Myocardial Tissue Characterization

Monday 12 May 2014

Walter RT Witschey¹, Jeremy R McGarvey¹, Madonna Lee¹, Francisco Contijoch², Victor Ferrari³, Yuchi Han³, Julio A Chirinos³, Chikashi Aoki¹, Satoshi Takebayashi⁴, Joseph H Gorman III¹, James J Pilla⁴, and Robert C Gorman^1
1Surgery, University of Pennsylvania, Philadelphia, PA, United States, ²Bioengineering, University of Pennsylvania, Philadelphia, PA, United States,³Cardiology, University of Pennsylvania, Philadelphia, PA, United States, ⁴Radiology, University of Pennsylvania, Philadelphia, PA, United States

T1rho MRI has been shown to detect myocardial fibrosis and has potential to be used as a biomarker for heart disease. The progression of T1rho relaxation times in inflammation, wound healing and scar have been reported for direct ligation animal models, mimicking only the most severe types of human ischemic heart disease. Our objective was to determine the relationship between T1rho relaxation times and pathology, at 1 day, 1 and 4 weeks post-infarction in an ischemia-reperfusion pig model. We found that there was a significant increase in T1rho relaxation times at 1 week in pigs and this was indicative of future ventricular remodeling. There was excellent correlation between T1rho MRI-determined infarction area, coronary artery perfusion watershed and fibrosis.

Avinash Kali^1,2, Ivan Cokic¹, Richard Tang¹, Hsin-Jung Yang^1,3, Behzad Sharif¹, Eduardo Marbán¹, Debiao Li^4,5, Daniel Berman^5,6, and Rohan Dharmakumar^1,7
1Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA, United States, ²Department of Bioengineering, University of California, Los Angeles, CA, United States, ³Department of Bioengineering, University of California, Los Angeles, California, United States, ⁴Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, United States, ⁵Cedars-Sinai Heart Institute, Cedars-Sinai Medical Center, Los Angeles, CA, United States, ⁶Department of Medicine, University of California, Los Angeles, CA, United States, ⁷Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, California, United States

We tested whether contrast-freeT1 maps at 3T can detect chronic MIs (CMI) with high diagnostic accuracy relative to Late Gadolinium Enhancement (LGE) images in a canine model. At 3T, T1 maps showed no difference in infarct size (IS) and transmurality (IT) relative to LGE images in CMI, but overestimated IS and IT in AMI. At 1.5T, T1 maps underestimated IS and IT relative to LGE images in AMI and CMI. Relative to the remote territories, T1 of the infarcted myocardium was elevated in AMI and CMI at 3T and 1.5T. Contrast-free T1 maps can reliably characterize CMIs at 3T relative to LGE images.

Lin Wang¹, Shijun Zhang¹, Yixiang Wang², and Shenghong Ju^1
1Radiology, Zhongda Hospital, Nanjing, Jiangsu, China, ²Prince of Wales Hospital, the Chinese University of Hong Kong, Hong Kong, China

Autopsy studies demontstrated that the typical pathologic characteristic of the myocardium of End-Stage Renal Disease (ESRD) hemodialysis patients was left ventricular hypertrophy (LVH) and diffused collagen and fibrosis deposition in extracellular matrix. Due to the contraindication of the contrast medium of this kind of patients, the myocardial fibrosis is hardly evaluated with current modalities. The purpose of this study was to determine whether T1rho imaging can be used as a noninvasive method with no contrast enhancement to detect myocardial fibrosis in ESRD maintained on hemodialysis patients.

Rebecca E Thornhill^1,2, Myra Cocker³, Girish Dwivedi^3,4, Carole Dennie^1,2, Lyanne Fuller³, Alexander Dick^3,4, Terrence Ruddy^3,4, and Elena Pena-Fernandez^1,2
1Medical Imaging, The Ottawa Hospital, Ottawa, Ontario, Canada, ²Radiology, University of Ottawa, Ottawa, Ontario, Canada, ³University of Ottawa Heart Institute, Ottawa, Ontario, Canada, ⁴Medicine, University of Ottawa, Ottawa, Ontario, Canada

Late gadolinium enhanced MRI (LGE) can assess the presence and extent of fibrosis in hypertrophic cardiomyopathy (HCM), which is associated with the development of arrhythmias and sudden cardiac death. One of the challenges is how best to describe LGE patterns in HCM, as enhancement may appear subtle or heterogeneous in distribution. Texture analysis was applied to quantify gray-level heterogeneity metrics in both HCM patients and healthy volunteers. These features were significantly elevated in patients with HCM, even in non-hypertrophic, non-fibrotic segments (ie, normal appearing), compared to healthy volunteers. Thus, textural features show potential for markers of cardiomyopathic changes in HCM.

J.B.M. Warntjes^1,2, S. Kvernby^1,2, C.J. Carlhäll^1,2, J. Engvall^1,2, and T. Ebbers^1,2
1Center for Medical Image Science and Visualisation, Linköping, Östergötland, Sweden, ²Department of Medical and Health Sciences, Division of Cardiovascular Medicine, Linköping, Östergötland, Sweden

A single breath-hold 3D method was developed for simultaneous quantification of the T1 and T2 relaxation time over the complete myocardial volume. T1 and T2 maps of 13 slices were acquired in 15 heart-beats. The method was based on a 3D cardiac triggered, interleaved Look-Locker sequence, combined with T2 prep pulses. The measured T1 and T2 values correlated well with T1 and T2 measurements using other methods such as inversion recovery and multi-echo CPMG.

Mao-Yuan Marine Su¹, Lian-Yu Lin², Chin-Chen Chang¹, Yao-Hui Elton Tseng¹, Cho-Kai Wu², Jiunn-Lee Lin², and Wen-Yih Isaac Tseng^1,3
1Department of Medical Imaging, National Taiwan University Hospital, Taipei, Taiwan, ²Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan, ³Center for Optoelectronic Medicine, National Taiwan University College of Medicine, Taipei, Taiwan

This study investigated whether the diastolic dysfunction of left ventricular (LV) was associated with diffuse myocardial fibrosis in patients with diastolic heart failure (DHF). Forty patients with DHF, 27 patients with systolic heart failure (SHF) and 22 patients without heart failure (control) were studied using cardiovascular magnetic resonance. Patients with SHF and DHF both showed increased diffuse myocardial fibrosis and decreased diastolic function as compared to controls. Correlation analysis demonstrated that the extracellular volume fraction (ECV) was significantly correlated with systolic and diastolic function in DHF. There was no significant correlation between ECV and the other functional indices in SHF and non-HF controls. Our findings support that increased diffuse myocardial fibrosis may impair the diastolic function but also affect the systolic function in patients with DHF.

Choukri Mekkaoui¹, Marcel P Jackowski², Sava Sakadzic³, Christian T Stoeck⁴, Timothy G Reese³, Sebastian Kozerke⁵, Harald C Ott⁶, and David E Sosnovik^7
1Harvard Medical School - Massachusetts General Hospital, Boston, MA, United States, ²Department of Computer Science, Institute of Mathematics and Statistics, University of São Paulo, São Paulo, Brazil, ³Athinoula A Martinos center for Biomedical imaging, Boston, United States, ⁴Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland, ⁵University and ETH Zurich, Zurich, Switzerland, ⁶Massachusetts General Hospital, Boston, United States, ⁷Harvard Medical School - Massachusetts General Hospital, Boston, United States

The myocardium consists of a branching network of muscle fibers and a supporting network of connective tissue fibers, whose relative contributions to diffusion restriction remain unknown. We performed high-resolution DTI and two-photon microscopy of a decellularized human heart and compared the findings with normal human hearts and patients with recent myocardial infarction. Diffusion in the decellularized heart was minimally restricted, despite a fairly dense, ordered and anisotropic collagen network. Diffusion restriction in the myocardium thus reflects its cellular components with little impact from the connective tissue network at commonly-used b-values.

Christopher Nguyen^1,2, Yibin Xie^1,2, Zhaoyang Fan¹, Behzad Sharif¹, James Dawkins³, Eleni Tseliou³, Xiaoming Bi⁴, Rohan Dharmakumar¹, Eduardo Marban³, and Debiao Li^1,2
1Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA, United States, ²Bioengineering, University of California Los Angeles, Los Angeles, CA, United States, ³Heart Institute, Cedars-Sinai Medical Center, Los Angeles, CA, United States, ⁴MR R&D, Siemens Healthcare, Los Angeles, CA, United States

Using a chronic myocardial infarction (MI) pig model, we demonstrated that motion compensated cardiac diffusion-prepared turbo-spin echo was able to reveal statistically significant increases (~50%) in trace apparent diffusion coefficient (trADC) in late gadolinium enhanced (LGE)-defined chronic MI regions. Because the infarcted region is akinetic, bulk motion corruption would have resulted in a decrease in trADC, which is opposite to the expected and reported increase in trADC. Furthermore, the agreement in trADC-defined MI location and area with LGE-defined MI regions suggests that the proposed technique delineated infarct tissue. This may potentially allow for non-contrast tissue characterization of chronic MI.

Peter A Wassenaar¹, Chethanya N Eleswarpu¹, Richard D White¹, and Arunark Kolipaka^1
1Radiology, The Ohio State University, Columbus, Ohio, United States

Myocardial stiffness has been a significant biomarker for various cardiovascular disease processes, such as myocardial infarction, hypertension, diastolic dysfunction and tissue rejection in heart transplant patients. Pressure/volume based techniques are commonly used to measure left ventricular chamber stiffness, but are limited to global measurements, are invasive, and do not provide true intrinsic properties of the myocardium. Recently, Cardiac MR Elastography was used to estimate stiffness of the myocardium. In this study, a retrogated, multi-phase MRE sequence was developed and used to measure LV myocardial stiffness across the cardiac cycle as a function of age in healthy subjects.

Marloes Marteijn¹, Carlijn CV Bouten², Klaas Nicolay¹, and Gustav J Strijkers^1
1Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, Netherlands, ²Soft Tissue Biomechanics & Tissue Engineering, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, Netherlands

Hydrogels have the potential to improve cardiac function after myocardial infarction (MI). Furthermore, hydrogels can be used to improve cell engraftment in case of stem cell therapy post-MI. In this study, we investigated the efficacy and retention of collagen I-Matrigel after intramyocardial injection post-MI in a mouse model by applying multiple in vivo cardiac MRI techniques. Here, we show that collagen I-Matrigel treatment resulted in a temporary increased cardiac function post-MI, but also provoked an enhanced edema and/or inflammatory response in the cardiac tissue surrounding the collagen I-Matrigel as indicated by T2-mapping as well as by histology.