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Co M, Dong H, Boulter DJ, Nguyen XV, Khan SN, Raterman B, Klamer B, Kolipaka A, Walter BA. Magnetic Resonance Elastography of Intervertebral Discs: Spin-Echo Echo-Planar Imaging Sequence Validation. J Magn Reson Imaging 2022; 56:1722-1732. [PMID: 35289470 PMCID: PMC9475395 DOI: 10.1002/jmri.28151] [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: 07/08/2021] [Revised: 02/23/2022] [Accepted: 02/25/2022] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND Magnetic resonance elastography (MRE) is an imaging technique that can noninvasively assess the shear properties of the intervertebral disc (IVD). Unlike the standard gradient recalled echo (GRE) MRE technique, a spin-echo echo-planar imaging (SE-EPI) sequence has the potential to improve imaging efficiency and patient compliance. PURPOSE To validate the use of an SE-EPI sequence for MRE of the IVD compared against the standard GRE sequence. STUDY TYPE Cross-over. SUBJECTS Twenty-eight healthy volunteers (15 males and 13 females, age range: 19-55). FIELD STRENGTH/SEQUENCE 3 T; GRE, SE-EPI with breath holds (SE-EPI-BH) and SE-EPI with free breathing (SE-EPI-FB) MRE sequences. ASSESSMENT MRE-derived shear stiffnesses were calculated via principal frequency analysis. SE-EPI derived shear stiffness and octahedral shear strain signal-to-noise ratios (OSS-SNR) were compared against those derived using the GRE sequence. The reproducibility and repeatability of SE-EPI stiffness measurements were determined. Shear stiffness was evaluated in the nucleus pulposus (NP) and annulus fibrosus (AF) regions of the disc. Scan times between sequences were compared. STATISTICAL TESTS Linear mixed models, Bland-Altman plots, and Lin's concordance correlation coefficients (CCCs) were used with P < 0.05 considered statistically significant. RESULTS Good correlation was observed between shear stiffnesses derived from the SE-EPI sequences with those derived from the GRE sequence with CCC values greater than 0.73 and 0.78 for the NP and AF regions, respectively. OSS-SNR was not significantly different between GRE and SE-EPI sequences (P > 0.05). SE-EPI sequences generated highly reproducible and repeatable stiffness measurements with CCC values greater than 0.97 in the NP and AF regions and reduced scan time by at least 51% compared to GRE. SE-EPI-BH and SE-EPI-FB stiffness measurements were similar with CCC values greater than 0.98 for both regions. DATA CONCLUSION SE-EPI-based MRE-derived stiffnesses were highly reproducible and repeatable and correlated with current standard GRE MRE-derived stiffness estimates while reducing scan times. LEVEL OF EVIDENCE 1 TECHNICAL EFFICACY STAGE: 1.
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Affiliation(s)
- Megan Co
- Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio, USA
| | - Huiming Dong
- Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
| | - Daniel J Boulter
- Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
| | - Xuan V Nguyen
- Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
| | - Safdar N Khan
- Department of Orthopedics, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
| | - Brian Raterman
- Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
| | - Brett Klamer
- Center for Biostatistics, The Ohio State University, Columbus, Ohio, USA
| | - Arunark Kolipaka
- Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio, USA
- Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
| | - Benjamin A Walter
- Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio, USA
- Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
- Spine Research Institute, The Ohio State University, Columbus, Ohio, USA
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Mangarova DB, Bertalan G, Jordan J, Brangsch J, Kader A, Möckel J, Adams LC, Sack I, Taupitz M, Hamm B, Braun J, Makowski MR. Microscopic multifrequency magnetic resonance elastography of ex vivo abdominal aortic aneurysms for extracellular matrix imaging in a mouse model. Acta Biomater 2022; 140:389-397. [PMID: 34818577 DOI: 10.1016/j.actbio.2021.11.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 11/16/2021] [Accepted: 11/17/2021] [Indexed: 11/27/2022]
Abstract
An abdominal aortic aneurysm (AAA) is a permanent dilatation of the abdominal aorta, usually accompanied by thrombus formation. The current clinical imaging modalities cannot reliably visualize the thrombus composition. Remodeling of the extracellular matrix (ECM) during AAA development leads to stiffness changes, providing a potential imaging marker. 14 apolipoprotein E-deficient mice underwent surgery for angiotensin II-loaded osmotic minipump implantation. 4 weeks post-op, 5 animals developed an AAA. The aneurysm was imaged ex vivo by microscopic multifrequency magnetic resonance elastography (µMMRE) with an in-plane resolution of 40 microns. Experiments were performed on a 7-Tesla preclinical magnetic resonance imaging scanner with drive frequencies between 1000 Hz and 1400 Hz. Shear wave speed (SWS) maps indicating stiffness were computed based on tomoelastography multifrequency inversion. As control, the aortas of 5 C57BL/6J mice were examined with the same imaging protocol. The regional variation of SWS in the thrombus ranging from 0.44 ± 0.07 to 1.20 ± 0.31 m/s was correlated fairly strong with regional histology-quantified ECM accumulation (R2 = 0.79). Our results suggest that stiffness changes in aneurysmal thrombus reflect ECM remodeling, which is critical for AAA risk assessment. In the future, µMMRE could be used for a mechanics-based clinical characterization of AAAs in patients. STATEMENT OF SIGNIFICANCE: To our knowledge, this is the first study mapping the stiffness of abdominal aortic aneurysms with microscopic resolution of 40 µm. Our work revealed that stiffness critically changes due to extracellular matrix (ECM) remodeling in the aneurysmal thrombus. We were able to image various levels of ECM remodeling in the aneurysm reflected in distinct shear wave speed patterns with a strong correlation to regional histology-quantified ECM accumulation. The generated results are significant for the application of microscopic multifrequency magnetic resonance elastography for quantification of pathological remodeling of the ECM and may be of great interest for detailed characterization of AAAs in patients.
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Affiliation(s)
- Dilyana B Mangarova
- Department of Radiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Charitéplatz 1, Berlin 10117, Germany; Department of Veterinary Medicine, Institute of Veterinary Pathology, Freie Universität Berlin, Robert-von-Ostertag-Str. 15, Building 12, Berlin 4163, Germany.
| | - Gergely Bertalan
- Department of Radiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Charitéplatz 1, Berlin 10117, Germany.
| | - Jakob Jordan
- Department of Radiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Charitéplatz 1, Berlin 10117, Germany.
| | - Julia Brangsch
- Department of Radiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Charitéplatz 1, Berlin 10117, Germany.
| | - Avan Kader
- Department of Radiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Charitéplatz 1, Berlin 10117, Germany; Department of Biology, Chemistry and Pharmacy, Institute of Biology, Freie Universität Berlin, Königin-Luise-Str. 1-3, Berlin 14195, Germany.
| | - Jana Möckel
- Department of Radiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Charitéplatz 1, Berlin 10117, Germany.
| | - Lisa C Adams
- Department of Radiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Charitéplatz 1, Berlin 10117, Germany.
| | - Ingolf Sack
- Department of Radiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Charitéplatz 1, Berlin 10117, Germany.
| | - Matthias Taupitz
- Department of Radiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Charitéplatz 1, Berlin 10117, Germany.
| | - Bernd Hamm
- Department of Radiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Charitéplatz 1, Berlin 10117, Germany.
| | - Jürgen Braun
- Department of Radiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Charitéplatz 1, Berlin 10117, Germany; Institute for Medical Informatics, Charité - Universitätsmedizin Berlin, Berlin, Germany, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Hindenburgdamm 30, Berlin 12200, Germany.
| | - Marcus R Makowski
- Department of Radiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Charitéplatz 1, Berlin 10117, Germany; Department of Diagnostic and Interventional Radiology, Technical University of Munich, Ismaninger Str. 22, Munich 81675, Germany.
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Practical and clinical applications of pancreatic magnetic resonance elastography: a systematic review. Abdom Radiol (NY) 2021; 46:4744-4764. [PMID: 34076721 DOI: 10.1007/s00261-021-03143-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 05/20/2021] [Accepted: 05/22/2021] [Indexed: 12/13/2022]
Abstract
Magnetic resonance elastography (MRE) is a non-invasive technique suitable for assessing mechanical properties of tissues, i.e., stiffness. MRE of the pancreas is relatively new, but recently an increasing number of studies have successfully assessed pancreas diseases with MRE aiming to differentiate healthy from pathological pancreatic tissue with or without fibrosis. This review will systematically describe the practical and clinical applications of pancreatic MRE. We conducted a systematic literature search with a pre-specified search strategy using PubMed and Embase according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. English peer-reviewed articles applying MRE of the pancreas were included. Two independent reviewers assessed the studies. The literature search yielded 14 studies. The pancreatic stiffness for healthy volunteers ranged from 1.11. to 1.21 kPa at a driver frequency of 40 Hz. In benign tumors, the stiffness values were slightly higher or sometimes even lower (range 0.78 to 2.00 kPa), compared to the healthy pancreas parenchyma whereas, in malignant tumors, the stiffness values tended to be higher (1.42 to 6.06 kPa). The pancreatic stiffness was increased in both acute (median: 1.99 kPa) and chronic pancreatitis (> 1.50 kPa). MRE is a promising technique for detecting and quantifying pancreatic stiffness. It is related to fibrosis and seems to be useful in assessing treatment response and clinical follow-up of pancreatic diseases. However, most of the described practical settings were characterized by a lack of uniformity and inconsistency in reporting standards across studies. Harmonization between centers is necessary to achieve more consensus and optimization of pancreatic MRE protocols.
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Seyedpour SM, Nabati M, Lambers L, Nafisi S, Tautenhahn HM, Sack I, Reichenbach JR, Ricken T. Application of Magnetic Resonance Imaging in Liver Biomechanics: A Systematic Review. Front Physiol 2021; 12:733393. [PMID: 34630152 PMCID: PMC8493836 DOI: 10.3389/fphys.2021.733393] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 08/25/2021] [Indexed: 12/15/2022] Open
Abstract
MRI-based biomechanical studies can provide a deep understanding of the mechanisms governing liver function, its mechanical performance but also liver diseases. In addition, comprehensive modeling of the liver can help improve liver disease treatment. Furthermore, such studies demonstrate the beginning of an engineering-level approach to how the liver disease affects material properties and liver function. Aimed at researchers in the field of MRI-based liver simulation, research articles pertinent to MRI-based liver modeling were identified, reviewed, and summarized systematically. Various MRI applications for liver biomechanics are highlighted, and the limitations of different viscoelastic models used in magnetic resonance elastography are addressed. The clinical application of the simulations and the diseases studied are also discussed. Based on the developed questionnaire, the papers' quality was assessed, and of the 46 reviewed papers, 32 papers were determined to be of high-quality. Due to the lack of the suitable material models for different liver diseases studied by magnetic resonance elastography, researchers may consider the effect of liver diseases on constitutive models. In the future, research groups may incorporate various aspects of machine learning (ML) into constitutive models and MRI data extraction to further refine the study methodology. Moreover, researchers should strive for further reproducibility and rigorous model validation and verification.
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Affiliation(s)
- Seyed M. Seyedpour
- Institute of Mechanics, Structural Analysis and Dynamics, Faculty of Aerospace Engineering and Geodesy, University of Stuttgart, Stuttgart, Germany
- Biomechanics Lab, Institute of Mechanics, Structural Analysis and Dynamics, Faculty of Aerospace Engineering and Geodesy, University of Stuttgart, Stuttgart, Germany
| | - Mehdi Nabati
- Department of Mechanical Engineering, Faculty of Engineering, Boğaziçi University, Istanbul, Turkey
| | - Lena Lambers
- Institute of Mechanics, Structural Analysis and Dynamics, Faculty of Aerospace Engineering and Geodesy, University of Stuttgart, Stuttgart, Germany
- Biomechanics Lab, Institute of Mechanics, Structural Analysis and Dynamics, Faculty of Aerospace Engineering and Geodesy, University of Stuttgart, Stuttgart, Germany
| | - Sara Nafisi
- Faculty of Pharmacy, Istinye University, Istanbul, Turkey
| | - Hans-Michael Tautenhahn
- Department of General, Visceral and Vascular Surgery, Jena University Hospital, Jena, Germany
| | - Ingolf Sack
- Department of Radiology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Campus Charité Mitte, Berlin, Germany
| | - Jürgen R. Reichenbach
- Medical Physics Group, Institute of Diagnostic and Interventional Radiology, Jena University Hospital-Friedrich Schiller University Jena, Jena, Germany
- Center of Medical Optics and Photonics, Friedrich Schiller University, Jena, Germany
- Michael Stifel Center for Data-driven and Simulation Science Jena, Friedrich Schiller University, Jena, Germany
| | - Tim Ricken
- Institute of Mechanics, Structural Analysis and Dynamics, Faculty of Aerospace Engineering and Geodesy, University of Stuttgart, Stuttgart, Germany
- Biomechanics Lab, Institute of Mechanics, Structural Analysis and Dynamics, Faculty of Aerospace Engineering and Geodesy, University of Stuttgart, Stuttgart, Germany
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Lilaj L, Herthum H, Meyer T, Shahryari M, Bertalan G, Caiazzo A, Braun J, Fischer T, Hirsch S, Sack I. Inversion-recovery MR elastography of the human brain for improved stiffness quantification near fluid-solid boundaries. Magn Reson Med 2021; 86:2552-2561. [PMID: 34184306 DOI: 10.1002/mrm.28898] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 05/10/2021] [Accepted: 06/02/2021] [Indexed: 12/31/2022]
Abstract
PURPOSE In vivo MR elastography (MRE) holds promise as a neuroimaging marker. In cerebral MRE, shear waves are introduced into the brain, which also stimulate vibrations in adjacent CSF, resulting in blurring and biased stiffness values near brain surfaces. We here propose inversion-recovery MRE (IR-MRE) to suppress CSF signal and improve stiffness quantification in brain surface areas. METHODS Inversion-recovery MRE was demonstrated in agar-based phantoms with solid-fluid interfaces and 11 healthy volunteers using 31.25-Hz harmonic vibrations. It was performed by standard single-shot, spin-echo EPI MRE following 2800-ms IR preparation. Wave fields were acquired in 10 axial slices and analyzed for shear wave speed (SWS) as a surrogate marker of tissue stiffness by wavenumber-based multicomponent inversion. RESULTS Phantom SWS values near fluid interfaces were 7.5 ± 3.0% higher in IR-MRE than MRE (P = .01). In the brain, IR-MRE SNR was 17% lower than in MRE, without influencing parenchymal SWS (MRE: 1.38 ± 0.02 m/s; IR-MRE: 1.39 ± 0.03 m/s; P = .18). The IR-MRE tissue-CSF interfaces appeared sharper, showing 10% higher SWS near brain surfaces (MRE: 1.01 ± 0.03 m/s; IR-MRE: 1.11 ± 0.01 m/s; P < .001) and 39% smaller ventricle sizes than MRE (P < .001). CONCLUSIONS Our results show that brain MRE is affected by fluid oscillations that can be suppressed by IR-MRE, which improves the depiction of anatomy in stiffness maps and the quantification of stiffness values in brain surface areas. Moreover, we measured similar stiffness values in brain parenchyma with and without fluid suppression, which indicates that shear wavelengths in solid and fluid compartments are identical, consistent with the theory of biphasic poroelastic media.
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Affiliation(s)
- Ledia Lilaj
- Department of Radiology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Helge Herthum
- Department of Radiology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Tom Meyer
- Department of Radiology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Mehrgan Shahryari
- Department of Radiology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Gergely Bertalan
- Department of Radiology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Alfonso Caiazzo
- Weierstrass Institute for Applied Analysis and Stochastics, Berlin, Germany
| | - Jürgen Braun
- Institute of Medical Informatics, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Thomas Fischer
- Department of Radiology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Sebastian Hirsch
- Berlin Center for Advanced Neuroimaging, Charité-Universitätsmedizin Berlin, Berlin, Germany.,Bernstein Center for Computational Neuroscience, Berlin, Germany
| | - Ingolf Sack
- Department of Radiology, Charité-Universitätsmedizin Berlin, Berlin, Germany
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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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Ariyurek C, Tasdelen B, Ider YZ, Atalar E. SNR Weighting for Shear Wave Speed Reconstruction in Tomoelastography. NMR IN BIOMEDICINE 2021; 34:e4413. [PMID: 32956538 DOI: 10.1002/nbm.4413] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 08/31/2020] [Accepted: 09/06/2020] [Indexed: 06/11/2023]
Abstract
In tomoelastography, to achieve a final wave speed map by combining reconstructions obtained from all spatial directions and excitation frequencies, the use of weights is inevitable. Here, a new weighting scheme, which maximizes the signal-to-noise ratio (SNR) of the final wave speed map, has been proposed. To maximize the SNR of the final wave speed map, the use of squares of estimated SNR values of reconstructed individual maps has been proposed. Therefore, derivations of the SNR of the reconstructed wave speed maps have become necessary. Considering the noise on the complex MRI signal, the SNR of the reconstructed wave speed map was formulated by an analytical approach assuming a high SNR, and the results were verified using Monte Carlo simulations (MCSs). It has been assumed that the noise remains approximately Gaussian when the image SNR is high enough, despite the nonlinear operations in tomoelastography inversion. Hence, the SNR threshold was determined by comparing the SNR computed by MCSs and analytical approximations. The weighting scheme was evaluated for accuracy, spatial resolution and SNR performances on simulated phantoms. MR elastography (MRE) experiments on two different phantoms were conducted. Wave speed maps were generated for simulated 3D human abdomen MRE data and experimental human abdomen MRE data. The simulation results demonstrated that the SNR-weighted inversion improved the SNR performance of the wave speed map by a factor of two compared to the performance of the original (i.e., amplitude-weighted) reconstruction. In the case of a low SNR, no bias occurred in the wave speed map when SNR weighting was used, whereas 10% bias occurred when the original weighting (i.e., amplitude weighting) was used. Thus, while not altering the accuracy or spatial resolution of the wave speed map with the proposed weighting method, the SNR of the wave speed map has been significantly improved.
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Affiliation(s)
- Cemre Ariyurek
- Department of Electrical and Electronics Engineering, Bilkent University, Ankara, Turkey
- National Magnetic Resonance Research Center (UMRAM), Bilkent University, Ankara, Turkey
| | - Bilal Tasdelen
- Department of Electrical and Electronics Engineering, Bilkent University, Ankara, Turkey
- National Magnetic Resonance Research Center (UMRAM), Bilkent University, Ankara, Turkey
| | - Yusuf Ziya Ider
- Department of Electrical and Electronics Engineering, Bilkent University, Ankara, Turkey
| | - Ergin Atalar
- Department of Electrical and Electronics Engineering, Bilkent University, Ankara, Turkey
- National Magnetic Resonance Research Center (UMRAM), Bilkent University, Ankara, Turkey
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Steady-State Multifrequency Magnetic Resonance Elastography of the Thoracic and Abdominal Human Aorta-Validation and Reference Values. Invest Radiol 2020; 55:451-456. [PMID: 32520515 DOI: 10.1097/rli.0000000000000654] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVES The aim of this study was to investigate the potential of stroboscopic-wavefield-sampling-based multifrequency magnetic resonance elastography (sMRE) for quantifying the stiffness of the human thoracic and abdominal aorta in vivo. MATERIALS AND METHODS The sMRE of the thoracic and abdominal aorta was performed at 1.5 T field strength in 20 healthy volunteers aged 27 to 77 years (3 women; median age, 33 years; interquartile range [IQR], 16 years). Compound maps of shear wave speed (SWS) were reconstructed and evaluated during the diastolic phase in 3 anatomical regions: ascending thoracic aorta (AA), descending thoracic aorta (AD), and abdominal aorta (AAb). The SWS maps were read by 2 readers. Blood pressure and pulse wave velocity were determined noninvasively before sMRE. Data are given as median (IQR) and were compared using the Kruskal-Wallis and Wilcoxon rank sum tests. Intraclass correlation was used to determine interobserver and intraobserver agreement, as well as reproducibility. Multiple linear regression analysis was performed to evaluate effects of age, sex, vessel diameter, blood pressure, pulse wave velocity, and aortic segment on measured SWS. RESULTS All 20 participants underwent successful sMRE, resulting in a total of 60 aortic segments. The median SWS (IQR) of AA, AD, and AAb was 1.62 (0.16) m/s, 2.40 (0.24) m/s, and 2.48 (0.58) m/s, respectively. The SWS in AA was significantly lower (P < 0.001), and no differences in SWS (P = 0.67) were found between AD and AAb. Interobserver and intraobserver agreement, as well as reproducibility, was excellent, with intraclass correlation coefficients ranging between 0.957 and 0.998. A significant but weak influence of age on measured SWS was found, which increased from AA to AD and AAb (R = 0.229, 0.275, 0.377, respectively; P = 0.001-0.005). CONCLUSIONS Quantification of aortic stiffness in different segments of the human aorta is possible with sMRE. Our results correlate well with known aortic stiffness differences in different anatomical locations and demonstrate the potential of sMRE for clinical stiffness measurement of the thoracoabdominal aorta, which may allow detection of physiological variation and cardiovascular diseases.
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Majeed W, Kalra P, Kolipaka A. Simultaneous multislice rapid magnetic resonance elastography of the liver. NMR IN BIOMEDICINE 2020; 33:e4252. [PMID: 31971301 PMCID: PMC7286422 DOI: 10.1002/nbm.4252] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/12/2018] [Revised: 12/09/2019] [Accepted: 12/10/2019] [Indexed: 06/10/2023]
Abstract
To design and validate a rapid Simultaneous Multi-slice (SMS) Magnetic Resonance Elastography technique (MRE), which combines SMS acquisition, in-plane undersampling and an existing rapid Magnetic Resonance Elastography (MREr) scheme to allow accelerated data acquisition in healthy volunteers and comparison against MREr. SMS-MREr sequence was developed by incorporating SMS acquisition scheme into an existing MREr sequence that accelerates MRE acquisition by acquiring data during opposite phases of mechanical vibrations. The MREr sequence accelerated MRE acquisition by acquiring data during opposite phases of mechanical vibrations. Liver MRE was performed on 23 healthy subjects using MREr and SMS-MREr sequences, and mean stiffness values were obtained for manually drawn regions of interest. Linear correlation and agreement between MREr- and SMS-MREr-based stiffness values were investigated. SMS-MREr reduced the scan time by half relative to MREr, and allowed acquisition of four-slice MRE data in a single 17-second breath-hold. Visual comparison suggested agreement between MREr and SMS-MREr elastograms. A Pearson's correlation of 0.93 was observed between stiffness values derived from MREr and SMS-MREr. Bland-Altman analysis demonstrated good agreement, with -0.08 kPa mean bias and narrow limits of agreement (95% CI: 0.23 to -0.39 kPa) between stiffness values obtained using MREr and SMS-MREr. SMS can be combined with other fast MRE approaches to achieve further acceleration. This pushes the limit on the acceleration that can be achieved in MRE acquisition, and makes it possible to conduct liver MRE exams in a single breath-hold.
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Affiliation(s)
- Waqas Majeed
- Department of RadiologyThe Ohio State University Wexner Medical CenterColumbusOhioUSA
| | - Prateek Kalra
- Department of RadiologyThe Ohio State University Wexner Medical CenterColumbusOhioUSA
| | - Arunark Kolipaka
- Department of RadiologyThe Ohio State University Wexner Medical CenterColumbusOhioUSA
- Department of Biomedical EngineeringThe Ohio State UniversityColumbusOhioUSA
- Department of Internal Medicine ‐ Division of CardiologyThe Ohio State University Wexner Medical CenterColumbusOhioUSA
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Gandhi D, Kalra P, Raterman B, Mo X, Dong H, Kolipaka A. Magnetic Resonance Elastography of kidneys: SE-EPI MRE reproducibility and its comparison to GRE MRE. NMR IN BIOMEDICINE 2019; 32:e4141. [PMID: 31329347 PMCID: PMC6817380 DOI: 10.1002/nbm.4141] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Revised: 05/09/2019] [Accepted: 06/17/2019] [Indexed: 05/10/2023]
Abstract
The purpose of this study is 1) to demonstrate reproducibility of spin echo-echo planar imaging (SE-EPI) magnetic resonance elastography (MRE) to estimate kidney stiffness; and 2) to compare SE-EPI MRE and gradient recalled echo (GRE) MRE-derived stiffness estimations in various anatomical regions of the kidney. Kidney MRE was performed on 33 healthy subjects (8 for SE-EPI MRE reproducibility and 25 for comparison with GRE MRE; age range: 22-66 years) in a 3 T MRI scanner. To demonstrate SE-EPI MRE reproducibility, subjects were scanned for the first scan and then asked to leave the scan room and repositioned again for the second (repeat) scan. Similar set-up was used for GRE MRE as well. The displacement data was then processed to obtain overall stiffness estimates of the kidney. Concordance correlation analyses were performed to determine SE-EPI MRE reproducibility and agreement between GRE MRE and SE-EPI MRE derived stiffness. A high concordance correlation (ρc = 0.95; p-value<0.0001) was obtained for SE-EPI MRE reproducibility. Good concordance correlation was observed (ρc = 0.84; p < 0.0001 for both kidneys, ρc = 0.91; p < 0.0001 for right kidney and ρc = 0.78; p < 0.0001 for left kidney) between GRE MRE and SE-EPI MRE derived stiffness measurements. Paired t-test results showed that stiffness value of medulla was significantly (p < 0.0001) greater than cortex using SE-EPI MRE as well as GRE MRE. SE-EPI MRE was reproducible and good agreement was observed in MRE-derived stiffness measurements obtained using SE-EPI and GRE sequences. Therefore, SE-EPI can be used for kidney MRE applications.
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Affiliation(s)
- Deep Gandhi
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH
- Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, OH
| | - Prateek Kalra
- Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, OH
| | - Brian Raterman
- Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, OH
| | - Xiaokui Mo
- Center for Biostatistics, Department of Biomedical Informatics, The Ohio State University, Columbus, OH
| | - Huiming Dong
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH
- Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, OH
| | - Arunark Kolipaka
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH
- Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, OH
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12
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Golemati S, Patelaki E, Nikita KS. Image-Based Motion and Strain Estimation of the Vessel Wall. ACTA ACUST UNITED AC 2019. [DOI: 10.1007/978-981-10-5092-3_9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/26/2023]
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13
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Wang CK, Fang YHD, Lin LC, Lin CF, Kuo LC, Chiu FM, Chen CH. Magnetic Resonance Elastography in the Assessment of Acute Effects of Kinesio Taping on Lumbar Paraspinal Muscles. J Magn Reson Imaging 2018; 49:1039-1045. [PMID: 30284358 DOI: 10.1002/jmri.26281] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 07/18/2018] [Accepted: 07/19/2018] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Kinesio tape (KT) is an elastic therapeutic tape used for treating sports-related injuries and a number of other disorders. To date, the objective evidence to link pathophysiological effects and actual reactions triggered by KT is limited. PURPOSE To explore the effect of KT on the lumbar paraspinal muscles by magnetic resonance (MR) elastography. STUDY TYPE Prospective observational study. POPULATION Sixty-six asymptomatic volunteers with 31 women and 35 men. FIELD STRENGTH/SEQUENCE 3.0T MRI and elastography with vibration frequency of 120 Hz. ASSESSMENT The 5-cm-width KT with full tension was placed on a single side of the lumbar paraspinal muscle. The taping side and adhering direction were randomly decided. Two rectangular regions of interest (ROIs) of 5- and 2.5-cm-width were positioned at the bilateral paraspinal regions from the L2 to L4 level on the confidence map of MR elastography before and after KT taping. The mean shear stiffness values of the ROIs at the superficial, middle, and deep depths were recorded; then the differences between the taping and reference sides were calculated. STATISTICAL TESTS Paired t-test and Pearson correlations were used to evaluate the stiffness changes after KT application and intraoperator errors of the stiffness measures on the reference side, respectively. RESULTS A significant decrease in the muscle stiffness value between taping and reference sides (-0.71 kPa ± 0.60 with KT and -0.25 kPa ± 0.78 without KT, P < 0.0001 for 5-cm ROI; -0.67 kPa ± 1.12 with KT and -0.16 kPa ± 1.17 without KT, P = 0.0004 for 2.5-cm ROI) was found in the superficial depth, but no significant differences in the middle and deep depths (P = 0.25 and P = 0.79 for 5-cm ROI; P = 0.09 and P = 0.67 for 2.5-cm ROI, respectively). There were no significant differences of muscle stiffness differences between gender (P = 0.11 for superficial, P = 0.37 for middle, P = 0.78 for deep) and taping direction (P = 0.18 for superficial, P = 0.13 for middle, P = 0.15 for deep). DATA CONCLUSION Our results demonstrate that KT can reduce the MR elastography-derived shear stiffness in the superficial depth of paraspinal muscles. LEVEL OF EVIDENCE 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;49:1039-1045.
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Affiliation(s)
- Chien-Kuo Wang
- Department of Radiology, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Yu-Hua Dean Fang
- Department of Biomedical Engineering, National Cheng Kung University, Tainan, Taiwan
| | - Liang-Ching Lin
- Department of Statistics, National Cheng Kung University, Tainan, Taiwan
| | - Cheng-Feng Lin
- Department of Physical Therapy, National Cheng Kung University, Tainan, Taiwan
| | - Li-Chieh Kuo
- Department of Occupational Therapy, National Cheng Kung University, Tainan, Taiwan
| | | | - Chia-Hui Chen
- College of Photonics, National Chiao Tung University, Tainan, Taiwan.,Department of Medical Imaging and Radiological Science, Central Taiwan University of Science and Technology, Taichung, Taiwan
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Khan S, Fakhouri F, Majeed W, Kolipaka A. Cardiovascular magnetic resonance elastography: A review. NMR IN BIOMEDICINE 2018; 31:e3853. [PMID: 29193358 PMCID: PMC5975119 DOI: 10.1002/nbm.3853] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Revised: 08/25/2017] [Accepted: 09/29/2017] [Indexed: 05/19/2023]
Abstract
Cardiovascular diseases are the leading cause of death worldwide. These cardiovascular diseases are associated with mechanical changes in the myocardium and aorta. It is known that stiffness is altered in many diseases, including the spectrum of ischemia, diastolic dysfunction, hypertension and hypertrophic cardiomyopathy. In addition, the stiffness of the aortic wall is altered in multiple diseases, including hypertension, coronary artery disease and aortic aneurysm formation. For example, in diastolic dysfunction in which the ejection fraction is preserved, stiffness can potentially be an important biomarker. Similarly, in aortic aneurysms, stiffness can provide valuable information with regard to rupture potential. A number of studies have addressed invasive and non-invasive approaches to test and measure the mechanical properties of the myocardium and aorta. One of the non-invasive approaches is magnetic resonance elastography (MRE). MRE is a phase-contrast magnetic resonance imaging technique that measures tissue stiffness non-invasively. This review article highlights the technical details and application of MRE in the quantification of myocardial and aortic stiffness in different disease states.
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Affiliation(s)
- Saad Khan
- Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, OH, 43210, USA
| | - Faisal Fakhouri
- Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, OH, 43210, USA
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH, 43210, USA
| | - Waqas Majeed
- Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, OH, 43210, USA
| | - Arunark Kolipaka
- Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, OH, 43210, USA
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH, 43210, USA
- Department of Internal Medicine-Division of Cardiology, The Ohio State University Wexner Medical Center, Columbus, OH, 43210, USA
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Abstract
The mechanical properties of soft tissues are closely associated with a variety of diseases. This motivates the development of elastography techniques in which tissue mechanical properties are quantitatively estimated through imaging. Magnetic resonance elastography (MRE) is a noninvasive phase-contrast MR technique wherein shear modulus of soft tissue can be spatially and temporally estimated. MRE has recently received significant attention due to its capability in noninvasively estimating tissue mechanical properties, which can offer considerable diagnostic potential. In this work, recent technology advances of MRE, its future clinical applications, and the related limitations will be discussed.
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Affiliation(s)
- Huiming Dong
- Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, OH, 43210, USA
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH, 43210, USA
| | - Richard D. White
- Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, OH, 43210, USA
- Department of Internal Medicine-Division of Cardiology, The Ohio State University Wexner Medical Center, Columbus, OH, 43210, USA
| | - Arunark Kolipaka
- Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, OH, 43210, USA
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH, 43210, USA
- Department of Internal Medicine-Division of Cardiology, The Ohio State University Wexner Medical Center, Columbus, OH, 43210, USA
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Application of laser scanning cytometry in vascular smooth muscle remodeling. Hypertens Res 2018; 41:869-885. [PMID: 30214031 DOI: 10.1038/s41440-018-0077-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Revised: 02/02/2018] [Accepted: 02/20/2018] [Indexed: 02/07/2023]
Abstract
Pulmonary artery hyperplasia is the result of proliferation of the pulmonary arterial smooth muscles (PASM). Hypoxia-induced PASM proliferation in the fetus and the newborn is the primary cause of persistent pulmonary hypertension of the newborn (PPHN). This study was performed to characterize the utility of the Laser Scanning Cytometry (LSC) method in elucidating arterial cytoskeletal remodeling in an in vitro model of PPHN. The aim was to demonstrate the following: (a) LSC is a valid method for the analysis of nuclear and cytosolic fluorescence and (b) the cumulative effects of mechanical stretch together with hypoxia promote reactive oxygen species (ROS) formation. The molecular events in response to hypoxia and the mechanical overload of the pulmonary circuit were demonstrated in vitro by subjecting hypoxic cultured primary PASM or human airway smooth muscles (hASM) to repetitive stretch-relaxation cycles at rates comparable to dynamic stretch in vivo. The altered cytoskeleton in the form of filamentous to globular actin (F:G actin) ratio was imaged and quantified at the cellular level by LSC as an endpoint. LSC can remove the nuclear G-actin fluorescence from the total G-actin fluorescence. Pulsatile stretch was found to significantly increase the total endogenous ROS and superoxide anion release in normoxic and hypoxic conditions in primary PASM fibers. The effect of stretch was predominant in increasing superoxide anion release, only under hypoxic conditions. These findings, obtained by LSC in vitro are amenable to validation in any in vivo model of interest. The in vitro model is clinically relevant to human pulmonary vascular remodeling.
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Schaafs LA, Tzschätzsch H, van der Giet M, Reshetnik A, Steffen IG, Hamm B, Braun J, Sack I, Elgeti T. Time-Harmonic Ultrasound elastography of the Descending Abdominal Aorta: Initial Results. ULTRASOUND IN MEDICINE & BIOLOGY 2017; 43:2550-2557. [PMID: 28818306 DOI: 10.1016/j.ultrasmedbio.2017.07.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2017] [Revised: 06/28/2017] [Accepted: 07/07/2017] [Indexed: 06/07/2023]
Abstract
Stiffening of central large vessels is considered a key pathophysiologic factor within the cardiovascular system. Current diagnostic parameters such as pulse wave velocity (PWV) indirectly measure aortic stiffness, a hallmark of coronary diseases. The aim of the present study was to perform elastography of the proximal abdominal aorta based on externally induced time-harmonic shear waves. Experiments were performed in 30 healthy volunteers (25 young, 5 old, >50 y) and 5 patients with longstanding hypertension (PWV >10 m/s). B-Mode-guided sonographic time-harmonic elastography was used for measurement of externally induced shear waves at 30-Hz vibration frequency. Thirty-hertz shear wave amplitudes (SWAs) within the abdominal aorta were measured and displayed in real time and processed offline for differences in SWA between systole and diastole (ΔSWA). Data were analyzed using the Kruskal-Wallis test and receiver operating characteristic curve analysis. The change in SWA over the cardiac cycle was reduced significantly in all patients as assessed with ΔSWA (volunteers: mean = 10 ± 5 μm, patients: mean = 4 ± 1 μm; p < 0.001). The best separation of healthy volunteers from patients was obtained with a ΔSWA threshold of 4.7 μm, resulting in a sensitivity of 0.9 and a specificity of 1.0, with an overall area under the curve of 0.96. Time harmonic elastography of the abdominal aorta is feasible and shows promise for the exploitation of time-varying shear wave amplitudes as a diagnostic marker for aortic wall stiffening. Patients with elevated PWVs suggesting increased aortic wall stiffness were best identified by ΔSWA-a parameter that could be related to the ability of the vessel walls to distend on passages of the pulse wave.
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Affiliation(s)
- Lars-Arne Schaafs
- Klinik und Hochschulambulanz für Radiologie, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Heiko Tzschätzsch
- Klinik und Hochschulambulanz für Radiologie, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Markus van der Giet
- Medizinische Klinik mit Schwerpunkt Nephrologie, Transplantationszentrum-Hypertoniezentrum, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Alexander Reshetnik
- Medizinische Klinik mit Schwerpunkt Nephrologie, Transplantationszentrum-Hypertoniezentrum, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Ingo G Steffen
- Klinik und Hochschulambulanz für Radiologie, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Bernd Hamm
- Klinik und Hochschulambulanz für Radiologie, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Jürgen Braun
- Institut für Medizinische Informatik, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Ingolf Sack
- Klinik und Hochschulambulanz für Radiologie, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Thomas Elgeti
- Klinik und Hochschulambulanz für Radiologie, Charité-Universitätsmedizin Berlin, Berlin, Germany.
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McGarry M, Nauleau P, Apostolakis I, Konofagou E. In vivo repeatability of the pulse wave inverse problem in human carotid arteries. J Biomech 2017; 64:136-144. [PMID: 29050824 DOI: 10.1016/j.jbiomech.2017.09.017] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Revised: 08/08/2017] [Accepted: 09/19/2017] [Indexed: 10/18/2022]
Abstract
Accurate arterial stiffness measurement would improve diagnosis and monitoring for many diseases. Atherosclerotic plaques and aneurysms are expected to involve focal changes in vessel wall properties; therefore, a method to image the stiffness variation would be a valuable clinical tool. The pulse wave inverse problem (PWIP) fits unknown parameters from a computational model of arterial pulse wave propagation to ultrasound-based measurements of vessel wall displacements by minimizing the difference between the model and measured displacements. The PWIP has been validated in phantoms, and this study presents the first in vivo demonstration. The common carotid arteries of five healthy volunteers were imaged five times in a single session with repositioning of the probe and subject between each scan. The 1D finite difference computational model used in the PWIP spanned from the start of the transducer to the carotid bifurcation, where a resistance outlet boundary condition was applied to approximately model the downstream reflection of the pulse wave. Unknown parameters that were estimated by the PWIP included a 10-segment linear piecewise compliance distribution and 16 discrete cosine transformation coefficients for each of the inlet boundary conditions. Input data was selected to include pulse waves resulting from the primary pulse and dicrotic notch. The recovered compliance maps indicate that the compliance increases close to the bifurcation, and the variability of the average pulse wave velocity estimated through the PWIP is on the order of 11%, which is similar to that of the conventional processing technique which tracks the wavefront arrival time (13%).
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Affiliation(s)
- Matthew McGarry
- Department of Biomedical Engineering, Columbia University, New York, NY, United States; Thayer School of Engineering, Dartmouth College, Hanover, NH, United States
| | - Pierre Nauleau
- Department of Biomedical Engineering, Columbia University, New York, NY, United States
| | - Iason Apostolakis
- Department of Biomedical Engineering, Columbia University, New York, NY, United States
| | - Elisa Konofagou
- Department of Biomedical Engineering, Columbia University, New York, NY, United States; Department of Radiology, Columbia University, New York, NY, United States.
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Walter BA, Mageswaran P, Mo X, Boulter DJ, Mashaly H, Nguyen XV, Prevedello LM, Thoman W, Raterman BD, Kalra P, Mendel E, Marras WS, Kolipaka A. MR Elastography-derived Stiffness: A Biomarker for Intervertebral Disc Degeneration. Radiology 2017; 285:167-175. [PMID: 28471737 DOI: 10.1148/radiol.2017162287] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Purpose To determine the repeatability of magnetic resonance (MR) elastography-derived shear stiffness measurements of the intervertebral disc (IVD) taken throughout the day and their relationship with IVD degeneration and subject age. Materials and Methods In a cross-sectional study, in vivo lumbar MR elastography was performed once in the morning and once in the afternoon in 47 subjects without current low back pain (IVDs = 230; age range, 20-71 years) after obtaining written consent under approval of the institutional review board. The Pfirrmann degeneration grade and MR elastography-derived shear stiffness of the nucleus pulposus and annulus fibrosus regions of all lumbar IVDs were assessed by means of principal frequency analysis. One-way analysis of variance, paired t tests, concordance and Bland-Altman tests, and Pearson correlations were used to evaluate degeneration, diurnal changes, repeatability, and age effects, respectively. Results There were no significant differences between morning and afternoon shear stiffness across all levels and there was very good technical repeatability between the morning and afternoon imaging results for both nucleus pulposus (R = 0.92) and annulus fibrosus (R = 0.83) regions. There was a significant increase in both nucleus pulposus and annulus fibrosus MR elastography-derived shear stiffness with increasing Pfirrmann degeneration grade (nucleus pulposus grade 1, 12.5 kPa ± 1.3; grade 5, 16.5 kPa ± 2.1; annulus fibrosus grade 1, 90.4 kPa ± 9.3; grade 5, 120.1 kPa ± 15.4), and there were weak correlations between shear stiffness and age across all levels (R ≤ 0.32). Conclusion Our results demonstrate that MR elastography-derived shear stiffness measurements are highly repeatable, weakly correlate with age, and increase with advancing IVD degeneration. These results suggest that MR elastography-derived shear stiffness may provide an objective biomarker of the IVD degeneration process. © RSNA, 2017 Online supplemental material is available for this article.
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Affiliation(s)
- Benjamin A Walter
- From the Spine Research Institute (B.A.W., P.M., H.M., W.T., E.M., W.S.M., A.K.), Department of Biomedical Engineering (B.A.W., A.K.), Department of Integrated Systems Engineering (P.M., W.S.M.), and Department of Biomedical Informatics (X.M.), the Ohio State University, 395 W 12th Ave, 4th Floor Radiology, Columbus, OH 43210; and Departments of Radiology (D.J.B., X.V.N., L.M.P., B.D.R., P.K., A.K.) and Neurologic Surgery (H.M., W.T., E.M.), the Ohio State University Wexner Medical Center, Columbus, Ohio
| | - Prasath Mageswaran
- From the Spine Research Institute (B.A.W., P.M., H.M., W.T., E.M., W.S.M., A.K.), Department of Biomedical Engineering (B.A.W., A.K.), Department of Integrated Systems Engineering (P.M., W.S.M.), and Department of Biomedical Informatics (X.M.), the Ohio State University, 395 W 12th Ave, 4th Floor Radiology, Columbus, OH 43210; and Departments of Radiology (D.J.B., X.V.N., L.M.P., B.D.R., P.K., A.K.) and Neurologic Surgery (H.M., W.T., E.M.), the Ohio State University Wexner Medical Center, Columbus, Ohio
| | - Xiaokui Mo
- From the Spine Research Institute (B.A.W., P.M., H.M., W.T., E.M., W.S.M., A.K.), Department of Biomedical Engineering (B.A.W., A.K.), Department of Integrated Systems Engineering (P.M., W.S.M.), and Department of Biomedical Informatics (X.M.), the Ohio State University, 395 W 12th Ave, 4th Floor Radiology, Columbus, OH 43210; and Departments of Radiology (D.J.B., X.V.N., L.M.P., B.D.R., P.K., A.K.) and Neurologic Surgery (H.M., W.T., E.M.), the Ohio State University Wexner Medical Center, Columbus, Ohio
| | - Daniel J Boulter
- From the Spine Research Institute (B.A.W., P.M., H.M., W.T., E.M., W.S.M., A.K.), Department of Biomedical Engineering (B.A.W., A.K.), Department of Integrated Systems Engineering (P.M., W.S.M.), and Department of Biomedical Informatics (X.M.), the Ohio State University, 395 W 12th Ave, 4th Floor Radiology, Columbus, OH 43210; and Departments of Radiology (D.J.B., X.V.N., L.M.P., B.D.R., P.K., A.K.) and Neurologic Surgery (H.M., W.T., E.M.), the Ohio State University Wexner Medical Center, Columbus, Ohio
| | - Hazem Mashaly
- From the Spine Research Institute (B.A.W., P.M., H.M., W.T., E.M., W.S.M., A.K.), Department of Biomedical Engineering (B.A.W., A.K.), Department of Integrated Systems Engineering (P.M., W.S.M.), and Department of Biomedical Informatics (X.M.), the Ohio State University, 395 W 12th Ave, 4th Floor Radiology, Columbus, OH 43210; and Departments of Radiology (D.J.B., X.V.N., L.M.P., B.D.R., P.K., A.K.) and Neurologic Surgery (H.M., W.T., E.M.), the Ohio State University Wexner Medical Center, Columbus, Ohio
| | - Xuan V Nguyen
- From the Spine Research Institute (B.A.W., P.M., H.M., W.T., E.M., W.S.M., A.K.), Department of Biomedical Engineering (B.A.W., A.K.), Department of Integrated Systems Engineering (P.M., W.S.M.), and Department of Biomedical Informatics (X.M.), the Ohio State University, 395 W 12th Ave, 4th Floor Radiology, Columbus, OH 43210; and Departments of Radiology (D.J.B., X.V.N., L.M.P., B.D.R., P.K., A.K.) and Neurologic Surgery (H.M., W.T., E.M.), the Ohio State University Wexner Medical Center, Columbus, Ohio
| | - Luciano M Prevedello
- From the Spine Research Institute (B.A.W., P.M., H.M., W.T., E.M., W.S.M., A.K.), Department of Biomedical Engineering (B.A.W., A.K.), Department of Integrated Systems Engineering (P.M., W.S.M.), and Department of Biomedical Informatics (X.M.), the Ohio State University, 395 W 12th Ave, 4th Floor Radiology, Columbus, OH 43210; and Departments of Radiology (D.J.B., X.V.N., L.M.P., B.D.R., P.K., A.K.) and Neurologic Surgery (H.M., W.T., E.M.), the Ohio State University Wexner Medical Center, Columbus, Ohio
| | - William Thoman
- From the Spine Research Institute (B.A.W., P.M., H.M., W.T., E.M., W.S.M., A.K.), Department of Biomedical Engineering (B.A.W., A.K.), Department of Integrated Systems Engineering (P.M., W.S.M.), and Department of Biomedical Informatics (X.M.), the Ohio State University, 395 W 12th Ave, 4th Floor Radiology, Columbus, OH 43210; and Departments of Radiology (D.J.B., X.V.N., L.M.P., B.D.R., P.K., A.K.) and Neurologic Surgery (H.M., W.T., E.M.), the Ohio State University Wexner Medical Center, Columbus, Ohio
| | - Brian D Raterman
- From the Spine Research Institute (B.A.W., P.M., H.M., W.T., E.M., W.S.M., A.K.), Department of Biomedical Engineering (B.A.W., A.K.), Department of Integrated Systems Engineering (P.M., W.S.M.), and Department of Biomedical Informatics (X.M.), the Ohio State University, 395 W 12th Ave, 4th Floor Radiology, Columbus, OH 43210; and Departments of Radiology (D.J.B., X.V.N., L.M.P., B.D.R., P.K., A.K.) and Neurologic Surgery (H.M., W.T., E.M.), the Ohio State University Wexner Medical Center, Columbus, Ohio
| | - Prateek Kalra
- From the Spine Research Institute (B.A.W., P.M., H.M., W.T., E.M., W.S.M., A.K.), Department of Biomedical Engineering (B.A.W., A.K.), Department of Integrated Systems Engineering (P.M., W.S.M.), and Department of Biomedical Informatics (X.M.), the Ohio State University, 395 W 12th Ave, 4th Floor Radiology, Columbus, OH 43210; and Departments of Radiology (D.J.B., X.V.N., L.M.P., B.D.R., P.K., A.K.) and Neurologic Surgery (H.M., W.T., E.M.), the Ohio State University Wexner Medical Center, Columbus, Ohio
| | - Ehud Mendel
- From the Spine Research Institute (B.A.W., P.M., H.M., W.T., E.M., W.S.M., A.K.), Department of Biomedical Engineering (B.A.W., A.K.), Department of Integrated Systems Engineering (P.M., W.S.M.), and Department of Biomedical Informatics (X.M.), the Ohio State University, 395 W 12th Ave, 4th Floor Radiology, Columbus, OH 43210; and Departments of Radiology (D.J.B., X.V.N., L.M.P., B.D.R., P.K., A.K.) and Neurologic Surgery (H.M., W.T., E.M.), the Ohio State University Wexner Medical Center, Columbus, Ohio
| | - William S Marras
- From the Spine Research Institute (B.A.W., P.M., H.M., W.T., E.M., W.S.M., A.K.), Department of Biomedical Engineering (B.A.W., A.K.), Department of Integrated Systems Engineering (P.M., W.S.M.), and Department of Biomedical Informatics (X.M.), the Ohio State University, 395 W 12th Ave, 4th Floor Radiology, Columbus, OH 43210; and Departments of Radiology (D.J.B., X.V.N., L.M.P., B.D.R., P.K., A.K.) and Neurologic Surgery (H.M., W.T., E.M.), the Ohio State University Wexner Medical Center, Columbus, Ohio
| | - Arunark Kolipaka
- From the Spine Research Institute (B.A.W., P.M., H.M., W.T., E.M., W.S.M., A.K.), Department of Biomedical Engineering (B.A.W., A.K.), Department of Integrated Systems Engineering (P.M., W.S.M.), and Department of Biomedical Informatics (X.M.), the Ohio State University, 395 W 12th Ave, 4th Floor Radiology, Columbus, OH 43210; and Departments of Radiology (D.J.B., X.V.N., L.M.P., B.D.R., P.K., A.K.) and Neurologic Surgery (H.M., W.T., E.M.), the Ohio State University Wexner Medical Center, Columbus, Ohio
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Kolipaka A, Schroeder S, Mo X, Shah Z, Hart PA, Conwell DL. Magnetic resonance elastography of the pancreas: Measurement reproducibility and relationship with age. Magn Reson Imaging 2017; 42:1-7. [PMID: 28476308 DOI: 10.1016/j.mri.2017.04.015] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Revised: 04/20/2017] [Accepted: 04/30/2017] [Indexed: 02/07/2023]
Abstract
PURPOSE To determine magnetic resonance elastography (MRE)-derived stiffness of pancreas in healthy volunteers with emphasis on: 1) short term and midterm repeatability; and 2) variance as a function of age. METHODS Pancreatic MRE was performed on 22 healthy volunteers (age range:20-64years) in a 3T-scanner. For evaluation of reproducibility of stiffness estimates, the scans were repeated per volunteer on the same day (short term) and one month apart (midterm). MRE wave images were analyzed using 3D inversion to estimate the stiffness of overall pancreas and different anatomic regions (i.e., head, neck, body, and tail). Concordance and Spearman correlation tests were performed to determine reproducibility of stiffness measurements and relationship to age. RESULTS A strong concordance correlation (ρc=0.99; p-value<0.001) was found between short term and midterm repeatability pancreatic stiffness measurements. Additionally, the pancreatic stiffness significantly increased with age with good Spearman correlation coefficient (all ρ>0.81; p<0.001). The older age group (>45yrs) had significantly higher stiffness compared to the younger group (≤45yrs) (p<0.001). No significant difference (p>0.05) in stiffness measurements was observed between different anatomical regions of pancreas, except neck stiffness was slightly lower (p<0.012) compared to head and overall pancreas at month 1. CONCLUSION MRE-derived pancreatic stiffness measurements are highly reproducible in the short and midterm and increase linearly with age in healthy volunteers. Further studies are needed to examine these effects in patients with various pancreatic diseases to understand potential clinical applications.
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Affiliation(s)
- Arunark Kolipaka
- Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, OH, United States; Department of Internal Medicine-Division of Cardiovascular Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, United States.
| | - Samuel Schroeder
- Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, OH, United States; Department of Mechanical Engineering, The Ohio State University, Columbus, OH, United States
| | - Xiaokui Mo
- Center for Biostatistics, Department of Biomedical Informatics, The Ohio State University, Columbus, OH, United States
| | - Zarine Shah
- Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, OH, United States
| | - Phil A Hart
- Division of Gastroenterology, Hepatology, and Nutrition, The Ohio State University Wexner Medical Center, Columbus, OH, United States
| | - Darwin L Conwell
- Division of Gastroenterology, Hepatology, and Nutrition, The Ohio State University Wexner Medical Center, Columbus, OH, United States
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Dong H, Mazumder R, Illapani VSP, Mo X, White RD, Kolipaka A. In vivo quantification of aortic stiffness using MR elastography in hypertensive porcine model. Magn Reson Med 2017; 78:2315-2321. [PMID: 28164361 DOI: 10.1002/mrm.26601] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2016] [Revised: 11/23/2016] [Accepted: 12/14/2016] [Indexed: 02/02/2023]
Abstract
PURPOSE Aortic stiffness plays an important role in evaluating and predicting the progression of systemic arterial hypertension (SAH). The aim of this study is to determine the stiffness of aortic wall using MR elastography (MRE) in a hypertensive porcine model and compare it against invasive aortic pressure measurements. METHODS Renal wrapping surgery was performed on eight pigs to induce SAH. Aortic MRE was performed at baseline and 2 months postsurgery using a retrospectively pulse-gated gradient-echo MRE sequence on a 1.5 tesla scanner. Mechanical waves of 70 Hz were introduced into the aorta. Invasive central aortic pressure measurements were obtained prior to each scan to calculate mean arterial pressure (MAP). MRE data were analyzed to obtain effective aortic stiffness. Spearman's rank correlation analysis was performed to assess the relationship between MAP and MRE-derived aortic stiffness. RESULTS Significant increase in effective aortic stiffness was observed between baseline and 2 months postsurgery measurements (paired t test; P = 0.004). The average MAP, determined by pooling all animals, was 65.24 ± 9.42 mm Hg at baseline and 92.57 ± 11.80 mm Hg 2 months postsurgery with P < 0.0001. Moderate linear correlation was observed between MAP and effective aortic stiffness (ρ = 0.52; P = 0.046). CONCLUSION This study demonstrated that, in a SAH porcine model, MRE-derived aortic stiffness increased with increase in MAP. Magn Reson Med 78:2315-2321, 2017. © 2017 International Society for Magnetic Resonance in Medicine.
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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
| | - Ria Mazumder
- Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA.,Department of Electrical and Computer Engineering, The Ohio State University, Columbus, Ohio, USA.,Department of Biomedical Engineering, Widener University, Chester, Pennsylvania, USA
| | - Venkata Sita Priyanka Illapani
- Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA.,Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio, USA
| | - Xiaokui Mo
- Center for Biostatistics, Department of Biomedical Informatics, The Ohio State University, Columbus, Ohio, USA
| | - Richard D White
- Department of Radiology, The Ohio State University Wexner Medical Center, 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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22
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Kolipaka A, Illapani VSP, Kalra P, Garcia J, Mo X, Markl M, White RD. Quantification and comparison of 4D-flow MRI-derived wall shear stress and MRE-derived wall stiffness of the abdominal aorta. J Magn Reson Imaging 2016; 45:771-778. [PMID: 27603433 DOI: 10.1002/jmri.25445] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 08/10/2016] [Indexed: 02/01/2023] Open
Abstract
PURPOSE Aortic wall shear stress (WSSFlow ) alters endothelial function, which in-turn changes aortic wall stiffness leading to remodeling in different disease states. Therefore, the aims of this study are to determine normal physiologic correlations between: (1) Magnetic Resonance Elastography (MRE)-derived aortic wall stiffness (WSMRE ) and WSSFlow ; (2) WSMRE and mean velocity; (3) WSMRE and pulse wave velocity (PWV);( 4) WSMRE and mean peak flow; and (5) WSMRE , WSSFlow and age using MRE and 4D-flow MRI in the abdominal aorta in healthy human subjects. MATERIALS AND METHODS Cardiac-gated aortic MRE and 4D-flow MRI data were acquired in 24 healthy volunteers using a 3 Tesla scanner. For MRE, 70 Hz external motion was applied to obtain wave images in all spatial directions in a separate breathhold. Whereas, 4D-flow data was acquired under free-breathing. Wave images in all the directions were processed to obtain three-dimensional-weighted stiffness map at end-systole (ES). WSSFlow , mean velocity, PWV and mean peak flow were obtained using 4D-flow data. Pearson correlation was performed to determine association between all variables. RESULTS A significant negative correlation was observed between: (1) ES WSMRE and WSSFlow in both axial (r = -0.62; P = 0.006) and circumferential (r = -0.52; P = 0.016) directions; (2) ES WSMRE and mean velocity (r = -0.58; P = 0.012); and (3) age and WSSFlow in both axial (r = -0.71; P < 0.0001) and circumferential (r = -0.58; P = 0.0012) directions. A significant positive correlation was observed between: (1) ES WSMRE and PWV (r = 0.69; P < 0.0001); (2) ES WSMRE and mean peak flow (r = 0.53; P = 0.016); and (3) ES WSMRE and age (r = 0.63;P = 0.006). CONCLUSION The negative significant correlation between aortic WSSFlow and WSMRE in normal volunteers demonstrates a relationship between WSMRE and WSSFlow . LEVEL OF EVIDENCE 2 J. Magn. Reson. Imaging 2017;45:771-778.
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Affiliation(s)
- Arunark Kolipaka
- Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA.,Department of Internal Medicine-Division of Cardiology, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
| | - Venkata Sita Priyanka Illapani
- Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA.,Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio, USA
| | - Prateek Kalra
- Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
| | - Julio Garcia
- Department of Radiology, Feinberg School of Medicine Northwestern University, Chicago, Illinois, USA
| | - Xiaokui Mo
- Center for Biostatistics, Department of Biomedical Informatics, Columbus, Ohio, USA
| | - Michael Markl
- Department of Radiology, Feinberg School of Medicine Northwestern University, Chicago, Illinois, USA.,Biomedical Engineering, McCormick School of Engineering, Northwestern University, Chicago, Illinois, USA
| | - Richard D White
- Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA.,Department of Internal Medicine-Division of Cardiology, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
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Hollis L, Conlisk N, Thomas-Seale LEJ, Roberts N, Pankaj P, Hoskins PR. Computational simulations of MR elastography in idealised abdominal aortic aneurysms. Biomed Phys Eng Express 2016. [DOI: 10.1088/2057-1976/2/4/045016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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24
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Quantification of abdominal aortic aneurysm stiffness using magnetic resonance elastography and its comparison to aneurysm diameter. J Vasc Surg 2016; 64:966-74. [PMID: 27131923 DOI: 10.1016/j.jvs.2016.03.426] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Accepted: 03/12/2016] [Indexed: 01/29/2023]
Abstract
OBJECTIVE Abdominal aortic aneurysm (AAA) wall stiffness has been suggested to be an important factor in the overall rupture risk assessment compared with anatomic measure. We hypothesize that AAA diameter will have no correlation to AAA wall stiffness. The aim of this study is to (1) determine magnetic resonance elastography (MRE)-derived aortic wall stiffness in AAA patients and its correlation to AAA diameter; (2) determine the correlation between AAA stiffness and amount of thrombus and calcium; and (3) compare the AAA stiffness measurements against age-matched healthy individuals. METHODS In vivo abdominal aortic MRE was performed on 36 individuals (24 patients with AAA measuring 3-10 cm and 12 healthy volunteers), aged 36 to 78 years, after obtaining written informed consent under the approval of the Institutional Review Board. MRE images were processed to obtain spatial stiffness maps of the aorta. AAA diameter, amount of thrombus, and calcium score were reported by experienced interventional radiologists. Spearman correlation, Wilcoxon signed rank test, and Mann-Whitney test were performed to determine the correlation between AAA stiffness and diameter and to determine the significant difference in stiffness measurements between AAA patients and healthy individuals. RESULTS No significant correlation (P > .1) was found between AAA stiffness and diameter or amount of thrombus or calcium score. AAA stiffness (mean 13.97 ± 4.2 kPa) is significantly (P ≤ .02) higher than remote normal aorta in AAA (mean 8.87 ± 2.2 kPa) patients and in normal individuals (mean 7.1 ± 1.9 kPa). CONCLUSIONS Our results suggest that AAA wall stiffness may provide additional information independent of AAA diameter, which may contribute to our understanding of AAA pathophysiology, biomechanics, and risk for rupture.
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25
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The simulation of magnetic resonance elastography through atherosclerosis. J Biomech 2016; 49:1781-1788. [PMID: 27130475 DOI: 10.1016/j.jbiomech.2016.04.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2015] [Revised: 04/07/2016] [Accepted: 04/09/2016] [Indexed: 11/23/2022]
Abstract
The clinical diagnosis of atherosclerosis via the measurement of stenosis size is widely acknowledged as an imperfect criterion. The vulnerability of an atherosclerotic plaque to rupture is associated with its mechanical properties. The potential to image these mechanical properties using magnetic resonance elastography (MRE) was investigated through synthetic datasets. An image of the steady state wave propagation, equivalent to the first harmonic, can be extracted directly from finite element analysis. Inversion of this displacement data yields a map of the shear modulus, known as an elastogram. The variation of plaque composition, stenosis size, Gaussian noise, filter thresholds and excitation frequency were explored. A decreasing mean shear modulus with an increasing lipid composition was identified through all stenosis sizes. However the inversion algorithm showed sensitivity to parameter variation leading to artefacts which disrupted both the elastograms and quantitative trends. As noise was increased up to a realistic level, the contrast was maintained between the fully fibrous and lipid plaques but lost between the interim compositions. Although incorporating a Butterworth filter improved the performance of the algorithm, restrictive filter thresholds resulted in a reduction of the sensitivity of the algorithm to composition and noise variation. Increasing the excitation frequency improved the techniques ability to image the magnitude of the shear modulus and identify a contrast between compositions. In conclusion, whilst the technique has the potential to image the shear modulus of atherosclerotic plaques, future research will require the integration of a heterogeneous inversion algorithm.
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26
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Low G, Kruse SA, Lomas DJ. General review of magnetic resonance elastography. World J Radiol 2016; 8:59-72. [PMID: 26834944 PMCID: PMC4731349 DOI: 10.4329/wjr.v8.i1.59] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Revised: 11/14/2015] [Accepted: 12/04/2015] [Indexed: 02/06/2023] Open
Abstract
Magnetic resonance elastography (MRE) is an innovative imaging technique for the non-invasive quantification of the biomechanical properties of soft tissues via the direct visualization of propagating shear waves in vivo using a modified phase-contrast magnetic resonance imaging (MRI) sequence. Fundamentally, MRE employs the same physical property that physicians utilize when performing manual palpation - that healthy and diseased tissues can be differentiated on the basis of widely differing mechanical stiffness. By performing “virtual palpation”, MRE is able to provide information that is beyond the capabilities of conventional morphologic imaging modalities. In an era of increasing adoption of multi-parametric imaging approaches for solving complex problems, MRE can be seamlessly incorporated into a standard MRI examination to provide a rapid, reliable and comprehensive imaging evaluation at a single patient appointment. Originally described by the Mayo Clinic in 1995, the technique represents the most accurate non-invasive method for the detection and staging of liver fibrosis and is currently performed in more than 100 centers worldwide. In this general review, the mechanical properties of soft tissues, principles of MRE, clinical applications of MRE in the liver and beyond, and limitations and future directions of this discipline -are discussed. Selected diagrams and images are provided for illustration.
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27
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Zhang N, Chen J, Yin M, Glaser KJ, Xu L, Ehman RL. Quantification of regional aortic stiffness using MR elastography: A phantom and ex-vivo porcine aorta study. Magn Reson Imaging 2015; 34:91-6. [PMID: 26597836 DOI: 10.1016/j.mri.2015.10.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Revised: 09/19/2015] [Accepted: 10/18/2015] [Indexed: 02/06/2023]
Abstract
MR Elastography (MRE) is a noninvasive technique for measuring tissue stiffness that has been used to assess the average stiffness of the abdominal aorta. The utility of aortic MRE would be improved if it could provide information about local variations in aortic stiffness. We hypothesize that regional variations in aortic stiffness can also be measured with MRE and the purpose of this work was to demonstrate that MRE can measure regional stiffness variations in a vascular phantom and in ex vivo porcine aortas. A vascular phantom was fabricated, containing two silicone tubes embedded in gel. A segment of one of the tubes was modified to increase its stiffness. MRE was performed on the phantom with a continuous flow of water through the tubes. The stiffness distribution along the modified tube was measured and compared to the reference tube. MRE was also performed in porcine aortas embedded in gel with segments treated with saline or formalin for 4 days. The stiffness difference between saline- and formalin-treated aortic segments was measured by MRE and mechanical tests. A positive correlation was found between the regional stiffnesses measured by MRE and mechanical tests. The results indicate that MRE can be used to evaluate the local stiffness distribution in silicone tubes and ex vivo porcine aortas. It may therefore be possible to apply MRE to measure regional stiffness variations of the aorta in vivo.
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Affiliation(s)
- Nan Zhang
- Department of Radiology, Mayo Clinic, 200 First Street SW, Rochester 55905, MN, USA; Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, Chaoyang District Anzhen Road 2nd, Beijing 100029, China
| | - Jun Chen
- Department of Radiology, Mayo Clinic, 200 First Street SW, Rochester 55905, MN, USA.
| | - Meng Yin
- Department of Radiology, Mayo Clinic, 200 First Street SW, Rochester 55905, MN, USA
| | - Kevin J Glaser
- Department of Radiology, Mayo Clinic, 200 First Street SW, Rochester 55905, MN, USA
| | - Lei Xu
- Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, Chaoyang District Anzhen Road 2nd, Beijing 100029, China.
| | - Richard L Ehman
- Department of Radiology, Mayo Clinic, 200 First Street SW, Rochester 55905, MN, USA
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Kenyhercz WE, Raterman B, Illapani VSP, Dowell J, Mo X, White RD, Kolipaka A. Quantification of aortic stiffness using magnetic resonance elastography: Measurement reproducibility, pulse wave velocity comparison, changes over cardiac cycle, and relationship with age. Magn Reson Med 2015; 75:1920-6. [PMID: 26096227 DOI: 10.1002/mrm.25719] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Revised: 03/11/2015] [Accepted: 03/12/2015] [Indexed: 12/22/2022]
Abstract
PURPOSE To assess MR elastography (MRE)-derived aortic shear stiffness (μMRE ) measurements for: 1) reproducibility, 2) comparison to pulse wave velocity, 3) changes over the cardiac cycle, and 4) relationship with age. METHODS Cardiac-gated aortic MRE was performed on 20 healthy volunteers (aged 20-73 years). For assessing reproducibility of stiffness measurements, scans were repeated per volunteer. MRE wave images were analyzed to obtain stiffness of the abdominal aorta across the cardiac cycle, and comparisons were made with subject age. RESULTS Analysis of concordance correlation coefficient between scans 1 and 2 showed that rc = 0.86 (95% confidence interval, 0.77, 0.94) with P < 0.0001. Significantly higher μMRE was observed for all volunteers during end-systole when compared to end-diastole (P < 0.0001). μMRE increased with age; end-systolic stiffness demonstrated a relatively stronger correlation with age (r = 0.62, P = 0.003) when compared to end-diastolic stiffness (r = 0.51, P = 0.023); and the slopes of end-systole and end-diastole were found to be significantly different (P = 0.011). [Formula: see text] at end-systole and end-diastole correlated linearly with pulse wave velocity, with an r = 0.54 (P = 0.013) and r = 0.58 (P = 0.008), respectively. CONCLUSION The results of this study indicate that MRE-derived aortic shear stiffness measurements are robust (reproducible and comparable to similar techniques). Mean μMRE was higher during end-systole when compared to end-diastole. μMRE was found to increase with age and showed a stronger correlation with end-systolic stiffness than with end-diastolic stiffness.
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Affiliation(s)
- William E Kenyhercz
- Department of Radiology, Wexner Medical Center, The Ohio State University, Columbus, Ohio, USA
| | - Brian Raterman
- Department of Radiology, Wexner Medical Center, The Ohio State University, Columbus, Ohio, USA
| | - Venkata Sita Priyanka Illapani
- Department of Radiology, Wexner Medical Center, The Ohio State University, Columbus, Ohio, USA.,Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio, USA
| | - Joshua Dowell
- Department of Internal Medicine, Division of Cardiovascular Medicine, Wexner Medical Center, The Ohio State University, Columbus, Ohio, USA
| | - Xiaokui Mo
- Center for Biostatistics, The Ohio State University, Columbus, Ohio, USA
| | - Richard D White
- Department of Radiology, Wexner Medical Center, The Ohio State University, Columbus, Ohio, USA.,Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio, USA.,Department of Internal Medicine, Division of Cardiovascular Medicine, Wexner Medical Center, The Ohio State University, Columbus, Ohio, USA
| | - Arunark Kolipaka
- Department of Radiology, Wexner Medical Center, The Ohio State University, Columbus, Ohio, USA.,Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio, USA.,Department of Internal Medicine, Division of Cardiovascular Medicine, Wexner Medical Center, The Ohio State University, Columbus, Ohio, USA
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Fediuk J, Dakshinamurti S. A role for actin polymerization in persistent pulmonary hypertension of the newborn. Can J Physiol Pharmacol 2015; 93:185-94. [PMID: 25695400 DOI: 10.1139/cjpp-2014-0413] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Persistent pulmonary hypertension of the newborn (PPHN) is defined as the failure of normal pulmonary vascular relaxation at birth. Hypoxia is known to impede postnatal disassembly of the actin cytoskeleton in pulmonary arterial myocytes, resulting in elevation of smooth muscle α-actin and γ-actin content in elastic and resistance pulmonary arteries in PPHN compared with age-matched controls. This review examines the original histological characterization of PPHN with attention to cytoskeletal structural remodeling and actin isoform abundance, reviews the existing evidence for understanding the biophysical and biochemical forces at play during neonatal circulatory transition, and specifically addresses the role of the cortical actin architecture, primarily identified as γ-actin, in the transduction of mechanical force in the hypoxic PPHN pulmonary circuit.
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Affiliation(s)
- Jena Fediuk
- Biology of Breathing Group, Manitoba Institute of Child Health, 715 McDermot Avenue, Winnipeg, MB R3E 3P4, Canada., Department of Physiology, University of Manitoba, Winnipeg, Manitoba, Canada
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Cunnane E, Mulvihill J, Barrett H, Healy D, Kavanagh E, Walsh S, Walsh M. Mechanical, biological and structural characterization of human atherosclerotic femoral plaque tissue. Acta Biomater 2015; 11:295-303. [PMID: 25242646 DOI: 10.1016/j.actbio.2014.09.024] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Revised: 08/26/2014] [Accepted: 09/05/2014] [Indexed: 01/09/2023]
Abstract
The failure of endovascular treatments of peripheral arterial disease represents a critical clinical issue. Specialized data are required to tailor such procedures to account for the mechanical response of the diseased femoral arterial tissue to medical device deployment. The purpose of this study is to characterize the mechanical response of atherosclerotic femoral arterial tissue to large deformation, the conditions typical of angioplasty and stenting, and also to determine the mechanically induced failure properties and to relate this behaviour to biological content and structural composition using uniaxial testing, Fourier transform infrared spectroscopy and scanning electron microscopy. Mechanical and biological characterization of 20 plaque samples obtained from femoral endarterectomy identified three distinct classifications. "Lightly calcified" samples display linear mechanical responses and fail at relatively high stretch. "Moderately calcified" samples undergo an increase in stiffness and ultimate strength coupled with a decrease in ductility. Structural characterization reveals calcified nodules within this group that may be acting to reinforce the tissue matrix, thus increasing the stiffness and ultimate strength. "Heavily calcified" samples account for the majority of samples tested and exhibit significantly reduced ultimate strength and ductility compared to the preceding groups. Structural characterization of this group reveals large areas of calcified tissue dominating the failure cross-sections of the samples. The frequency and structural dominance of these features solely within this group offers an explanation as to the reduced ultimate strength and ductility and highlights the need for modern peripheral endovascular devices to account for this behaviour during novel medical device design.
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A module of human peripheral blood mononuclear cell transcriptional network containing primitive and differentiation markers is related to specific cardiovascular health variables. PLoS One 2014; 9:e95124. [PMID: 24759906 PMCID: PMC3997360 DOI: 10.1371/journal.pone.0095124] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Accepted: 03/24/2014] [Indexed: 12/30/2022] Open
Abstract
Peripheral blood mononuclear cells (PBMCs), including rare circulating stem and progenitor cells (CSPCs), have important yet poorly understood roles in the maintenance and repair of blood vessels and perfused organs. Our hypothesis was that the identities and functions of CSPCs in cardiovascular health could be ascertained by analyzing the patterns of their co-expressed markers in unselected PBMC samples. Because gene microarrays had failed to detect many stem cell-associated genes, we performed quantitative real-time PCR to measure the expression of 45 primitive and tissue differentiation markers in PBMCs from healthy and hypertensive human subjects. We compared these expression levels to the subjects' demographic and cardiovascular risk factors, including vascular stiffness. The tested marker genes were expressed in all of samples and organized in hierarchical transcriptional network modules, constructed by a bottom-up approach. An index of gene expression in one of these modules (metagene), defined as the average standardized relative copy numbers of 15 pluripotency and cardiovascular differentiation markers, was negatively correlated (all p<0.03) with age (R2 = −0.23), vascular stiffness (R2 = −0.24), and central aortic pressure (R2 = −0.19) and positively correlated with body mass index (R2 = 0.72, in women). The co-expression of three neovascular markers was validated at the single-cell level using mRNA in situ hybridization and immunocytochemistry. The overall gene expression in this cardiovascular module was reduced by 72±22% in the patients compared with controls. However, the compactness of both modules was increased in the patients' samples, which was reflected in reduced dispersion of their nodes' degrees of connectivity, suggesting a more primitive character of the patients' CSPCs. In conclusion, our results show that the relationship between CSPCs and vascular function is encoded in modules of the PBMCs transcriptional network. Furthermore, the coordinated gene expression in these modules can be linked to cardiovascular risk factors and subclinical cardiovascular disease; thus, this measure may be useful for their diagnosis and prognosis.
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Rapid acquisition technique for MR elastography of the liver. Magn Reson Imaging 2014; 32:679-83. [PMID: 24637083 DOI: 10.1016/j.mri.2014.02.013] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2013] [Revised: 02/05/2014] [Accepted: 02/06/2014] [Indexed: 12/19/2022]
Abstract
Magnetic resonance elastography (MRE) of the liver is a novel noninvasive clinical diagnostic tool to stage fibrosis based on measured stiffness. The purpose of this study is to design, evaluate and validate a rapid MRE acquisition technique for noninvasively quantitating liver stiffness which reduces by half the scan time, thereby decreasing image registration errors between four MRE phase offsets. In vivo liver MRE was performed on 16 healthy volunteers and 14 patients with biopsy-proven liver fibrosis using the standard clinical gradient recalled echo (GRE) MRE sequence (MREs) and a developed rapid GRE MRE sequence (MREr) to obtain the mean stiffness in an axial slice. The mean stiffness values obtained from the entire group using MREs and MREr were 2.72±0.85 kPa and 2.7±0.85 kPa, respectively, representing an insignificant difference. A linear correlation of R(2)=0.99 was determined between stiffness values obtained using MREs and MREr. Therefore, we can conclude that MREr can replace MREs, which reduces the scan time to half of that of the current standard acquisition (MREs), which will facilitate MRE imaging in patients with inability to hold their breath for long periods.
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Walsh MT, Cunnane EM, Mulvihill JJ, Akyildiz AC, Gijsen FJH, Holzapfel GA. Uniaxial tensile testing approaches for characterisation of atherosclerotic plaques. J Biomech 2014; 47:793-804. [PMID: 24508324 DOI: 10.1016/j.jbiomech.2014.01.017] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/13/2014] [Indexed: 01/19/2023]
Abstract
The pathological changes associated with the development of atherosclerotic plaques within arterial vessels result in significant alterations to the mechanical properties of the diseased arterial wall. There are several methods available to characterise the mechanical behaviour of atherosclerotic plaque tissue, and it is the aim of this paper to review the use of uniaxial mechanical testing. In the case of atherosclerotic plaques, there are nine studies that employ uniaxial testing to characterise mechanical behaviour. A primary concern regarding this limited cohort of published studies is the wide range of testing techniques that are employed. These differing techniques have resulted in a large variance in the reported data making comparison of the mechanical behaviour of plaques from different vasculatures, and even the same vasculature, difficult and sometimes impossible. In order to address this issue, this paper proposes a more standardised protocol for uniaxial testing of diseased arterial tissue that allows for better comparisons and firmer conclusions to be drawn between studies. To develop such a protocol, this paper reviews the acquisition and storage of the tissue, the testing approaches, the post-processing techniques and the stress-strain measures employed by each of the nine studies. Future trends are also outlined to establish the role that uniaxial testing can play in the future of arterial plaque mechanical characterisation.
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Affiliation(s)
- M T Walsh
- Centre for Applied Biomedical Engineering Research, Department of Mechanical, Aeronautical and Biomedical Engineering and the Materials and Surface Science Institute University of Limerick, Limerick, Ireland.
| | - E M Cunnane
- Centre for Applied Biomedical Engineering Research, Department of Mechanical, Aeronautical and Biomedical Engineering and the Materials and Surface Science Institute University of Limerick, Limerick, Ireland
| | - J J Mulvihill
- Centre for Applied Biomedical Engineering Research, Department of Mechanical, Aeronautical and Biomedical Engineering and the Materials and Surface Science Institute University of Limerick, Limerick, Ireland
| | - A C Akyildiz
- Department of Biomedical Engineering, Thoraxcenter, Erasmus Medical Centre, Rotterdam, The Netherlands
| | - F J H Gijsen
- Department of Biomedical Engineering, Thoraxcenter, Erasmus Medical Centre, Rotterdam, The Netherlands
| | - G A Holzapfel
- Graz University of Technology, Center of Biomedical Engineering Institute of Biomechanics, Kronesgasse 5-I, 8010 Graz, Austria; Royal Institute of Technology (KTH), Department of Solid Mechanics School of Engineering Sciences, Teknikringen 8d, 100 44 Stockholm, Sweden
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Nederveen AJ, Avril S, Speelman L. MRI strain imaging of the carotid artery: present limitations and future challenges. J Biomech 2014; 47:824-33. [PMID: 24468207 DOI: 10.1016/j.jbiomech.2014.01.014] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/13/2014] [Indexed: 11/18/2022]
Abstract
Rupture of atherosclerotic plaques in the carotid artery is a main cause of stroke. Current diagnostics are not sufficient to identify all rupture-prone plaques, and studies have shown that biomechanical factors improve current plaque risk assessment. Strain imaging may be a valuable contribution to this risk assessment. MRI is a versatile imaging technique that offers various methods that are capable of measuring tissue strain. In this review, MR imaging techniques with displacement (DENSE), velocity (PC MRI), or strain (SENC) encoding protocols are discussed, together with post-processing techniques based on time-resolved MRI data. Although several MRI techniques are being developed to improve time-resolved MR imaging, current technical limitations related to spatial and temporal resolutions render MRI strain imaging currently unfit for carotid plaque strain evaluation. A novel approach using non-rigid image registration of MR images to determine strain in carotid arteries based on black blood cine MRI is proposed in this review. This and other post-processing techniques based on time-resolved MRI data may provide a good estimate of plaque strain, but are also dependent on the spatial and temporal resolution of the MR images. However, they seem to be the most promising approach for MRI based plaque strain analysis in the near future.
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Affiliation(s)
- Aart J Nederveen
- Department of Radiology, Academic Medical Center Amsterdam, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands.
| | - Stéphane Avril
- Center for Biomedical and Healthcare Engineering, Ecole Nationale Supérieure des Mines de Saint-Étienne, France
| | - Lambert Speelman
- Department of Biomedical Engineering, Erasmus MC Rotterdam, The Netherlands
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Kenyhercz W, Damughatla A, Raterman B, Wassenaar PA, White RD, Kolipaka A. Quantification of aortic stiffness across the cardiac cycle using magnetic resonance elastography. J Cardiovasc Magn Reson 2014. [PMCID: PMC4044450 DOI: 10.1186/1532-429x-16-s1-p389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Damughatla AR, Raterman B, Sharkey-Toppen T, Jin N, Simonetti OP, White RD, Kolipaka A. Quantification of aortic stiffness using MR elastography and its comparison to MRI-based pulse wave velocity. J Magn Reson Imaging 2013; 41:44-51. [PMID: 24243654 DOI: 10.1002/jmri.24506] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Accepted: 10/19/2013] [Indexed: 01/11/2023] Open
Abstract
PURPOSE To determine the correlation in abdominal aortic stiffness obtained using magnetic resonance elastography (MRE) (μ(MRE)) and MRI-based pulse wave velocity (PWV) shear stiffness (μ(PWV)) estimates in normal volunteers of varying age, and also to determine the correlation between μ(MRE) and μ(PWV). MATERIALS AND METHODS In vivo aortic MRE and MRI were performed on 21 healthy volunteers with ages ranging from 18 to 65 years to obtain wave and velocity data along the long axis of the abdominal aorta. The MRE wave images were analyzed to obtain mean stiffness and the phase contrast images were analyzed to obtain PWV measurements and indirectly estimate stiffness values from the Moens-Korteweg equation. RESULTS Both μ(MRE) and μ(PWV) measurements increased with age, demonstrating linear correlations with R(2) values of 0.81 and 0.67, respectively. Significant difference (P ≤ 0.001) in mean μ(MRE) and μ(PWV) between young and old healthy volunteers was also observed. Furthermore, a poor linear correlation of R(2) value of 0.43 was determined between μ(MRE) and μ(PWV) in the initial pool of volunteers. CONCLUSION The results of this study indicate linear correlations between μ(MRE) and μ(PWV) with normal aging of the abdominal aorta. Significant differences in mean μ(MRE) and μ(PWV) between young and old healthy volunteers were observed.
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Affiliation(s)
- Anirudh R Damughatla
- Department of Biomedical Engineering, Ohio State University, Columbus, Ohio, USA
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Godfrey EM, Mannelli L, Griffin N, Lomas DJ. Magnetic resonance elastography in the diagnosis of hepatic fibrosis. Semin Ultrasound CT MR 2013; 34:81-8. [PMID: 23395320 DOI: 10.1053/j.sult.2012.11.007] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Liver fibrosis is a common feature of many chronic liver diseases, and can ultimately progress to cirrhosis. Conventional imaging is insensitive to liver fibrosis, necessitating a liver biopsy for diagnosis and monitoring of progression. However, liver biopsy risks complications, and is an imperfect gold standard in view of sampling error and intraobserver or interobserver variation. Magnetic resonance elastography (MRE) is a noninvasive method for assessing the mechanical properties of tissues and is gaining credence as a method of assessment for hepatic fibrosis. The aim of this review is to describe how MRE is performed, to review the present literature on the subject, to compare MRE with other noninvasive techniques used to assess for liver fibrosis, and to highlight areas of future research.
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Affiliation(s)
- Edmund M Godfrey
- Department of Radiology, Leeds Teaching Hospitals NHS Trust, UK.
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Lim YH, Enkhdorj R, Kim BK, Kim SG, Kim JH, Shin J. Correlation between Proximal Abdominal Aortic Stiffness Measured by Ultrasound and Brachial-Ankle Pulse Wave Velocity. Korean Circ J 2013; 43:391-9. [PMID: 23882288 PMCID: PMC3717422 DOI: 10.4070/kcj.2013.43.6.391] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Revised: 05/27/2013] [Accepted: 06/12/2013] [Indexed: 11/21/2022] Open
Abstract
Background and Objectives The proximal portion of the abdominal aorta (AA) is characterized by minimal arteriosclerosis compared with other aortic segments. To assess the clinical usefulness of this characteristic, the correlation between ultrasonographically measured proximal AA stiffness and brachial-ankle pulse wave velocity (baPWV) was examined. Subjects and Methods 285 subjects were analyzed, half with hypertension and half with normal blood pressure. Proximal AA was examined using ultrasonography; strain, distensibility, elastic modulus, and the stiffness index were determined. After adjustment for age, gender, body mass index (BMI), systolic blood pressure (SBP), and heart rate, the relationships between baPWV and all these parameters were tested. Results The mean age of the study subjects was 58.1±12.8 years and the mean BMI was 24.3±3.8 kg/cm2. 58.9% of the subjects were female. 42.8% were hypertensive subjects. Among the hypertensive subjects, 56.0% were taking antihypertensive medication. Adjusted partial correlation coefficients for the relationship between baPWV with strain, distensibility, elastic modulus, and the stiffness index of the proximal AA were -0.203 (p=0.01), -0.121 (p=0.129), 0.304 (p=0.0001), and 0.299 (p=0.0001), respectively, in normotensive subjects. In the multivariate analyses, such correlations were observed mainly in the normotensive group, whereas there was no association among hypertensive subjects regardless of antihypertensive medication status. Conclusion baPWV is moderately correlated with the stiffness parameters for the proximal AA, mainly in normotensive subjects.
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Affiliation(s)
- Young-Hyo Lim
- Division of Cardiology, Department of Internal Medicine, Hanyang University College of Medicine, Seoul, Korea
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Doyle BJ, Callanan A, Grace PA, Kavanagh EG. On the influence of patient-specific material properties in computational simulations: a case study of a large ruptured abdominal aortic aneurysm. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2013; 29:150-164. [PMID: 23345202 DOI: 10.1002/cnm.2515] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2012] [Revised: 08/30/2012] [Accepted: 08/31/2012] [Indexed: 06/01/2023]
Abstract
Patient-specific modelling of abdominal aortic aneurysm has been shown to have clinical potential. This paper examines a large ruptured abdominal aortic aneurysm where the tissue from the diseased wall and the intraluminal thrombus was excised during open surgical repair and experimentally characterised. The mechanical data were used to develop material parameters that were incorporated into finite element models with measured nonuniform wall thickness. Implementation of the material data into the numerical model increased peak wall stress by 67%, wall strain by 320% and displacement by 177%, when compared with simulations based on material properties available in the literature. Distributions of numerical results were similar for both material data. Magnitudes of numerical results can differ significantly when using patient-specific material properties and therefore, care should be taken when interpreting numerical results derived from population-based data.
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Affiliation(s)
- Barry J Doyle
- Centre for Applied Biomedical Engineering Research-CABER, Department of Mechanical, Aeronautical and Biomedical Engineering, and Materials and Surface Science Institute, University of Limerick, Ireland.
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Damughatla A, Raterman B, Simonetti OP, Sharkey-Toppen T, Jin N, White RD, Kolipaka A. MR elastography as a method to estimate aortic stiffness and its comparison against MR based pulse wave velocity measurement. J Cardiovasc Magn Reson 2013. [PMCID: PMC3559925 DOI: 10.1186/1532-429x-15-s1-p240] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Chen D, Müller-Eschner M, Rengier F, Kotelis D, Böckler D, Ventikos Y, Xu Y, Zeng Y, Peng Y, von Tengg-Kobligk H. A Preliminary Study of Fast Virtual Stent-Graft Deployment: Application to Stanford Type B Aortic Dissection. INT J ADV ROBOT SYST 2013. [DOI: 10.5772/55269] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Aortic dissection is the result of blood intruding into the layers of the aortic wall creating a duplicate channel along the aortic course. This considerably changes aortic morphology and thereby alters blood flow, inducing severe pathological conditions. Endovascular stent-graft placement has become an accepted treatment option for complicated Stanford type B aortic dissection. Stent-graft deployment aims to cover the primary entry, preventing most of the inflow to the false lumen, thereby promoting false lumen thrombosis and true lumen expansion. In recent years the application of this treatment has increased continuously. However, a fast and reasonable prediction for the released stent-graft and the resulting aortic remodelling prior to intervention is still lacking. In this paper, we propose a preliminary study on the fast virtual stent-graft deployment algorithm based on contact mechanics, spring analogy and deformable meshes. By virtually releasing a stent-graft in a patient-specific model of an aortic dissection type Stanford B, we simulate the interaction between the expanding stent-graft and the vessel wall (with low computational cost), and estimate the post-interventional configuration of the true lumen. This preliminary study can be finished within minutes and the results present good consistency with the post-interventional computed tomography angiography. It therefore confirms the feasibility and rationality of this algorithm, encouraging further research on this topic, which may provide more accurate results and could assist in medical decision-making.
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Affiliation(s)
- Duanduan Chen
- School of Life Science, Beijing Institute of Technology, China
| | - Matthias Müller-Eschner
- Department of Diagnostic and Interventional Radiology, University Hospital Heidelberg, Germany
| | - Fabian Rengier
- Department of Diagnostic and Interventional Radiology, University Hospital Heidelberg, Germany
| | - Drosos Kotelis
- Department of Vascular Surgery, University Hospital Heidelberg, Germany
| | - Dittmar Böckler
- Department of Vascular Surgery, University Hospital Heidelberg, Germany
| | - Yiannis Ventikos
- Department of Engineering Science & Institute of Biomedical Engineering, University of Oxford, UK
| | - Yong Xu
- General Hospital of Chinese PLA, China
| | - Yanjun Zeng
- Biomechanics and Medical Information Institute, Beijing University of Technology, China
| | - Yuhua Peng
- School of Life Science, Beijing Institute of Technology, China
| | - Hendrik von Tengg-Kobligk
- Department of Diagnostic and Interventional Radiology, University Hospital Heidelberg, Germany
- Radiology, German Cancer Research Center (dkfz), Heidelberg, Germany
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Current world literature. Curr Opin Cardiol 2012; 27:682-95. [PMID: 23075824 DOI: 10.1097/hco.0b013e32835a0ad8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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