Comparison of different semiquantitative parameters for the assessment of a myocardial perfusion reserve index by magnetic resonance imaging

For the assessment of myocardial perfusion with cardiac magnetic resonance imaging, different semiquantitative parameters of the first pass signal int ensity time curves can be calculated nd myocardial perfusion reserve indice s can be determined. In this study we evaluated the feasibility of differen t perfusion parameters and their perfusion reserve indices for the detectio n of significant coronary artery stenosis. The signal intensity time curves of the first pass of a gadolinium-DTPA bolus injected via a central vein c atheter before and after dipyridamole infusion were investigated in 15 pati ents with single vessel (stenosis greater than or equal to 75% area reducti on) and Five patients without significant coronary artery disease. For the distinction of ischemic and nonischemic myocardial segments, semiquantitati ve parameters, such as maximal signal intensity, contrast appearance time, time to maximal signal intensity and the steepness of the signal intensity curve's upslope determined by a linear fit, were assessed after correction for the input function. For each parameter a myocardial perfusion reserve i ndex was calculated and cut off values for the detection of significant cor onary stenosis were defined. The diagnostic accuracy of each parameter was then examined prospectively in 36 patients with coronary artery disease and compared with coronary angiography. Where as a distinction of ischemic and normal myocardium was possible with myocardial perfusion reserve indices, semiquantitative parameters at rest or after vasodilation alone did not all ow such a distinction. The perfusion reserve index calculated from the upsl ope showed the most significant difference between ischemic and nonischemic myocardial segments (1.19 +/- 0.4 and 2.38 +/- 0.45, p +/- 0.001) followed by maximum signal intensity, time to maximum signal intensity and contrast appearance time. Sensitivity, specificity and diagnostic accuracy was 87, 82 and 85% for the detection of hypoperfusion induced by significant corona ry artery stenoses using the perfusion reserve index calculated from the up slope. The steepness of the First pass signal intensity curve's upslope, de termined by a linear fit, is a feasible parameter for the detection of sign ificant coronary artery disease with MR. Based on a myocardial perfusion re serve index of this parameter, ischemic myocardium can be identified with h igh diagnostic accuracy.