Hyperpolarized 13C Metabolic MRI of the Human Heart Initial Experience

Rationale: Altered cardiac energetics is known to play an important role in the progression toward heart failure. A noninvasive method for imaging metabolic markers that could be used in longitudinal studies would be useful for understanding therapeutic approaches that target metabolism. Objective: To demonstrate the first hyperpolarized C-13 metabolic magnetic resonance imaging of the human heart. Methods and Results: Four healthy subjects underwent conventional proton cardiac magnetic resonance imaging followed by C-13 imaging and spectroscopic acquisition immediately after intravenous administration of a 0.1 mmol/kg dose of hyperpolarized [1-C-13] pyruvate. All subjects tolerated the procedure well with no adverse effects reported <= 1 month post procedure. The [1-C-13] pyruvate signal appeared within the chambers but not within the muscle. Imaging of the downstream metabolites showed C-13-bicarbonate signal mainly confined to the left ventricular myocardium, whereas the [1-C-13] lactate signal appeared both within the chambers and in the myocardium. The mean C-13 image signal: noise ratio was 115 for [1-C-13] pyruvate, 56 for C-13-bicarbonate, and 53 for [1-C-13] lactate. Conclusions: These results represent the first C-13 images of the human heart. The appearance of C-13-bicarbonate signal after administration of hyperpolarized [1-C-13] pyruvate was readily detected in this healthy cohort (n=4). This shows that assessment of pyruvate metabolism in vivo in humans is feasible using current technology.