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Abstract
The field of regenerative medicine has experienced considerable growth in recent years as the translation of pre-clinical biomaterials and cell- and gene-based therapies begin to reach clinical application. Until recently, the ability to monitor the serial responses to therapeutic treatments has been limited to post-mortem tissue analyses. With improvements in existing imaging modalities and the emergence of hybrid imaging systems, it is now possible to combine information related to structural remodeling with associated molecular events using non-invasive imaging. This review summarizes the established and emerging imaging modalities that are available for in vivo monitoring of clinical regenerative medicine therapies and discusses the strengths and limitations of each imaging modality.
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Affiliation(s)
- Mitchel R. Stacy
- Department of Internal Medicine, Yale University School of Medicine, P.O. Box 208017, Dana-3, New Haven, CT 06520 USA
| | - Albert J. Sinusas
- Departments of Internal Medicine & Diagnostic Radiology, Yale University School of Medicine, P.O. Box 208017, Dana-3, New Haven, CT 06520 USA
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Abdullah OM, Drakos SG, Diakos NA, Wever-Pinzon O, Kfoury AG, Stehlik J, Selzman CH, Reid BB, Brunisholz K, Verma DR, Myrick C, Sachse FB, Li DY, Hsu EW. Characterization of diffuse fibrosis in the failing human heart via diffusion tensor imaging and quantitative histological validation. NMR IN BIOMEDICINE 2014; 27:1378-86. [PMID: 25200106 PMCID: PMC4215542 DOI: 10.1002/nbm.3200] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2014] [Revised: 07/09/2014] [Accepted: 08/15/2014] [Indexed: 05/16/2023]
Abstract
Non-invasive imaging techniques are highly desirable as an alternative to conventional biopsy for the characterization of the remodeling of tissues associated with disease progression, including end-stage heart failure. Cardiac diffusion tensor imaging (DTI) has become an established method for the characterization of myocardial microstructure. However, the relationships between diffuse myocardial fibrosis, which is a key biomarker for staging and treatment planning of the failing heart, and measured DTI parameters have yet to be investigated systematically. In this study, DTI was performed on left ventricular specimens collected from patients with chronic end-stage heart failure as a result of idiopathic dilated cardiomyopathy (n = 14) and from normal donors (n = 5). Scalar DTI parameters, including fractional anisotropy (FA) and mean (MD), primary (D1 ), secondary (D2 ) and tertiary (D3 ) diffusivities, were correlated with collagen content measured by digital microscopy. Compared with hearts from normal subjects, the FA in failing hearts decreased by 22%, whereas the MD, D2 and D3 increased by 12%, 14% and 24%, respectively (P < 0.01). No significant change was detected for D1 between the two groups. Furthermore, significant correlation was observed between the DTI scalar indices and quantitative histological measurements of collagen (i.e. fibrosis). Pearson's correlation coefficients (r) between collagen content and FA, MD, D2 and D3 were -0.51, 0.59, 0.56 and 0.62 (P < 0.05), respectively. The correlation between D1 and collagen content was not significant (r = 0.46, P = 0.05). Computational modeling analysis indicated that the behaviors of the DTI parameters as a function of the degree of fibrosis were well explained by compartmental exchange between myocardial and collagenous tissues. Combined, these findings suggest that scalar DTI parameters can be used as metrics for the non-invasive assessment of diffuse fibrosis in failing hearts.
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Affiliation(s)
| | - Stavros G. Drakos
- Molecular Medicine Program, University of Utah
- UTAH Cardiac Transplant Program (University of Utah Hospital, Intermountain Medical Center, Salt Lake Veterans Affairs Medical Center)
| | | | - Omar Wever-Pinzon
- UTAH Cardiac Transplant Program (University of Utah Hospital, Intermountain Medical Center, Salt Lake Veterans Affairs Medical Center)
| | - Abdallah G. Kfoury
- UTAH Cardiac Transplant Program (University of Utah Hospital, Intermountain Medical Center, Salt Lake Veterans Affairs Medical Center)
| | - Josef Stehlik
- UTAH Cardiac Transplant Program (University of Utah Hospital, Intermountain Medical Center, Salt Lake Veterans Affairs Medical Center)
| | - Craig H. Selzman
- UTAH Cardiac Transplant Program (University of Utah Hospital, Intermountain Medical Center, Salt Lake Veterans Affairs Medical Center)
| | - Bruce B. Reid
- UTAH Cardiac Transplant Program (University of Utah Hospital, Intermountain Medical Center, Salt Lake Veterans Affairs Medical Center)
| | - Kim Brunisholz
- UTAH Cardiac Transplant Program (University of Utah Hospital, Intermountain Medical Center, Salt Lake Veterans Affairs Medical Center)
| | - Divya Ratan Verma
- UTAH Cardiac Transplant Program (University of Utah Hospital, Intermountain Medical Center, Salt Lake Veterans Affairs Medical Center)
| | | | - Frank B. Sachse
- Department of Bioengineering, University of Utah
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah
| | - Dean Y. Li
- Molecular Medicine Program, University of Utah
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Nguyen C, Fan Z, Xie Y, Dawkins J, Tseliou E, Bi X, Sharif B, Dharmakumar R, Marbán E, Li D. In vivo contrast free chronic myocardial infarction characterization using diffusion-weighted cardiovascular magnetic resonance. J Cardiovasc Magn Reson 2014; 16:68. [PMID: 25230598 PMCID: PMC4167272 DOI: 10.1186/s12968-014-0068-y] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Accepted: 08/13/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Despite the established role of late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) in characterizing chronic myocardial infarction (MI), a significant portion of chronic MI patients are contraindicative for the use of contrast agents. One promising alternative contrast free technique is diffusion weighted CMR (dwCMR), which has been shown ex vivo to be sensitive to myocardial fibrosis. We used a recently developed in vivo dwCMR in chronic MI pigs to compare apparent diffusion coefficient (ADC) maps with LGE imaging for infarct characterization. METHODS In eleven mini pigs, chronic MI was induced by complete occlusion of the left anterior descending artery for 150 minutes. LGE, cine, and dwCMR imaging was performed 8 weeks post MI. ADC maps were derived from three orthogonal diffusion directions (b = 400 s/mm2) and one non-diffusion weighted image. Two semi-automatic infarct classification methods, threshold and full width half max (FWHM), were performed in both LGE and ADC maps. Regional wall motion (RWM) analysis was performed and compared to ADC maps to determine if any observed ADC change was significantly influenced by bulk motion. RESULTS ADC of chronic MI territories was significantly increased (threshold: 2.4 ± 0.3 μm2/ms, FWHM: 2.4 ± 0.2 μm2/ms) compared to remote myocardium (1.4 ± 0.3 μm2/ms). RWM was significantly reduced (threshold: 1.0 ± 0.4 mm, FWHM: 0.9 ± 0.4 mm) in infarcted regions delineated by ADC compared to remote myocardium (8.3 ± 0.1 mm). ADC-derived infarct volume and location had excellent agreement with LGE. Both LGE and ADC were in complete agreement when identifying transmural infarcts. Additionally, ADC was able to detect LGE-delineated infarcted segments with high sensitivity, specificity, PPV, and NPV. (threshold: 0.88, 0.93, 0.87, and 0.94, FWHM: 0.98, 0.97, 0.93, and 0.99, respectively). CONCLUSIONS In vivo diffusion weighted CMR has potential as a contrast free alternative for LGE in characterizing chronic MI.
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Affiliation(s)
- Christopher Nguyen
- />Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, 116 N. Robertson Blvd Suite 800, Los Angeles, CA 90048 USA
- />Department of Bioengineering, University of California Los Angeles, 420 Westwood Plaza, Engineering V Room 5121, PO Box 951600, Los Angeles, CA 90095 USA
| | - Zhaoyang Fan
- />Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, 116 N. Robertson Blvd Suite 800, Los Angeles, CA 90048 USA
| | - Yibin Xie
- />Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, 116 N. Robertson Blvd Suite 800, Los Angeles, CA 90048 USA
- />Department of Bioengineering, University of California Los Angeles, 420 Westwood Plaza, Engineering V Room 5121, PO Box 951600, Los Angeles, CA 90095 USA
| | - James Dawkins
- />Heart Institute, Cedars-Sinai Medical Center, 127 S. San Vincente Blvd. Advanced Health Sciences Pavilion A3600, Los Angeles, CA 90048 USA
| | - Eleni Tseliou
- />Heart Institute, Cedars-Sinai Medical Center, 127 S. San Vincente Blvd. Advanced Health Sciences Pavilion A3600, Los Angeles, CA 90048 USA
| | - Xiaoming Bi
- />MR Research and Development, Siemens Healthcare, 116 N. Robertson Blvd Suite 800, Los Angeles, 90048 CA USA
| | - Behzad Sharif
- />Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, 116 N. Robertson Blvd Suite 800, Los Angeles, CA 90048 USA
| | - Rohan Dharmakumar
- />Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, 116 N. Robertson Blvd Suite 800, Los Angeles, CA 90048 USA
- />Department of Bioengineering, University of California Los Angeles, 420 Westwood Plaza, Engineering V Room 5121, PO Box 951600, Los Angeles, CA 90095 USA
- />Heart Institute, Cedars-Sinai Medical Center, 127 S. San Vincente Blvd. Advanced Health Sciences Pavilion A3600, Los Angeles, CA 90048 USA
| | - Eduardo Marbán
- />Heart Institute, Cedars-Sinai Medical Center, 127 S. San Vincente Blvd. Advanced Health Sciences Pavilion A3600, Los Angeles, CA 90048 USA
| | - Debiao Li
- />Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, 116 N. Robertson Blvd Suite 800, Los Angeles, CA 90048 USA
- />Department of Bioengineering, University of California Los Angeles, 420 Westwood Plaza, Engineering V Room 5121, PO Box 951600, Los Angeles, CA 90095 USA
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Stoeck CT, Kalinowska A, von Deuster C, Harmer J, Chan RW, Niemann M, Manka R, Atkinson D, Sosnovik DE, Mekkaoui C, Kozerke S. Dual-phase cardiac diffusion tensor imaging with strain correction. PLoS One 2014; 9:e107159. [PMID: 25191900 PMCID: PMC4156436 DOI: 10.1371/journal.pone.0107159] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Accepted: 08/05/2014] [Indexed: 12/03/2022] Open
Abstract
Purpose In this work we present a dual-phase diffusion tensor imaging (DTI) technique that incorporates a correction scheme for the cardiac material strain, based on 3D myocardial tagging. Methods In vivo dual-phase cardiac DTI with a stimulated echo approach and 3D tagging was performed in 10 healthy volunteers. The time course of material strain was estimated from the tagging data and used to correct for strain effects in the diffusion weighted acquisition. Mean diffusivity, fractional anisotropy, helix, transverse and sheet angles were calculated and compared between systole and diastole, with and without strain correction. Data acquired at the systolic sweet spot, where the effects of strain are eliminated, served as a reference. Results The impact of strain correction on helix angle was small. However, large differences were observed in the transverse and sheet angle values, with and without strain correction. The standard deviation of systolic transverse angles was significantly reduced from 35.9±3.9° to 27.8°±3.5° (p<0.001) upon strain-correction indicating more coherent fiber tracks after correction. Myocyte aggregate structure was aligned more longitudinally in systole compared to diastole as reflected by an increased transmural range of helix angles (71.8°±3.9° systole vs. 55.6°±5.6°, p<0.001 diastole). While diastolic sheet angle histograms had dominant counts at high sheet angle values, systolic histograms showed lower sheet angle values indicating a reorientation of myocyte sheets during contraction. Conclusion An approach for dual-phase cardiac DTI with correction for material strain has been successfully implemented. This technique allows assessing dynamic changes in myofiber architecture between systole and diastole, and emphasizes the need for strain correction when sheet architecture in the heart is imaged with a stimulated echo approach.
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Affiliation(s)
- Christian T. Stoeck
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
| | - Aleksandra Kalinowska
- Department of Mechanical and Biomedical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Constantin von Deuster
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
- Imaging Sciences and Biomedical Engineering, King's College London, London, United Kingdom
| | - Jack Harmer
- Imaging Sciences and Biomedical Engineering, King's College London, London, United Kingdom
| | - Rachel W. Chan
- Centre for Medical Imaging, University College London, London, United Kingdom
| | - Markus Niemann
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
- Department of Cardiology, University Hospital Zurich, Zurich, Switzerland
| | - Robert Manka
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
- Department of Cardiology, University Hospital Zurich, Zurich, Switzerland
- Department of Radiology, University Hospital Zurich, Zurich, Switzerland
| | - David Atkinson
- Centre for Medical Imaging, University College London, London, United Kingdom
| | - David E. Sosnovik
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
- Cardiovascular Research Center, Cardiology Division, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Choukri Mekkaoui
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Radiology, University Hospital Center of Nîmes, EA 2415, Nîmes, France
- Faculty of Medicine, Montpellier 1 University, Montpellier, France
| | - Sebastian Kozerke
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
- Imaging Sciences and Biomedical Engineering, King's College London, London, United Kingdom
- * E-mail:
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Images as drivers of progress in cardiac computational modelling. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2014; 115:198-212. [PMID: 25117497 PMCID: PMC4210662 DOI: 10.1016/j.pbiomolbio.2014.08.005] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Accepted: 08/02/2014] [Indexed: 11/28/2022]
Abstract
Computational models have become a fundamental tool in cardiac research. Models are evolving to cover multiple scales and physical mechanisms. They are moving towards mechanistic descriptions of personalised structure and function, including effects of natural variability. These developments are underpinned to a large extent by advances in imaging technologies. This article reviews how novel imaging technologies, or the innovative use and extension of established ones, integrate with computational models and drive novel insights into cardiac biophysics. In terms of structural characterization, we discuss how imaging is allowing a wide range of scales to be considered, from cellular levels to whole organs. We analyse how the evolution from structural to functional imaging is opening new avenues for computational models, and in this respect we review methods for measurement of electrical activity, mechanics and flow. Finally, we consider ways in which combined imaging and modelling research is likely to continue advancing cardiac research, and identify some of the main challenges that remain to be solved.
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Lohezic M, Teh I, Bollensdorff C, Peyronnet R, Hales PW, Grau V, Kohl P, Schneider JE. Interrogation of living myocardium in multiple static deformation states with diffusion tensor and diffusion spectrum imaging. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2014; 115:213-25. [PMID: 25117498 PMCID: PMC4210665 DOI: 10.1016/j.pbiomolbio.2014.08.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Accepted: 08/02/2014] [Indexed: 11/27/2022]
Abstract
Diffusion tensor magnetic resonance imaging (MRI) reveals valuable insights into tissue histo-anatomy and microstructure, and has steadily gained traction in the cardiac community. Its wider use in small animal cardiac imaging in vivo has been constrained by its extreme sensitivity to motion, exaggerated by the high heart rates usually seen in rodents. Imaging of the isolated heart eliminates respiratory motion and, if conducted on arrested hearts, cardiac pulsation. This serves as an important intermediate step for basic and translational studies. However, investigating the micro-structural basis of cardiac deformation in the same heart requires observations in different deformation states. Here, we illustrate the imaging of isolated rat hearts in three mechanical states mimicking diastole (cardioplegic arrest), left-ventricular (LV) volume overload (cardioplegic arrest plus LV balloon inflation), and peak systole (lithium-induced contracture). An optimised MRI-compatible Langendorff perfusion setup with the radio-frequency (RF) coil integrated into the wet chamber was developed for use in a 9.4T horizontal bore scanner. Signal-to-noise ratio improved significantly, by 75% compared to a previous design with external RF coil, and stability tests showed no significant changes in mean T1, T2 or LV wall thickness over a 170 min period. In contracture, we observed a significant reduction in mean fractional anisotropy from 0.32 ± 0.02 to 0.28 ± 0.02, as well as a significant rightward shift in helix angles with a decrease in the proportion of left-handed fibres, as referring to the locally prevailing cell orientation in the heart, from 24.9% to 23.3%, and an increase in the proportion of right-handed fibres from 25.5% to 28.4%. LV overload, in contrast, gave rise to a decrease in the proportion of left-handed fibres from 24.9% to 21.4% and an increase in the proportion of right-handed fibres from 25.5% to 26.0%. The modified perfusion and coil setup offers better performance and control over cardiac contraction states. We subsequently performed high-resolution diffusion spectrum imaging (DSI) and 3D whole heart fibre tracking in fixed ex vivo rat hearts in slack state and contracture. As a model-free method, DSI augmented the measurements of water diffusion by also informing on multiple intra-voxel diffusion orientations and non-Gaussian diffusion. This enabled us to identify the transition from right- to left-handed fibres from the subendocardium to the subepicardium, as well as voxels in apical regions that were traversed by multiple fibres. We observed that both the mean generalised fractional anisotropy and mean kurtosis were lower in hearts in contracture compared to the slack state, by 23% and 9.3%, respectively. While its heavy acquisition burden currently limits the application of DSI in vivo, ongoing work in acceleration techniques may enable its use in live animals and patients. This would provide access to the as yet unexplored dimension of non-Gaussian diffusion that could serve as a highly sensitive marker of cardiac micro-structural integrity.
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Affiliation(s)
- Maelene Lohezic
- British Heart Foundation Experimental Magnetic Resonance Unit, Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Irvin Teh
- British Heart Foundation Experimental Magnetic Resonance Unit, Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Christian Bollensdorff
- National Heart and Lung Institute, Imperial College London, London, UK; Qatar Cardiovascular Research Center, Qatar Foundation, Doha, Qatar
| | - Rémi Peyronnet
- National Heart and Lung Institute, Imperial College London, London, UK
| | - Patrick W Hales
- Imaging and Biophysics Unit, Institute of Child Health, University College London, London, UK
| | - Vicente Grau
- Department of Engineering Science, University of Oxford, Oxford, UK
| | - Peter Kohl
- National Heart and Lung Institute, Imperial College London, London, UK; Department of Computer Science, University of Oxford, Oxford, UK
| | - Jürgen E Schneider
- British Heart Foundation Experimental Magnetic Resonance Unit, Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK.
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Naumova AV, Modo M, Moore A, Murry CE, Frank JA. Clinical imaging in regenerative medicine. Nat Biotechnol 2014; 32:804-18. [PMID: 25093889 PMCID: PMC4164232 DOI: 10.1038/nbt.2993] [Citation(s) in RCA: 170] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Accepted: 07/15/2014] [Indexed: 01/09/2023]
Abstract
In regenerative medicine, clinical imaging is indispensable for characterizing damaged tissue and for measuring the safety and efficacy of therapy. However, the ability to track the fate and function of transplanted cells with current technologies is limited. Exogenous contrast labels such as nanoparticles give a strong signal in the short term but are unreliable long term. Genetically encoded labels are good both short- and long-term in animals, but in the human setting they raise regulatory issues related to the safety of genomic integration and potential immunogenicity of reporter proteins. Imaging studies in brain, heart and islets share a common set of challenges, including developing novel labeling approaches to improve detection thresholds and early delineation of toxicity and function. Key areas for future research include addressing safety concerns associated with genetic labels and developing methods to follow cell survival, differentiation and integration with host tissue. Imaging may bridge the gap between cell therapies and health outcomes by elucidating mechanisms of action through longitudinal monitoring.
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Affiliation(s)
- Anna V Naumova
- 1] Department of Radiology, University of Washington, Seattle, Washington, USA. [2] Center for Cardiovascular Biology, University of Washington, Seattle, Washington, USA. [3] Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, Washington, USA
| | - Michel Modo
- 1] McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA. [2] Centre for the Neural Basis of Cognition, University of Pittsburgh, Pittsburgh, Pennsylvania, USA. [3] Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA. [4] Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Anna Moore
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts, USA
| | - Charles E Murry
- 1] Center for Cardiovascular Biology, University of Washington, Seattle, Washington, USA. [2] Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, Washington, USA. [3] Department of Pathology, University of Washington, Seattle, Washington, USA. [4] Department of Bioengineering, University of Washington, Seattle, Washington, USA. [5] Department of Medicine/Cardiology, University of Washington, Seattle, Washington, USA
| | - Joseph A Frank
- 1] Radiology and Imaging Sciences, Clinical, National Institutes of Health, Bethesda, Maryland, USA. [2] National Institutes of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, Maryland, USA
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Katz MY, Kusakari Y, Aoyagi H, Higa JK, Xiao CY, Abdelkarim AZ, Marh K, Aoyagi T, Rosenzweig A, Lozanoff S, Matsui T. Three-dimensional myocardial scarring along myofibers after coronary ischemia-reperfusion revealed by computerized images of histological assays. Physiol Rep 2014; 2:2/7/e12072. [PMID: 25347856 PMCID: PMC4187547 DOI: 10.14814/phy2.12072] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Adverse left ventricular (LV) remodeling after acute myocardial infarction is characterized by LV dilatation and development of a fibrotic scar, and is a critical factor for the prognosis of subsequent development of heart failure. Although myofiber organization is recognized as being important for preserving physiological cardiac function and structure, the anatomical features of injured myofibers during LV remodeling have not been fully defined. In a mouse model of ischemia-reperfusion (I/R) injury induced by left anterior descending coronary artery ligation, our previous histological assays demonstrated that broad fibrotic scarring extended from the initial infarct zone to the remote zone, and was clearly demarcated along midcircumferential myofibers. Additionally, no fibrosis was observed in longitudinal myofibers in the subendocardium and subepicardium. However, a histological analysis of tissue sections does not adequately indicate myofiber injury distribution throughout the entire heart. To address this, we investigated patterns of scar formation along myofibers using three-dimensional (3D) images obtained from multiple tissue sections from mouse hearts subjected to I/R injury. The fibrotic scar area observed in the 3D images was consistent with the distribution of the midcircumferential myofibers. At the apex, the scar formation tracked along the myofibers in an incomplete C-shaped ring that converged to a triangular shape toward the end. Our findings suggest that myocyte injury after transient coronary ligation extends along myofibers, rather than following the path of coronary arteries penetrating the myocardium. The injury pattern observed along myofibers after I/R injury could be used to predict prognoses for patients with myocardial infarction.
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Affiliation(s)
- Monica Y Katz
- Department of Anatomy, Biochemistry & Physiology, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii
| | - Yoichiro Kusakari
- Cardiovascular Institute, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
| | - Hiroko Aoyagi
- Department of Anatomy, Biochemistry & Physiology, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii
| | - Jason K Higa
- Department of Anatomy, Biochemistry & Physiology, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii
| | - Chun-Yang Xiao
- Cardiovascular Institute, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
| | - Ahmed Z Abdelkarim
- Department of Anatomy, Biochemistry & Physiology, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii
| | - Karra Marh
- Department of Anatomy, Biochemistry & Physiology, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii
| | - Toshinori Aoyagi
- Department of Anatomy, Biochemistry & Physiology, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii
| | - Anthony Rosenzweig
- Cardiovascular Institute, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
| | - Scott Lozanoff
- Department of Anatomy, Biochemistry & Physiology, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii
| | - Takashi Matsui
- Department of Anatomy, Biochemistry & Physiology, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii Cardiovascular Institute, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
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Lohezic M, Bollensdorff C, Korn M, Lanz T, Grau V, Kohl P, Schneider JE. Optimized radiofrequency coil setup for MR examination of living isolated rat hearts in a horizontal 9.4T magnet. Magn Reson Med 2014; 73:2398-405. [PMID: 25045897 DOI: 10.1002/mrm.25369] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2014] [Revised: 06/12/2014] [Accepted: 06/24/2014] [Indexed: 12/12/2022]
Abstract
PURPOSE (i) To optimize an MR-compatible organ perfusion setup for the nondestructive investigation of isolated rat hearts by placing the radiofrequency (RF) coil inside the perfusion chamber; (ii) to characterize the benefit of this system for diffusion tensor imaging and proton ((1) H-) MR spectroscopy. METHODS Coil quality assessment was conducted both on the bench, and in the magnet. The benefit of the new RF-coil was quantified by measuring signal-to-noise ratio (SNR), accuracy, and precision of diffusion tensor imaging/error in metabolite amplitude estimation, and compared to an RF-coil placed externally to the perfusion chamber. RESULTS The new design provided a 59% gain in signal-to-noise ratio on a fixed rat heart compared to using an external resonator, which found reflection in an improvement of living heart data quality, compared to previous external resonator studies. This resulted in 14-29% improvement in accuracy and precision of diffusion tensor imaging. The Cramer-Rao lower bounds for metabolite amplitude estimations were up to 5-fold smaller. CONCLUSION Optimization of MR-compatible perfusion equipment advances the study of rat hearts with improved signal-to-noise ratio performance, and thus improved accuracy/precision.
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Affiliation(s)
- Maelene Lohezic
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Christian Bollensdorff
- National Heart and Lung Institute, Imperial College London, London, UK.,Qatar Cardiovascular Research Center, Qatar Foundation, Doha, Qatar
| | | | | | - Vicente Grau
- Department of Engineering Science, University of Oxford, Oxford, UK
| | - Peter Kohl
- National Heart and Lung Institute, Imperial College London, London, UK.,Department of Computer Science, University of Oxford, Oxford, UK
| | - Jürgen E Schneider
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
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