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Sophocleous F, Delchev K, De Garate E, Hamilton MCK, Caputo M, Bucciarelli-Ducci C, Biglino G. Feasibility of Wave Intensity Analysis from 4D Cardiovascular Magnetic Resonance Imaging Data. Bioengineering (Basel) 2023; 10:662. [PMID: 37370593 DOI: 10.3390/bioengineering10060662] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 04/26/2023] [Accepted: 05/03/2023] [Indexed: 06/29/2023] Open
Abstract
Congenital heart defects (CHD) introduce haemodynamic changes; e.g., bicuspid aortic valve (BAV) presents a turbulent helical flow, which activates aortic pathological processes. Flow quantification is crucial for diagnostics and to plan corrective strategies. Multiple imaging modalities exist, with phase contrast magnetic resonance imaging (PC-MRI) being the current gold standard; however, multiple predetermined site measurements may be required, while 4D MRI allows for measurements of area (A) and velocity (U) in all spatial dimensions, acquiring a single volume and enabling a retrospective analysis at multiple locations. We assessed the feasibility of gathering hemodynamic insight into aortic hemodynamics by means of wave intensity analysis (WIA) derived from 4D MRI. Data were collected in n = 12 BAV patients and n = 7 healthy controls. Following data acquisition, WIA was successfully derived at three planes (ascending, thoracic and descending aorta) in all cases. The values of wave speed were physiological and, while the small sample limited any clinical interpretation of the results, the study shows the possibility of studying wave travel and wave reflection based on 4D MRI. Below, we demonstrate for the first time the feasibility of deriving wave intensity analysis from 4D flow data and open the door to research applications in different cardiovascular scenarios.
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Affiliation(s)
- Froso Sophocleous
- Bristol Heart Institute, Bristol Medical School, University of Bristol, Bristol BS8 1QU, UK
| | - Kiril Delchev
- Bristol Heart Institute, Bristol Medical School, University of Bristol, Bristol BS8 1QU, UK
- University Hospitals Bristol and Weston NHS Foundation Trust, Bristol BS1 3NU, UK
| | - Estefania De Garate
- Bristol Heart Institute, Bristol Medical School, University of Bristol, Bristol BS8 1QU, UK
- University Hospitals Bristol and Weston NHS Foundation Trust, Bristol BS1 3NU, UK
| | - Mark C K Hamilton
- University Hospitals Bristol and Weston NHS Foundation Trust, Bristol BS1 3NU, UK
| | - Massimo Caputo
- Bristol Heart Institute, Bristol Medical School, University of Bristol, Bristol BS8 1QU, UK
- University Hospitals Bristol and Weston NHS Foundation Trust, Bristol BS1 3NU, UK
| | - Chiara Bucciarelli-Ducci
- Bristol Heart Institute, Bristol Medical School, University of Bristol, Bristol BS8 1QU, UK
- Royal Brompton and Harefield Hospitals, Guys and St Thomas NHS Trust, London UB9 6JH, UK
- School of Biomedical Engineering and Imaging Sciences, Faculty of Life Sciences and Medicine, Kings College London, London WC2R 2LS, UK
| | - Giovanni Biglino
- Bristol Heart Institute, Bristol Medical School, University of Bristol, Bristol BS8 1QU, UK
- National Heart and Lung Institute, Imperial College London, London SW7 2BX, UK
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Bianchini E, Lønnebakken MT, Wohlfahrt P, Piskin S, Terentes‐Printzios D, Alastruey J, Guala A. Magnetic Resonance Imaging and Computed Tomography for the Noninvasive Assessment of Arterial Aging: A Review by the VascAgeNet COST Action. J Am Heart Assoc 2023; 12:e027414. [PMID: 37183857 PMCID: PMC10227315 DOI: 10.1161/jaha.122.027414] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Magnetic resonance imaging and computed tomography allow the characterization of arterial state and function with high confidence and thus play a key role in the understanding of arterial aging and its translation into the clinic. Decades of research into the development of innovative imaging sequences and image analysis techniques have led to the identification of a large number of potential biomarkers, some bringing improvement in basic science, others in clinical practice. Nonetheless, the complexity of some of these biomarkers and the image analysis techniques required for their computation hamper their widespread use. In this narrative review, current biomarkers related to aging of the aorta, their founding principles, the sequence, and postprocessing required, and their predictive values for cardiovascular events are summarized. For each biomarker a summary of reference values and reproducibility studies and limitations is provided. The present review, developed in the COST Action VascAgeNet, aims to guide clinicians and technical researchers in the critical understanding of the possibilities offered by these advanced imaging modalities for studying the state and function of the aorta, and their possible clinically relevant relationships with aging.
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Affiliation(s)
| | - Mai Tone Lønnebakken
- Department of Clinical ScienceUniversity of BergenBergenNorway
- Department of Heart DiseaseHaukeland University HospitalBergenNorway
| | - Peter Wohlfahrt
- Department of Preventive CardiologyInstitute for Clinical and Experimental MedicinePragueCzech Republic
- Centre for Cardiovascular PreventionCharles University Medical School I and Thomayer HospitalPragueCzech Republic
- Department of Medicine IICharles University in Prague, First Faculty of MedicinePragueCzech Republic
| | - Senol Piskin
- Department of Mechanical Engineering, Faculty of Engineering and Natural SciencesIstinye UniversityIstanbulTurkey
- Modeling, Simulation and Extended Reality LaboratoryIstinye UniversityIstanbulTurkey
| | - Dimitrios Terentes‐Printzios
- First Department of Cardiology, Hippokration Hospital, Athens Medical SchoolNational and Kapodistrian University of AthensGreece
| | - Jordi Alastruey
- School of Biomedical Engineering and Imaging SciencesKing’s College LondonLondonUK
| | - Andrea Guala
- Vall d’Hebron Institut de Recerca (VHIR)BarcelonaSpain
- CIBER‐CV, Instituto de Salud Carlos IIIMadridSpain
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Viscoelasticity of human descending thoracic aorta in a mock circulatory loop. J Mech Behav Biomed Mater 2022; 130:105205. [PMID: 35390678 DOI: 10.1016/j.jmbbm.2022.105205] [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: 01/27/2022] [Revised: 02/26/2022] [Accepted: 03/26/2022] [Indexed: 12/11/2022]
Abstract
Healthy human descending thoracic aortas, obtained during organ donation for transplant and research, were tested in a mock circulatory loop to measure the mechanical response to physiological pulsatile pressure and flow. The viscoelastic properties of the aortic segments were investigated at three different pulse rates. The same aortic segments were also subjected to quasi-static pressure tests in order to identify the aortic dynamic stiffness ratio, which is defined as the ratio between the stiffness in case of pulsatile pressure and the stiffness measured for static pressurization, both at the same value of pressure. The loss factor was also identified. The shape of the deformed aorta under static and dynamic pressure was measured by image processing to verify the compatibility of the end supports with the natural deformation of the aorta in the human body. In addition, layer-specific experiments on 10 human descending thoracic aortas allowed to precisely identify the mass density of the aortic tissue, which is an important parameter in cardiovascular dynamic models.
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Mangarova DB, Bertalan G, Jordan J, Brangsch J, Kader A, Möckel J, Adams LC, Sack I, Taupitz M, Hamm B, Braun J, Makowski MR. Microscopic multifrequency magnetic resonance elastography of ex vivo abdominal aortic aneurysms for extracellular matrix imaging in a mouse model. Acta Biomater 2022; 140:389-397. [PMID: 34818577 DOI: 10.1016/j.actbio.2021.11.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 11/16/2021] [Accepted: 11/17/2021] [Indexed: 11/27/2022]
Abstract
An abdominal aortic aneurysm (AAA) is a permanent dilatation of the abdominal aorta, usually accompanied by thrombus formation. The current clinical imaging modalities cannot reliably visualize the thrombus composition. Remodeling of the extracellular matrix (ECM) during AAA development leads to stiffness changes, providing a potential imaging marker. 14 apolipoprotein E-deficient mice underwent surgery for angiotensin II-loaded osmotic minipump implantation. 4 weeks post-op, 5 animals developed an AAA. The aneurysm was imaged ex vivo by microscopic multifrequency magnetic resonance elastography (µMMRE) with an in-plane resolution of 40 microns. Experiments were performed on a 7-Tesla preclinical magnetic resonance imaging scanner with drive frequencies between 1000 Hz and 1400 Hz. Shear wave speed (SWS) maps indicating stiffness were computed based on tomoelastography multifrequency inversion. As control, the aortas of 5 C57BL/6J mice were examined with the same imaging protocol. The regional variation of SWS in the thrombus ranging from 0.44 ± 0.07 to 1.20 ± 0.31 m/s was correlated fairly strong with regional histology-quantified ECM accumulation (R2 = 0.79). Our results suggest that stiffness changes in aneurysmal thrombus reflect ECM remodeling, which is critical for AAA risk assessment. In the future, µMMRE could be used for a mechanics-based clinical characterization of AAAs in patients. STATEMENT OF SIGNIFICANCE: To our knowledge, this is the first study mapping the stiffness of abdominal aortic aneurysms with microscopic resolution of 40 µm. Our work revealed that stiffness critically changes due to extracellular matrix (ECM) remodeling in the aneurysmal thrombus. We were able to image various levels of ECM remodeling in the aneurysm reflected in distinct shear wave speed patterns with a strong correlation to regional histology-quantified ECM accumulation. The generated results are significant for the application of microscopic multifrequency magnetic resonance elastography for quantification of pathological remodeling of the ECM and may be of great interest for detailed characterization of AAAs in patients.
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Affiliation(s)
- Dilyana B Mangarova
- Department of Radiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Charitéplatz 1, Berlin 10117, Germany; Department of Veterinary Medicine, Institute of Veterinary Pathology, Freie Universität Berlin, Robert-von-Ostertag-Str. 15, Building 12, Berlin 4163, Germany.
| | - Gergely Bertalan
- Department of Radiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Charitéplatz 1, Berlin 10117, Germany.
| | - Jakob Jordan
- Department of Radiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Charitéplatz 1, Berlin 10117, Germany.
| | - Julia Brangsch
- Department of Radiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Charitéplatz 1, Berlin 10117, Germany.
| | - Avan Kader
- Department of Radiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Charitéplatz 1, Berlin 10117, Germany; Department of Biology, Chemistry and Pharmacy, Institute of Biology, Freie Universität Berlin, Königin-Luise-Str. 1-3, Berlin 14195, Germany.
| | - Jana Möckel
- Department of Radiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Charitéplatz 1, Berlin 10117, Germany.
| | - Lisa C Adams
- Department of Radiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Charitéplatz 1, Berlin 10117, Germany.
| | - Ingolf Sack
- Department of Radiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Charitéplatz 1, Berlin 10117, Germany.
| | - Matthias Taupitz
- Department of Radiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Charitéplatz 1, Berlin 10117, Germany.
| | - Bernd Hamm
- Department of Radiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Charitéplatz 1, Berlin 10117, Germany.
| | - Jürgen Braun
- Department of Radiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Charitéplatz 1, Berlin 10117, Germany; Institute for Medical Informatics, Charité - Universitätsmedizin Berlin, Berlin, Germany, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Hindenburgdamm 30, Berlin 12200, Germany.
| | - Marcus R Makowski
- Department of Radiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Charitéplatz 1, Berlin 10117, Germany; Department of Diagnostic and Interventional Radiology, Technical University of Munich, Ismaninger Str. 22, Munich 81675, Germany.
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Fakhouri F, Kannengiesser S, Pfeuffer J, Gokun Y, Kolipaka A. Free-breathing MR elastography of the lungs: An in vivo study. Magn Reson Med 2022; 87:236-248. [PMID: 34463400 PMCID: PMC8616792 DOI: 10.1002/mrm.28986] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 08/04/2021] [Accepted: 08/06/2021] [Indexed: 01/03/2023]
Abstract
PURPOSE Lung stiffness alters with many diseases; therefore, several MR elastography (MRE) studies were performed earlier to investigate the stiffness of the right lung during breathhold at residual volume and total lung capacity. The aims of this study were 1) to estimate shear stiffness of the lungs using MRE under free breathing and demonstrate the measurements' repeatability and reproducibility, and 2) to compare lung stiffness under free breathing to breathhold and as a function of age and gender. METHODS Twenty-five healthy volunteers were scanned on a 1.5 Tesla MRI scanner. Spin-echo dual-density spiral and a spin-echo EPI MRE sequences were used to measure shear stiffness of the lungs during free breathing and breathhold at midpoint of tidal volume, respectively. Concordance correlation coefficient and Bland-Altman analyses were performed to determine the repeatability and reproducibility of the spin-echo dual-density spiral-derived shear stiffness. Repeated measures analyses of variances were used to investigate differences in shear stiffness between spin-echo dual-density spiral and spin-echo EPI, right and left lungs, males and females, and different age groups. RESULTS Free-breathing MRE sequence was highly repeatable and reproducible (concordance correlation coefficient > 0.86 for both lungs). Lung stiffness was significantly lower in breathhold than in free breathing (P < .001), which can be attributed to potential stress relaxation of lung parenchyma or breathhold inconsistencies. However, there was no significant difference between different age groups (P = .08). The left lung showed slightly higher stiffness values than the right lung (P = .14). There is no significant difference in lung stiffness between genders. CONCLUSION This study demonstrated the feasibility of free-breathing lung MRE with excellent repeatability and reproducibility. Stiffness changes with age and during the respiratory cycle. However, gender does not influence lungs stiffness.
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Affiliation(s)
- Faisal Fakhouri
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH, 43210, USA.,Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, OH, 43210, USA
| | | | - Josef Pfeuffer
- MR Application Development, Siemens Healthcare GmbH, Erlangen, Germany
| | - Yevgeniya Gokun
- Department of Biomedical Informatics, Center for Biostatistics, The Ohio State University, Columbus, OH 43210, USA
| | - Arunark Kolipaka
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH, 43210, USA.,Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, OH, 43210, USA
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Mahmoud M, Mayer M, Cancel LM, Bartosch AM, Mathews R, Tarbell JM. The glycocalyx core protein Glypican 1 protects vessel wall endothelial cells from stiffness-mediated dysfunction and disease. Cardiovasc Res 2021; 117:1592-1605. [PMID: 32647868 PMCID: PMC8152694 DOI: 10.1093/cvr/cvaa201] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 05/22/2020] [Accepted: 07/02/2020] [Indexed: 12/25/2022] Open
Abstract
AIMS Arterial stiffness is an underlying risk factor and a hallmark of cardiovascular diseases. The endothelial cell (EC) glycocalyx is a glycan rich surface layer that plays a key role in protecting against EC dysfunction and vascular disease. However, the mechanisms by which arterial stiffness promotes EC dysfunction and vascular disease are not fully understood, and whether the mechanism involves the protective endothelial glycocalyx is yet to be determined. We hypothesized that endothelial glycocalyx protects the endothelial cells lining the vascular wall from dysfunction and disease in response to arterial stiffness. METHODS AND RESULTS Cells cultured on polyacrylamide (PA) gels of substrate stiffness 10 kPa (mimicking the subendothelial stiffness of aged, unhealthy arteries) showed a significant inhibition of glycocalyx expression compared to cells cultured on softer PA gels (2.5 kPa, mimicking the subendothelial stiffness of young, healthy arteries). Specifically, gene and protein analyses revealed that a glycocalyx core protein Glypican 1 was inhibited in cells cultured on stiff PA gels. These cells had enhanced endothelial cell dysfunction as determined by enhanced cell inflammation (enhanced inflammatory gene expression, monocyte adhesion, and inhibited nitric oxide expression), proliferation, and EndMT. Removal of Glypican 1 using gene-specific silencing with siRNA or gene overexpression using a plasmid revealed that Glypican 1 is required to protect against stiffness-mediated endothelial cell dysfunction. Consistent with this, using a model of age-mediated stiffness, older mice exhibited a reduced expression of Glypican 1 and enhanced endothelial cell dysfunction compared to young mice. Glypican 1 gene deletion in knockout mice (GPC1-/-) exacerbated endothelial dysfunction in young mice, which normally had high endothelial expression, but not in old mice that normally expressed low levels. Endothelial cell dysfunction was exacerbated in young, but not aged, Glypican 1 knockout mice (GPC1-/-). CONCLUSION Arterial stiffness promotes EC dysfunction and vascular disease at least partly through the suppression of the glycocalyx protein Glypican 1. Glypican 1 contributes to the protection against endothelial cell dysfunction and vascular disease in endothelial cells.
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Affiliation(s)
- Marwa Mahmoud
- Department of Biomedical Engineering, The City College of New York, New York, NY, USA
| | - Mariya Mayer
- Department of Biomedical Engineering, The City College of New York, New York, NY, USA
| | - Limary M Cancel
- Department of Biomedical Engineering, The City College of New York, New York, NY, USA
| | - Anne Marie Bartosch
- Department of Pathology and Cell Biology, Columbia University, New York, NY, USA
| | - Rick Mathews
- Oregon Health & Science University, School of Medicine, Portland, OR, USA
| | - John M Tarbell
- Department of Biomedical Engineering, The City College of New York, New York, NY, USA
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In Vivo Aortic Magnetic Resonance Elastography in Abdominal Aortic Aneurysm: A Validation in an Animal Model. Invest Radiol 2021; 55:463-472. [PMID: 32520516 DOI: 10.1097/rli.0000000000000660] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
OBJECTIVES Using maximum diameter of an abdominal aortic aneurysm (AAA) alone for management can lead to delayed interventions or unnecessary urgent repairs. Abdominal aortic aneurysm stiffness plays an important role in its expansion and rupture. In vivo aortic magnetic resonance elastography (MRE) was developed to spatially measure AAA stiffness in previous pilot studies and has not been thoroughly validated and evaluated for its potential clinical value. This study aims to evaluate noninvasive in vivo aortic MRE-derived stiffness in an AAA porcine model and investigate the relationships between MRE-derived AAA stiffness and (1) histopathology, (2) uniaxial tensile test, and (3) burst testing for assessing MRE's potential in evaluating AAA rupture risk. MATERIALS AND METHODS Abdominal aortic aneurysm was induced in 31 Yorkshire pigs (n = 226 stiffness measurements). Animals were randomly divided into 3 cohorts: 2-week, 4-week, and 4-week-burst. Aortic MRE was sequentially performed. Histopathologic analyses were performed to quantify elastin, collagen, and mineral densities. Uniaxial tensile test and burst testing were conducted to measure peak stress and burst pressure for assessing the ultimate wall strength. RESULTS Magnetic resonance elastography-derived AAA stiffness was significantly higher than the normal aorta. Significant reduction in elastin and collagen densities as well as increased mineralization was observed in AAAs. Uniaxial tensile test and burst testing revealed reduced ultimate wall strength. Magnetic resonance elastography-derived aortic stiffness correlated to elastin density (ρ = -0.68; P < 0.0001; n = 60) and mineralization (ρ = 0.59; P < 0.0001; n = 60). Inverse correlations were observed between aortic stiffness and peak stress (ρ = -0.32; P = 0.0495; n = 38) as well as burst pressure (ρ = -0.55; P = 0.0116; n = 20). CONCLUSIONS Noninvasive in vivo aortic MRE successfully detected aortic wall stiffening, confirming the extracellular matrix remodeling observed in the histopathologic analyses. These mural changes diminished wall strength. Inverse correlation between MRE-derived aortic stiffness and aortic wall strength suggests that MRE-derived stiffness can be a potential biomarker for clinically assessing AAA wall status and rupture potential.
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Dong H, Jin N, Kannengiesser S, Raterman B, White RD, Kolipaka A. Magnetic resonance elastography for estimating in vivo stiffness of the abdominal aorta using cardiac-gated spin-echo echo-planar imaging: a feasibility study. NMR IN BIOMEDICINE 2021; 34:e4420. [PMID: 33021342 DOI: 10.1002/nbm.4420] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 09/02/2020] [Accepted: 09/10/2020] [Indexed: 06/11/2023]
Abstract
INTRODUCTION Magnetic resonance elastography (MRE)-derived aortic stiffness is a potential biomarker for multiple cardiovascular diseases. Currently, gradient-recalled echo (GRE) MRE is a widely accepted technique to estimate aortic stiffness. However, multi-slice GRE MRE requires multiple breath-holds (BHs), which can be challenging for patients who cannot consistently hold their breath. The aim of this study was to investigate the feasibility of a multi-slice spin-echo echo-planar imaging (SE-EPI) MRE sequence for quantifying in vivo aortic stiffness using a free-breathing (FB) protocol and a single-BH protocol. METHOD On Scanner 1, 25 healthy subjects participated in the validation of FB SE-EPI against FB GRE. On Scanner 2, another 15 healthy subjects were recruited to compare FB SE-EPI with single-BH SE-EPI. Among all volunteers, five participants were studied on both scanners to investigate the inter-scanner reproducibility of FB SE-EPI aortic MRE. Bland-Altman analysis, Lin's concordance correlation coefficient (LCCC) and coefficient of variation (COV) were evaluated. The phase-difference signal-to-noise ratios (PD SNR) were compared. RESULTS Aortic MRE using FB SE-EPI and FB GRE yielded similar stiffnesses (paired t-test, P = 0.19), with LCCC = 0.97. The FB SE-EPI measurements were reproducible (intra-scanner LCCC = 0.96) and highly repeatable (LCCC = 0.99). The FB SE-EPI MRE was also reproducible across different scanners (inter-scanner LCCC = 0.96). Single-BH SE-EPI scans yielded similar stiffness to FB SE-EPI scans (LCCC = 0.99) and demonstrated a low COV of 2.67% across five repeated measurements. CONCLUSION Multi-slice SE-EPI aortic MRE using an FB protocol or a single-BH protocol is reproducible and repeatable with advantage over multi-slice FB GRE in reducing acquisition time. Additionally, FB SE-EPI MRE provides a potential alternative to BH scans for patients who have challenges in holding their breath.
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Affiliation(s)
- Huiming Dong
- Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
- Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio, USA
| | - Ning Jin
- Siemens Medical Solution, Columbus, Ohio, USA
| | | | - Brian Raterman
- Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
| | - Richard D White
- Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
- Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio, USA
- Department of Internal Medicine-Division of Cardiology, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
| | - Arunark Kolipaka
- Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
- Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio, USA
- Department of Internal Medicine-Division of Cardiology, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
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Steady-State Multifrequency Magnetic Resonance Elastography of the Thoracic and Abdominal Human Aorta-Validation and Reference Values. Invest Radiol 2020; 55:451-456. [PMID: 32520515 DOI: 10.1097/rli.0000000000000654] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVES The aim of this study was to investigate the potential of stroboscopic-wavefield-sampling-based multifrequency magnetic resonance elastography (sMRE) for quantifying the stiffness of the human thoracic and abdominal aorta in vivo. MATERIALS AND METHODS The sMRE of the thoracic and abdominal aorta was performed at 1.5 T field strength in 20 healthy volunteers aged 27 to 77 years (3 women; median age, 33 years; interquartile range [IQR], 16 years). Compound maps of shear wave speed (SWS) were reconstructed and evaluated during the diastolic phase in 3 anatomical regions: ascending thoracic aorta (AA), descending thoracic aorta (AD), and abdominal aorta (AAb). The SWS maps were read by 2 readers. Blood pressure and pulse wave velocity were determined noninvasively before sMRE. Data are given as median (IQR) and were compared using the Kruskal-Wallis and Wilcoxon rank sum tests. Intraclass correlation was used to determine interobserver and intraobserver agreement, as well as reproducibility. Multiple linear regression analysis was performed to evaluate effects of age, sex, vessel diameter, blood pressure, pulse wave velocity, and aortic segment on measured SWS. RESULTS All 20 participants underwent successful sMRE, resulting in a total of 60 aortic segments. The median SWS (IQR) of AA, AD, and AAb was 1.62 (0.16) m/s, 2.40 (0.24) m/s, and 2.48 (0.58) m/s, respectively. The SWS in AA was significantly lower (P < 0.001), and no differences in SWS (P = 0.67) were found between AD and AAb. Interobserver and intraobserver agreement, as well as reproducibility, was excellent, with intraclass correlation coefficients ranging between 0.957 and 0.998. A significant but weak influence of age on measured SWS was found, which increased from AA to AD and AAb (R = 0.229, 0.275, 0.377, respectively; P = 0.001-0.005). CONCLUSIONS Quantification of aortic stiffness in different segments of the human aorta is possible with sMRE. Our results correlate well with known aortic stiffness differences in different anatomical locations and demonstrate the potential of sMRE for clinical stiffness measurement of the thoracoabdominal aorta, which may allow detection of physiological variation and cardiovascular diseases.
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Wang Y, Li H, Guo Y, Lee WN. Bidirectional Ultrasound Elastographic Imaging Framework for Non-invasive Assessment of the Non-linear Behavior of a Physiologically Pressurized Artery. ULTRASOUND IN MEDICINE & BIOLOGY 2019; 45:1184-1196. [PMID: 30876671 DOI: 10.1016/j.ultrasmedbio.2019.01.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Revised: 01/10/2019] [Accepted: 01/15/2019] [Indexed: 06/09/2023]
Abstract
Studies of non-destructive bidirectional ultrasound assessment of non-linear mechanical behavior of the artery are scarce in the literature. We hereby propose derivation of a strain-shear modulus relationship as a new graphical diagnostic index using an ultrasound elastographic imaging framework, which encompasses our in-house bidirectional vascular guided wave imaging (VGWI) and ultrasound strain imaging (USI). This framework is used to assess arterial non-linearity in two orthogonal (i.e., longitudinal and circumferential) directions in the absence of non-invasive pressure measurement. Bidirectional VGWI estimates longitudinal (μL) and transverse (μT) shear moduli, whereas USI estimates radial strain (ɛr). Vessel-mimicking phantoms (with and without longitudinal pre-stretch) and in vitro porcine aortas under static and/or dynamic physiologic intraluminal pressure loads were examined. ɛr was found to be a suitable alternative to intraluminal pressure for representation of cyclic loading on the artery wall. Results revealed that μT values of all samples examined increased non-linearly with εr magnitude and more drastically than μL, whereas μL values of only the pre-stretched phantoms and aortas increased with ɛr magnitude. As a new graphical representation of arterial non-linearity and function, strain-shear modulus loops derived by the proposed framework over two consecutive dynamic loading cycles differentiated sample pre-conditions and corroborated direction-dependent non-linear mechanical behaviors of the aorta with high estimation repeatability.
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Affiliation(s)
- Yahua Wang
- Department of Electrical and Electronic Engineering, University of Hong Kong, Hong Kong
| | - He Li
- Department of Electrical and Electronic Engineering, University of Hong Kong, Hong Kong
| | - Yuexin Guo
- Department of Electrical and Electronic Engineering, University of Hong Kong, Hong Kong
| | - Wei-Ning Lee
- Department of Electrical and Electronic Engineering, University of Hong Kong, Hong Kong; Medical Engineering Programme, University of Hong Kong, Hong Kong.
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Tanaka LY, Araujo TLS, Rodriguez AI, Ferraz MS, Pelegati VB, Morais MCC, Santos AMD, Cesar CL, Ramos AF, Alencar AM, Laurindo FRM. Peri/epicellular protein disulfide isomerase-A1 acts as an upstream organizer of cytoskeletal mechanoadaptation in vascular smooth muscle cells. Am J Physiol Heart Circ Physiol 2018; 316:H566-H579. [PMID: 30499716 DOI: 10.1152/ajpheart.00379.2018] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Although redox processes closely interplay with mechanoresponses to control vascular remodeling, redox pathways coupling mechanostimulation to cellular cytoskeletal organization remain unclear. The peri/epicellular pool of protein disulfide isomerase-A1 (pecPDIA1) supports postinjury vessel remodeling. Using distinct models, we investigated whether pecPDIA1 could work as a redox-dependent organizer of cytoskeletal mechanoresponses. In vascular smooth muscle cells (VSMCs), pecPDIA1 immunoneutralization impaired stress fiber assembly in response to equibiaxial stretch and, under uniaxial stretch, significantly perturbed cell repositioning perpendicularly to stretch orientation. During cyclic stretch, pecPDIA1 supported thiol oxidation of the known mechanosensor β1-integrin and promoted polarized compartmentalization of sulfenylated proteins. Using traction force microscopy, we showed that pecPDIA1 organizes intracellular force distribution. The net contractile moment ratio of platelet-derived growth factor-exposed to basal VSMCs decreased from 0.90 ± 0.09 (IgG-exposed controls) to 0.70 ± 0.08 after pecPDI neutralization ( P < 0.05), together with an enhanced coefficient of variation for distribution of force modules, suggesting increased noise. Moreover, in a single cell model, pecPDIA1 neutralization impaired migration persistence without affecting total distance or velocity, whereas siRNA-mediated total PDIA1 silencing disabled all such variables of VSMC migration. Neither expression nor total activity of the master mechanotransmitter/regulator RhoA was affected by pecPDIA1 neutralization. However, cyclic stretch-induced focal distribution of membrane-bound RhoA was disrupted by pecPDI inhibition, which promoted a nonpolarized pattern of RhoA/caveolin-3 cluster colocalization. Accordingly, FRET biosensors showed that pecPDIA1 supports localized RhoA activity at cell protrusions versus perinuclear regions. Thus, pecPDI acts as a thiol redox-dependent organizer and noise reducer mechanism of cytoskeletal repositioning, oxidant generation, and localized RhoA activation during a variety of VSMC mechanoresponses. NEW & NOTEWORTHY Effects of a peri/epicellular pool of protein disulfide isomerase-A1 (pecPDIA1) during mechanoregulation in vascular smooth muscle cells (VSMCs) were highlighted using approaches such as equibiaxial and uniaxial stretch, random single cell migration, and traction force microscopy. pecPDIA1 regulates organization of the cytoskeleton and minimizes the noise of cell alignment, migration directionality, and persistence. pecPDIA1 mechanisms involve redox control of β1-integrin and localized RhoA activation. pecPDIA1 acts as a novel organizer of mechanoadaptation responses in VSMCs.
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Affiliation(s)
- Leonardo Y Tanaka
- Vascular Biology Laboratory, Heart Institute, University of São Paulo School of Medicine , São Paulo , Brazil
| | - Thaís L S Araujo
- Vascular Biology Laboratory, Heart Institute, University of São Paulo School of Medicine , São Paulo , Brazil
| | - Andres I Rodriguez
- Vascular Biology Laboratory, Heart Institute, University of São Paulo School of Medicine , São Paulo , Brazil.,Group of Research and Innovation in Vascular Health, Department of Basic Sciences, Faculty of Sciences, University of Bío-Bío , Chillán , Chile
| | - Mariana S Ferraz
- Institute of Physics, University of São Paulo , São Paulo , Brazil
| | - Vitor B Pelegati
- "Gleb Wataghin" Institute of Physics, University of Campinas , Campinas , Brazil
| | - Mauro C C Morais
- Escola de Artes, Ciências e Humanidades e Núcleo de Estudos Interdisciplinares em Sistemas Complexos, Departamento de Radiologia e Oncologia e Centro de Pesquisa Translacional em Oncologia - Instituto do Cancer do Estado São Paulo, Faculdade de Medicina, Universidade de São Paulo , São Paulo , Brazil
| | - Aline M Dos Santos
- Department of Structural and Functional Biology, Institute of Biology, University of Campinas , Campinas , Brazil
| | - Carlos L Cesar
- "Gleb Wataghin" Institute of Physics, University of Campinas , Campinas , Brazil
| | - Alexandre F Ramos
- Escola de Artes, Ciências e Humanidades e Núcleo de Estudos Interdisciplinares em Sistemas Complexos, Departamento de Radiologia e Oncologia e Centro de Pesquisa Translacional em Oncologia - Instituto do Cancer do Estado São Paulo, Faculdade de Medicina, Universidade de São Paulo , São Paulo , Brazil
| | | | - Francisco R M Laurindo
- Vascular Biology Laboratory, Heart Institute, University of São Paulo School of Medicine , São Paulo , Brazil
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14
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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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15
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Ebersole C, Ahmad R, Rich AV, Potter LC, Dong H, Kolipaka A. A bayesian method for accelerated magnetic resonance elastography of the liver. Magn Reson Med 2018; 80:1178-1188. [PMID: 29334131 PMCID: PMC5980673 DOI: 10.1002/mrm.27083] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Revised: 12/08/2017] [Accepted: 12/18/2017] [Indexed: 02/06/2023]
Abstract
Purpose Magnetic resonance elastography (MRE) is a noninvasive tool for quantifying soft tissue stiffness. MRE has been adopted as a clinical method for staging liver fibrosis. The application of liver MRE, however, requires multiple lengthy breath holds. We propose a new data acquisition and processing method to reduce MRE scan time. Theory and Methods A Bayesian image reconstruction method that utilizes transform sparsity and magnitude consistency across different phase offsets to recover images from highly undersampled data is proposed. The method is validated using retrospectively downsampled phantom data and prospectively downsampled in vivo data (n=86). Results The proposed technique allows accurate quantification of mean liver stiffness up to an acceleration factor of R=6, enabling acquisition of a slice in 4.3 seconds. Bland Altman analysis indicates that the proposed technique (R=6) has a bias of −0.04 kPa and limits of agreement of –0.36 to +0.28 kPa when compared to traditional GRAPPA reconstruction (R=1.4). Conclusion By exploiting transform sparsity and magnitude consistency, accurate quantification of mean stiffness in the liver can be obtained at acceleration rate of up to R=6. This potentially enables collection of three to four liver slices, as per clinical protocol, within a single breath hold.
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Affiliation(s)
- Christopher Ebersole
- Department of Electrical and Computer Engineering, The Ohio State University
- Department of Radiology, The Ohio State University
| | - Rizwan Ahmad
- Department of Biomedical Engineering, The Ohio State University
| | - Adam V. Rich
- Department of Electrical and Computer Engineering, The Ohio State University
| | - Lee C. Potter
- Department of Electrical and Computer Engineering, The Ohio State University
| | - Huiming Dong
- Department of Radiology, The Ohio State University
- Department of Biomedical Engineering, The Ohio State University
| | - Arunark Kolipaka
- Department of Electrical and Computer Engineering, The Ohio State University
- Department of Radiology, The Ohio State University
- Department of Biomedical Engineering, The Ohio State University
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16
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Farotto D, Segers P, Meuris B, Vander Sloten J, Famaey N. The role of biomechanics in aortic aneurysm management: requirements, open problems and future prospects. J Mech Behav Biomed Mater 2018; 77:295-307. [DOI: 10.1016/j.jmbbm.2017.08.019] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Revised: 08/09/2017] [Accepted: 08/15/2017] [Indexed: 12/18/2022]
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17
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Mix DS, Yang L, Johnson CC, Couper N, Zarras B, Arabadjis I, Trakimas LE, Stoner MC, Day SW, Richards MS. Detecting Regional Stiffness Changes in Aortic Aneurysmal Geometries Using Pressure-Normalized Strain. ULTRASOUND IN MEDICINE & BIOLOGY 2017; 43:2372-2394. [PMID: 28728780 PMCID: PMC5562537 DOI: 10.1016/j.ultrasmedbio.2017.06.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Revised: 04/26/2017] [Accepted: 06/02/2017] [Indexed: 06/07/2023]
Abstract
Transabdominal ultrasound elasticity imaging could improve the assessment of rupture risk for abdominal aortic aneurysms by providing information on the mechanical properties and stress or strain states of vessel walls. We implemented a non-rigid image registration method to visualize the pressure-normalized strain within vascular tissues and adapted it to measure total strain over an entire cardiac cycle. We validated the algorithm's performance with both simulated ultrasound images with known principal strains and anatomically accurate heterogeneous polyvinyl alcohol cryogel vessel phantoms. Patient images of abdominal aortic aneurysm were also used to illustrate the clinical feasibility of our imaging algorithm and the potential value of pressure-normalized strain as a clinical metric. Our results indicated that pressure-normalized strain could be used to identify spatial variations in vessel tissue stiffness. The results of this investigation were sufficiently encouraging to warrant a clinical study measuring abdominal aortic pressure-normalized strain in a patient population with aneurysmal disease.
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Affiliation(s)
- Doran S Mix
- Division of Vascular Surgery, Department of Surgery, University of Rochester Medical Center, Rochester, New York, USA; Department of Biomedical Engineering, Rochester Institute of Technology, Rochester, New York, USA.
| | - Ling Yang
- Department of Biomedical Engineering, University of Rochester, Rochester, New York, USA
| | - Camille C Johnson
- Department of Biomedical Engineering, Rochester Institute of Technology, Rochester, New York, USA
| | - Nathan Couper
- Division of Vascular Surgery, Department of Surgery, University of Rochester Medical Center, Rochester, New York, USA; Department of Biomedical Engineering, University of Rochester, Rochester, New York, USA
| | - Ben Zarras
- Department of Biomedical Engineering, University of Rochester, Rochester, New York, USA
| | - Isaac Arabadjis
- Department of Biomedical Engineering, Rochester Institute of Technology, Rochester, New York, USA
| | - Lauren E Trakimas
- Division of Vascular Surgery, Department of Surgery, University of Rochester Medical Center, Rochester, New York, USA
| | - Michael C Stoner
- Division of Vascular Surgery, Department of Surgery, University of Rochester Medical Center, Rochester, New York, USA
| | - Steven W Day
- Department of Biomedical Engineering, Rochester Institute of Technology, Rochester, New York, USA
| | - Michael S Richards
- Division of Vascular Surgery, Department of Surgery, University of Rochester Medical Center, Rochester, New York, USA; Department of Biomedical Engineering, Rochester Institute of Technology, Rochester, New York, USA
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18
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Kolipaka A, Schroeder S, Mo X, Shah Z, Hart PA, Conwell DL. Magnetic resonance elastography of the pancreas: Measurement reproducibility and relationship with age. Magn Reson Imaging 2017; 42:1-7. [PMID: 28476308 DOI: 10.1016/j.mri.2017.04.015] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Revised: 04/20/2017] [Accepted: 04/30/2017] [Indexed: 02/07/2023]
Abstract
PURPOSE To determine magnetic resonance elastography (MRE)-derived stiffness of pancreas in healthy volunteers with emphasis on: 1) short term and midterm repeatability; and 2) variance as a function of age. METHODS Pancreatic MRE was performed on 22 healthy volunteers (age range:20-64years) in a 3T-scanner. For evaluation of reproducibility of stiffness estimates, the scans were repeated per volunteer on the same day (short term) and one month apart (midterm). MRE wave images were analyzed using 3D inversion to estimate the stiffness of overall pancreas and different anatomic regions (i.e., head, neck, body, and tail). Concordance and Spearman correlation tests were performed to determine reproducibility of stiffness measurements and relationship to age. RESULTS A strong concordance correlation (ρc=0.99; p-value<0.001) was found between short term and midterm repeatability pancreatic stiffness measurements. Additionally, the pancreatic stiffness significantly increased with age with good Spearman correlation coefficient (all ρ>0.81; p<0.001). The older age group (>45yrs) had significantly higher stiffness compared to the younger group (≤45yrs) (p<0.001). No significant difference (p>0.05) in stiffness measurements was observed between different anatomical regions of pancreas, except neck stiffness was slightly lower (p<0.012) compared to head and overall pancreas at month 1. CONCLUSION MRE-derived pancreatic stiffness measurements are highly reproducible in the short and midterm and increase linearly with age in healthy volunteers. Further studies are needed to examine these effects in patients with various pancreatic diseases to understand potential clinical applications.
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Affiliation(s)
- Arunark Kolipaka
- Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, OH, United States; Department of Internal Medicine-Division of Cardiovascular Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, United States.
| | - Samuel Schroeder
- Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, OH, United States; Department of Mechanical Engineering, The Ohio State University, Columbus, OH, United States
| | - Xiaokui Mo
- Center for Biostatistics, Department of Biomedical Informatics, The Ohio State University, Columbus, OH, United States
| | - Zarine Shah
- Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, OH, United States
| | - Phil A Hart
- Division of Gastroenterology, Hepatology, and Nutrition, The Ohio State University Wexner Medical Center, Columbus, OH, United States
| | - Darwin L Conwell
- Division of Gastroenterology, Hepatology, and Nutrition, The Ohio State University Wexner Medical Center, Columbus, OH, United States
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19
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Dong H, Mazumder R, Illapani VSP, Mo X, White RD, Kolipaka A. In vivo quantification of aortic stiffness using MR elastography in hypertensive porcine model. Magn Reson Med 2017; 78:2315-2321. [PMID: 28164361 DOI: 10.1002/mrm.26601] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2016] [Revised: 11/23/2016] [Accepted: 12/14/2016] [Indexed: 02/02/2023]
Abstract
PURPOSE Aortic stiffness plays an important role in evaluating and predicting the progression of systemic arterial hypertension (SAH). The aim of this study is to determine the stiffness of aortic wall using MR elastography (MRE) in a hypertensive porcine model and compare it against invasive aortic pressure measurements. METHODS Renal wrapping surgery was performed on eight pigs to induce SAH. Aortic MRE was performed at baseline and 2 months postsurgery using a retrospectively pulse-gated gradient-echo MRE sequence on a 1.5 tesla scanner. Mechanical waves of 70 Hz were introduced into the aorta. Invasive central aortic pressure measurements were obtained prior to each scan to calculate mean arterial pressure (MAP). MRE data were analyzed to obtain effective aortic stiffness. Spearman's rank correlation analysis was performed to assess the relationship between MAP and MRE-derived aortic stiffness. RESULTS Significant increase in effective aortic stiffness was observed between baseline and 2 months postsurgery measurements (paired t test; P = 0.004). The average MAP, determined by pooling all animals, was 65.24 ± 9.42 mm Hg at baseline and 92.57 ± 11.80 mm Hg 2 months postsurgery with P < 0.0001. Moderate linear correlation was observed between MAP and effective aortic stiffness (ρ = 0.52; P = 0.046). CONCLUSION This study demonstrated that, in a SAH porcine model, MRE-derived aortic stiffness increased with increase in MAP. Magn Reson Med 78:2315-2321, 2017. © 2017 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Huiming Dong
- Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA.,Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio, USA
| | - Ria Mazumder
- Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA.,Department of Electrical and Computer Engineering, The Ohio State University, Columbus, Ohio, USA.,Department of Biomedical Engineering, Widener University, Chester, Pennsylvania, USA
| | - Venkata Sita Priyanka Illapani
- Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA.,Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio, USA
| | - Xiaokui Mo
- Center for Biostatistics, Department of Biomedical Informatics, The Ohio State University, Columbus, Ohio, USA
| | - Richard D White
- Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA.,Department of Internal Medicine-Division of Cardiology, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
| | - Arunark Kolipaka
- Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA.,Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio, USA.,Department of Internal Medicine-Division of Cardiology, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
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20
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Animal Models Used to Explore Abdominal Aortic Aneurysms: A Systematic Review. Eur J Vasc Endovasc Surg 2016; 52:487-499. [DOI: 10.1016/j.ejvs.2016.07.004] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2015] [Accepted: 07/01/2016] [Indexed: 01/09/2023]
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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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22
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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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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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The simulation of magnetic resonance elastography through atherosclerosis. J Biomech 2016; 49:1781-1788. [PMID: 27130475 DOI: 10.1016/j.jbiomech.2016.04.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2015] [Revised: 04/07/2016] [Accepted: 04/09/2016] [Indexed: 11/23/2022]
Abstract
The clinical diagnosis of atherosclerosis via the measurement of stenosis size is widely acknowledged as an imperfect criterion. The vulnerability of an atherosclerotic plaque to rupture is associated with its mechanical properties. The potential to image these mechanical properties using magnetic resonance elastography (MRE) was investigated through synthetic datasets. An image of the steady state wave propagation, equivalent to the first harmonic, can be extracted directly from finite element analysis. Inversion of this displacement data yields a map of the shear modulus, known as an elastogram. The variation of plaque composition, stenosis size, Gaussian noise, filter thresholds and excitation frequency were explored. A decreasing mean shear modulus with an increasing lipid composition was identified through all stenosis sizes. However the inversion algorithm showed sensitivity to parameter variation leading to artefacts which disrupted both the elastograms and quantitative trends. As noise was increased up to a realistic level, the contrast was maintained between the fully fibrous and lipid plaques but lost between the interim compositions. Although incorporating a Butterworth filter improved the performance of the algorithm, restrictive filter thresholds resulted in a reduction of the sensitivity of the algorithm to composition and noise variation. Increasing the excitation frequency improved the techniques ability to image the magnitude of the shear modulus and identify a contrast between compositions. In conclusion, whilst the technique has the potential to image the shear modulus of atherosclerotic plaques, future research will require the integration of a heterogeneous inversion algorithm.
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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: 62] [Impact Index Per Article: 7.8] [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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Time-Resolved Analysis of Left Ventricular Shear Wave Amplitudes in Cardiac Elastography for the Diagnosis of Diastolic Dysfunction. Invest Radiol 2016; 51:1-6. [DOI: 10.1097/rli.0000000000000198] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Zhang N, Chen J, Yin M, Glaser KJ, Xu L, Ehman RL. Quantification of regional aortic stiffness using MR elastography: A phantom and ex-vivo porcine aorta study. Magn Reson Imaging 2015; 34:91-6. [PMID: 26597836 DOI: 10.1016/j.mri.2015.10.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Revised: 09/19/2015] [Accepted: 10/18/2015] [Indexed: 02/06/2023]
Abstract
MR Elastography (MRE) is a noninvasive technique for measuring tissue stiffness that has been used to assess the average stiffness of the abdominal aorta. The utility of aortic MRE would be improved if it could provide information about local variations in aortic stiffness. We hypothesize that regional variations in aortic stiffness can also be measured with MRE and the purpose of this work was to demonstrate that MRE can measure regional stiffness variations in a vascular phantom and in ex vivo porcine aortas. A vascular phantom was fabricated, containing two silicone tubes embedded in gel. A segment of one of the tubes was modified to increase its stiffness. MRE was performed on the phantom with a continuous flow of water through the tubes. The stiffness distribution along the modified tube was measured and compared to the reference tube. MRE was also performed in porcine aortas embedded in gel with segments treated with saline or formalin for 4 days. The stiffness difference between saline- and formalin-treated aortic segments was measured by MRE and mechanical tests. A positive correlation was found between the regional stiffnesses measured by MRE and mechanical tests. The results indicate that MRE can be used to evaluate the local stiffness distribution in silicone tubes and ex vivo porcine aortas. It may therefore be possible to apply MRE to measure regional stiffness variations of the aorta in vivo.
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Affiliation(s)
- Nan Zhang
- Department of Radiology, Mayo Clinic, 200 First Street SW, Rochester 55905, MN, USA; Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, Chaoyang District Anzhen Road 2nd, Beijing 100029, China
| | - Jun Chen
- Department of Radiology, Mayo Clinic, 200 First Street SW, Rochester 55905, MN, USA.
| | - Meng Yin
- Department of Radiology, Mayo Clinic, 200 First Street SW, Rochester 55905, MN, USA
| | - Kevin J Glaser
- Department of Radiology, Mayo Clinic, 200 First Street SW, Rochester 55905, MN, USA
| | - Lei Xu
- Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, Chaoyang District Anzhen Road 2nd, Beijing 100029, China.
| | - Richard L Ehman
- Department of Radiology, Mayo Clinic, 200 First Street SW, Rochester 55905, MN, USA
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Kenyhercz WE, Raterman B, Illapani VSP, Dowell J, Mo X, White RD, Kolipaka A. Quantification of aortic stiffness using magnetic resonance elastography: Measurement reproducibility, pulse wave velocity comparison, changes over cardiac cycle, and relationship with age. Magn Reson Med 2015; 75:1920-6. [PMID: 26096227 DOI: 10.1002/mrm.25719] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Revised: 03/11/2015] [Accepted: 03/12/2015] [Indexed: 12/22/2022]
Abstract
PURPOSE To assess MR elastography (MRE)-derived aortic shear stiffness (μMRE ) measurements for: 1) reproducibility, 2) comparison to pulse wave velocity, 3) changes over the cardiac cycle, and 4) relationship with age. METHODS Cardiac-gated aortic MRE was performed on 20 healthy volunteers (aged 20-73 years). For assessing reproducibility of stiffness measurements, scans were repeated per volunteer. MRE wave images were analyzed to obtain stiffness of the abdominal aorta across the cardiac cycle, and comparisons were made with subject age. RESULTS Analysis of concordance correlation coefficient between scans 1 and 2 showed that rc = 0.86 (95% confidence interval, 0.77, 0.94) with P < 0.0001. Significantly higher μMRE was observed for all volunteers during end-systole when compared to end-diastole (P < 0.0001). μMRE increased with age; end-systolic stiffness demonstrated a relatively stronger correlation with age (r = 0.62, P = 0.003) when compared to end-diastolic stiffness (r = 0.51, P = 0.023); and the slopes of end-systole and end-diastole were found to be significantly different (P = 0.011). [Formula: see text] at end-systole and end-diastole correlated linearly with pulse wave velocity, with an r = 0.54 (P = 0.013) and r = 0.58 (P = 0.008), respectively. CONCLUSION The results of this study indicate that MRE-derived aortic shear stiffness measurements are robust (reproducible and comparable to similar techniques). Mean μMRE was higher during end-systole when compared to end-diastole. μMRE was found to increase with age and showed a stronger correlation with end-systolic stiffness than with end-diastolic stiffness.
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Affiliation(s)
- William E Kenyhercz
- Department of Radiology, Wexner Medical Center, The Ohio State University, Columbus, Ohio, USA
| | - Brian Raterman
- Department of Radiology, Wexner Medical Center, The Ohio State University, Columbus, Ohio, USA
| | - Venkata Sita Priyanka Illapani
- Department of Radiology, Wexner Medical Center, The Ohio State University, Columbus, Ohio, USA.,Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio, USA
| | - Joshua Dowell
- Department of Internal Medicine, Division of Cardiovascular Medicine, Wexner Medical Center, The Ohio State University, Columbus, Ohio, USA
| | - Xiaokui Mo
- Center for Biostatistics, The Ohio State University, Columbus, Ohio, USA
| | - Richard D White
- Department of Radiology, Wexner Medical Center, The Ohio State University, Columbus, Ohio, USA.,Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio, USA.,Department of Internal Medicine, Division of Cardiovascular Medicine, Wexner Medical Center, The Ohio State University, Columbus, Ohio, USA
| | - Arunark Kolipaka
- Department of Radiology, Wexner Medical Center, The Ohio State University, Columbus, Ohio, USA.,Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio, USA.,Department of Internal Medicine, Division of Cardiovascular Medicine, Wexner Medical Center, The Ohio State University, Columbus, Ohio, USA
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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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A module of human peripheral blood mononuclear cell transcriptional network containing primitive and differentiation markers is related to specific cardiovascular health variables. PLoS One 2014; 9:e95124. [PMID: 24759906 PMCID: PMC3997360 DOI: 10.1371/journal.pone.0095124] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Accepted: 03/24/2014] [Indexed: 12/30/2022] Open
Abstract
Peripheral blood mononuclear cells (PBMCs), including rare circulating stem and progenitor cells (CSPCs), have important yet poorly understood roles in the maintenance and repair of blood vessels and perfused organs. Our hypothesis was that the identities and functions of CSPCs in cardiovascular health could be ascertained by analyzing the patterns of their co-expressed markers in unselected PBMC samples. Because gene microarrays had failed to detect many stem cell-associated genes, we performed quantitative real-time PCR to measure the expression of 45 primitive and tissue differentiation markers in PBMCs from healthy and hypertensive human subjects. We compared these expression levels to the subjects' demographic and cardiovascular risk factors, including vascular stiffness. The tested marker genes were expressed in all of samples and organized in hierarchical transcriptional network modules, constructed by a bottom-up approach. An index of gene expression in one of these modules (metagene), defined as the average standardized relative copy numbers of 15 pluripotency and cardiovascular differentiation markers, was negatively correlated (all p<0.03) with age (R2 = −0.23), vascular stiffness (R2 = −0.24), and central aortic pressure (R2 = −0.19) and positively correlated with body mass index (R2 = 0.72, in women). The co-expression of three neovascular markers was validated at the single-cell level using mRNA in situ hybridization and immunocytochemistry. The overall gene expression in this cardiovascular module was reduced by 72±22% in the patients compared with controls. However, the compactness of both modules was increased in the patients' samples, which was reflected in reduced dispersion of their nodes' degrees of connectivity, suggesting a more primitive character of the patients' CSPCs. In conclusion, our results show that the relationship between CSPCs and vascular function is encoded in modules of the PBMCs transcriptional network. Furthermore, the coordinated gene expression in these modules can be linked to cardiovascular risk factors and subclinical cardiovascular disease; thus, this measure may be useful for their diagnosis and prognosis.
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