T-1 mapping in patients with acute myocardial infarction

Pixel-by-pixel calculation of T-1 values (T-1 mapping) has been used in different tissues to focus on T-1 changes in a quantitative fashion. The aim of this study was to establish T-1 mapping of human myocardium on a 1.5 Tesla system and to examine its diagnostic potential in patients with acute myocardial infarction (AMI). 8 patients with reperfused AMI (day 3 1) underwent multi-breath-hold MRI in a 1.5 Tesla system. Sets of five images with varying T-1 weighting were acquired prior to and after the administration of contrast agent to generate images from calculated T-1 values (T-1 mapping). Prior to the contrast agent administration, all patients showed T-1 prolongation -in the area of infarction, which was identified in separate measurements using the delayed enhancement approach. Compared to noninfarcted areas, T-1 values in the infarcted areas were increased by 18 7% (SE, p < 0.05). The spatial extent of the area of T-1 prolongation was larger than that of the hyper-enhanced areas in conventional contrast-enhanced images. T-1 maps obtained after the application of Gadolinium-DTPA revealed a T-1 reduction of 27 +/- 4% in infarcted tissue compared to noninfarcted areas (p < 0.05). The areas showing T-1 reduction were in agreement with the hyper-enhanced regions in conventional T-1-weighted images. T-1 mapping visualizes changes in the longitudinal relaxation time induced by AMI. T-1 mapping can detect myocardial necrosis without the use of contrast media. Information that can be extracted from a combination of pre- and postcontrast T-1 maps exceeds that from conventional contrast studies.