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Nguyen KD, Bonner BP, Foster AN, Sadighi M, Nguyen CT. Asynchronous magnetic resonance elastography: Shear wave speed reconstruction using noise correlation of incoherent waves. Magn Reson Med 2023; 89:990-1001. [PMID: 36300861 PMCID: PMC9792433 DOI: 10.1002/mrm.29502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 09/30/2022] [Accepted: 10/05/2022] [Indexed: 02/02/2023]
Abstract
PURPOSE The noninvasive measurement of biological tissue elasticity is an evolving technology that enables the robust characterization of soft tissue mechanics for a wide array of biomedical engineering and clinical applications. We propose, design, and implement here a new MRI technique termed asynchronous magnetic resonance elastography (aMRE) that pushes the measurement technology toward a driverless implementation. This technique can be added to clinical MRI scanners without any additional specialized hardware. THEORY Asynchronous MRE is founded on the theory of diffuse wavefields and noise correlation previously developed in ultrasound to reconstruct shear wave speeds using seemingly incoherent wavefields. Unlike conventional elastography methods that solve an inverse problem, aMRE directly reconstructs a pixel-wise mapping of wave speed using the spatial-temporal statistics of the measured wavefield. METHODS Incoherent finger tapping served as the wave-generating source for all aMRE measurements. Asynchronous MRE was performed on a phantom using a Siemens Prismafit as an experimental validation of the theory. It was further performed on thigh muscles as a proof-of-concept implementation of in vivo imaging using a Siemens Skyra scanner. RESULTS Numerical and phantom experiments show an accurate reconstruction of wave speeds from seemingly noisy wavefields. The proof-of-concept thigh experiments also show that the aMRE protocol can reconstruct a pixel-wise mapping of wave speeds. CONCLUSION Asynchronous MRE is shown to accurately reconstruct shear wave speeds in phantom experiments and remains at the proof-of-concept stage for in vivo imaging. After further validation and improvements, it has the potential to lower both the technical and monetary barriers of entry to measuring tissue elasticity.
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Affiliation(s)
- Khoi D. Nguyen
- Cardiovascular Innovation Research Center, Heart Vascular & Thoracic Institute, Cleveland Clinic, Cleveland, OH,Cardiovascular Research Center, Massachusetts General Hospital, Charlestown, MA,Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA
| | - Benjamin P. Bonner
- Cardiovascular Research Center, Massachusetts General Hospital, Charlestown, MA,Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA
| | - Anna N. Foster
- Cardiovascular Research Center, Massachusetts General Hospital, Charlestown, MA,Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA
| | - Mehdi Sadighi
- Cardiovascular Innovation Research Center, Heart Vascular & Thoracic Institute, Cleveland Clinic, Cleveland, OH,Cardiovascular Research Center, Massachusetts General Hospital, Charlestown, MA,Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA
| | - Christopher T. Nguyen
- Cardiovascular Innovation Research Center, Heart Vascular & Thoracic Institute, Cleveland Clinic, Cleveland, OH,Cardiovascular Research Center, Massachusetts General Hospital, Charlestown, MA,Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA,Department of Diagnostic Radiology Imaging, Imaging Institute, Cleveland Clinic, Cleveland, OH,Department of Cardiovascular & Metabolic Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH,Corresponding author.
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Ehman RL. Magnetic resonance elastography: from invention to standard of care. Abdom Radiol (NY) 2022; 47:3028-3036. [PMID: 35852570 PMCID: PMC9538645 DOI: 10.1007/s00261-022-03597-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 06/15/2022] [Accepted: 06/16/2022] [Indexed: 01/18/2023]
Abstract
In 1995, a vivid image of diffracting waves in red and blue was published on the cover of the journal SCIENCE. An article in that issue described a new imaging technology called magnetic resonance elastography (MRE) (Muthupillai in Science 269:1854-1857, 1995). In 2004, quantitative images of liver stiffness in vivo, obtained with MRE, were demonstrated for the first time at the annual meeting of the International Society for Magnetic Resonance in Medicine. Only five years later, the technology had become widely available as an FDA-cleared diagnostic tool for patient care. MRE has emerged as a reliable non-invasive diagnostic method for detecting and staging liver fibrosis. Deployed on more than 2000 MRI systems worldwide, MRE has received a Category I CPT code from the American Medical Association, based on clinical availability and efficacy. For many patients, MRE now provides a safe, more comfortable, and much less expensive alternative to liver biopsy for diagnosing liver fibrosis. Although progress in radiology is notable for a history of very rapid translation of technology innovations to patient care, the path is rarely linear. This article reflects on the story of MRE, the advances and the setbacks, and the lessons that were learned in the process.
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Hu X, Zhou J, Li Y, Wang Y, Guo J, Sack I, Chen W, Yan F, Li R, Wang C. Added Value of Viscoelasticity for MRI-Based Prediction of Ki-67 Expression of Hepatocellular Carcinoma Using a Deep Learning Combined Radiomics (DLCR) Model. Cancers (Basel) 2022; 14:cancers14112575. [PMID: 35681558 PMCID: PMC9179448 DOI: 10.3390/cancers14112575] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2022] [Revised: 05/14/2022] [Accepted: 05/17/2022] [Indexed: 12/11/2022] Open
Abstract
Simple Summary This study aimed to explore the added value of magnetic resonance elastography (MRE) in the prediction of Ki-67 expression in hepatocellular carcinoma (HCC) using a deep learning combined radiomics (DLCR) model. A total of 108 histopathology-proven HCC patients who underwent preoperative MRI and MR elastography were included. All the patients were divided into training and validation cohorts. An independent cohort including 43 patients was included for testing. A DLCR model was proposed to predict the expression of Ki-67 with conventional MRI (cMRI) as inputs. The images of shear wave speed (c-map) and phase angle (φ-map) derived from MRE were also fed into the DLCR model. Experimental results show that both c and φ values were ranked within the top six features for Ki-67 prediction with random forest selection, which revealed the value of MRE-based viscosity for the assessment of the tumor proliferation status in HCC. The model with all modalities (MRE, AFP, and cMRI) as inputs achieved the highest AUC of 0.90 ± 0.03 (CI: 0.89–0.91) in the validation cohort. The same finding was observed in the independent testing cohort with an AUC of 0.83 ± 0.03 (CI: 0.82–0.84). MRE-based c and φ-maps can serve as important parameters to assess the tumor proliferation status in HCC. Abstract This study aimed to explore the added value of viscoelasticity measured by magnetic resonance elastography (MRE) in the prediction of Ki-67 expression in hepatocellular carcinoma (HCC) using a deep learning combined radiomics (DLCR) model. This retrospective study included 108 histopathology-proven HCC patients (93 males; age, 59.6 ± 11.0 years) who underwent preoperative MRI and MR elastography. They were divided into training (n = 87; 61.0 ± 9.8 years) and testing (n = 21; 60.6 ± 10.1 years) cohorts. An independent validation cohort including 43 patients (60.1 ± 11.3 years) was included for testing. A DLCR model was proposed to predict the expression of Ki-67 with cMRI, including T2W, DW, and dynamic contrast enhancement (DCE) images as inputs. The images of the shear wave speed (c-map) and phase angle (φ-map) derived from MRE were also fed into the DLCR model. The Ki-67 expression was classified into low and high groups with a threshold of 20%. Both c and φ values were ranked within the top six features for Ki-67 prediction with random forest selection, which revealed the value of MRE-based viscosity for the assessment of tumor proliferation status in HCC. When comparing the six CNN models, Xception showed the best performance for classifying the Ki-67 expression, with an AUC of 0.80 ± 0.03 (CI: 0.79–0.81) and accuracy of 0.77 ± 0.04 (CI: 0.76–0.78) when cMRI were fed into the model. The model with all modalities (MRE, AFP, and cMRI) as inputs achieved the highest AUC of 0.90 ± 0.03 (CI: 0.89–0.91) in the validation cohort. The same finding was observed in the independent testing cohort, with an AUC of 0.83 ± 0.03 (CI: 0.82–0.84). The shear wave speed and phase angle improved the performance of the DLCR model significantly for Ki-67 prediction, suggesting that MRE-based c and φ-maps can serve as important parameters to assess the tumor proliferation status in HCC.
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Affiliation(s)
- Xumei Hu
- Human Phenome Institute, Fudan University, Shanghai 201203, China;
| | - Jiahao Zhou
- Department of Radiology, Ruijin Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200025, China; (J.Z.); (Y.L.); (Y.W.); (F.Y.)
| | - Yan Li
- Department of Radiology, Ruijin Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200025, China; (J.Z.); (Y.L.); (Y.W.); (F.Y.)
| | - Yikun Wang
- Department of Radiology, Ruijin Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200025, China; (J.Z.); (Y.L.); (Y.W.); (F.Y.)
| | - Jing Guo
- Department of Radiology, Charité–Universitätsmedizin Berlin, 10117 Berlin, Germany; (J.G.); (I.S.)
| | - Ingolf Sack
- Department of Radiology, Charité–Universitätsmedizin Berlin, 10117 Berlin, Germany; (J.G.); (I.S.)
| | - Weibo Chen
- Philips Healthcare, Shanghai 200070, China;
| | - Fuhua Yan
- Department of Radiology, Ruijin Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200025, China; (J.Z.); (Y.L.); (Y.W.); (F.Y.)
| | - Ruokun Li
- Department of Radiology, Ruijin Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200025, China; (J.Z.); (Y.L.); (Y.W.); (F.Y.)
- Correspondence: (R.L.); (C.W.)
| | - Chengyan Wang
- Human Phenome Institute, Fudan University, Shanghai 201203, China;
- Correspondence: (R.L.); (C.W.)
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Herthum H, Carrillo H, Osses A, Uribe S, Sack I, Bertoglio C. Multiple motion encoding in phase-contrast MRI: A general theory and application to elastography imaging. Med Image Anal 2022; 78:102416. [PMID: 35334444 DOI: 10.1016/j.media.2022.102416] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 12/23/2021] [Accepted: 03/01/2022] [Indexed: 01/04/2023]
Abstract
While MRI allows to encode the motion of tissue in the magnetization's phase, it remains yet a challenge to obtain high fidelity motion images due to wraps in the phase for high encoding efficiencies. Therefore, we propose an optimal multiple motion encoding method (OMME) and exemplify it in Magnetic Resonance Elastography (MRE) data. OMME is formulated as a non-convex least-squares problem for the motion using an arbitrary number of phase-contrast measurements with different motion encoding gradients (MEGs). The mathematical properties of OMME are proved in terms of standard deviation and dynamic range of the motion's estimate for arbitrary MEGs combination which are confirmed using synthetically generated data. OMME's performance is assessed on MRE data from in vivo human brain experiments and compared to dual encoding strategies. The unwrapped images are further used to reconstruct stiffness maps and compared to the ones obtained using conventional unwrapping methods. OMME allowed to successfully combine several MRE phase images with different MEGs, outperforming dual encoding strategies in either motion-to-noise ratio (MNR) or number of successfully reconstructed voxels with good noise stability. This lead to stiffness maps with greater resolution of details than obtained with conventional unwrapping methods. The proposed OMME method allows for a flexible and noise robust increase in the dynamic range and thus provides wrap-free phase images with high MNR. In MRE, the method may be especially suitable when high resolution images with high MNR are needed.
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Affiliation(s)
- Helge Herthum
- Institute of Medical Informatics, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universitt zu Berlin, and Berlin Institute of Health, Berlin, 10117, Germany
| | - Hugo Carrillo
- Center for Mathematical Modeling, Universidad de Chile, Santiago, 8370456, Chile; Bernoulli Institute, University of Groningen, Groningen, 9747AG, the Netherlands
| | - Axel Osses
- Center for Mathematical Modeling, Universidad de Chile, Santiago, 8370456, Chile; Department of Mathematical Engineering, Universidad de Chile, Santiago, 8370456, Chile; ANID - Millennium Nucleus in Cardiovascular Magnetic Resonance, Santiago, 7820436, Chile; ANID - Millenium Nucleus in Applied Control and Inverse Problems ACIP, Santiago, 7820436, Chile
| | - Sergio Uribe
- ANID - Millennium Nucleus in Cardiovascular Magnetic Resonance, Santiago, 7820436, Chile; Biomedical Imaging Center, Pontificia Universidad Católica de Chile, Santiago, 7820436, Chile
| | - Ingolf Sack
- Institute of Medical Informatics, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universitt zu Berlin, and Berlin Institute of Health, Berlin, 10117, Germany
| | - Cristóbal Bertoglio
- Bernoulli Institute, University of Groningen, Groningen, 9747AG, the Netherlands.
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Schick F, Pieper CC, Kupczyk P, Almansour H, Keller G, Springer F, Mürtz P, Endler C, Sprinkart AM, Kaufmann S, Herrmann J, Attenberger UI. 1.5 vs 3 Tesla Magnetic Resonance Imaging: A Review of Favorite Clinical Applications for Both Field Strengths-Part 1. Invest Radiol 2021; 56:680-691. [PMID: 34324464 DOI: 10.1097/rli.0000000000000812] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
ABSTRACT Whole-body magnetic resonance imaging (MRI) systems with a field strength of 3 T have been offered by all leading manufacturers for approximately 2 decades and are increasingly used in clinical diagnostics despite higher costs. Technologically, MRI systems operating at 3 T have reached a high standard in recent years, as well as the 1.5-T devices that have been in use for a longer time. For modern MRI systems with 3 T, more complexity is required, especially for the magnet and the radiofrequency (RF) system (with multichannel transmission). Many clinical applications benefit greatly from the higher field strength due to the higher signal yield (eg, imaging of the brain or extremities), but there are also applications where the disadvantages of 3 T might outweigh the advantages (eg, lung imaging or examinations in the presence of implants). This review describes some technical features of modern 1.5-T and 3-T whole-body MRI systems, and reports on the experience of using both types of devices in different clinical settings, with all sections written by specialist radiologists in the respective fields.This first part of the review includes an overview of the general physicotechnical aspects of both field strengths and elaborates the special conditions of diffusion imaging. Many relevant aspects in the application areas of musculoskeletal imaging, abdominal imaging, and prostate diagnostics are discussed.
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Affiliation(s)
- Fritz Schick
- From the Section of Experimental Radiology, Department of Radiology, Diagnostic, and Interventional Radiology, University of Tübingen, Tübingen
| | | | - Patrick Kupczyk
- Clinic for Diagnostic and Interventional Radiology, University Hospital Bonn, Bonn
| | - Haidara Almansour
- Department of Radiology, Diagnostic, and Interventional Radiology, University of Tübingen, Tübingen, Germany
| | - Gabriel Keller
- Department of Radiology, Diagnostic, and Interventional Radiology, University of Tübingen, Tübingen, Germany
| | - Fabian Springer
- Department of Radiology, Diagnostic, and Interventional Radiology, University of Tübingen, Tübingen, Germany
| | - Petra Mürtz
- Clinic for Diagnostic and Interventional Radiology, University Hospital Bonn, Bonn
| | - Christoph Endler
- Clinic for Diagnostic and Interventional Radiology, University Hospital Bonn, Bonn
| | - Alois M Sprinkart
- Clinic for Diagnostic and Interventional Radiology, University Hospital Bonn, Bonn
| | - Sascha Kaufmann
- Department of Radiology, Diagnostic, and Interventional Radiology, University of Tübingen, Tübingen, Germany
| | - Judith Herrmann
- Department of Radiology, Diagnostic, and Interventional Radiology, University of Tübingen, Tübingen, Germany
| | - Ulrike I Attenberger
- Clinic for Diagnostic and Interventional Radiology, University Hospital Bonn, Bonn
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In Vivo Aortic Magnetic Resonance Elastography in Abdominal Aortic Aneurysm: A Validation in an Animal Model. Invest Radiol 2021; 55:463-472. [PMID: 32520516 DOI: 10.1097/rli.0000000000000660] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
OBJECTIVES Using maximum diameter of an abdominal aortic aneurysm (AAA) alone for management can lead to delayed interventions or unnecessary urgent repairs. Abdominal aortic aneurysm stiffness plays an important role in its expansion and rupture. In vivo aortic magnetic resonance elastography (MRE) was developed to spatially measure AAA stiffness in previous pilot studies and has not been thoroughly validated and evaluated for its potential clinical value. This study aims to evaluate noninvasive in vivo aortic MRE-derived stiffness in an AAA porcine model and investigate the relationships between MRE-derived AAA stiffness and (1) histopathology, (2) uniaxial tensile test, and (3) burst testing for assessing MRE's potential in evaluating AAA rupture risk. MATERIALS AND METHODS Abdominal aortic aneurysm was induced in 31 Yorkshire pigs (n = 226 stiffness measurements). Animals were randomly divided into 3 cohorts: 2-week, 4-week, and 4-week-burst. Aortic MRE was sequentially performed. Histopathologic analyses were performed to quantify elastin, collagen, and mineral densities. Uniaxial tensile test and burst testing were conducted to measure peak stress and burst pressure for assessing the ultimate wall strength. RESULTS Magnetic resonance elastography-derived AAA stiffness was significantly higher than the normal aorta. Significant reduction in elastin and collagen densities as well as increased mineralization was observed in AAAs. Uniaxial tensile test and burst testing revealed reduced ultimate wall strength. Magnetic resonance elastography-derived aortic stiffness correlated to elastin density (ρ = -0.68; P < 0.0001; n = 60) and mineralization (ρ = 0.59; P < 0.0001; n = 60). Inverse correlations were observed between aortic stiffness and peak stress (ρ = -0.32; P = 0.0495; n = 38) as well as burst pressure (ρ = -0.55; P = 0.0116; n = 20). CONCLUSIONS Noninvasive in vivo aortic MRE successfully detected aortic wall stiffening, confirming the extracellular matrix remodeling observed in the histopathologic analyses. These mural changes diminished wall strength. Inverse correlation between MRE-derived aortic stiffness and aortic wall strength suggests that MRE-derived stiffness can be a potential biomarker for clinically assessing AAA wall status and rupture potential.
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Dong H, Jin N, Kannengiesser S, Raterman B, White RD, Kolipaka A. Magnetic resonance elastography for estimating in vivo stiffness of the abdominal aorta using cardiac-gated spin-echo echo-planar imaging: a feasibility study. NMR IN BIOMEDICINE 2021; 34:e4420. [PMID: 33021342 DOI: 10.1002/nbm.4420] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 09/02/2020] [Accepted: 09/10/2020] [Indexed: 06/11/2023]
Abstract
INTRODUCTION Magnetic resonance elastography (MRE)-derived aortic stiffness is a potential biomarker for multiple cardiovascular diseases. Currently, gradient-recalled echo (GRE) MRE is a widely accepted technique to estimate aortic stiffness. However, multi-slice GRE MRE requires multiple breath-holds (BHs), which can be challenging for patients who cannot consistently hold their breath. The aim of this study was to investigate the feasibility of a multi-slice spin-echo echo-planar imaging (SE-EPI) MRE sequence for quantifying in vivo aortic stiffness using a free-breathing (FB) protocol and a single-BH protocol. METHOD On Scanner 1, 25 healthy subjects participated in the validation of FB SE-EPI against FB GRE. On Scanner 2, another 15 healthy subjects were recruited to compare FB SE-EPI with single-BH SE-EPI. Among all volunteers, five participants were studied on both scanners to investigate the inter-scanner reproducibility of FB SE-EPI aortic MRE. Bland-Altman analysis, Lin's concordance correlation coefficient (LCCC) and coefficient of variation (COV) were evaluated. The phase-difference signal-to-noise ratios (PD SNR) were compared. RESULTS Aortic MRE using FB SE-EPI and FB GRE yielded similar stiffnesses (paired t-test, P = 0.19), with LCCC = 0.97. The FB SE-EPI measurements were reproducible (intra-scanner LCCC = 0.96) and highly repeatable (LCCC = 0.99). The FB SE-EPI MRE was also reproducible across different scanners (inter-scanner LCCC = 0.96). Single-BH SE-EPI scans yielded similar stiffness to FB SE-EPI scans (LCCC = 0.99) and demonstrated a low COV of 2.67% across five repeated measurements. CONCLUSION Multi-slice SE-EPI aortic MRE using an FB protocol or a single-BH protocol is reproducible and repeatable with advantage over multi-slice FB GRE in reducing acquisition time. Additionally, FB SE-EPI MRE provides a potential alternative to BH scans for patients who have challenges in holding their breath.
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Affiliation(s)
- Huiming Dong
- Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
- Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio, USA
| | - Ning Jin
- Siemens Medical Solution, Columbus, Ohio, USA
| | | | - Brian Raterman
- Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
| | - Richard D White
- Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
- Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio, USA
- Department of Internal Medicine-Division of Cardiology, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
| | - Arunark Kolipaka
- Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
- Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio, USA
- Department of Internal Medicine-Division of Cardiology, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
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