Analysis of microvascularity after reperfused acute myocardial infarction using the maximum slope method of contrast-enhanced magnetic resonance imaging.

Purpose: The aim of this study was to analyze microvas-cularity after reperfused acute myocardial infarction (AMI) using the maximum slope method of contrastenhanced cardiac magnetic resonance imaging (CMR).

Materials and methods: CMR and resting (201)T1 single photon emission computed tomography (SPECT) images were obtained in 30 consecutive patients after reperfused AMI and 10 controls. After bolus injection of gadolinium diethylenetriamine pentaacetic acid, first-pass CMR images were obtained using the True-FISP sequence. Time-intensity curves were generated by measuring the signal intensity in the myocardium and left ventricle. The arterial input function was obtained from the left ventricular time-intensity curve. On the basis of the maximum slope method, the microvascular index (MVI) was calculated by dividing the maximum initial upslope of the myocardium by the initial upslope of the left ventricle.

Results: The MVI was significantly lower in the segments related to the occluded coronary artery. MVIs in segments with (201)Tl uptake of 50%-59% of peak were significantly lower than in those with (201)Tl uptake of 60%-69%. MVIs in segments with (201)Tl uptake of <50% of peak were significantly lower than in those with (201)Tl uptake of 50%-59%.

Conclusion: This study presents a method that directly assesses microvascularity after reperfused AMI.