Comparison of Gadolinium Polylysine and Gadopentetate in Contrast Enhanced MR Imaging of IVlyocardial Ischemia-Reperfusion in Cats

PURPOSE: To assess the signal enhancement by gadolinium-DTPA-polylysine (Gd-polylysine) as compared to gadopentetate (Gd-DTPA) in MR imaging of heart that have undergone ischemia-reperfusion, and to estimate the extent of myocardial damage covered bythe MR signal enhancement. MATERIALS AND METHODS: A series of contrast enhanced cardiac MR images were obtained from 17 cats subjected to a 90 minutes of occlusion of the left anterior descending coronary artery (LAD) followed by a 90 minutes of raperfusion. Time courses of changes in the signal intensity (Sl) of the ischemic area were measu red in Gd-polylysine group (8 cats) and Gd- DTPA group (9 cats). The size of U R signal enhanced area was then compared to the sizes of infarction and the area at risk revealed byTTC histochemical staining. RESULTS: Maximum Sis were obtained at 60 minutes and 30 minutes after injection of the contrast material, respectively for Gd-polylysine group and Gd-DTPA group. Signal enhancement was stronger and persistent for a longer period in Gd-polylysine group than in GD-DTPA group. Sizes of the enhanced area, the infarction, and the area at risk were about 30%, 15%, and 50% of the total left ventricle (LV) area; the difference between the groups was statistically insignificant. CONCLUSION: Gd-polylysine can be used better for a blood pool marker than Gd-DTPA in MR imaging of myocardial ischemia, due to its strong and persistent signal enhancement. The MR signal enhanced area includes both the infarcted area and a portion of the area at risk.