e0195 Research on the evaluation of OCT on atherosclerotic plaques of carotid artery in rabbits with insulin resistance

Objective The purpose was to analyse the feasibility and repeatability of OCT to evaluate atherosclerotic plaque diagnosed by pathologic examination of common carotid artery in rabbits with insulin resistance. Methods There were 26 male China White rabbits. 20 rabbits were made atherosclerotic with a high-cholesterol diet after injury of the left carotid artery endothelium. Another 6 rabbits were fed common diet, no injury. At the beginning and feeding for 12 weeks, TG, TC, HDL, LDL, FBG, fasting insulin and insulin sensitivity index were tested, analysis the correlation between HOMA-IR and lipid. After 12 weeks, OCT images of the left carotid artery were performed. After OCT, specimens were taken. Histology embedded in paraffin and HE stained was performed on arterial regions that was showed plaques in the OCT scan. OCT results were compared with pathological results. Results 4 rabbits died, no death in normal. Feeding high fat diet for 12 weeks, their weight, TC, TG, LDL-C, HDL-C were significantly higher than normal (p<0.01). Though the difference of FBG was not statistically significant compared with normal (p=0.423), FSI, ISI and HOMA-IR was statistically significantly different (p=0.001, 0.000, 0.000 respectively). HOMA-IR and TG were positively correlated (r=0.52, p=0.039), and TC, HDL, LDL no significant correlation (p>0.05). OCT images of the left carotid artery in 22 rabbits were performed. 60 OCT images analysis after two experts9 discussions were held. There were 50 lipid-rich plaques, seven fibrous plaques and three suspected as calcified plaques. In addition, four thrombosis and intima tear in two sites were found. The pathological section was made in corresponding sites to OCT, HE staining. Comparing with the pathology results, OCT had high sensitivity and specificity for atherosclerotic plaque, respectively 96%, 89%. Plaque burden, external elastic membrane area and lumens area between the two methods were not statistically different (p>0.05). Conclusion OCT imaging can clearly visualise different types of atherosclerotic plaques and provide detailed information on plaque characteristics. Comparing with histopathology, OCT had high sensitivity and specificity for characterising atherosclerotic plaque.