The potential of gadolinium (Gd)-DTPA to improve the detection of acute myocardial infarction by MR has been shown in experimental canine studies. To determine its value in humans, we studied five patients 2-17 days after myocardial infarction by using ECG-gated MR before and after administration of 0.1 mmol/kg Gd-DTPA. One patient had a rupture of the interventricular septum, complicating an acute inferior-wall infarction. Spin-echo images were obtained before and immediately after injection of Gd-DTPA and were repeated every 10 min for up to 40 min. In four patients, intensity-vs-time curves revealed increasing signal intensity in the infarcted area in the first 20 min after injection of gadolinium. Contrast between normal and infarcted myocardium was greatest 20-30 min after Gd-DTPA injection. In one patient, increasing signal intensity of the infarcted myocardium was observed up to 40 min after Gd-DTPA injection. The precontrast intensity ratio between infarcted and normal myocardium was 1.1 at echo time (TE) = 30 msec and was 1.4 at TE = 60 msec (p less than .05). The postcontrast intensity ratio was 1.6, which was not statistically different from the ratio at TE = 60 msec but which was significantly higher than the ratio at TE = 30 msec (p less than .01). Infarct definition was substantially improved on postcontrast images. The septal rupture was clearly seen, and the infarcted myocardium surrounding the septal rupture showed enhancement on postcontrast images. These results suggest that Gd-DTPA can improve MR visualization and detection of acute myocardial infarction.