Development of Integrated Backscatter Intravascular Ultrasound for Tissue Characterization of Peripheral Artery and Comparison with Angioscopy

Abstract

Background: The purpose of the present study was to determine the differences in integrated backscatter (IB) values between a new IB intravascular ultrasound (IB-IVUS) mode for peripheral artery and the previous mode for coronary arteries for the tissue characterization of plaques. Methods: A cross-validation study was performed with the 40 patients divided into a training study to determine the difference in IB value and the most appropriate correction for ultrasound signal attenuation between the mode for coronary and peripheral arteries (n = 20) and a testing study to validate the similarity of the images (n = 20). Comparison between the findings of IB-IVUS and angioscopy was performed in 10 patients. Results: In the training study, 57 cross sections were subjected to the comparison. The IB value of +4.5 dB was the most appropriate setting compared with the mode for coronary arteries. The slope of regression lines were 1.00 in the measurement of lipid area and 1.00 in the measurement of fibrous area. The most appropriate correlation for ultrasound signal attenuation was +3.0 dB/mm. In the testing study, the slopes of regression lines in the measurement of lipid and fibrous areas were excellent in 20 cross sections (1.00 and 1.02, respectively) based on the settings that were determined in the training study. In the comparison with angioscopy, thickness of fibrous cap was associated with the color of plaques in peripheral arteries. Conclusions: The IB-IVUS system with the new mode for peripheral arteries provides high diagnostic accuracy for the analysis of tissue characteristics of plaques.