Reproducibility of intravascular ultrasound radiofrequency data analysis: Implications for the design of longitudinal studies

Objectives: The purpose of this study was to assess in vivo the reproducibility of tissue characterization using spectral analysis of intravascular ultrasound (IVUS) radiofrequency data (IVUS-VH). Background: Despite the need for reproducibility data to design longitudinal studies, such information remains unexplored. Methods and results: IVUS-VH (Volcano Corp., Rancho Cordova, USA) was performed in patients referred for elective percutaneous intervention and in whom a non-intervened vessel was judged suitable for a safe IVUS interrogation. The IVUS catheters used were commercially available catheters (20 MHz, Volcano Corp., Rancho Cordova, USA). Following IVUS-VH acquisition, and after the disengagement and re-engagement of the guiding catheter, an additional acquisition was performed using a new IVUS catheter. Fifteen patients with 16 non-significant lesions were assessed by 2 independent observers. The relative inter-catheter differences regarding geometrical measurements were negligible for both observers. The inter-catheter relative difference in plaque cross-sectional area (CSA) was 3.2% for observer 1 and 0.5% for observer 2. The limits of agreement for (observer 1 measurements) lumen, vessel, plaque and plaque burden measurements were 0.82, -1.10 mm ²;0.80, -0.66 mm²;1.08, -0.66 mm²; and 5.83, -3.89%; respectively. Limits of agreement for calcium, fibrous, fibrolipidic and necrotic core CSA measurements were 0.22, -0.25 mm²;1.02, -0.71 mm²;0.61, -0.65 mm²; and 0.43, -0.38 mm² respectively. Regarding the inter-observer agreement, the limits of agreement for lumen, vessel, plaque and plaque burden measurements were 2.61, -2.09 mm²;2.20-3.03 mm²;1.70, -3.04 mm²; and 9.16, -16.41%; respectively, and for calcium, fibrous, fibrolipidic and necrotic core measurements of 0.08, -0.09 mm²;0.89, -1.28 mm²;0.74, -1.06 mm²; and 0.16, -0.20 mm²; respectively. Conclusions: The present study demonstrates that the geometrical and compositional output of IVUS-VH is acceptably reproducible.