Matthew Merritt, Ph.D.

Charles H. Cunningham, Ph.D.

Kevin M. Brindle, Ph.D.

Hikari A. I. Yoshihara^1,2, Jessica A. M. Bastiaansen^2,3, Magnus Karlsson⁴, Mathilde Lerche⁴, Arnaud Comment^2,5, and Juerg Schwitter^1
1Division of Cardiology and Cardiac MR Center, Lausanne University Hospital, Lausanne, Switzerland, ²Center for Biomedical Imaging (CIBM), Lausanne, Switzerland, ³Department of Radiology, Lausanne University Hospital and University of Lausanne, Switzerland, ⁴Albeda Research ApS, Copenhagen, Denmark, ⁵Institute of Physics of Biological Systems, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland

The heart is fueled mainly by long-chain fatty acids. We report the in vivo myocardial metabolism of hyperpolarized [1-¹³C]octanoate, a medium-chain fatty acid. The hyperpolarized signal is short-lived in the blood, but a metabolite signal from [1-¹³C]acetylcarnitine was observed, indicating the uptake of octanoate into the mitochondria and its -oxidation to acetyl-CoA. Additional metabolite signals from [5-¹³C]glutamate, [5-¹³C]citrate and [1-¹³C]acetoacetate were occasionally observed. The acetylcarnitine signal relative to octanoate tended to be lower and more variable in fasted versus fed rats. This study demonstrates that hyperpolarized ¹³C-labeled medium-chain fatty acids can be used as metabolic probes in the heart.

Cornelius von Morze¹, Robert A Bok¹, Michael A Ohliger¹, Daniel B Vigneron¹, and John Kurhanewicz^1
1Department of Radiology & Biomedical Imaging, UCSF, San Francisco, California, United States

In this work we demonstrate hyperpolarization and rapid in vivo enzymatic conversion of an endogenous structural analog of ¹³C-pyruvate, ¹³C-alpha-ketobutyrate, via lactate dehydrogenase (LDH). Based on prior non-MR work and our own initial results, this hyperpolarized probe may exhibit useful selectivity for LDHB-expressed isoforms of LDH, such as heart or kidney LDH.

Benjamin J. Geraghty^1,2, Justin Y.C. Lau^1,2, Albert P. Chen³, William Dominguez-Viqueira¹, and Charles H. Cunningham^1,2
1Imaging Research, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada, ²Dept. of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada, ³GE Healthcare, Toronto, Ontario, Canada

Spectral-spatial excitation can be used for rapid time resolved 3D acquisitions; however, maintaining adequate spatial and temporal resolution is limited by the required field-of-view coverage. Here, we demonstrate a slice blipped EPI compressed sensing acquisition strategy for accelerated 3D time resolved imaging of [1-13C]pyruvate and lactate across a large field-of-view. Image reconstructions of both retrospectively and prospectively 2X undersampled in vivo data is presented. Close agreement is shown between fully and undersampled lactate to pyruvate area under curve ratio.

Wenwen Jiang¹, Michael Lustig², and Peder E.Z. Larson^3
1Bioengineering, UC Berkeley/UCSF, Berkeley, CA - California, United States, ²EECS, UC Berkeley, Berkeley, California, United States, ³Radiology and Biomedical Imaging, UCSF, San Francisco, CA - California, United States

The short-lived effect of hyperpolarization of ¹³C poses severe challenges to develop rapid and robust imaging techniques. The concentric rings trajectory is such a technique for hyperpolarized ¹³C spectroscopic imaging that it is favorable for parallel imaging for additional acceleration. Preclinical studies have been performed to evaluate the feasibility of using concentric rings hyperpolarized ¹³C MRSI parallel imaging. Simulation of g-factor maps demonstrates its advantages of the lower noise amplification compared to Cartesian counterpart. Concentric rings trajectory shows great potential to be applied with parallel imaging.

Patrick Wespi¹, Darach O h-Ici^1,2, Julia Busch¹, Lukas Wissmann¹, Marcin Krajewski¹, Kilian Weiss¹, Andreas Sigfridsson¹, Daniel Messroghli², and Sebastian Kozerke^1,3
1Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland, ²Department of Congenital Heart Disease and Pediatric Cardiology, German Heart Institute, Berlin, Germany, ³Division of Imaging Sciences and Biomedical Engineering, King's College London, London, United Kingdom

The aim of the present work was to study in vivo the metabolic changes following left coronary artery occlusion. Rats were scanned using hyperpolarized [1-13C] pyruvate before coronary occlusion and directly after reopening of the coronary artery after 15 minutes of ischemia. Scans were repeated throughout the first hour of reperfusion, and then at 1 week following coronary occlusion. Data were correlated to local regional function using cine imaging and to myocardial injury based on late gadolinium enhancement (LGE) imaging. Myocardial metabolism was abnormal in the area-at-risk during the first 60 minutes following ischemia, but returned to normal one week later.