Human hyperpolarized [1-13C] pyruvate CMR and adenosine stress test

Abstract

Abstract Background Hyperpolarized (HP) [1-13C]pyruvate cardiac magnetic resonance (CMR) imaging can visualize myocardial perfusion and metabolism beyound glucose uptake. Depending on the prevailing metabolic conditions, buid-up of either [1-13C]lactate or 13C-bicarbonate can be measured. The aim of the present study was to assess cardiac metabolism using HP [1-13C]pyruvate rest-stress CMR. Methods Six healthy volunteers underwent cine CMR and HP [1-13C]pyruvate CMR at rest and during an adenosine stress test. Signal from HP [1-13C]pyruvate and its downstream metabolites was measured at the mid-left-ventricle (LV) level. We did semi-quantitative assessment of first-pass myocardial [1-13C]pyruvate perfusion. Pressure-volume loops were assessed non-invasively. Results Myocardial [1-13C]pyruvate perfusion was significantly increased during stress with a reduction in time-to-peak from 6.2±2.8 sec to 2.7±1.3 sec, p=0.04. This higher perfusion was accompanied by an overall increased myocardial uptake and metabolism. The conversion rate constant (kPL) for lactate increased from 0.011±0.009 sec–1 to 0.020±0.010 sec–1, p=0.04. The pyruvate oxidation (kPB) increased from 0.004±0.004 sec–1 to 0.012±0.007 sec–1, p=0.008. This increase in oxidative metabolism was positively correlated with heart rate (R2=0.44, p=0.02). Conclusion We observed a significant increase in carbohydrate oxidation during cardiac stress in the healthy human heart. The present study forms the basis for comparisons in future research in patients with heart failure and coronary artery disease. HP [1-13C]pyruvate CMR could be a possible alternative to PET in the future. Funding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Danish Heart FoundationIndependent Research Fund, Denmark Increased conversion rate of pyruvateIncreased metabolite signal in LV