Myocardial Function & Perfusion

Thursday 15 May 2014

Mehdi H Moghari¹, Rukmini Komarlu¹, David Annese¹, Tal Geva¹, and Andrew J Powell^1
1Department of Cardiology, Boston Children's Hospital, Boston, MA, United States

We developed a novel respiratory motion compensation method utilizing a pencil-beam diaphragmatic navigator for free-breathing steady-state free precession imaging of the heart. Image quality and volumetric data with this method was comparable to the standard breath-hold technique and superior to the multiple signal averages approach in patients.

Vincent Wu¹, Sohae Chung¹, Sharath Bhagavatula¹, and Leon Axel^1
1Department of Radiology, New York University School of Medicine, New York, NY, United States

Cardiac magnetic resonance (CMR) methods of assessing diastolic dysfunction remain a developing area. This study presents a novel CMR approach to quantification of diastolic dynamics, using 3D volume tracking of the mitral annulus (MA). The utility of this method is demonstrated by distinguishing diastolic MA excursion profiles between normal subjects and hypertrophic cardiomyopathy (HCM) patients. Results show that HCM hearts have slower relative MA sweep volume rates during early diastole, but higher MA sweep volume rates during atrial contraction. This technique offers further insight into ventricular filling biomechanics, and it incorporates information from both axial and longitudinal MA motions.

Lidia S. Szczepaniak¹, Janet Wei¹, Michael D. Nelson¹, Laura G. Smith¹, Edward W. Szczepaniak¹, Louise Thomson¹, Daniel Berman¹, Debiao Li¹, and C. Noel Bairey Merz^1
1Cedars-Sinai Medical Center, Los Angeles, California, United States

Impaired left ventricular (LV) filling is an important manifestation of heart failure with preserved LV ejection fraction (HFpEF), and is regarded as a primary contributor to morbidity and mortality in this population. Despite our general understanding, however, the exact mechanism for diastolic dysfunction remains unclear. Myocardial fat accumulation is associated with diastolic dysfunction in other disease states and thus may play an important role in the pathogenesis of HFpEF. We directly address this hypothesis by evaluating myocardial triglyceride content and diastolic function in a patient population at increased risk for HFpEF.

Bhairav Bipin Mehta¹, Sujith Kuruvilla², Michael Salerno^1,2, and Frederick H Epstein^1,3
1Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia, United States, ²Department of Medicine, Cardiology Division, University of Virginia, Charlottesville, Virginia, United States, ³Department of Radiology and Medical Imaging, University of Virginia, Charlottesville, Virginia, United States

Diastolic dysfunction is independently associated with increased cardiovascular mortality. Echocardiography is commonly used for assessment of diastolic function. However, echocardiographic techniques have limitations which are not present in strain and strain rate measurement using MRI. We previously developed a full-cycle cine DENSE sequence that can accurately compute systolic and diastolic strains and strain rates. In the present study we compared full-cycle cine DENSE results between hypertensive patients and healthy volunteers. The patients showed significantly reduced peak early diastolic strain rate and increased peak atrial systolic strain rate compared to volunteers, illustrating full-cycle DENSE’s ability to assess diastolic dysfunction.

Thomas Elgeti¹, Fabian Knebel², Ingo Steffen¹, Bernd Hamm¹, Jürgen Braun³, and Ingolf Sack^1
1Department of Radiology, Charité Universitätsmedizin Berlin, Berlin, Germany, ²Department of Cardiology and Angiology, Charité Universitätsmedizin Berlin, Berlin, Germany, ³Department of Medical Informatics, Charité Universitätsmedizin Berlin, Berlin, Germany

Cardiac MR elastography (cMRE) can detect altered mechanical tissue properties, which cause diastolic dysfunction. In this study, time harmonic shear wave amplitudes (SWA) were measured in 50 subjects including 30 patients with cardiac relaxation abnormalities by cMRE for the quantification of the symptomatic and asymptomatic ability of the myocardium to mechanically relax. Compared to controls, patients displayed significantly reduced SWA which was inversely correlated to the severity of diastolic dysfunction. Best cutoff-value to differentiate between volunteers and patients was 0.43 yielding an AUROC value of 0.92 with 90% sensitivity and 89.7% specificity.

Aurelien F. Stalder¹, Michaela Schmidt¹, Andreas Greiser¹, Peter Speier¹, Jens Guehring¹, Matthias G Friedrich^2,3, and Edgar Mueller^1
1Siemens AG Healthcare Sector, Erlangen, Germany, ²Departments of Cardiology and Radiology, Montreal Heart Institute, Université de Montréal, Montreal, QC, Canada, ³Departments of Cardiac Sciences and Radiology, University of Calgary, Calgary, AB, Canada

The diagnostic accuracy of cardiac BOLD MRI remains limited by its signal amplitude being in the order of magnitude of noise and signal variations due to hardware instabilities or other physiological effects, and cardiac and respiratory motion. In this work, we combined a fast BOLD-sensitive acquisition technique with elastic motion-correction and an fMRI-like (GLM) data analysis. The method was applied in 13 volunteers performing repeated breath-holds. Pixel and ROI based analysis derived statistically significant BOLD activations in the myocardium. Robust oxygenation-sensitive CMR as a non-invasive contrast-free technique may become an alternative to current diagnostic tools in patients with suspected CAD.

Yang Yang¹, Xiao Chen¹, Frederick H. Epstein^1,2, Craig H. Meyer^1,2, Christopher M. Kramer^2,3, and Michael Salerno^2,3
1Biomedical Engineering, University of Virginia, Charlottesville, VA, United States, ²Radiology, University of Virginia, Charlottesville, VA, United States,³Medcine, University of Virginia, Charlottesville, VA, United States

Volumetric quantitative myocardial first-pass perfusion CMR imaging with adenosine stress could improve diagnosis of coronary artery disease and quantification of ischemic burden. Spiral pulse sequences have multiple advantages for perfusion imaging, and preliminary studies have suggested that a 3D stack-of-spirals pulse sequence is feasible for first pass perfusion imaging. To obtain a full 3D quantitative assessment of myocardial perfusion, we have developed an accelerated 3D stack-of-spirals pulse sequence using motion compensated parallel imaging, compressed sensing, and an integrated single-shot arterial input function acquisition and demonstrate its successful application in healthy human subjects.

Behzad Sharif¹, Reza Arsanjani¹, Rohan Dharmakumar¹, Noel Bairey Merz¹, Daniel S Berman¹, and Debiao Li^1
1Biomedical Imaging Research Institute, Dept. of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, California, United States

Conventional first-pass myocardial perfusion MRI methods are prone to dark-rim artifacts, require accurate ECG gating, and do not provide the freedom to image all slices at the same end-systolic phase. We present a method that overcomes these challenges and is an attractive alternative with the advantage of simplicity (no gating), higher accuracy in the subendocardium (no dark rims, and all-systolic imaging), and thereby potentially improved reliability. Preliminary results in patients with suspected CAD were of high quality and showed high accuracy compared to nuclear PET/SPECT myocardial perfusion imaging.

Xiao Chen¹, Yang Yang¹, Michael Salerno^2,3, and Frederick H. Epstein^1
1Biomedical Engineering, University of Virginia, Charlottesville, VA, United States, ²Radiology, University of Virginia, Charlottesville, VA, United States,³Cardiology, University of Virginia, Charlottesville, VA, United States

We recently developed a motion-compensated compressed sensing (CS) method to accelerate dynamic MRI of the heart that exploits matrix low-rank sparsity within motion-tracked regions of temporal image sequences (Block LOw-rank Sparsity with Motion guidance, or BLOSM). Initial results showed that BLOSM appears promising for accelerating first-pass myocardial perfusion imaging, even when substantial respiratory motion occurs. Presently, we implemented improved motion tracking for BLOSM and compared the improved BLOSM method to other CS methods using computer-simulated motions and using first-pass perfusion datasets from patients with respiratory motion.

Lukas Wissmann¹, Markus Niemann^1,2, Robert Manka^1,2, and Sebastian Kozerke^1,3
1Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland, ²Department of Cardiology, University Hospital Zurich, Zurich, Switzerland, ³Division of Imaging Sciences & Biomedical Engineering, King's College London, London, United Kingdom

First-pass myocardial perfusion imaging requires high contrast agent dose to achieve sufficient contrast-to-noise ratio for reliable qualitative diagnosis. On the other hand, myocardial blood flow quantification at high dose suffers from signal saturation. In conventional approaches this results in underestimation of the peak arterial input function, leading to overestimation of myocardial blood flow. The study at hand presents an interleaved 2D AIF navigator for whole-heart 3D perfusion imaging. It is demonstrated that accurate quantification of blood flow is achieved while maintaining excellent contrast-to-noise ratios for simultaneous qualitative assessment with high-dose contrast injections.