PURPOSE: To compare T2-weighted and Gadomer-17– and bis-gadolinium mesoporphyrins–enhanced magnetic resonance (MR) images for distinguishing reversibly from irreversibly damaged myocardium in a cat model of reperfused myocardial infarction.

MATERIALS AND METHODS: Twelve cats underwent 90 minutes of occlusion and 90 minutes of reperfusion of the left anterior descending coronary artery. After baseline T1- and T2-weighted MR images were obtained, Gadomer-17–enhanced and bis-gadolinium mesoporphyrins–enhanced T1-weighted images were sequentially obtained for 6 hours and 2 hours, respectively. After MR imaging, all cats were sacrificed for 2,3,5-triphenyltetrazolium chloride (TTC) histochemical tissue staining. Areas of abnormal signal intensity on T2-weighted and Gadomer-17–enhanced and bis-gadolinium mesoporphyrins–enhanced T1-weighted MR images were compared with the areas of infarction seen at TTC histochemical staining by using repeated-measures two-way analysis of variance, linear regression analysis, and Bland-Altman analysis.

RESULTS: Mean areas of abnormally high signal intensity on T2-weighted and Gadomer-17–enhanced T1-weighted MR images (43.9% of the left ventricular surface area ± 11.9 [SD] and 37.7% ± 10.1, respectively) were significantly larger than the mean area of myocardial infarction at TTC staining (25.7% ± 12.5) (P < .001). However, there was excellent correlation between the size of an enhancing area on bis-gadolinium mesoporphyrins–enhanced T1-weighted MR images and that of myocardial infarction at TTC staining (r = 0.916, P < .001).

CONCLUSION:bis-Gadolinium mesoporphyrins–enhanced T1-weighted MR images accurately reflect the area of infarction, whereas the size of infarction is overestimated on T2-weighted and Gadomer-17–enhanced T1-weighted MR images, which seem to depict the periinfarct area as well as the infarct area.

© RSNA, 2003