Abstract
Eleven patients (7 anterior and 4 inferior) with Q-wave myocardial infarction (QMI) undergoing radionuclide imaging were studied using MR perfusion imaging techniques and quantitative computer analysis of the signal intensity (SI)-time curves. The purpose of this study was to determine the relative accuracy of slope (wash-in) and peak SI when compared to radionuclide images in myocardial regions with corresponding a-waves on the electrocardiogram. Patients underwent MR perfusion imaging using an ultrafast interpolated keyhole acquisition during bolus administration of gadoteridol (0.1 mmol/kg). Perfusion images were obtained under resting conditions and after dipyridamole (0.56 mg/kg). Radionuclide images were obtained the same day by either thallium exercise testing or hybrid thallium-99m Tc sestamibi restdipyridamole stress testing and available for comparison. The slope of the SItime curve (regression analysis) and peak SI were compared between normal and infarcted myocardium. The slope and SI were normalized to left ventricular cavity values, averaged, and compared using t-test statistical analysis. Eight QMI patients with scarred myocardium determined by the radionuclide study had decreased slope (0.14 vs 0.47, P < 0.001) and peak SI (0.38 vs 0.58, P = 0.01) compared to normal regions. Slope (0.14 vs 0.23) and SI (0.38 vs 0.46) increased in the scarred regions following dipyridamole but not significantly. Normal regions had increased slope (0.47 vs 0.66, p = 0.02) but not SI following dipyridamole. Three QMI patients had reversible ischemia in Q-wave regions. Slopes were higher when compared to patients with scar (0.39 vs 0.14, p = 0.02) and more closely approximated normal regions (0.39 vs 0.55, p = NS). Ischemic regions had no significant change in slope (0.39 vs 0.40) or SI (0.54 vs 0.50) following dipyridamole. These data suggest that slope may be a stronger indicator of artery patency and closely parallels the results of radionuclide imaging.
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