Objective: To determine whether myocardial circumferential shortening assessed in the different myocardial layers by SPAMM cine-MRI may help to discriminate between various degrees of myocardial injury in reperfused myocardium.
Methods: Dogs underwent 90 minutes of coronary occlusion and 24 hours of reperfusion. Using a 1.5 T whole-body MR scanner, SPAMM cine-MRI images were acquired before and 24 hours after surgery on the short axis plan of the left ventricle and analyzed to evaluate the mean myocardial circumferential shortening (% MCS) in the different layers. Based on the residual blood flow, animals were assigned to group I (residual flow < 22.5%) or group II (residual flow > 22.5%).
Results: Dogs in group I developed larger infarctions (25.3% +/- 14.6 of the area at risk, n = 5) compared with those in group II (5.81% +/- 1.1, n = 7, P < 0.05). In the jeopardized zone, the % MCS of the subendocardium decreased more significantly in group I (-0.03% +/- 3.7 to 2.2% +/- 5.2) compared with group II (14.7% +/- 1.5 to 18.4% +/- 1.4).
Conclusions: SPAMM cine-MRI is a fast and noninvasive means of measuring % MCS. The MR measurement of this parameter in the subendocardial layer appears quite accurate in describing the degree of damage in reperfused myocardium.