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

Abstract

The aim of this study was to determine whether the use of a magnetic resonance (MR) susceptibility contrast medium, dysprosium diethylenetriamine pentaacetic acid‐bismethylamide (Dy DTPA‐BMA; Sprodiamide), may characterize myocardial perfusion abnormalities in a dog model of 90 minutes of coronary occlusion followed by 24 hours of reperfusion (no‐reflow phenomenon installed). First‐pass MR imaging after an intravenous bolus administration of the contrast agent was performed at the end of reperfusion. Signal intensity analysis on MR imaging, planimetry of pathological data, and blood flow determination were obtained by reference methods for comparison. Dogs were separated into two groups according to the level of collateral blood flow level (group I, <22.5 % of the flow in the non‐ischemic zone; group II, >22.5 % of the flow in the non‐ischemic zone). Signal intensity‐time curves in the ischemic and non‐ischemic left ventricle walls were extracted. Mean collateral blood flow 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 collateral blood flow; 25.3 ± 14.6%) than in group II (high collateral blood flow; 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 myocardium. Hence, during the transit of a susceptibility‐type contrast agent, ischemic myocardium after ischemia and reperfusion appeared as a relative high signal intensity area. First‐pass MR imaging with susceptibility contrast agent demonstrated the no‐ or low‐reflow phenomenon. However, the behavior of the myocardial signal intensity–time‐related curves did not allow distinction between the two groups of dogs. J. Magn. Reson. Imaging 9:679–684, 1999. © 1999 Wiley‐Liss, Inc.

Predictors of no- reflow during primary angioplasty for acute myocardial infarction, from Medical College Hospital, Trivandrum

“…Diminished flow through the microvasculature compared with normal zones is usually referred to as ‘low reflow.’ 30 No-reflow can also occur in vein grafts or even in native coronaries. Distal protection devices may prevent no-reflow.…”

Towards Stratifying Ischemic Components by Cardiac MRI and Multifunctional Stainings in a Rabbit Model of Myocardial Infarction

“…Because of the increased water content and mobility, both infarct and peri-infarct zones appear hyperintense on T2WI 41. Choi et al showed that the high SI on T2WI reflects both irreversible infarct and reversibly injured but essentially viable peri-infarct zone 16, 17. Aletras et al showed a high accuracy of T2WI in identifying the spatial extent of the AAR 41.…”

“…Second, first-pass perfusion weighted imaging (PWI) demarcates normal myocardium from the AAR utilizing dynamic contrast enhancement 15, which requires ultrafast techniques to increase temporal resolution to catch the first-pass of injected contrast agent. So far, PWI has been mainly performed in larger animals such as dogs, sheep, and pigs, due to their lower heart rates and larger cardiac mass 16, 17. Third, cMRI coronary angiography has been validated for estimation of the AAR, which is based on Aldrich score for individual assessment of the length and caliber of the coronary arteries 18.…”