VALIDATION OF AUTOMATED BORDER DETECTION IN INTRAVASCULAR ULTRASOUND IMAGES

Intravascular ultrasound (IVUS) imaging provides cross-sectional views of the vessel lumen; however, lumen measurements still rely on operat or-dependent border delineation and time-consuming lumen tracings. We tested a new system for automated lumen border detection in IVUS image s based on acoustic quantification of blood and vessel wall. In 10 rab bits, 29 segments of the aorta were imaged in vivo using a 2.9-Fr IVUS catheter. IVUS images were obtained during motorized pullbacks of aor tic segments of 18 mm length. Automated measurements of lumen dimensio ns were compared to automated measurements of a second pullback throug h the same segment, lumen measurements derived from visual border trac ings in IVUS images, and to quantitative angiography. The automated sy stem showed good reproducibility. Correlations for repeated measuremen ts of lumen area, maximal and minimal lumen diameters were r = 0.97, r = 0.91, and r = 0.93, respectively. Automated measurements also corre lated well to visual image analysis (lumen area, r = 0.97; maximal lum en diameter, r = 0.89; minimal lumen diameter, r = 0.89) and to angiog raphic measurements (lumen area, r = 0.93; lumen diameter, r = 0.95). In 12% of the images, the automated system overestimated lumen dimensi ons because of weak wall signals in the presence of echolucent structu res next to the wall. Signal artifacts from the IVUS catheter itself o r strong blood backscatter resulted in lumen underestimation in 6% of the images. Over- and underestimation of lumen by the border detection . system were often associated with eccentric catheter position. Thus, lumen, measurements in vivo IVUS images can be performed using an aut omated border detection system based on acoustic quantification of blo od and vessel wall. The system allows reproducible and accurate measur ements of lumen area and diameters.