ASSESSMENT OF MYOCARDIAL PERFUSION DURING ISCHEMIA AND REPERFUSION IN ISOLATED RAT HEARTS USING GADOPENTETIC ACID ENHANCED MAGNETIC-RESONANCE-IMAGING

The value of gadopentetic acid (Gd-DTPA)-enhanced magnetic resonance (MR) imaging to identify normal, ischemic, and reperfused myocardium was assessed in 21 isolated isovolumically contracting rat hearts. Ischemia was induced by reduction of the perfusion pressure from 80 to 30 mm Hg for 60 or 120 minutes, followed by reperfusion for 0, 20, or 60 minutes. Six of the 21 hearts without ischemia served as controls. Evans blue and Gd-DTPA were infused during the last 5 minutes of each experiment. Evans blue distribution in histologic cross-sections was compared with myocardial contrast enhancement on Gd-DTPA-enhanced T1-weighted spin-echo MR images. Homogeneous signal enhancement was seen in control hearts. After induction of ischemia, unperfused subendocardial areas were detected on both the MR images and Evans blue-stained slices. After reperfusion, the unperfused areas dissolved on both MR images and Evans blue-stained slices, depending on duration and severity of ischemia. This study emphasizes the potential of Gd-DTPA-enhanced MR imaging to identify myocardial ischemia and reperfusion by enhancing the contrast between normally perfused and ischemic myocardium in an isolated rat heart model.