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Arani A, Murphy MC, Bhopalwala H, Arunachalam SP, Rossman PJ, Trzasko JD, Glaser K, Sui Y, Gunderson T, Arruda-Olson AM, Manduca A, Kantarci K, Ehman RL, Araoz PA. Sex Differences in Aging-related Myocardial Stiffening Quantitatively Measured with MR Elastography. Radiol Cardiothorac Imaging 2024; 6:e230140. [PMID: 38780427 PMCID: PMC11211939 DOI: 10.1148/ryct.230140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 03/06/2024] [Accepted: 04/15/2024] [Indexed: 05/25/2024]
Abstract
Purpose To investigate the feasibility of using quantitative MR elastography (MRE) to characterize the influence of aging and sex on left ventricular (LV) shear stiffness. Materials and Methods In this prospective study, LV myocardial shear stiffness was measured in 109 healthy volunteers (age range: 18-84 years; mean age, 40 years ± 18 [SD]; 57 women, 52 men) enrolled between November 2018 and September 2019, using a 5-minute MRE acquisition added to a clinical MRI protocol. Linear regression models were used to estimate the association of cardiac MRI and MRE characteristics with age and sex; models were also fit to assess potential age-sex interaction. Results Myocardial shear stiffness significantly increased with age in female (age slope = 0.03 kPa/year ± 0.01, P = .009) but not male (age slope = 0.008 kPa/year ± 0.009, P = .38) volunteers. LV ejection fraction (LVEF) increased significantly with age in female volunteers (0.23% ± 0.08 per year, P = .005). LV end-systolic volume (LVESV) decreased with age in female volunteers (-0.20 mL/m2 ± 0.07, P = .003). MRI parameters, including T1, strain, and LV mass, did not demonstrate this interaction (P > .05). Myocardial shear stiffness was not significantly correlated with LVEF, LV stroke volume, body mass index, or any MRI strain metrics (P > .05) but showed significant correlations with LV end-diastolic volume/body surface area (BSA) (slope = -3 kPa/mL/m2 ± 1, P = .004, r2 = 0.08) and LVESV/BSA (-1.6 kPa/mL/m2 ± 0.5, P = .003, r2 = 0.08). Conclusion This study demonstrates that female, but not male, individuals experience disproportionate LV stiffening with natural aging, and these changes can be noninvasively measured with MRE. Keywords: Cardiac, Elastography, Biological Effects, Experimental Investigations, Sexual Dimorphisms, MR Elastography, Myocardial Shear Stiffness, Quantitative Stiffness Imaging, Aging Heart, Myocardial Biomechanics, Cardiac MRE Supplemental material is available for this article. Published under a CC BY 4.0 license.
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Affiliation(s)
- Arvin Arani
- From the Departments of Radiology (A.A., M.C.M., H.B., S.P.A.,
P.J.R., J.D.T., K.G., Y.S., A.M., K.K., R.L.E., P.A.A.), Quantitative Health
Science (T.G.), and Cardiology (A.M.A.O.), Mayo Clinic, 200 First St SW,
Rochester, MN 55905
| | - Matthew C. Murphy
- From the Departments of Radiology (A.A., M.C.M., H.B., S.P.A.,
P.J.R., J.D.T., K.G., Y.S., A.M., K.K., R.L.E., P.A.A.), Quantitative Health
Science (T.G.), and Cardiology (A.M.A.O.), Mayo Clinic, 200 First St SW,
Rochester, MN 55905
| | - Huzefa Bhopalwala
- From the Departments of Radiology (A.A., M.C.M., H.B., S.P.A.,
P.J.R., J.D.T., K.G., Y.S., A.M., K.K., R.L.E., P.A.A.), Quantitative Health
Science (T.G.), and Cardiology (A.M.A.O.), Mayo Clinic, 200 First St SW,
Rochester, MN 55905
| | - Shivaram P. Arunachalam
- From the Departments of Radiology (A.A., M.C.M., H.B., S.P.A.,
P.J.R., J.D.T., K.G., Y.S., A.M., K.K., R.L.E., P.A.A.), Quantitative Health
Science (T.G.), and Cardiology (A.M.A.O.), Mayo Clinic, 200 First St SW,
Rochester, MN 55905
| | - Phillip J. Rossman
- From the Departments of Radiology (A.A., M.C.M., H.B., S.P.A.,
P.J.R., J.D.T., K.G., Y.S., A.M., K.K., R.L.E., P.A.A.), Quantitative Health
Science (T.G.), and Cardiology (A.M.A.O.), Mayo Clinic, 200 First St SW,
Rochester, MN 55905
| | - Joshua D. Trzasko
- From the Departments of Radiology (A.A., M.C.M., H.B., S.P.A.,
P.J.R., J.D.T., K.G., Y.S., A.M., K.K., R.L.E., P.A.A.), Quantitative Health
Science (T.G.), and Cardiology (A.M.A.O.), Mayo Clinic, 200 First St SW,
Rochester, MN 55905
| | - Kevin Glaser
- From the Departments of Radiology (A.A., M.C.M., H.B., S.P.A.,
P.J.R., J.D.T., K.G., Y.S., A.M., K.K., R.L.E., P.A.A.), Quantitative Health
Science (T.G.), and Cardiology (A.M.A.O.), Mayo Clinic, 200 First St SW,
Rochester, MN 55905
| | - Yi Sui
- From the Departments of Radiology (A.A., M.C.M., H.B., S.P.A.,
P.J.R., J.D.T., K.G., Y.S., A.M., K.K., R.L.E., P.A.A.), Quantitative Health
Science (T.G.), and Cardiology (A.M.A.O.), Mayo Clinic, 200 First St SW,
Rochester, MN 55905
| | - Tina Gunderson
- From the Departments of Radiology (A.A., M.C.M., H.B., S.P.A.,
P.J.R., J.D.T., K.G., Y.S., A.M., K.K., R.L.E., P.A.A.), Quantitative Health
Science (T.G.), and Cardiology (A.M.A.O.), Mayo Clinic, 200 First St SW,
Rochester, MN 55905
| | - Adelaide M. Arruda-Olson
- From the Departments of Radiology (A.A., M.C.M., H.B., S.P.A.,
P.J.R., J.D.T., K.G., Y.S., A.M., K.K., R.L.E., P.A.A.), Quantitative Health
Science (T.G.), and Cardiology (A.M.A.O.), Mayo Clinic, 200 First St SW,
Rochester, MN 55905
| | - Armando Manduca
- From the Departments of Radiology (A.A., M.C.M., H.B., S.P.A.,
P.J.R., J.D.T., K.G., Y.S., A.M., K.K., R.L.E., P.A.A.), Quantitative Health
Science (T.G.), and Cardiology (A.M.A.O.), Mayo Clinic, 200 First St SW,
Rochester, MN 55905
| | - Kejal Kantarci
- From the Departments of Radiology (A.A., M.C.M., H.B., S.P.A.,
P.J.R., J.D.T., K.G., Y.S., A.M., K.K., R.L.E., P.A.A.), Quantitative Health
Science (T.G.), and Cardiology (A.M.A.O.), Mayo Clinic, 200 First St SW,
Rochester, MN 55905
| | - Richard L. Ehman
- From the Departments of Radiology (A.A., M.C.M., H.B., S.P.A.,
P.J.R., J.D.T., K.G., Y.S., A.M., K.K., R.L.E., P.A.A.), Quantitative Health
Science (T.G.), and Cardiology (A.M.A.O.), Mayo Clinic, 200 First St SW,
Rochester, MN 55905
| | - Philip A. Araoz
- From the Departments of Radiology (A.A., M.C.M., H.B., S.P.A.,
P.J.R., J.D.T., K.G., Y.S., A.M., K.K., R.L.E., P.A.A.), Quantitative Health
Science (T.G.), and Cardiology (A.M.A.O.), Mayo Clinic, 200 First St SW,
Rochester, MN 55905
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Harbo MB, Stokke MK, Sjaastad I, Espe EKS. One step closer to myocardial physiology: From PV loop analysis to state-of-the-art myocardial imaging. Acta Physiol (Oxf) 2022; 234:e13759. [PMID: 34978759 DOI: 10.1111/apha.13759] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 12/14/2021] [Accepted: 01/01/2022] [Indexed: 11/29/2022]
Abstract
Recent advances in cardiac imaging have revitalized the assessment of fundamental physiological concepts. In the field of cardiac physiology, invasive measurements with pressure-volume (PV) loops have served as the gold standard methodology for the characterization of left ventricular (LV) function. From PV loop data, fundamental aspects of LV chamber function are derived such as work, efficiency, stiffness and contractility. However, the parametrization of these aspects is limited because of the need for invasive procedures. Through the utilization of recent advances in echocardiography, magnetic resonance imaging and positron emission tomography, it has become increasingly feasible to quantify these fundamental aspects of LV function non-invasively. Importantly, state-of-the-art imaging technology enables direct assessment of myocardial performance, thereby extending functional assessment from the net function of the LV chamber, as is done with PV loops, to the myocardium itself. With a strong coupling to underlying myocardial physiology, imaging measurements of myocardial work, efficiency, stiffness and contractility could represent the next generation of functional parameters. The purpose of this review is to discuss how the new imaging parameters of myocardial work, efficiency, stiffness and contractility can bring cardiac physiologists, researchers and clinicians alike one step closer to underlying myocardial physiology.
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Affiliation(s)
- Markus Borge Harbo
- Institute for Experimental Medical Research Oslo University Hospital and University of Oslo Oslo Norway
- K.G. Jebsen Center for Cardiac Research University of Oslo Oslo Norway
| | - Mathis Korseberg Stokke
- Institute for Experimental Medical Research Oslo University Hospital and University of Oslo Oslo Norway
- K.G. Jebsen Center for Cardiac Research University of Oslo Oslo Norway
- Department of Cardiology Oslo University Hospital Rikshospitalet Oslo Norway
| | - Ivar Sjaastad
- Institute for Experimental Medical Research Oslo University Hospital and University of Oslo Oslo Norway
- K.G. Jebsen Center for Cardiac Research University of Oslo Oslo Norway
| | - Emil Knut Stenersen Espe
- Institute for Experimental Medical Research Oslo University Hospital and University of Oslo Oslo Norway
- K.G. Jebsen Center for Cardiac Research University of Oslo Oslo Norway
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Kemper PPN, Mahmoudi S, Apostolakis IZ, Konofagou EE. Feasibility of Bilinear Mechanical Characterization of the Abdominal Aorta in a Hypertensive Mouse Model. ULTRASOUND IN MEDICINE & BIOLOGY 2021; 47:3480-3490. [PMID: 34507874 PMCID: PMC8693438 DOI: 10.1016/j.ultrasmedbio.2021.08.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 07/28/2021] [Accepted: 08/01/2021] [Indexed: 05/19/2023]
Abstract
A change in elastin and collagen content is indicative of damage caused by hypertension, which changes the non-linear behavior of the vessel wall. This study was aimed at investigating the feasibility of monitoring the non-linear material behavior in an angiotensin II hypertensive mice model. Aortas from 13 hypertensive mice were imaged with pulse wave imaging (PWI) over 4 wk using a 40-MHz linear array. The pulse wave velocity was estimated using two wave features: (i) the maximum axial acceleration of the foot (PWVdia) and (ii) the maximum axial acceleration of the dicrotic notch (PWVend-sys). The Bramwell-Hill equation was used to derive the compliance at diastolic and end-systolic pressure. This study determined the potential of PWI in a hypertensive mouse model to image and quantify the non-linear material behavior in vivo. End-systolic compliance could differentiate between the sham and angiotensin II groups, whereas diastolic compliance could not, indicating that PWI can detect early collagen-dominated remodeling.
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Affiliation(s)
- Paul P N Kemper
- Ultrasound and Elasticity Imaging Laboratory, Department of Biomedical Engineering, Columbia University, New York, New York, USA.
| | - Salah Mahmoudi
- Ultrasound and Elasticity Imaging Laboratory, Department of Biomedical Engineering, Columbia University, New York, New York, USA
| | - Iason Zacharias Apostolakis
- Ultrasound and Elasticity Imaging Laboratory, Department of Biomedical Engineering, Columbia University, New York, New York, USA
| | - Elisa E Konofagou
- Ultrasound and Elasticity Imaging Laboratory, Department of Biomedical Engineering, Columbia University, New York, New York, USA; Department of Radiology, Columbia University, New York, New York, USA
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Kharat A, Vanpully NS, Jeeson JC. Simplified Guide to MR Elastography in Early Detection of Hepatic Fibrosis with Case Reports: The New Norm in Assessing Liver Health. Indian J Radiol Imaging 2021; 31:644-652. [PMID: 34790310 PMCID: PMC8590563 DOI: 10.1055/s-0041-1735929] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The current unhealthy diets and sedentary lifestyle have led to increase in the prevalence of diabetes and metabolic syndrome globally. Fatty liver is a common occurrence in metabolic syndrome. The liver health is often ignored due to delayed warning signs. Fatty changes of the liver is one of the common findings in ultrasonography. Ultrasound does not detect fibrosis except when cirrhosis is developed. Early stages of fibrosis are asymptomatic with no significant laboratory or preliminary imaging findings. With fibrosis, the elasticity of the liver is reduced and becomes stiffer. Over the years, many techniques have developed to assess the stiffness of the liver, starting from palpation, ultrasonography, and recently developed magnetic resonance elastography (MRE). In this article, we have tried to simplify the concepts of MRE to detect fibrosis and present few case reports. The basic steps involved in generating elastograms and interpretation with some insight on how to incorporate it into the clinical workflow are discussed. MRE is superior to various other available techniques and even offers certain advantages over biopsy. MRE is FDA approved for liver fibrosis since 2009, yet it is hardly used in the Indian setting. MRE is a safe and noninvasive technique to evaluate a large volume of the liver and can be a new norm for the evaluation of fatty liver. Magnetic resonance imaging (MRI)-based elastography techniques hold an exciting future in providing mechanical properties of tissues in various organs like spleen, brain, kidney, and heart.
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Affiliation(s)
- Amit Kharat
- Department of Radiology, Dr. D.Y. Patil Medical College, Hospital & Research Centre, Pimpri, Pune, Maharashtra, India
| | - Nikhith Soman Vanpully
- Department of Radiology, Dr. D.Y. Patil Medical College, Hospital & Research Centre, Pimpri, Pune, Maharashtra, India
| | - Jacob Cheeran Jeeson
- Department of Radiology, Dr. D.Y. Patil Medical College, Hospital & Research Centre, Pimpri, Pune, Maharashtra, India
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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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Kakkad V, LeFevre M, Hollender P, Kisslo J, Trahey GE. Non-invasive Measurement of Dynamic Myocardial Stiffness Using Acoustic Radiation Force Impulse Imaging. ULTRASOUND IN MEDICINE & BIOLOGY 2019; 45:1112-1130. [PMID: 30890282 PMCID: PMC6462419 DOI: 10.1016/j.ultrasmedbio.2018.12.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Revised: 12/20/2018] [Accepted: 12/21/2018] [Indexed: 05/23/2023]
Abstract
Myocardial stiffness exhibits cyclic variations over the course of the cardiac cycle. These trends are closely tied to the electromechanical and hemodynamic changes in the heart. Characterization of dynamic myocardialstiffness can provide insights into the functional state of the myocardium, as well as allow for differentiation between the underlying physiologic mechanisms that lead to congestive heart failure. Previous work has revealed the potential of acoustic radiation force impulse (ARFI) imaging to capture temporal trends in myocardial stiffness in experimental preparations such as the Langendorff heart, as well as on animals in open-chest and intracardiac settings. This study was aimed at investigating the potential of ARFI to measure dynamic myocardial stiffness in human subjects, in a non-invasive manner through transthoracic imaging windows. ARFI imaging was performed on 12 healthy volunteers to track stiffness changes within the interventricular septum in parasternal long-axis and short-axis views. Myocardial stiffness dynamics over the cardiac cycle was quantified using five indices: stiffness ratio, rates of relaxation and contraction and time constants of relaxation and contraction. The yield of ARFI acquisitions was evaluated based on metrics of signal strength and tracking fidelity such as displacement signal-to-noise ratio, signal-to-clutter level, temporal coherence of speckle and spatial similarity within the region of excitation. These were quantified using the mean ARF-induced displacements over the cardiac cycle, the contrast between the myocardium and the cardiac chambers, the minimum correlation coefficients of radiofrequency signals and the correlation between displacement traces across simultaneously acquired azimuthal beams, respectively. Forty-one percent of ARFI acquisitions were determined to be "successful" using a mean ARF-induced displacement threshold of 1.5 μm. "Successful" acquisitions were found to have higher (i) signal-to-clutter levels, (ii) temporal coherence and (iii) spatial similarity compared with "unsuccessful" acquisitions. Median values of these three metrics, between the two groups, were measured to be 13.42dB versus 5.42dB, 0.988 versus 0.976 and 0.984 versus 0.849, respectively. Signal-to-clutter level, temporal coherence and spatial similarity were also found to correlate with each other. Across the cohort of healthy volunteers, the stiffness ratio measured was 2.74 ± 0.86; the rate of relaxation, 7.82 ± 4.69/s; and the rate of contraction, -7.31±3.79 /s. The time constant of relaxation was 35.90 ± 20.04ms, and that of contraction was 37.24 ± 19.85ms. ARFI-derived indices of myocardial stiffness were found to be similar in both views. These results indicate the feasibility of using ARFI to measure dynamic myocardial stiffness trends in a non-invasive manner and also highlightthe technical challenges of implementing this method in the transthoracic imaging environment.
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Affiliation(s)
- Vaibhav Kakkad
- Department of Biomedical Engineering, Duke University, Durham, North Carolina, USA.
| | - Melissa LeFevre
- Department of Cardiology, Duke University Hospital, Durham, North Carolina, USA
| | - Peter Hollender
- Department of Biomedical Engineering, Duke University, Durham, North Carolina, USA
| | - Joseph Kisslo
- Department of Cardiology, Duke University Hospital, Durham, North Carolina, USA
| | - Gregg E Trahey
- Department of Biomedical Engineering, Duke University, Durham, North Carolina, USA; Department of Radiology, Duke University Medical Center, Durham, North Carolina, USA
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Neumann W, Bichert A, Fleischhauer J, Stern A, Figuli R, Wilhelm M, Schad LR, Zöllner FG. A novel 3D printed mechanical actuator using centrifugal force for magnetic resonance elastography: Initial results in an anthropomorphic prostate phantom. PLoS One 2018; 13:e0205442. [PMID: 30296308 PMCID: PMC6175527 DOI: 10.1371/journal.pone.0205442] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 09/25/2018] [Indexed: 12/12/2022] Open
Abstract
This work demonstrates a new method for the generation of mechanical shear wave during magnetic resonance elastography (MRE) that creates greater forces at higher vibrational frequencies as opposed to conventionally used pneumatic transducers. We developed an MR-compatible pneumatic turbine with an eccentric mass that creates a sinusoidal centrifugal force. The turbine was assessed with respect to its technical parameters and evaluated for MRE on a custom-made anthropomorphic prostate phantom. The silicone-based tissue-mimicking materials of the phantom were selected with regard to their complex shear moduli examined by rheometric testing. The tissue-mimicking materials closely matched human soft tissue elasticity values with a complex shear modulus ranging from 3.21 kPa to 7.29 kPa. We acquired MRE images on this phantom at 3 T with actuation frequencies of 50, 60 Hz, 70 Hz, and 80 Hz. The turbine generated vibrational wave amplitudes sufficiently large to entirely penetrate the phantoms during the feasibility study. Increased wave length in the stiffer inclusions compared to softer background material were detected. Our initial results suggest that silicone-based phantoms are useful for the evaluation of elasticities during MRE. Furthermore, our turbine seems suitable for the mechanical assessment of soft tissue during MRE.
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Affiliation(s)
- Wiebke Neumann
- Department of Computer Assisted Clinical Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Andreas Bichert
- Department of Computer Assisted Clinical Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Jonas Fleischhauer
- Department of Computer Assisted Clinical Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Antonia Stern
- Department of Computer Assisted Clinical Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Roxana Figuli
- Institute for Chemical Technology and Polymer Chemistry of Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Manfred Wilhelm
- Institute for Chemical Technology and Polymer Chemistry of Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Lothar R. Schad
- Department of Computer Assisted Clinical Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Frank G. Zöllner
- Department of Computer Assisted Clinical Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
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Guenthner C, Kozerke S. Encoding and readout strategies in magnetic resonance elastography. NMR IN BIOMEDICINE 2018; 31:e3919. [PMID: 29806865 DOI: 10.1002/nbm.3919] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Revised: 12/15/2017] [Accepted: 02/15/2018] [Indexed: 06/08/2023]
Abstract
Magnetic resonance elastography (MRE) has evolved significantly since its inception. Advances in motion-encoding gradient design and readout strategies have led to improved encoding and signal-to-noise ratio (SNR) efficiencies, which in turn allow for higher spatial resolution, increased coverage, and/or shorter scan times. The purpose of this review is to summarize MRE wave-encoding and readout approaches in a unified mathematical framework to allow for a comparative assessment of encoding and SNR efficiency of the various methods available. Besides standard full- and fractional-wave-encoding approaches, advanced techniques including flow compensation, sample interval modulation and multi-shot encoding are considered. Signal readout using fast k-space trajectories, reduced field of view, multi-slice, and undersampling techniques are summarized and put into perspective. The review is concluded with a foray into displacement and diffusion encoding as alternative and/or complementary techniques.
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Affiliation(s)
- Christian Guenthner
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
| | - Sebastian Kozerke
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
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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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Guidetti M, Royston TJ. Analytical solution for converging elliptic shear wave in a bounded transverse isotropic viscoelastic material with nonhomogeneous outer boundary. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2018; 144:2312. [PMID: 30404507 PMCID: PMC6197985 DOI: 10.1121/1.5064372] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2018] [Revised: 08/25/2018] [Accepted: 09/28/2018] [Indexed: 05/17/2023]
Abstract
Dynamic elastography methods-based on optical, ultrasonic, or magnetic resonance imaging-are being developed for quantitatively mapping the shear viscoelastic properties of biological tissues, which are often altered by disease and injury. These diagnostic imaging methods involve analysis of shear wave motion in order to estimate or reconstruct the tissue's shear viscoelastic properties. Most reconstruction methods to date have assumed isotropic tissue properties. However, application to tissues like skeletal muscle and brain white matter with aligned fibrous structure resulting in local transverse isotropic mechanical properties would benefit from analysis that takes into consideration anisotropy. A theoretical approach is developed for the elliptic shear wave pattern observed in transverse isotropic materials subjected to axisymmetric excitation creating radially converging shear waves normal to the fiber axis. This approach, utilizing Mathieu functions, is enabled via a transformation to an elliptic coordinate system with isotropic properties and a ratio of minor and major axes matching the ratio of shear wavelengths perpendicular and parallel to the plane of isotropy in the transverse isotropic material. The approach is validated via numerical finite element analysis case studies. This strategy of coordinate transformation to equivalent isotropic systems could aid in analysis of other anisotropic tissue structures.
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Affiliation(s)
- Martina Guidetti
- Richard and Loan Hill Department of Bioengineering, 851 South Morgan Street, MC 063, University of Illinois at Chicago, Chicago, Illinois 60607, USA
| | - Thomas J Royston
- Richard and Loan Hill Department of Bioengineering, 851 South Morgan Street, MC 063, University of Illinois at Chicago, Chicago, Illinois 60607, USA
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11
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Miller R, Kolipaka A, Nash MP, Young AA. Relative identifiability of anisotropic properties from magnetic resonance elastography. NMR IN BIOMEDICINE 2018; 31:e3848. [PMID: 29106765 PMCID: PMC5936684 DOI: 10.1002/nbm.3848] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Revised: 07/31/2017] [Accepted: 09/20/2017] [Indexed: 05/24/2023]
Abstract
Although magnetic resonance elastography (MRE) has been used to estimate isotropic stiffness in the heart, myocardium is known to have anisotropic properties. This study investigated the determinability of global transversely isotropic material parameters using MRE and finite-element modeling (FEM). A FEM-based material parameter identification method, using a displacement-matching objective function, was evaluated in a gel phantom and simulations of a left ventricular (LV) geometry with a histology-derived fiber field. Material parameter estimation was performed in the presence of Gaussian noise. Parameter sweeps were analyzed and characteristics of the Hessian matrix at the optimal solution were used to evaluate the determinability of each constitutive parameter. Four out of five material stiffness parameters (Young's modulii E1 and E3 , shear modulus G13 and damping coefficient s), which describe a transversely isotropic linear elastic material, were well determined from the MRE displacement field using an iterative FEM inversion method. However, the remaining parameter, Poisson's ratio, was less identifiable. In conclusion, Young's modulii, shear modulii and damping can theoretically be well determined from MRE data, but Poisson's ratio is not as well determined and could be set to a reasonable value for biological tissue (close to 0.5).
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Affiliation(s)
- Renee Miller
- Department of Anatomy and Medical Imaging, University of Auckland, New Zealand
- Auckland Bioengineering Institute, University of Auckland, New Zealand
| | - Arunark Kolipaka
- Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, USA
| | - Martyn P Nash
- Auckland Bioengineering Institute, University of Auckland, New Zealand
- Department of Engineering Science, University of Auckland, New Zealand
| | - Alistair A Young
- Department of Anatomy and Medical Imaging, University of Auckland, New Zealand
- Auckland Bioengineering Institute, University of Auckland, New Zealand
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12
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Capilnasiu A, Hadjicharalambous M, Fovargue D, Patel D, Holub O, Bilston L, Screen H, Sinkus R, Nordsletten D. Magnetic resonance elastography in nonlinear viscoelastic materials under load. Biomech Model Mechanobiol 2018; 18:111-135. [PMID: 30151814 PMCID: PMC6373278 DOI: 10.1007/s10237-018-1072-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Accepted: 08/10/2018] [Indexed: 12/27/2022]
Abstract
Characterisation of soft tissue mechanical properties is a topic of increasing interest in translational and clinical research. Magnetic resonance elastography (MRE) has been used in this context to assess the mechanical properties of tissues in vivo noninvasively. Typically, these analyses rely on linear viscoelastic wave equations to assess material properties from measured wave dynamics. However, deformations that occur in some tissues (e.g. liver during respiration, heart during the cardiac cycle, or external compression during a breast exam) can yield loading bias, complicating the interpretation of tissue stiffness from MRE measurements. In this paper, it is shown how combined knowledge of a material's rheology and loading state can be used to eliminate loading bias and enable interpretation of intrinsic (unloaded) stiffness properties. Equations are derived utilising perturbation theory and Cauchy's equations of motion to demonstrate the impact of loading state on periodic steady-state wave behaviour in nonlinear viscoelastic materials. These equations demonstrate how loading bias yields apparent material stiffening, softening and anisotropy. MRE sensitivity to deformation is demonstrated in an experimental phantom, showing a loading bias of up to twofold. From an unbiased stiffness of [Formula: see text] Pa in unloaded state, the biased stiffness increases to 9767.5 [Formula: see text]1949.9 Pa under a load of [Formula: see text] 34% uniaxial compression. Integrating knowledge of phantom loading and rheology into a novel MRE reconstruction, it is shown that it is possible to characterise intrinsic material characteristics, eliminating the loading bias from MRE data. The framework introduced and demonstrated in phantoms illustrates a pathway that can be translated and applied to MRE in complex deforming tissues. This would contribute to a better assessment of material properties in soft tissues employing elastography.
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Affiliation(s)
- Adela Capilnasiu
- Division of Biomedical Engineering and Imaging Sciences, King's College London, London, UK.
| | - Myrianthi Hadjicharalambous
- Division of Biomedical Engineering and Imaging Sciences, King's College London, London, UK.,KIOS Research and Innovation Centre of Excellence, University of Cyprus, Nicosia, Cyprus
| | - Daniel Fovargue
- Division of Biomedical Engineering and Imaging Sciences, King's College London, London, UK
| | - Dharmesh Patel
- Institute of Bioengineering, Queen Mary University of London, London, UK
| | - Ondrej Holub
- Division of Biomedical Engineering and Imaging Sciences, King's College London, London, UK
| | - Lynne Bilston
- Prince of Wales Clinical School, University of New South Wales, Sydney, Australia.,Neuroscience Research Australia, Sydney, Australia
| | - Hazel Screen
- Institute of Bioengineering, Queen Mary University of London, London, UK
| | - Ralph Sinkus
- Division of Biomedical Engineering and Imaging Sciences, King's College London, London, UK.,Inserm U1148, LVTS, University Paris Diderot, University Paris 13, 75018, Paris, France
| | - David Nordsletten
- Division of Biomedical Engineering and Imaging Sciences, King's College London, London, UK.,Department of Biomedical Engineering and Cardiac Surgery, University of Michigan, Ann Arbor, USA
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13
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Manduca A, Rossman TL, Lake DS, Glaser KJ, Arani A, Arunachalam SP, Rossman PJ, Trzasko JD, Ehman RL, Dragomir-Daescu D, Araoz PA. Waveguide effects and implications for cardiac magnetic resonance elastography: A finite element study. NMR IN BIOMEDICINE 2018; 31:e3996. [PMID: 30101999 PMCID: PMC6783328 DOI: 10.1002/nbm.3996] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2017] [Revised: 06/07/2018] [Accepted: 06/12/2018] [Indexed: 06/08/2023]
Abstract
Magnetic resonance elastography (MRE) is increasingly being applied to thin or small structures in which wave propagation is dominated by waveguide effects, which can substantially bias stiffness results with common processing approaches. The purpose of this work was to investigate the importance of such biases and artifacts on MRE inversion results in: (i) various idealized 2D and 3D geometries with one or more dimensions that are small relative to the shear wavelength; and (ii) a realistic cardiac geometry. Finite element models were created using simple 2D geometries as well as a simplified and a realistic 3D cardiac geometry, and simulated displacements acquired by MRE from harmonic excitations from 60 to 220 Hz across a range of frequencies. The displacement wave fields were inverted with direct inversion of the Helmholtz equation with and without the application of bandpass filtering and/or the curl operator to the displacement field. In all geometries considered, and at all frequencies considered, strong biases and artifacts were present in inversion results when the curl operator was not applied. Bandpass filtering without the curl was not sufficient to yield accurate recovery. In the 3D geometries, strong biases and artifacts were present in 2D inversions even when the curl was applied, while only 3D inversions with application of the curl yielded accurate recovery of the complex shear modulus. These results establish that taking the curl of the wave field and performing a full 3D inversion are both necessary steps for accurate estimation of the shear modulus both in simple thin-walled or small structures and in a realistic cardiac geometry when using simple inversions that neglect the hydrostatic pressure term. In practice, sufficient wave amplitude, signal-to-noise ratio, and resolution will be required to achieve accurate results.
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Affiliation(s)
- A Manduca
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN, USA
| | - T L Rossman
- Division of Engineering, Mayo Clinic, Rochester, MN, USA
| | - D S Lake
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN, USA
| | - K J Glaser
- Department of Radiology, Mayo Clinic, Rochester, MN, USA
| | - A Arani
- Department of Radiology, Mayo Clinic, Rochester, MN, USA
| | | | - P J Rossman
- Department of Radiology, Mayo Clinic, Rochester, MN, USA
| | - J D Trzasko
- Department of Radiology, Mayo Clinic, Rochester, MN, USA
| | - R L Ehman
- Department of Radiology, Mayo Clinic, Rochester, MN, USA
| | | | - P A Araoz
- Department of Radiology, Mayo Clinic, Rochester, MN, USA
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14
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Miller R, Kolipaka A, Nash MP, Young AA. Estimation of transversely isotropic material properties from magnetic resonance elastography using the optimised virtual fields method. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2018; 34. [PMID: 29528568 PMCID: PMC5993646 DOI: 10.1002/cnm.2979] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Magnetic resonance elastography (MRE) has been used to estimate isotropic myocardial stiffness. However, anisotropic stiffness estimates may give insight into structural changes that occur in the myocardium as a result of pathologies such as diastolic heart failure. The virtual fields method (VFM) has been proposed for estimating material stiffness from image data. This study applied the optimised VFM to identify transversely isotropic material properties from both simulated harmonic displacements in a left ventricular (LV) model with a fibre field measured from histology as well as isotropic phantom MRE data. Two material model formulations were implemented, estimating either 3 or 5 material properties. The 3-parameter formulation writes the transversely isotropic constitutive relation in a way that dissociates the bulk modulus from other parameters. Accurate identification of transversely isotropic material properties in the LV model was shown to be dependent on the loading condition applied, amount of Gaussian noise in the signal, and frequency of excitation. Parameter sensitivity values showed that shear moduli are less sensitive to noise than the other parameters. This preliminary investigation showed the feasibility and limitations of using the VFM to identify transversely isotropic material properties from MRE images of a phantom as well as simulated harmonic displacements in an LV geometry.
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Affiliation(s)
- Renee Miller
- Department of Anatomy and Medical Imaging, University of Auckland, Auckland, New Zealand
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Arunark Kolipaka
- Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Martyn P. Nash
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
- Department of Engineering Science, University of Auckland, Auckland, New Zealand
| | - Alistair A. Young
- Department of Anatomy and Medical Imaging, University of Auckland, Auckland, New Zealand
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
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15
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Sui Y, Arunachalam SP, Arani A, Trzasko JD, Young PM, Glockner JF, Glaser KJ, Lake DS, McGee KP, Manduca A, Rossman PJ, Ehman RL, Araoz PA. Cardiac MR elastography using reduced-FOV, single-shot, spin-echo EPI. Magn Reson Med 2017; 80:231-238. [PMID: 29194738 PMCID: PMC5876088 DOI: 10.1002/mrm.27029] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Revised: 10/29/2017] [Accepted: 11/09/2017] [Indexed: 12/13/2022]
Abstract
Purpose To implement a reduced field of view (rFOV) technique for cardiac MR elastography (MRE) and to demonstrate the improvement in image quality of both magnitude images and post‐processed MRE stiffness maps compared to the conventional full field of view (full‐FOV) acquisition. Methods With Institutional Review Board approval, 17 healthy volunteers underwent both full‐FOV and rFOV cardiac MRE scans using 140‐Hz vibrations. Two cardiac radiologists blindly compared the magnitude images and stiffness maps and graded the images based on several image quality attributes using a 5‐point ordinal scale. Fisher's combined probability test was performed to assess the overall evaluation. The octahedral shear strain‐based signal‐to‐noise ratio (OSS‐SNR) and median stiffness over the left ventricular myocardium were also compared. Results One volunteer was excluded because of an inconsistent imaging resolution during the exam. In the remaining 16 volunteers (9 males, 7 females), the rFOV scans outperformed the full‐FOV scans in terms of subjective image quality and ghosting artifacts in the magnitude images and stiffness maps, as well as the overall preference. The quantitative measurements showed that rFOV had significantly higher OSS‐SNR (median: 1.4 [95% confidence interval (CI): 1.2–1.5] vs. 2.1 [95% CI: 1.8–2.4]), P < 0.05) compared to full‐FOV. Although no significant change was found in the median myocardial stiffness between the 2 scans, we observed a decrease in the stiffness variation within the myocardium from 2.1 kPa (95% CI: [1.9, 2.3]) to 1.9 kPa (95% CI: [1.7, 2.0]) for full‐FOV and rFOV, respectively (P < 0.05) in a subgroup of 7 subjects with ghosting present in the myocardium. Conclusion This pilot volunteer study demonstrated that rFOV cardiac MRE has the capability to reduce ghosting and to improve image quality in both MRE magnitude images and stiffness maps. Magn Reson Med 80:231–238, 2018. © 2017 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.
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Affiliation(s)
- Yi Sui
- Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA
| | | | - Arvin Arani
- Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA
| | | | - Phillip M Young
- Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA
| | | | - Kevin J Glaser
- Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA
| | - David S Lake
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, USA
| | - Kiaran P McGee
- Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA
| | - Armando Manduca
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, USA
| | | | - Richard L Ehman
- Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA
| | - Philip A Araoz
- Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA
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16
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Hawley JR, Kalra P, Mo X, Raterman B, Yee LD, Kolipaka A. Quantification of breast stiffness using MR elastography at 3 Tesla with a soft sternal driver: A reproducibility study. J Magn Reson Imaging 2017; 45:1379-1384. [PMID: 27779802 PMCID: PMC5395339 DOI: 10.1002/jmri.25511] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Accepted: 09/27/2016] [Indexed: 12/31/2022] Open
Abstract
PURPOSE Previous studies of breast MR elastography (MRE) evaluated the technique at magnetic field strengths of 1.5 Tesla (T) with the breast in contact with the driver. The aim of this study is to evaluate breast stiffness measurements and their reproducibility using a soft sternal driver at 3T and compare the results with qualitative measures of breast density. MATERIALS AND METHODS Twenty-two healthy volunteers each underwent two separate breast MRE scans in a 3T MRI. MRE vibrations were introduced into the breasts at 60 Hz using a soft sternal driver and axial slices were collected using a gradient echo MRE sequence. Mean stiffness measurements were calculated for each volunteer as well as a measure of reproducibility using concordance correlation between scans. Mean stiffness values for each volunteer were assessed and related to amounts of fibroglandular tissue (i.e., breast lobules, ducts, and fibrous connective tissue). RESULTS The stiffness values were reproducible with a significant P-value < 0.0001 between two scans with concordance correlation of 0.87 and 0.91 for center slice and grouping all slices, respectively. Volunteers with dense breasts (i.e., higher grades of fibroglandular tissue) had mean stiffness values of 0.96 kPa (center slice) and 0.92 kPa (all slices) while those without dense breasts had mean stiffness values of 0.85 kPa (center slice) and 0.83 kPa (all slices) (P ≤ 0.05). CONCLUSION Breast MRE is a reproducible technique at 3T using a soft sternal driver. Dense breasts had significantly higher stiffness measurements compared with nondense breasts. LEVEL OF EVIDENCE 2 J. MAGN. RESON. IMAGING 2017;45:1379-1384.
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Affiliation(s)
- Jeffrey R. Hawley
- Department of Radiology, The Ohio State University Wexner Medical Center Columbus, Ohio
| | - Prateek Kalra
- Department of Radiology, The Ohio State University Wexner Medical Center Columbus, Ohio
| | - Xiaokui Mo
- Department of Radiology, The Ohio State University Wexner Medical Center Columbus, Ohio
| | - Brian Raterman
- Department of Radiology, The Ohio State University Wexner Medical Center Columbus, Ohio
| | - Lisa D. Yee
- Department of Surgical Oncology, The Ohio State University Wexner Medical Center Columbus, Ohio
| | - Arunark Kolipaka
- Department of Radiology, The Ohio State University Wexner Medical Center Columbus, Ohio
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17
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Arunachalam SP, Arani A, Baffour F, Rysavy JA, Rossman PJ, Glaser KJ, Lake DS, Trzasko JD, Manduca A, McGee KP, Ehman RL, Araoz PA. Regional assessment of in vivo myocardial stiffness using 3D magnetic resonance elastography in a porcine model of myocardial infarction. Magn Reson Med 2017; 79:361-369. [PMID: 28382658 DOI: 10.1002/mrm.26695] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Revised: 03/03/2017] [Accepted: 03/09/2017] [Indexed: 12/11/2022]
Abstract
PURPOSE The stiffness of a myocardial infarct affects the left ventricular pump function and remodeling. Magnetic resonance elastography (MRE) is a noninvasive imaging technique for measuring soft-tissue stiffness in vivo. The purpose of this study was to investigate the feasibility of assessing in vivo regional myocardial stiffness with high-frequency 3D cardiac MRE in a porcine model of myocardial infarction, and compare the results with ex vivo uniaxial tensile testing. METHODS Myocardial infarct was induced in a porcine model by embolizing the left circumflex artery. Fourteen days postinfarction, MRE imaging was performed in diastole using an echocardiogram-gated spin-echo echo-planar-imaging sequence with 140-Hz vibrations and 3D MRE processing. The MRE stiffness and tensile modulus from uniaxial testing were compared between the remote and infarcted myocardium. RESULTS Myocardial infarcts showed increased in vivo MRE stiffness compared with remote myocardium (4.6 ± 0.7 kPa versus 3.0 ± 0.6 kPa, P = 0.02) within the same pig. Ex vivo uniaxial mechanical testing confirmed the in vivo MRE results, showing that myocardial infarcts were stiffer than remote myocardium (650 ± 80 kPa versus 110 ± 20 kPa, P = 0.01). CONCLUSIONS These results demonstrate the feasibility of assessing in vivo regional myocardial stiffness with high-frequency 3D cardiac MRE. Magn Reson Med 79:361-369, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
| | - Arvin Arani
- Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA
| | - Francis Baffour
- Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA
| | - Joseph A Rysavy
- Department of Surgery, Mayo Clinic, Rochester, Minnesota, USA
| | | | - Kevin J Glaser
- Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA
| | - David S Lake
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, USA
| | | | - Armando Manduca
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, USA
| | - Kiaran P McGee
- Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA
| | - Richard L Ehman
- Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA
| | - Philip A Araoz
- Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA
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18
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Arani A, Arunachalam SP, Chang ICY, Baffour F, Rossman PJ, Glaser KJ, Trzasko JD, McGee KP, Manduca A, Grogan M, Dispenzieri A, Ehman RL, Araoz PA. Cardiac MR elastography for quantitative assessment of elevated myocardial stiffness in cardiac amyloidosis. J Magn Reson Imaging 2017; 46:1361-1367. [PMID: 28236336 PMCID: PMC5572539 DOI: 10.1002/jmri.25678] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Accepted: 02/06/2017] [Indexed: 12/13/2022] Open
Abstract
Purpose To evaluate if cardiac magnetic resonance elastography (MRE) can measure increased stiffness in patients with cardiac amyloidosis. Myocardial tissue stiffness plays an important role in cardiac function. A noninvasive quantitative imaging technique capable of measuring myocardial stiffness could aid in disease diagnosis, therapy monitoring, and disease prognostic strategies. We recently developed a high‐frequency cardiac MRE technique capable of making noninvasive stiffness measurements. Materials and Methods In all, 16 volunteers and 22 patients with cardiac amyloidosis were enrolled in this study after Institutional Review Board approval and obtaining formal written consent. All subjects were imaged head‐first in the supine position in a 1.5T closed‐bore MR imager. 3D MRE was performed using 5 mm isotropic resolution oblique short‐axis slices and a vibration frequency of 140 Hz to obtain global quantitative in vivo left ventricular stiffness measurements. The median stiffness was compared between the two cohorts. An octahedral shear strain signal‐to‐noise ratio (OSS‐SNR) threshold of 1.17 was used to exclude exams with insufficient motion amplitude. Results Five volunteers and six patients had to be excluded from the study because they fell below the 1.17 OSS‐SNR threshold. The myocardial stiffness of cardiac amyloid patients (median: 11.4 kPa, min: 9.2, max: 15.7) was significantly higher (P = 0.0008) than normal controls (median: 8.2 kPa, min: 7.2, max: 11.8). Conclusion This study demonstrates the feasibility of 3D high‐frequency cardiac MRE as a contrast‐agent‐free diagnostic imaging technique for cardiac amyloidosis. Level of Evidence: 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2017;46:1361–1367.
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Affiliation(s)
- Arvin Arani
- Radiology, Mayo Clinic, Rochester, Minnesota, USA
| | | | - Ian C Y Chang
- Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota, USA
| | | | | | | | | | | | | | - Martha Grogan
- Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota, USA
| | - Angela Dispenzieri
- Medicine: Division of Hematology, Mayo Clinic, Rochester, Minnesota, USA.,Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota, USA
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19
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Vejdani-Jahromi M, Freedman J, Nagle M, Kim YJ, Trahey GE, Wolf PD. Quantifying Myocardial Contractility Changes Using Ultrasound-Based Shear Wave Elastography. J Am Soc Echocardiogr 2016; 30:90-96. [PMID: 27843103 DOI: 10.1016/j.echo.2016.10.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Indexed: 01/06/2023]
Abstract
BACKGROUND Myocardial contractility, a significant determinant of cardiac function, is valuable for diagnosis and evaluation of treatment in cardiovascular disorders including heart failure. Shear wave elasticity imaging (SWEI) is a newly developed ultrasound-based elastographic technique that can directly assess the stiffness of cardiac tissue. The aim of this study was to verify the ability of this technique to quantify contractility changes in the myocardium. METHODS In 12 isolated rabbit hearts, SWEI measurements were made of systolic stiffness at five different coronary perfusion pressures from 0 to 92 mm Hg. The changes in coronary perfusion were used to induce acute stepwise reversible changes in cardiac contractility via the Gregg effect. The Gregg effect is the dependency of contractility on coronary perfusion. In four of the hearts, the measurements were repeated after delivery of gadolinium, which is known to block the Gregg effect. RESULTS Systolic stiffness measured by SWEI changed linearly with coronary perfusion pressure, with a slope of 0.27 kPa/mm Hg (mean of 95% CI, R2 = 0.73). As expected, the change in contractility due to the Gregg effect was blocked by gadolinium, with a significant reduction of the slope to 0.08 kPa/mm Hg. CONCLUSIONS SWEI measurements of systolic stiffness provide an index of contractility in the unloaded isolated rabbit heart. Although this study was done under ideal imaging conditions and with nonphysiologic loading conditions, it reinforces the concept that this ultrasound technique has the potential to provide a direct and noninvasive index of cardiac contractility.
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Affiliation(s)
| | - Jenna Freedman
- Biomedical Engineering Department, Duke University, Durham, North Carolina
| | - Matthew Nagle
- Biomedical Engineering Department, Duke University, Durham, North Carolina
| | - Young-Joong Kim
- Biomedical Engineering Department, Duke University, Durham, North Carolina
| | - Gregg E Trahey
- Biomedical Engineering Department, Duke University, Durham, North Carolina
| | - Patrick D Wolf
- Biomedical Engineering Department, Duke University, Durham, North Carolina.
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20
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Brinker S, Klatt D. Demonstration of concurrent tensile testing and magnetic resonance elastography. J Mech Behav Biomed Mater 2016; 63:232-243. [DOI: 10.1016/j.jmbbm.2016.06.020] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Revised: 06/15/2016] [Accepted: 06/23/2016] [Indexed: 12/01/2022]
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21
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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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Mazumder R, Schroeder S, Mo X, Clymer BD, White RD, Kolipaka A. In vivo quantification of myocardial stiffness in hypertensive porcine hearts using MR elastography. J Magn Reson Imaging 2016; 45:813-820. [PMID: 27564862 DOI: 10.1002/jmri.25423] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Accepted: 07/29/2016] [Indexed: 12/24/2022] Open
Abstract
PURPOSE To determine alteration in left ventricular (LV) myocardial stiffness (MS) with hypertension (HTN). Cardiac MR elastography (MRE) was used to estimate MS in HTN induced pigs and MRE-derived MS measurements were compared against LV pressure, thickness and circumferential strain. MATERIALS AND METHODS Renal-wrapping surgery was performed to induce HTN in eight pigs. LV catheterization (to measure pressure) and cardiac MRI (1.5 Tesla; gradient echo-MRE and tagging) was performed pre-surgery at baseline (Bx), and post-surgery at month 1 (M1) and month 2 (M2). Images were analyzed to estimate LV-MS, thickness, and circumferential strain across the cardiac cycle. The associations between end-diastolic (ED) and end-systolic (ES) MS and (i) mean LV pressure; (ii) ED and ES thickness, respectively; and (iii) circumferential strain were evaluated using Spearman's correlation method. RESULTS From Bx to M2, mean pressure, MRE-derived stiffness, and thickness increased while circumferential strain decreased significantly (slope test, P ≤ 0.05). Both ED and ES MS had significant positive correlation with (i) mean pressure (ED MS: ρ = 0.56; P = 0.005 and ES MS: ρ = 0.45; P = 0.03); (ii) ED thickness ( ρ = 0.73; P < 0.0001) and ES thickness ( ρ = 0.84; P < 0.0001), respectively; but demonstrated a negative trend with circumferential strain (ED MS: ρ = 0.31 and ES MS: ρ = 0.37). CONCLUSION This study demonstrated that, in a HTN porcine model, MRE-derived MS increased with increase in pressure and thickness. LEVEL OF EVIDENCE 1 J. Magn. Reson. Imaging 2017;45:813-820.
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Affiliation(s)
- Ria Mazumder
- Department of Electrical and Computer Engineering, 205 Dreese Laboratories, The Ohio State University, Columbus, Ohio, USA.,Department of Radiology, Room 460, The Ohio State University, Columbus, Ohio, USA.,Department of Biomedical Engineering, 265 Kirkbride Hall, Walnut Street, Widener University, Chester, PA
| | - Samuel Schroeder
- Department of Radiology, Room 460, The Ohio State University, Columbus, Ohio, USA.,Department of Mechanical Engineering, The Ohio State University, Columbus, Ohio, USA
| | - Xiaokui Mo
- Center for Biostatistics, Department of Biomedical Informatics, Room 320D, Lincoln Tower, Columbus, Ohio, USA
| | - Bradley D Clymer
- Department of Electrical and Computer Engineering, 205 Dreese Laboratories, The Ohio State University, Columbus, Ohio, USA
| | - Richard D White
- Department of Radiology, Room 460, The Ohio State University, Columbus, Ohio, USA.,Department of Internal Medicine-Division of Cardiovascular Medicine, 244 Davis Heart & Lung Research Institute, The Ohio State University, Columbus, Ohio, USA
| | - Arunark Kolipaka
- Department of Radiology, Room 460, The Ohio State University, Columbus, Ohio, USA.,Department of Internal Medicine-Division of Cardiovascular Medicine, 244 Davis Heart & Lung Research Institute, The Ohio State University, Columbus, Ohio, USA
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23
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Mazumder R, Schroeder S, Mo X, Litsky AS, Clymer BD, White RD, Kolipaka A. In vivo magnetic resonance elastography to estimate left ventricular stiffness in a myocardial infarction induced porcine model. J Magn Reson Imaging 2016; 45:1024-1033. [PMID: 27533317 DOI: 10.1002/jmri.25432] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Accepted: 08/04/2016] [Indexed: 11/06/2022] Open
Abstract
PURPOSE To estimate change in left ventricular (LV) end-systolic and end-diastolic myocardial stiffness (MS) in pigs induced with myocardial infarction (MI) with disease progression using cardiac magnetic resonance elastography (MRE) and to compare it against ex vivo mechanical testing, LV circumferential strain, and magnetic resonance imaging (MRI) relaxometry parameters (T1 , T2 , and extracellular volume fraction [ECV]). MATERIALS AND METHODS MRI (1.5T) was performed on seven pigs, before surgery (Bx), and 10 (D10), and 21 (D21) days after creating MI. Cardiac MRE-derived MS was measured in infarcted region (MIR) and remote region (RR), and validated against mechanical testing-derived MS obtained postsacrifice on D21. Circumferential strain and MRI relaxometry parameters (T2 , T1 , and ECV) were also obtained. Multiparametric analysis was performed to determine correlation between cardiac MRE-derived MS and 1) strain, 2) relaxometry parameters, and 3) mechanical testing. RESULTS Mean diastolic (D10: 5.09 ± 0.6 kPa; D21: 5.45 ± 0.7 kPa) and systolic (D10: 5.72 ± 0.8 kPa; D21: 6.34 ± 1.0 kPa) MS in MIR were significantly higher (P < 0.01) compared to mean diastolic (D10: 3.97 ± 0.4 kPa; D21: 4.12 ± 0.2 kPa) and systolic (D10: 5.08 ± 0.6 kPa; and D21: 5.16 ± 0.6 kPa) MS in RR. The increase in cardiac MRE-derived MS at D21 (MIR) was consistent and correlated strongly with mechanical testing-derived MS (r(diastolic) = 0.86; r(systolic) = 0.89). Diastolic MS in MIR demonstrated a negative correlation with strain (r = 0.58). Additionally, cardiac MRE-derived MS demonstrated good correlations with post-contrast T1 (r(diastolic) = -0.549; r(systolic) = -0.741) and ECV (r(diastolic) = 0.548; r(systolic) = 0.703), and no correlation with T2 . CONCLUSION As MI progressed, cardiac MRE-derived MS increased in MIR compared to RR, which significantly correlated with mechanical testing-derived MS, T1 and ECV. LEVEL OF EVIDENCE 1 J. Magn. Reson. Imaging 2017;45:1024-1033.
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Affiliation(s)
- Ria Mazumder
- Department of Electrical and Computer Engineering, 205 Dreese Laboratories, Ohio State University, Columbus, Ohio, USA.,Department of Radiology, Ohio State University, Columbus, Ohio, USA
| | - Samuel Schroeder
- Department of Radiology, Ohio State University, Columbus, Ohio, USA.,Department of Mechanical Engineering, Ohio State University, Columbus, Ohio, USA
| | - Xiaokui Mo
- Center for Biostatistics, Department of Biomedical Informatics, Columbus, Ohio, USA
| | - Alan S Litsky
- Department of Biomedical Engineering, Ohio State University, Columbus, Ohio, USA.,Department of Orthopaedics, Columbus, Ohio, USA
| | - Bradley D Clymer
- Department of Electrical and Computer Engineering, 205 Dreese Laboratories, Ohio State University, Columbus, Ohio, USA
| | - Richard D White
- Department of Radiology, Ohio State University, Columbus, Ohio, USA.,Department of Internal Medicine-Division of Cardiovascular Medicine, 244 Davis Heart & Lung Research Institute, Ohio State University, Columbus, Ohio, USA
| | - Arunark Kolipaka
- Department of Radiology, Ohio State University, Columbus, Ohio, USA.,Department of Internal Medicine-Division of Cardiovascular Medicine, 244 Davis Heart & Lung Research Institute, Ohio State University, Columbus, Ohio, USA
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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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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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26
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Arani A, Glaser KL, Arunachalam SP, Rossman PJ, Lake DS, Trzasko JD, Manduca A, McGee KP, Ehman RL, Araoz PA. In vivo, high-frequency three-dimensional cardiac MR elastography: Feasibility in normal volunteers. Magn Reson Med 2016; 77:351-360. [PMID: 26778442 DOI: 10.1002/mrm.26101] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Revised: 11/24/2015] [Accepted: 12/01/2015] [Indexed: 01/08/2023]
Abstract
PURPOSE Noninvasive stiffness imaging techniques (elastography) can image myocardial tissue biomechanics in vivo. For cardiac MR elastography (MRE) techniques, the optimal vibration frequency for in vivo experiments is unknown. Furthermore, the accuracy of cardiac MRE has never been evaluated in a geometrically accurate phantom. Therefore, the purpose of this study was to determine the necessary driving frequency to obtain accurate three-dimensional (3D) cardiac MRE stiffness estimates in a geometrically accurate diastolic cardiac phantom and to determine the optimal vibration frequency that can be introduced in healthy volunteers. METHODS The 3D cardiac MRE was performed on eight healthy volunteers using 80 Hz, 100 Hz, 140 Hz, 180 Hz, and 220 Hz vibration frequencies. These frequencies were tested in a geometrically accurate diastolic heart phantom and compared with dynamic mechanical analysis (DMA). RESULTS The 3D Cardiac MRE was shown to be feasible in volunteers at frequencies as high as 180 Hz. MRE and DMA agreed within 5% at frequencies greater than 180 Hz in the cardiac phantom. However, octahedral shear strain signal to noise ratios and myocardial coverage was shown to be highest at a frequency of 140 Hz across all subjects. CONCLUSION This study motivates future evaluation of high-frequency 3D MRE in patient populations. Magn Reson Med 77:351-360, 2017. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Arvin Arani
- Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA
| | - Kevin L Glaser
- Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA
| | | | | | - David S Lake
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, USA
| | | | - Armando Manduca
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, USA
| | - Kiaran P McGee
- Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA
| | - Richard L Ehman
- Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA
| | - Philip A Araoz
- Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA
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27
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Liu Y, Royston TJ, Klatt D, Lewandowski ED. Cardiac MR elastography of the mouse: Initial results. Magn Reson Med 2016; 76:1879-1886. [PMID: 26749052 DOI: 10.1002/mrm.26030] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Revised: 10/09/2015] [Accepted: 10/10/2015] [Indexed: 12/22/2022]
Abstract
PURPOSE Many cardiovascular diseases are associated with abnormal function of myocardial contractility or dilatability, which is related to elasticity changes of the myocardium over the cardiac cycle. The mouse is a common animal model in studies of the progression of various cardiomyopathies. We introduce a novel noninvasive approach using microscopic scale MR elastography (MRE) to measure the myocardium stiffness change during the cardiac cycle on a mouse model. METHODS A harmonic mechanical wave of 400 Hz was introduced into the mouse body. An electrocardiograph-gated and respiratory-gated fractional encoding cine-MRE pulse sequence was applied to encode the resulting oscillatory motion on a short-axis slice of the heart. Five healthy mice (age range, 3-13.5 mo) were examined. The weighted summation effective stiffness of the left ventricle wall during the cardiac cycle was estimated. RESULTS The ratio of stiffness at end diastole and end systole was 0.5-0.67. Additionally, variation in shear wave amplitude in the left ventricle wall throughout the cardiac cycle was measured and found to correlate with estimates of stiffness variation. CONCLUSION This study demonstrates the feasibility of implementing cardiac MRE on a mouse model. Magn Reson Med 76:1879-1886, 2016. © 2016 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Yifei Liu
- Department of Mechanical & Industrial Engineering, University of Illinois at Chicago, Chicago, Illinois, USA
| | - Thomas J Royston
- Department of Mechanical & Industrial Engineering, University of Illinois at Chicago, Chicago, Illinois, USA.,Department of Bioengineering, University of Illinois at Chicago, Chicago, Illinois, USA
| | - Dieter Klatt
- Department of Bioengineering, University of Illinois at Chicago, Chicago, Illinois, USA
| | - E Douglas Lewandowski
- Department of Bioengineering, University of Illinois at Chicago, Chicago, Illinois, USA.,Center for Cardiovascular Research, University of Illinois at Chicago, Chicago, Illinois, USA.,Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, Illinois, USA
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28
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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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Wassenaar PA, Eleswarpu CN, Schroeder SA, Mo X, Raterman BD, White RD, Kolipaka A. Measuring age-dependent myocardial stiffness across the cardiac cycle using MR elastography: A reproducibility study. Magn Reson Med 2015; 75:1586-93. [PMID: 26010456 DOI: 10.1002/mrm.25760] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Revised: 04/08/2015] [Accepted: 04/11/2015] [Indexed: 12/23/2022]
Abstract
PURPOSE To assess reproducibility in measuring left ventricular (LV) myocardial stiffness in volunteers throughout the cardiac cycle using MR elastography (MRE) and to determine its correlation with age. METHODS Cardiac MRE (CMRE) was performed on 29 normal volunteers, with ages ranging from 21 to 73 years. For assessing reproducibility of CMRE-derived stiffness measurements, scans were repeated per volunteer. Wave images were acquired throughout the LV myocardium, and were analyzed to obtain mean stiffness during the cardiac cycle. CMRE-derived stiffness values were correlated to age. RESULTS Concordance correlation coefficient revealed good interscan agreement with rc of 0.77, with P-value < 0.0001. Significantly higher myocardial stiffness was observed during end-systole (ES) compared with end-diastole (ED) across all subjects. Additionally, increased deviation between ES and ED stiffness was observed with increased age. CONCLUSION CMRE-derived stiffness is reproducible, with myocardial stiffness changing cyclically across the cardiac cycle. Stiffness is significantly higher during ES compared with ED. With age, ES myocardial stiffness increases more than ED, giving rise to an increased deviation between the two.
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Affiliation(s)
- Peter A Wassenaar
- Department of Radiology, The Ohio State University College of Medicine, Columbus, Ohio, USA
| | - Chethanya N Eleswarpu
- Department of Radiology, The Ohio State University College of Medicine, Columbus, Ohio, USA.,Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio, USA
| | - Samuel A Schroeder
- Department of Radiology, The Ohio State University College of Medicine, Columbus, Ohio, USA.,Department of Mechanical Engineering, The Ohio State University, Columbus, Ohio, USA
| | - Xiaokui Mo
- Center for Biostatistics, The Ohio State University, Columbus, Ohio, USA
| | - Brian D Raterman
- Department of Radiology, The Ohio State University College of Medicine, Columbus, Ohio, USA
| | - Richard D White
- Department of Radiology, The Ohio State University College of Medicine, Columbus, Ohio, USA.,Department of Internal Medicine-Division of Cardiovascular Medicine, The Ohio State University College of Medicine, Columbus, Ohio, USA
| | - Arunark Kolipaka
- Department of Radiology, The Ohio State University College of Medicine, Columbus, Ohio, USA.,Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio, USA.,Department of Internal Medicine-Division of Cardiovascular Medicine, The Ohio State University College of Medicine, Columbus, Ohio, USA
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31
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Pislaru C, Urban MW, Pislaru SV, Kinnick RR, Greenleaf JF. Viscoelastic properties of normal and infarcted myocardium measured by a multifrequency shear wave method: comparison with pressure-segment length method. ULTRASOUND IN MEDICINE & BIOLOGY 2014; 40:1785-95. [PMID: 24814645 PMCID: PMC4118646 DOI: 10.1016/j.ultrasmedbio.2014.03.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Revised: 02/19/2014] [Accepted: 03/01/2014] [Indexed: 05/02/2023]
Abstract
Our aims were (i) to compare in vivo measurements of myocardial elasticity by shear wave dispersion ultrasound vibrometry (SDUV) with those by the conventional pressure-segment length method, and (ii) to quantify changes in myocardial viscoelasticity during systole and diastole after reperfused acute myocardial infarction. The shear elastic modulus (μ1) and viscous coefficient (μ2) of left ventricular myocardium were measured by SDUV in 10 pigs. Young's elastic modulus was independently measured by the pressure-segment length method. Measurements made with the SDUV and pressure-segment length methods were strongly correlated. At reperfusion, μ1 and μ2 in end-diastole were increased. Less consistent changes were found during systole. In all animals, μ1 increased linearly with left ventricular pressure developed during systole. Preliminary results suggest that μ1 is preload dependent. This is the first study to validate in vivo measurements of myocardial elasticity by a shear wave method. In this animal model, the alterations in myocardial viscoelasticity after a myocardial infarction were most consistently detected during diastole.
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Affiliation(s)
- Cristina Pislaru
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, Minnesota, USA.
| | - Matthew W Urban
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, Minnesota, USA
| | - Sorin V Pislaru
- Cardiovascular Division, Mayo Clinic College of Medicine, Rochester, Minnesota, USA
| | - Randall R Kinnick
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, Minnesota, USA
| | - James F Greenleaf
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, Minnesota, USA
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Abstract
In this article, functional magnetic resonance (MR) imaging techniques in the abdomen are discussed. Diffusion-weighted imaging (DWI) increases the confidence in detecting and characterizing focal hepatic lesions. The potential uses of DWI in kidneys, adrenal glands, bowel, and pancreas are outlined. Studies have shown potential use of quantitative dynamic contrast-enhanced MR imaging parameters, such as K(trans), in predicting outcomes in cancer therapy. MR elastography is considered to be a useful tool in staging liver fibrosis. A major issue with all functional MR imaging techniques is the lack of standardization of the protocol.
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Affiliation(s)
- Kumar Sandrasegaran
- Department of Radiology, Indiana University School of Medicine, 550 N University Blvd, UH 0279, Indianapolis, IN 46202, USA.
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33
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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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Should there be sex-specific criteria for the diagnosis and treatment of heart failure? J Cardiovasc Transl Res 2013; 7:139-55. [PMID: 24214112 PMCID: PMC3935102 DOI: 10.1007/s12265-013-9514-8] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Accepted: 10/07/2013] [Indexed: 12/17/2022]
Abstract
All-cause mortality from cardiovascular disease is declining in the USA. However, there remains a significant difference in risk factors for disease and in mortality between men and women. For example, prevalence and outcomes for heart failure with preserved ejection fraction differ between men and women. The reasons for these differences are multifactorial, but reflect, in part, an incomplete understanding of sex differences in the etiology of cardiovascular diseases and a failure to account for sex differences in pre-clinical studies including those designed to develop new diagnostic and treatment modalities. This review focuses on the underlying physiology of these sex differences and provides evidence that inclusion of female animals in pre-clinical studies of heart failure and in development of imaging modalities to assess cardiac function might provide new information from which one could develop sex-specific diagnostic criteria and approaches to treatment.
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