Background: While the utilization of integrated backscatter intravascular ultrasound (IB-IVUS) for the quantitative in vivo assessment of coronary plaque continues to grow, the validity of IB-IVUS images obtained from newly developed and conventional systems remains uncertain. Methods and Results: To assess the accuracy and reliability of a newly developed IB-IVUS system (VISIWAVE) as compared to the conventional system (Clearview), we compared quantitative IB-IVUS plaque characteristics in the 2 systems using 125 post-mortem specimens from 26 coronary arteries in 11 cadavers, as well as using 200 clinical plaques in 32 patients undergoing coronary intervention. The overall agreement between the histological and IB-IVUS diagnoses using VISIWAVE (Cohen's κ=0.82, 95%CI: 0.73-0.90) was similar to that using Clearview (Cohen's κ=0.80, 95%CI: 0.71-0.89). The 2 systems also demonstrated comparably high sensitivity and specificity. In the direct comparison, the overall agreement between IB-IVUS diagnoses using VISIWAVE and Clearview was also excellent (Cohen's κ=0.87, 95%CI: 0.78-0.95). In the clinical comparison, measured plaque dimensions were similar (VISIWAVE: 8.27±3.46 mm 2 vs. Clearview; 8.31±3.46 mm 2, P=0.44) and there was strong concordance between both greyscale and IB-IVUS parameters. Conclusions: There was close agreement of analyzed results in both systems when compared with the gold standard of histology. Both systems are able to reliably and accurately characterize coronary plaque and thereby make a valuable contribution to our understanding of atherosclerosis.
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