Justin YC Lau^1,2, Andrew Apps¹, Jack JJJ Miller^1,2,3, Andrew Tyler², Liam AJ Young¹, Andrew JM Lewis¹, Gareth Barnes⁴, Claire Trumper¹, Stefan Neubauer¹, Oliver J Rider¹, and Damian J Tyler^1,2
1Oxford Centre for Clinical Magnetic Resonance Research, Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom, ²Department of Physiology, Anatomy & Genetics, University of Oxford, Oxford, United Kingdom, ³Department of Physics, University of Oxford, Oxford, United Kingdom, ⁴Royal Brompton & Harefield NHS Foundation Trust, Harefield, United Kingdom

This study reports the clinical translation of a hybrid-shot spiral sequence (HYSS) for imaging the diseased heart and spleen. Two subjects with myocardial infarction from coronary artery disease were imaged following administration of hyperpolarized [1-¹³C]pyruvate. High lactate and bicarbonate signal were seen in the region adjacent to the infarcted zone, with no signal within the infarct. A large splenic lactate signal was observed in a subject with an active systemic inflammatory response post myocardial infarction.

Soham Shah¹, Yu Wang¹, Christopher Waters¹, Lanlin Chen¹, Brent French¹, and Frederick Epstein^1
1University of Virginia, Charlottesville, VA, United States

Oxidative stress plays a significant role in the pathogenesis of heart disease. Nitroxide free radicals have been used as redox-sensitive MRI contrast agents where oxidative stress is correlated to the nitroxide-enhanced signal decay rate. We developed a two-compartment exchange and reduction model (2CXRM) to quantify both myocardial nitroxide exchange and reduction and hypothesized that dynamic nitroxide-enhanced MRI can comprehensively assess nitroxide kinetics in mouse models of angiotensin II infusion (ANGII) and myocardial infarction (MI). The 2CXRM detected elevated reduction rates in ANGII and post-MI mice indicative of oxidative stress and reduced nitroxide delivery, consistent with microvascular damage, in post-MI mice.

Marylène Delcey^1,2,3,4, Isabelle Saniour⁵, Pierre Bour^1,2,4, Fanny Vaillant^1,2,4, Emma Abell^1,2,4, Wadie Benhassen³, Marie Poirier-Quinot⁵, and Bruno Quesson^1,2,4
1IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, Pessac, France, ²Univ. Bordeaux, Centre de recherche Cardio-Thoracique de Bordeaux, U1045, Bordeaux, France, ³Siemens Healthcare SAS, Saint-Denis, France, ⁴INSERM, Centre de recherche Cardio-Thoracique de Bordeaux, U1045, Bordeaux, France, ⁵IR4M, UMR8081, Université Paris-Sud/CNRS, Université Paris-Saclay, Orsay, France

In the context of cardiovascular diseases, precise determination of the extent and locations of the arrhythmogenic substrate could significantly improve diagnosis and treatment for both atrial and ventricular electrical diseases. However, the current spatial resolution and signal-to-noise ratio (SNR) in clinical scanners remain insufficient to provide relevant information of small structures like atrial wall or sub-millimeter fatty infiltration in ventricle. To address this limitation in SNR, two receiver coils were implemented at 1.5T for high resolution cardiac imaging, with different active decoupling techniques (safety aspects). Images at 200 µm in-plane spatial resolution were successfully obtained on a beating heart.

Eric Johnson^1,2, Anand Nair², Ivan Cokic^1,2, Hsin-Yung Yang², Andreas Kumar³, and Rohan Dharmakumar^1,2
1UCLA, Los Angeles, CA, United States, ²Cedars Sinai, Los Angeles, CA, United States, ³Northern Ontario School of Medicine, Thunder Bay, ON, Canada

Hemorrhagic myocardial infarction (hMI) patients are predisposed to adverse outcomes in the chronic stage of MI, yet physiological underpinnings contributing to this observation are not well understood. We hypothesized that hMI areas containing iron deposits would negatively impact endothelial function and tested our hypothesis by evaluating perfusion defects in patients and dogs with a history of hMI; with histological staining for iron, endothelial cells and nitric oxide synthase (NOS) in excised myocardial sections of dogs with chronic MI. Hemorrhagic subjects had significantly reduced perfusion and markedly elevated NOS activity.

Zheng Zhong^1,2, Kaibao Sun², Guangyu Dan^1,2, Muge Karaman^1,2, and Xiaohong Joe Zhou^1,2,3,4
1Bioengineering, University of Illinois at Chicago, Chicago, IL, United States, ²CMRR, University of Illinois at Chicago, Chicago, IL, United States, ³Radiology, University of Illinois at Chicago, Chicago, IL, United States, ⁴Neurosurgery, University of Illinois at Chicago, Chicago, IL, United States

Stenosis and regurgitation are two common valvular diseases currently diagnosed using echocardiography. Cardiac MR has potential to diagnose these two diseases, however, faces the challenge of inadequate temporal resolution for capturing the rapid opening or closing of aortic valve. Using a variation of a recently proposed technique, coined Sub-millisecond Periodic Event Encoded Dynamic Imaging or SPEEDI (formerly called SMILE), we demonstrated that this process can be visualized using MRI with sub-millisecond temporal resolution. This new capability has improved the accuracy and reliability in studying the dynamics of aortic valve, opening new opportunities to detect stenosis and regurgitation using MRI.

Ali Nahardani^1,2, Simon Leistikow^2,3, Katja Grün⁴, Martin Krämer¹, Karl Heinz Herrmann¹, Andrea Schrepper⁵, Reinhard Bauer⁶, Christian Jung⁷, Alexander Berndt⁸, P. Christian Schulze⁴, Lars Linsen³, Jürgen R. Reichenbach¹, Marcus Franz⁴, and Verena Hoerr^1,2,9
1Institute of Diagnostic and Interventional Radiology, Medical Physics Group, University Hospital Jena, Jena, Germany, ²Institute of Medical Microbiology, University Hospital Jena, Jena, Germany, ³Institute of Computer Science, Department of Mathematics and Computer Science, Westfälische Wilhelms-Universität Münster, Muenster, Germany, ⁴Department of Internal Medicine I, Division of Cardiology, Angiology, Pneumology, and Intensive Medical Care, University Hospital Jena, Jena, Germany, ⁵Department of Cardiothoracic Surgery, University Hospital Jena, Jena, Germany, ⁶Institute of Molecular Cell Biology, Center of Molecular Biomedicine, University Hospital Jena, Jena, Germany, ⁷Department of Internal Medicine, Division of Cardiology, University Hospital Düsseldorf, Düsseldorf, Germany, ⁸Institute of Legal Medicine, Section of Pathology, University Hospital Jena, Jena, Germany, ⁹Department of Clinical Radiology, University Hospital Muenster, Muenster, Germany

Potential hemodynamic biomarkers of pulmonary arterial hypertension (PAH) and consecutive right ventricular remodeling were investigated by 4D flow center-out stack-of-stars velocity mapping in a rat model of monocrotaline induced PAH in comparison to healthy controls and a treatment group taking Macitentan. The averaged-mean values of blood flow velocities of pulmonary tract were substantially decreased in the diseased animal group compared to the control and under-treatment group. Diseased animals further showed a pronounced pressure gradient drop between the pulmonary artery bronchial branches and pulmonary veins. The effect of vascular resistance was additionally noted in the velocity-time curve of the pulmonary arteries.

Kerstin N Timm¹, Vicky Ball¹, Benjamin Thackray¹, Michael P Murphy², Lisa C Heather¹, and Damian J Tyler^1
1Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom, ²MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, United Kingdom

Doxorubicin (DOX) is a commonly used chemotherapeutic agent for the treatment of many cancers. However, DOX has serious cardiotoxic side effects culminating in congestive heart failure. We have previously shown in a clinically-relevant rat model of DOX-induced heart failure (DOX-HF), that this is due to loss and dysfunction of mitochondria. We show here that 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR), an activator of AMPK, can prevent heart failure in DOX-treated rats. This cardioprotective effect appears to be, at least in part, achieved through improved fatty acid oxidation in cardiac mitochondria which can be indirectly assessed with hyperpolarized [2-¹³C]pyruvate MRS.

Daniel A. Herzka¹, Rajiv A. Ramasawmny¹, Toby Rogers¹, Kendall O'Brien¹, Delaney McGuirt¹, Adrienne Campbell-Washburn¹, and Robert J. Lederman^1
1National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD, United States

Off-label use of ferumoxytol as an intravascular contrast agent for cardiovascular imaging is increasing. Measurements of circulating blood volume using dilution techniques has been previously demonstrated with ferumoxytol at 1.5 T. The relaxivity of ferumoxytol at low field (0.55 T) is increased, making it an attractive approach potentially requiring reduced dosages. Here we successfully demonstrate the feasibility of measurement of total circulating blood volume  at lower field strength in swine.  

Alexander Gotschy^1,2,3, Constantin von Deuster¹, Lucas Weber⁴, Mareike Gastl⁵, Martin O. Schmiady⁶, Robbert J. H. van Gorkum¹, Jochen von Spiczak^1,4, Robert Manka^2,4, Sebastian Kozerke¹, and Christian T. Stoeck^1
1Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland, ²Department of Cardiology, University Hospital Zurich, Zurich, Switzerland, ³Great Ormond Street Hospital, London, United Kingdom, ⁴Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, Zurich, Switzerland, ⁵Division of Cardiology, Pulmonology and Vascular Medicine, University Hospital Duesseldorf, Duesseldorf, Germany, ⁶Department of Cardiac Surgery, University Hospital Zurich, Zurich, Switzerland

CMR diffusion tensor imaging (CMR DTI) allows for the assessment of cardiac microstructure in diseased hearts. We investigated changes of myocardial diffusion properties and myocyte orientation in patients with aortic stenosis (AS) before and after valve replacement (AVR) using DTI and T1-mapping. Mean diffusivity (MD), fractional anisotropy (FA), E2A sheet angle and the transmural helix angle (HA)-slope were altered in AS patients, while native T1 was not significantly different. After AVR, the HA-slope was the only parameter with reversible changes, whereas MD, FA and E2A remained abnormal. This study indicates that AS-induced alterations of myocardial microstructure partly persist following AVR.

Amanda L DiCarlo¹, Hassan Haji-Valizadeh², Suvai Gunasekaran¹, Patrick McCarthy³, Rod Passman⁴, Philip Greenland⁴, Daniel C Lee¹, Daniel Kim¹, and Michael Markl^1,5
1Radiology, Northwestern University, Chicago, IL, United States, ²Department of Medicine (Cardiovascular Division), Beth Israel Deaconess Medical Center & Harvard Medical School, Boston, MA, United States, ³Cardiac Surgery, Northwestern University, Chicago, IL, United States, ⁴Preventive Medicine, Northwestern University, Chicago, IL, United States, ⁵Biomedical Engineering, Northwestern University, Chicago, IL, United States

Stroke prevention is a major therapeutic goal in atrial fibrillation (AF) management. Flow quantification using MRI can provide information about left atrium hemodynamics implicated in stroke risk. This study evaluates the impact of cardiac arrhythmia on velocity and stasis, reflective of slow flow, measurements using both 4D-flow and real time phase contrast techniques in a cohort of healthy controls and AF patients in sinus rhythm and arrhythmia. Both real time phase contrast and 4D-flow showed a similar increase in left atrium stasis between controls and patients and between patients with low and high heart rate variability, but real time phase contrast was more sensitive to differences.