Computerized estimation of quality standards for the X-ray densitometric assessment of myocardial perfusion

The densitometric evaluation of heart-phase-gated digital subtraction coronary angiograms derives different parameters which provide information about coronary blood flow, myocardial perfusion, and coronary flow reserve: appearance time, rise time, mean ascending time, and maximum intensity. The reliability and reproducibility of these measurements and of the derived parameters were investigated. Four digital subtraction coronary angiograms were obtained in ten patients, including two baseline measurements and two measurements under hyperemia induced by papaverine ic. Different reproducibility results were found for the parameters, depending on the heart phase of the densogram (diastolic better than systolic) and the region of interest (ROI) (septal ROIs revealed better reproducibilities than apical). Results under hyperemia were improved compared to baseline. Best results were obtained for rise time and mean ascending time, while the worst result was obtained for maximum intensity. In general, the reproducibility was poor but was markedly improved when the parameters were calculated from quality checked densograms