1189-65 Measurement of Scatterer Density Using High Frequency Intracardiac Ultrasound Discriminates Normal From Reperfused Infarcted Myocardlum

Background: IschemiaJreperfusion results in structural changes (contraction bands, hemorrhage, edema) which may cause a change in myocardial scatterer density resulting in a variation in the distribution of backscattered ultrasound echoes from the myocardium. Using high-resolution intracardiac ultrasound (ICE) it may be possible to characterize this distribution variation and thus distinguish normal from infarcted roperfused myocardium. Aim: Using Homodynod K-distdbution (HK) analysis we sought to determine the scatterer density in myocardium from ICE images before and after ischemiaJreperfusion. Methods: Eight pigs were studied in an open chest balloon occlusion myocardial infarction model. Epicardial reference markers were placed on the anterior LV wall to span the area at risk and orient the ICE images. Demodulated radio frequency (I/Q) data were obtained using an 8.5 MHz phased array catheter tipped transducer in the RV cavity. The LAD was occluded for 120 rain and reopened for 30 min. Repeat ICE imaging of the selected region was performed using the ICE transducer. The heart was excised and area at risk and infarct determined using Evans Blue and TTC staining. The VQ data were reconstructed into gray-scale images and correlated with gross specimens. The scatterer density within the outlined infarct (before ischemia and after ischemia/reperfusion) was determined with the HK method. Results: In the infarcted region there was a significant difference in the fraction of resolution cells with scatterers _>10 before ischemia (1.5%±1.2%) and after reperfusion (18.4%±5.3%), p<0.05. Conclusion: An increase in scatterer density identifies repertused infarcted LV myocardium using analysis of ICE images.