Identifying Carotid Plaque Compositions Exhibiting Discordant Motion in B-Mode Ultrasound Videos

This study aimed to analyze 2D B-mode longitudinal carotid ultrasound videos to identify and characterize the motion of plaque compositions. Understanding these motion patterns in both asymptomatic (AS) and symptomatic (SY) cases may provide valuable insights into plaque instability and its potential role in rupture and ischemic stroke. We included 20 carotid ultrasound videos (10 AS and 10 SY patient videos). First, a previously trained and evaluated Deep Learning model segmented the whole plaque region of interest (ROIs), per video frame. Based on a heuristic computational approach, we contoured each ROI into 6 colors (6 grayscale, GS intensity ranges), depicting different histological compositions (e.g., calcified areas, areas with fibrous content and/or collagen, and lipid cores). We estimated motion of the whole plaque and that of each composition, across 3 systoles per video, calculating the Maximum Angular Spread (MAXFW) and the maximum median motion magnitude. The GS≤25 areas in highly-discordant AS and SY plaques exhibited the largest MAXFW (moderate-discordant motion), compared to other compositions. The MAXFW of the GS≤25 in concordant AS plaques, although higher compared to others, showed a concordant motion. Overall, the angular and the motion spread both showed a continuous increase from the brighter to the darkest areas in the highly-discordant AS and SY plaques. These findings might reflect a key involvement of the echolucent plaque areas in the development of discordant motion in both the AS and SY highly-discordant plaques. This could possibly help doctors detect high-risk areas more prone to rupture, in 2D B-mode longitudinal carotid ultrasound videos.Clinical Relevance- This study highlights the importance of estimating the motion of each composition present in the carotid plaques, when examining 2D B-mode ultrasound videos, to more effectively identify plaque areas more likely to rupture.