Multicenter assessment of the reproducibility of volumetric radiofrequency-based intravascular ultrasound measurements in coronary lesions that were consecutively stented

Abstract

To assess in a multicenter design the between-center reproducibility of volumetric virtual histology intravascular ultrasound (VH-IVUS) measurements with a semi-automated, computer-assisted contour detection system in coronary lesions that were consecutively stented. To evaluate the reproducibility of volumetric VH-IVUS measurements, experienced analysts of 4 European IVUS centers performed independent analyses (in total 8,052 cross-sectional analyses) to obtain volumetric data of 40 coronary segments (length 20.0 ± 0.3 mm) from target lesions prior to percutaneous intervention that were performed in the setting of stable (65%) or unstable angina pectoris (35%). Geometric and compositional VH-IVUS measurements were highly correlated for the different comparisons. Overall intraclass correlation for vessel, lumen, plaque volume and plaque burden was 0.99, 0.92, 0.96, and 0.83, respectively; for fibrous, fibro-lipidic, necrotic core and calcified volumes overall intraclass correlation was 0.96, 0.94, 0.98, and 0.99, respectively. Nevertheless, significant differences for both geometrical and compositional measurements were seen. Of the plaque components, fibrous tissue and necrotic core showed on average the highest measurement reproducibility. A central analysis for VH-IVUS multicenter studies of lesions prior to PCI should be pursued. Moreover, it may be problematical to pool VH-IVUS data of individual trials analyzed by independent centers.

Fig. 1

Image acquisition and data analysis. Motorized pullbacks at 0.5 mm/s (including image frame acquisition at the time of the R-wave peak) were performed by each IVUS center (A–D). These pullback sequences (obtained from 10 patients) were exchanged in order to obtain a ‘pullback pool’ of 40 pullbacks, which each analyst independently analyzed (I). Automated contour detection and, if required, manual correction of the lumen and vessel border were performed on all frames using the VH-images and software (II). Volumetric VH-IVUS data of vessel and plaque geometry and plaque composition were automatically generated for the analyzed segment based on the application of Trapezium method (III)

Fig. 2

Example of differences in contour detection in a single frame. The same coronary segment was analyzed by 2 different centers; please note that differences in contour detection resulted in differences in plaque composition. Center A (Greyscale (a) and VH-IVUS (b) analysis) versus Center B (c and d, resp)

Fig. 3

a Agreement of repeated VH-IVUS measurements of geometric volumes. Agreement of repeated VH-IVUS measurements of geometry between center A versus B (left), center A versus C (mid) and center A versus D (right). Δ = difference. b Agreement of repeated VH-IVUS measurements of geometric volumes. Agreement of repeated VH-IVUS measurements of geometry between center B versus C (left), center B versus D (mid) and center C versus D (right). Δ = difference

Fig. 3

a Agreement of repeated VH-IVUS measurements of geometric volumes. Agreement of repeated VH-IVUS measurements of geometry between center A versus B (left), center A versus C (mid) and center A versus D (right). Δ = difference. b Agreement of repeated VH-IVUS measurements of geometric volumes. Agreement of repeated VH-IVUS measurements of geometry between center B versus C (left), center B versus D (mid) and center C versus D (right). Δ = difference

Fig. 4

a Agreement of repeated VH-IVUS measurements of compositional volumes. Agreement of repeated VH-IVUS measurements of plaque composition between center A versus B (left), center A versus C (mid) and center A versus D (right). Δ = difference. b Agreement of repeated VH-IVUS measurements of compositional volumes. Agreement of repeated VH-IVUS measurements of plaque composition between center B versus C (left), center B versus D (mid) and center C versus D (right). Δ = difference

Fig. 4

a Agreement of repeated VH-IVUS measurements of compositional volumes. Agreement of repeated VH-IVUS measurements of plaque composition between center A versus B (left), center A versus C (mid) and center A versus D (right). Δ = difference. b Agreement of repeated VH-IVUS measurements of compositional volumes. Agreement of repeated VH-IVUS measurements of plaque composition between center B versus C (left), center B versus D (mid) and center C versus D (right). Δ = difference