, Mekkaoui C, Kozerke S. Dual-phase cardiac diffusion tensor imaging with strain correction. PLoS One 2014; 9:e107159. [PMID: 25191900 PMCID: PMC4156436 DOI: 10.1371/journal.pone.0107159] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Accepted: 08/05/2014] [Indexed: 12/03/2022] Open
Abstract
Purpose In this work we present a dual-phase diffusion tensor imaging (DTI) technique that incorporates a correction scheme for the cardiac material strain, based on 3D myocardial tagging. Methods In vivo dual-phase cardiac DTI with a stimulated echo approach and 3D tagging was performed in 10 healthy volunteers. The time course of material strain was estimated from the tagging data and used to correct for strain effects in the diffusion weighted acquisition. Mean diffusivity, fractional anisotropy, helix, transverse and sheet angles were calculated and compared between systole and diastole, with and without strain correction. Data acquired at the systolic sweet spot, where the effects of strain are eliminated, served as a reference. Results The impact of strain correction on helix angle was small. However, large differences were observed in the transverse and sheet angle values, with and without strain correction. The standard deviation of systolic transverse angles was significantly reduced from 35.9±3.9° to 27.8°±3.5° (p<0.001) upon strain-correction indicating more coherent fiber tracks after correction. Myocyte aggregate structure was aligned more longitudinally in systole compared to diastole as reflected by an increased transmural range of helix angles (71.8°±3.9° systole vs. 55.6°±5.6°, p<0.001 diastole). While diastolic sheet angle histograms had dominant counts at high sheet angle values, systolic histograms showed lower sheet angle values indicating a reorientation of myocyte sheets during contraction. Conclusion An approach for dual-phase cardiac DTI with correction for material strain has been successfully implemented. This technique allows assessing dynamic changes in myofiber architecture between systole and diastole, and emphasizes the need for strain correction when sheet architecture in the heart is imaged with a stimulated echo approach.
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Affiliation(s)
- Christian T. Stoeck
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
| | - Aleksandra Kalinowska
- Department of Mechanical and Biomedical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Constantin von Deuster
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
- Imaging Sciences and Biomedical Engineering, King's College London, London, United Kingdom
| | - Jack Harmer
- Imaging Sciences and Biomedical Engineering, King's College London, London, United Kingdom
| | - Rachel W. Chan
- Centre for Medical Imaging, University College London, London, United Kingdom
| | - Markus Niemann
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
- Department of Cardiology, University Hospital Zurich, Zurich, Switzerland
| | - Robert Manka
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
- Department of Cardiology, University Hospital Zurich, Zurich, Switzerland
- Department of Radiology, University Hospital Zurich, Zurich, Switzerland
| | - David Atkinson
- Centre for Medical Imaging, University College London, London, United Kingdom
| | - David E. Sosnovik
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
- Cardiovascular Research Center, Cardiology Division, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Choukri Mekkaoui
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Radiology, University Hospital Center of Nîmes, EA 2415, Nîmes, France
- Faculty of Medicine, Montpellier 1 University, Montpellier, France
| | - Sebastian Kozerke
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
- Imaging Sciences and Biomedical Engineering, King's College London, London, United Kingdom
- * E-mail:
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Lohezic M, Teh I, Bollensdorff C, Peyronnet R, Hales PW, Grau V, Kohl P, Schneider JE. Interrogation of living myocardium in multiple static deformation states with diffusion tensor and diffusion spectrum imaging. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2014; 115:213-25. [PMID: 25117498 PMCID: PMC4210665 DOI: 10.1016/j.pbiomolbio.2014.08.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Accepted: 08/02/2014] [Indexed: 11/27/2022]
Abstract
Diffusion tensor magnetic resonance imaging (MRI) reveals valuable insights into tissue histo-anatomy and microstructure, and has steadily gained traction in the cardiac community. Its wider use in small animal cardiac imaging in vivo has been constrained by its extreme sensitivity to motion, exaggerated by the high heart rates usually seen in rodents. Imaging of the isolated heart eliminates respiratory motion and, if conducted on arrested hearts, cardiac pulsation. This serves as an important intermediate step for basic and translational studies. However, investigating the micro-structural basis of cardiac deformation in the same heart requires observations in different deformation states. Here, we illustrate the imaging of isolated rat hearts in three mechanical states mimicking diastole (cardioplegic arrest), left-ventricular (LV) volume overload (cardioplegic arrest plus LV balloon inflation), and peak systole (lithium-induced contracture). An optimised MRI-compatible Langendorff perfusion setup with the radio-frequency (RF) coil integrated into the wet chamber was developed for use in a 9.4T horizontal bore scanner. Signal-to-noise ratio improved significantly, by 75% compared to a previous design with external RF coil, and stability tests showed no significant changes in mean T1, T2 or LV wall thickness over a 170 min period. In contracture, we observed a significant reduction in mean fractional anisotropy from 0.32 ± 0.02 to 0.28 ± 0.02, as well as a significant rightward shift in helix angles with a decrease in the proportion of left-handed fibres, as referring to the locally prevailing cell orientation in the heart, from 24.9% to 23.3%, and an increase in the proportion of right-handed fibres from 25.5% to 28.4%. LV overload, in contrast, gave rise to a decrease in the proportion of left-handed fibres from 24.9% to 21.4% and an increase in the proportion of right-handed fibres from 25.5% to 26.0%. The modified perfusion and coil setup offers better performance and control over cardiac contraction states. We subsequently performed high-resolution diffusion spectrum imaging (DSI) and 3D whole heart fibre tracking in fixed ex vivo rat hearts in slack state and contracture. As a model-free method, DSI augmented the measurements of water diffusion by also informing on multiple intra-voxel diffusion orientations and non-Gaussian diffusion. This enabled us to identify the transition from right- to left-handed fibres from the subendocardium to the subepicardium, as well as voxels in apical regions that were traversed by multiple fibres. We observed that both the mean generalised fractional anisotropy and mean kurtosis were lower in hearts in contracture compared to the slack state, by 23% and 9.3%, respectively. While its heavy acquisition burden currently limits the application of DSI in vivo, ongoing work in acceleration techniques may enable its use in live animals and patients. This would provide access to the as yet unexplored dimension of non-Gaussian diffusion that could serve as a highly sensitive marker of cardiac micro-structural integrity.
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Affiliation(s)
- Maelene Lohezic
- British Heart Foundation Experimental Magnetic Resonance Unit, Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Irvin Teh
- British Heart Foundation Experimental Magnetic Resonance Unit, Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Christian Bollensdorff
- National Heart and Lung Institute, Imperial College London, London, UK; Qatar Cardiovascular Research Center, Qatar Foundation, Doha, Qatar
| | - Rémi Peyronnet
- National Heart and Lung Institute, Imperial College London, London, UK
| | - Patrick W Hales
- Imaging and Biophysics Unit, Institute of Child Health, University College London, London, UK
| | - Vicente Grau
- Department of Engineering Science, University of Oxford, Oxford, UK
| | - Peter Kohl
- National Heart and Lung Institute, Imperial College London, London, UK; Department of Computer Science, University of Oxford, Oxford, UK
| | - Jürgen E Schneider
- British Heart Foundation Experimental Magnetic Resonance Unit, Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK.
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