Measurement of kinetic perfusion parameters of gadoteridol in intact myocardium: Effects of ischemia/reperfusion and coronary vasodilation

Quantitation of myocardial perfusion is feasible using contrast enhanced magnetic resonance imaging. A method to quantitate myocardial blood flow is provided by the Kety model modified to account for a diffusable tracer such as gadoteridol. In the present study, perfusion parameters of the modified Kety model (partition coefficient and extraction efficiency) were determined for gadoteridol in intact myocardium using a constant flow, isolated, perfused heart model. Perfusion conditions included hearts with normal perfusion, hearts made globally ischemic for 20 min then perfused normally, and hearts whose coronary flow was more than doubled with 9 μM adenosine. T1 relaxation times were rapidly measured at 0.5 T following step increases in perfusate gadoteridol concentration and at steady state. Both the partition coefficient and extraction efficiency were found to be significantly increased in ischemic/reperfused hearts compared to normal. While flow rates in adenosine hearts were too high for accurate extraction efficiency determination using this technique, the partition coefficient was no different between adenosine and normally perfused hearts. The method described in this article allowed the kinetic parameters of the modified Kety model to be determined in intact heart using NMR relaxation time measurements as the basis of the calculation.