Development of 60 MHz integrated backscatter intravascular ultrasound and tissue characterization of attenuated signal coronary plaques that cause myocardial injury after percutaneous coronary intervention.

The purpose of the present study was to develop a 60 MHz integrated backscatter intravascular ultrasound (IB-IVUS) and to evaluate its usefulness for the detection of lipid area with backward attenuation of ultrasound signal (AT) that for the prediction of post-procedural myocardial injury (PMI) after percutaneous coronary intervention (PCI). In a pathological study, images were acquired from 221 cross-sections of 18 coronary arteries from 13 cadavers obtained at autopsy. In the clinical training study, we compared non-targeted plaques in 38 patients by a previous IB-IVUS system (38 MHz) and a new IB-IVUS system (60 MHz). In the clinical testing study, we included 70 consecutive patients who underwent PCI. Serum troponin-I was measured just before and 24 h after PCI to evaluate PMI. As the % microcalcification + % cholesterol cleft area increased, the attenuation of IB values increased (r = 0.56, p < 0.001). The slopes of regression lines of the area of each tissue component between 38 and 60 MHz IB-IVUS were excellent. The lipid pool area with AT tended to be more useful than that of the conventional lipid pool area for the prediction of PMI (p = 0.11). We developed a 60 MHz IB-IVUS imaging system for tissue characterization of coronary plaques. Cutoff value of purple color was the most reliable value for the prediction of PMI.