Abstract
1068
Objectives: The C2A domain of Synaptotagmin I holds promise as a molecular probe in the specific imaging of myocardial infarction by targeting exposed anionic phospholipids as a near-universal marker for cell death. Here we test the hypothesis that the uptake of 99mTc-C2A is positively correlated with long-term cardiac function loss after ischemia/reperfusion. Methods: The left coronary artery was occluded in 14 Sprague-Dawley rats for 30 min (n = 7), 20 min (n = 3), 10 min (n = 3) and 0 min (as sham, n = 1). 99mTc-C2A was injected i.v. at 2 hr of reperfusion. Anterior planar images were acquired with 1 million counts on a gamma camera 3 hr after injection. 99mTc-C2A uptake was calculated as the total counts in the left ventricle (LV) region minus blood pool signal. Echocardiography was performed at 1 and 3 weeks after surgery. Short axis views of mid LV and apex were assigned a wall motion score (1-normal to 5-aneurysmal) as per ASE standard. Wall motion score index (WMSI) was computed as total segment score divided by the number of segments. Results: 99mTc-C2A uptake was higher with increased ischemic time (2808±847, 4054±1223 and 7156±1361 for 10, 20 and 30 min ischemia, ANOVA p<0.001). There is a significant correlation between 99mTc-C2A uptake and WMSI at 1 week (R=0.68, p=0.008) and 3 weeks (R=0.73, p=0.005). Conclusions: In this ischemia/reperfusion model, 99mTc-C2A uptake correlates significantly with functional abnormality at 1 and 3 weeks of reperfusion. This demonstrates the potential of 99mTc-C2A as a novel imaging agent for ongoing myocardial dysfunction.
- Society of Nuclear Medicine, Inc.