Myocardial "low reflow" assessed by Dy-DTPA-BMA-enhanced first-pass MR imaging in a dog model

The aim of this study was to determine whether the use of a magnetic resona nce (MR) susceptibility contrast medium, dysprosium diethylenetriamine pent aacetic acid-bismethylamide (Dy DTPA-BMA; Sprodiamide), may characterize my ocardial perfusion abnormalities in a dog model of 90 minutes of coronary o cclusion followed by 24 hours of reperfusion (no-reflow phenomenon installe d). First-pass MR imaging after an intravenous bolus administration of the contrast agent was performed at the end of reperfusion. Signal intensity an alysis on MR imaging, planimetry of pathological data, and blood now determ ination were obtained by reference methods for comparison. Dogs were separa ted into two groups according to the level of collateral blood now level (g roup I, <22.5% of the now in the non-ischemic zone; group II, >22.5% of the now in this non-ischemic zone). Signal intensity-time curves in the ischem ic and non-ischemic left ventricle walls were extracted. Mean collateral bl ood now was lower during occlusion in group I (9.8 +/- 5.4%, n = 5) than in group II (38 +/- 12.5%, n = 7, P < 0.05), Mean infarct size (expressed as a percentage of the area at risk) was significantly larger in group I(low c ollateral blood now; 25.3 +/- 14.6%) than in group II (high collateral bloo d now; 5.8 +/- 1.1%, P < 0.05), After rapid injection, a transient decrease of signal intensity induced by Dy DTPA-BMA was observed in both remote and ischemic myocardium but more markedly in remote normally perfused myocardi um, Hence, during the transit of a susceptibility-type contrast agent, isch emic myocardium after ischemia and reperfusion appeared as a relative high signal intensity area, First-pass MR imaging with susceptibility contrast a gent demonstrated the no- or low-reflow phenomenon. However, the behavior o f the myocardial signal intensity-time-related curves did not allow distinc tion between the two groups of dogs. (C) 1999 Wiley-Liss, Inc.