title: Reproducibility study for free-breathing measurements of pyruvate metabolism using hyperpolarized (13) C in the heart.
abstract: Spatially resolved images of hyperpolarized (13) C substrates and their downstream products provide insight into real-time metabolic processes occurring in vivo. Recently, hyperpolarized (13) C pyruvate has been used to characterize in vivo cardiac metabolism in the rat and pig, but accurate and reproducible measurements remain challenging due to the limited period available for imaging as well as physiological motion. In this article, time-resolved cardiac- and respiratory-gated images of [1-(13) C] pyruvate, [1-(13) C] lactate, and (13) C bicarbonate in the heart are acquired without the need for a breathhold. The robustness of these free-breathing measurements is demonstrated using the time-resolved data to produce a normalized metric of pyruvate dehydrogenase and lactate dehydrogenase activity in the heart. The values obtained are reproducible in a controlled metabolic state. In a 60-min ischemia/reperfusion model, significant differences in hyperpolarized bicarbonate and lactate, normalized using the left ventricular pyruvate signal, were detected between scans performed at baseline and 45 min after reperfusion. The sequence is anticipated to improve quantitative measurements of cardiac metabolism, leading to feasible validation studies using fewer subjects, and potentially improved diagnosis, serial monitoring, and treatment of cardiac disease in patients.
authors: Department of Medical Biophysics, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario, Canada. angus.lau@sri.utoronto.ca
authors: Angus Z
authors: AZ
authors: Lau
authors: Albert P
authors: AP
authors: Chen
authors: Jennifer
authors: J
authors: Barry
authors: John J
authors: JJ
authors: Graham
authors: William
authors: W
authors: Dominguez-Viqueira
authors: Nilesh R
authors: NR
authors: Ghugre
authors: Graham A
authors: GA
authors: Wright
authors: Charles H
authors: CH
authors: Cunningham
mesh_terms: D000818:Animals; D002247:Carbon Isotopes / Q000493:pharmacokinetics; D007770:L-Lactate Dehydrogenase / Q000378:metabolism*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D017202:Myocardial Ischemia / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism*; D011768:Pyruvate Dehydrogenase Complex / Q000378:metabolism*; D019289:Pyruvic Acid / Q000493:pharmacokinetics*; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D015203:Reproducibility of Results; D015656:Respiratory Mechanics; D055425:Respiratory-Gated Imaging Techniques / Q000379:methods*; D012680:Sensitivity and Specificity; D013552:Swine
chemical_list: D002247:Carbon Isotopes; D011768:Pyruvate Dehydrogenase Complex; D019275:Radiopharmaceuticals; D019289:Pyruvic Acid; D007770:L-Lactate Dehydrogenase