Relationship of T2-Weighted MRI Myocardial Hyperintensity and the Ischemic Area-At-Risk

RATIONALE:After acute myocardial infarction (MI), delineating the area-at-risk (AAR) is crucial for measuring how much, if any, ischemic myocardium has been salvaged. T2-weighted MRI is promoted as an excellent method to delineate the AAR. However, the evidence supporting the validity of this method to measure the AAR is indirect, and it has never been validated with direct anatomic measurements. OBJECTIVE:To determine whether T2-weighted MRI delineates the AAR. METHODS AND RESULTS:Twenty-one canines and 24 patients with acute MI were studied. We compared bright-blood and black-blood T2-weighted MRI with images of the AAR and MI by histopathology in canines and with MI by in vivo delayed-enhancement MRI in canines and patients. Abnormal regions on MRI and pathology were compared by (a) quantitative measurement of the transmural-extent of the abnormality and (b) picture matching of contours. We found no relationship between the transmural-extent of T2-hyperintense regions and that of the AAR (bright-blood-T2r=0.06, P=0.69; black-blood-T2r=0.01, P=0.97). Instead, there was a strong correlation with that of infarction (bright-blood-T2r=0.94, P