We studied the mechanism underlying regional enhancement of myocardial infarction using T1-weighted MRI with gadolinium (Gd)-DTPA. Anterior myocardial infarction (MI) was produced by left anterior descending coronary artery ligation in three groups of rats as follows: 60 minutes occlusion (occlusion group, N = 6), 60 minutes occlusion plus 120 minutes reperfusion (reperfusion group, N = 8), and sham-operated (control, N = 6). In Gd-DTPA-enhanced MRI, MI was demarcated as a hypoenhanced region in the occlusion group and as a homogeneous hyperenhanced region in the reperfusion group. Both Gd-DTPA tissue concentration and tissue water content in the anterior wall were highest in the reperfusion group (P<0.05), a finding suggestive of microscopically observed interstitial edema. The data suggest that regional accumulation of Gd-DTPA in the reperfused group can be explained by increased interstitial water content, contributing to the delayed washout of the water-soluble contrast medium.
Inoue et al. (1999) studied this question.