Mehri Mehrnia^1,2, Eugene Kholmovski³, Rod Passman⁴, Aggelos Katsaggelos^1,5,6, Saman Nazarian⁷, Daniel Kim¹, and Mohammed Elbaz^1
1Radiology, Northwestern University, Chicago, IL, United States, ²Biomedical Engineering, Northwestern University, Chicago, IL, United States, ³Johns Hopkins University, Baltimore, MD, United States, ⁴Cardiology, Northwestern University, Chicago, IL, United States, ⁵Electrical and Computer Engineering, Northwestern University, Chicago, IL, United States, ⁶Computer Science, Northwestern Universiy, Chicago, IL, United States, ⁷Division of Cardiovascular Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States

Assessment of left atrial (LA) fibrosis in atrial fibrillation (AF) patients from 3D LGE MRI have shown promise in evaluating atrial myopathy for selecting patients for catheter ablation and to predict AF recurrence post intervention. Nevertheless, current methods for fibrosis quantification suffer from lack of standardization and reproducibility as they rely on different thresholds for defining fibrosis. Hence, limiting the clinical translation of 3D LA LGE MRI. Here, we propose the first threshold-free technique to quantify LA fibrosis burden using novel stochastic fibrosis signature technique. We demonstrated feasibility and correlations to four of the previously published methods for fibrosis quantification. 

Erin K Englund¹, Lorna P Browne¹, Takashi Fujiwara¹, Richard Friesen², Mehdi H Moghari¹, and Alex J Barker^1
1Radiology, University of Colorado, Anschutz Medical Campus, Aurora, CO, United States, ²Pediatric Cardiology, University of Colorado, Anschutz Medical Campus, Aurora, CO, United States

Fetal CMR is difficult due to the lack of an ECG signal, fetal motion, small anatomic sizes and high fetal heart rates. Initial results are presented which use a doppler ultrasound gating device to capture fetal cardiac motion in standard cardiac views and blood flow was quantified with 4D flow MRI. bSSFP cine images were scored for image quality by two radiologists and flow in the umbilical vein, ascending aorta and main pulmonary artery were quantified and agreed well with reported values. Unique insight was provided with dynamic imaging regarding the fetal circulation and the impact of congenital disease.

Xingmin Guan^1,2, Hsin-Jung Yang¹, Zhehao Hu^2,3, Nan Wang⁴, Anthony Christodoulou¹, Behzad Sharif⁵, Debiao Li¹, and Rohan Dharmakumar^2,5
1Cedars-Sinai Medical Center, Los Angeles, CA, United States, ²University of California, Los Angeles, Los Angeles, CA, United States, ³University of Southern California, Los Angeles, CA, United States, ⁴Stanford University, Stanford, CA, United States, ⁵Indiana University, Indianapolis, IN, United States

A 3D fully ungated, free breathing cardiac T2* technique was developed using a low-rank tensor framework. An animal model with iron-oxide contrast-enhanced studies was used to test and validate the proposed technique. T2* images reconstructed from the proposed approach showed better image quality than those from conventional 2D T2* imaging approach. Excellent agreement of septal T2* was found between the proposed approach and conventional 2D approach. Our findings show that the proposed approach can accurately characterize T2* of myocardium under baseline and during iron overload conditions.

Johnathan V. Le^1,2, Jason K. Mendes², Mark Ibrahim³, Brent D. Wilson³, Edward V.R. DiBella^1,2, and Ganesh Adluru^1,2
1Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, United States, ²Utah Center for Advanced Imaging Research, University of Utah, Salt Lake City, UT, United States, ³Department of Cardiology, University of Utah, Salt Lake City, UT, United States

Cardiac T1 mapping has been shown to be a promising method for assessing different cardiomyopathies. Most cardiac T1 mapping methods require long breath holds during the acquisition which can be difficult for patients particularly during exercise or pharmacologically induced stress. Here we proposed using a multi-layer bidirectional LSTM with fully connected output and a cyclic model-based loss function to reduce the acquisition time of T1 mapping sequences without significant loss of quality.

Yanis Djebra^1,2, Thibault Marin¹, Paul Kyu Han¹, Isabelle Bloch³, Georges El Fakhri¹, and Chao Ma^1
1Gordon Center for Medical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States, ²LTCI, Telecom Paris, Institut Polytechnique de Paris, Paris, France, ³LIP6, Sorbonne University, CNRS, Paris, France

Cardiac T1 mapping allows assessment of tissue characteristics and functioning of the heart. However, existing methods are limited in terms of spatial resolution and coverage due to limitations in acquisition speed and the presence of cardiac and respiratory motion. This work proposes a new reconstruction framework for simultaneous, high-resolution 3D cardiac T1 mapping and cine imaging of the heart at 3T from sparsely sampled k-space data.

Alexander Wilson^1,2, Gregory B Sands³, Vicky Y Wang², Beau Pontre⁴, Daniel B Ennis^1,2, Alistair A Young⁵, Ian J LeGrice³, and Martyn P Nash^3,6
1Stanford Cardiovascular Institute, Stanford University, Stanford, CA, United States, ²Department of Radiology, Stanford University, Stanford, CA, United States, ³Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand, ⁴Department of Anatomy and Medical Imaging, University of Auckland, Auckland, New Zealand, ⁵Department of Biomedical Engineering, King's College London, London, United Kingdom, ⁶Department of Engineering Science, University of Auckland, Auckland, New Zealand

Tagged CMR was used to measure torsion and longitudinal strain in a rodent model of hypertensive heart disease. Long-term ACE inhibitor treatment restored ejection fraction, torsion and longitudinal strain by 24 months of age. Longitudinal strain was the first functional measure to be restored, and this may indicate that longitudinal strain is a sensitive imaging biomarker for assessing the efficacy of treatment with regards to reverse remodeling in hypertension.

Junjie Ma¹, Jun Chen¹, Elizabeth Zhang-Velten², Jayesh Sharma², Xuliang Wang³, Gabriele Schiattarella³, Thomas Gillette³, Joseph Hill^3,4, Craig R. Malloy^1,3,5, Vlad G. Zaha^1,3, Jae Mo Park^1,5,6, and Prasanna Alluri^2
1Advanced Imaging Research Center, UT Southwestern Medical Center, Dallas, TX, United States, ²Radiation Oncology, UT Southwestern Medical Center, Dallas, TX, United States, ³Internal Medicine, UT Southwestern Medical Center, Dallas, TX, United States, ⁴Molecular Biology, UT Southwestern Medical Center, Dallas, TX, United States, ⁵Radiology, UT Southwestern Medical Center, Dallas, TX, United States, ⁶Electrical and Computer Engineering, UT Dallas, Richardson, TX, United States

Radiation-induced heart disease is a major source of morbidity and mortality in patients receiving thoracic radiation. In this study, radiation-induced changes in cardiac metabolism is investigated using hyperpolarized [1-¹³C]pyruvate MRI in animals and patients. Myocardial bicarbonate-to-lactate ratios decreased following radiation treatments while no change was observed in the global strain, suggesting radiation-induced mitochondrial dysfunction in the heart. This translational study demonstrates clinical potential of hyperpolarized ¹³C pyruvate for early and noninvasive detection of radiation-induced cardiac injury.

Xinheng Zhang^1,2, Hsin-Jung Yang¹, and Rohan Dharmakumar^3
1Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA, United States, ²Bioengineering Department, UCLA, Los Angeles, CA, United States, ³Krannert Cardiovascular Research Center, Indiana University School of Medicine, Indianapolis, IN, United States

The influence of spatial resolution on T2*-based characterization of hemorrhage within myocardial infarctions (MI) has not been investigated. We hypothesized that partial volume could play a critical role in the detection and quantification of hemorrhagic remnants. Ex-vivo pig hearts with 8-week old MI were imaged with multi-gradient echo sequences with various in-plane and through-plane spatial resolutions. Our findings show that optimal detection of hemorrhagic remnants with T2* MRI at 3T requires imaging voxels to be between 5 and 7 mm³.

Kelvin Chow¹, Hui Xue², and Peter Kellman^2
1Cardiovascular MR R&D, Siemens Healthineers, Chicago, IL, United States, ²National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, United States

Parametric T₁ and T₂ mapping can provide valuable insight into myocardial tissue microstructure.  T_1ρ is a complimentary technique that is sensitive to macromolecular content and may potentially enable non-contrast scar visualization.  Characterization with all parameters is desirable as they may have different sensitivities to pathology but is time consuming with separate acquisitions for each.  We propose a novel mSASHA sequence with T₁, T₂, and T_1ρ maps in a single 13 HB breath-hold or free-breathing acquisition.  mSASHA had superior T₁ and T₂ accuracy and similar precision to conventional MOLLI and T₂p-bSSFP in phantoms and data is presented from 3 volunteers.

Soham Shah¹ and Fred H Epstein^1
1Biomedical Engineering, University of Virginia, Charlottesville, VA, United States

Epicardial adipose tissue (EAT) and its fatty acid composition (FAC) have been implicated in numerous cardiovascular diseases as saturated fatty acids are known to promote inflammation. FAC MRI techniques, while prominent, have not been applied to EAT due to extended scan times, thus, image acceleration is essential. Here, we demonstrate compressed sensing with a signal model-based dictionary (CS-DICT) to reconstruct psuedo-random undersampled images. Using CS-DICT, we achieve rate-3 acceleration while maintaining accurate EAT FAC maps and estimations in obese mice. These methods facilitate the application of FAC MRI to the EAT.

Kathryn Lamar-Bruno¹, Suma Anand¹, and Michael Lustig^1
1Electrical Engineering and Computer Sciences, University of California, Berkeley, Berkeley, CA, United States

We have previously proposed Beat Pilot Tone (BPT), a motion sensing method using ultra-high-frequency RF and preamplifier intermodulation. BPT uses ultra-high-frequencies, which provides greater sensitivity to motion compared to the Pilot Tone (PT). In this work, we use the motion estimates from the BPT to reconstruct respiratory and cardiac-resolved images and compare them to motion-resolved images obtained using PT, respiratory bellows, and electrocardiogram (ECG) data. We show that BPT provides comparable image quality to conventional motion sensing for respiratory and cardiac motion.

Jin Zhang¹, Karl Kiser¹, Ayesha Bharadwaj Das¹, Sawwal Qayyum¹, and Gene Kim^1
1Weill Cornell Medical College, New York, NY, United States

Dynamic contrast enhanced (DCE)-MRI can be used as a tool to measure intracellular water lifetime (τ_i) in tumor cells which can be used as a biomarker for tumor aggressiveness and treatment response. Contrast kinetic model analysis in DCE-MRI requires accurate pre-contrast T₁ measurement. We used multiple flip angles for active contrast encoding of both T₁ and τ_i during dynamic data acquisition with one injection. The present study demonstrates the feasibility of measuring T₁ and τ_i simultaneously from the active contrast encoding (ACE) MRI data. ACE-MRI also reduces the scan time by eliminating the need of separate pre-contrast T₁ measurement.

Ye Tian¹, Sophia X. Cui², Yongwan Lim¹, Nam G. Lee³, Ziwei Zhao¹, and Krishna S. Nayak^1
1Ming Hsieh Department of Electrical and Computer Engineering, University of Southern California, Los Angeles, CA, United States, ²Siemens Medical Solutions USA, Inc., Los Angeles, CA, United States, ³Biomedical Engineering, University of Southern California, Los Angeles, CA, United States

Balanced steady-state free precession (bSSFP) cardiac cine MRI at 1.5T and 3T is routinely used for cardiac function assessment. Simultaneous multi-slice (SMS) imaging significantly reduces the number of required breath holds, but is typically performed with suboptimal flip angles (FA) due to SAR constraints and banding artifacts, both of which are significantly relaxed at 0.55T. In this work, we demonstrate blipped-CAIPI bSSFP cine imaging combined with spiral sampling for ventricular function at 0.55T with optimal FA for blood-myocardium contrast (100^o-120^o) at SMS factors of 2 and 3.

Jiahao Li^1,2, Katherine Tak³, Rachel Meier³, Pablo Villar-Calle³, Justin Johannesen³, Jiwon Kim³, Yi Wang^1,2, Jonathan W. Weinsaft³, and Pascal Spincemaille^2
1Biomedical Engineering, Cornell University, New York, NY, United States, ²Radiology, Weill Cornell Medicine, New York, NY, United States, ³Medicine, Weill Cornell Medicine, New York, NY, United States

Pulmonary hypertension (PH) is a progressive and life shortening disorder with increased differential blood oxygen saturation (ΔSaO₂) between right and left heart. In this prospective study, we acquired cardiac QSM from patients undergoing clinically indicated right heart catheterization (RHC) for assessment of known or suspected PH. ΔSaO₂ estimated from QSM aligned well with RHC oxygenation data, showing QSM as a non-invasive CMR technique can be applied to clinically evaluate heart chamber oxygenation quantification in PH.

Yun Shang¹, Sebastian Theilenberg¹, Boyu Peng², Sachin R. Jambawalikar^1,2, Laura M. Schreiber^3,4, and Christoph Juchem^1,2
1Department of Biomedical Engineering, Columbia University, New York, NY, United States, ²Department of Radiology, Columbia University Irving Medical Center, New York, NY, United States, ³Section of Medical Physics, Department of Radiology, Mainz University Hospital, Mainz, Germany, ⁴Chair of Molecular and Cellular Imaging, Comprehensive Heart Failure Center (CHFC), Würzburg, Germany

Cardiac MRI suffers susceptibility-induced artifacts due to B₀ inhomogeneity across the heart. The lack of population data in cardiac B₀ conditions and the practical inability to obtain such data in large populations impedes the development of optimal cardiac B₀ shim strategy. Here, we establish population-based B₀ conditions from readily available CT images and simulate cardiac B₀ maps of 254 CT subjects with broad demographic parameters. The results are expected to develop optimal subject- and population-specific cardiac B₀ shim strategies.