Simultaneous Registration of Location and Orientation in Intravascular Ultrasound Pullbacks Pairs Via 3D Graph-Based Optimization

Abstract

A novel method is reported for simultaneous registration of location (axial direction) and orientation (circumferential direction) of two intravascular ultrasound (IVUS) pullbacks of the same vessel taken at different times. Monitoring plaque progression or regression (e.g., during lipid treatment) is of high clinical relevance. Our method uses a 3D graph optimization approach, in which the cost function jointly reflects similarity of plaque morphology and plaque/perivascular image appearance. Graph arcs incorporate prior information about temporal correspondence of the two IVUS sequences and limited angular twisting between consecutive IVUS images. Additionally, our approach automatically identifies starting and ending frame pairs in the two IVUS pullbacks. Validation of our method was performed in 29 pairs of IVUS baseline/follow-up pullback sequences consisting of 8,622 IVUS image frames in total. In comparison to manual registration by three experts, the average location and orientation registration errors ranged from 0.72 mm to 0.79 mm and from 7.3° to 9.3°, respectively, all close to the inter-observer variability with no difference being statistically significant (p = NS). Rotation angles determined by our automated approach and expert observers showed high correlation (r2 of 0.97 to 0.98) and agreed closely (mutual bias between the automated method and expert observers ranged from −1.57° to 0.15°). Compared with state-of-the-art approaches, the new method offers lower errors in both location and orientation registration. Our method offers highly automated and accurate IVUS pullback registration and can be employed in IVUS-based studies of coronary disease progression, enabling more focal studies of coronary plaque development and transition of vulnerability.

Predicting Locations of High-Risk Plaques in Coronary Arteries in Patients Receiving Statin Therapy

“…Moreover, due to the lack of clinical follow-up, we are unable to directly assess MACE prediction. While our methodology utilizes one of the most advanced and accurate intravascular image co-registration approaches [18], it is still possible that co-registration may not be perfect. Having added the expert-approval of co-registration to the analysis sequence for each pullback minimized this limitation.…”

“…Our validated IVUS pullback registration method established one-to-one correspondences of baseline and follow-up IVUS frame pairs by globally optimizing the registered B-mode image similarity in a geometrically feasible manner [18], [19]. To ensure high registration accuracy for frame-level prediction, we have added a step of semi-automated editing by expert cardiologist.…”

“…Using such long coronary segments fails to reflect the focal nature of clinical events and leads to excessive averaging of focal plaque morphology/composition indices [17]. Recently, we reported a highly-automated approach for frame-to-frame registration of baseline and follow-up IVUS pullback pairs based on 3D graph-based optimization [18]. Validation on 29 IVUS pullback pairs demonstrated registration performance statistically identical to that of human experts [18], [19].…”

“…Recently, we reported a highly-automated approach for frame-to-frame registration of baseline and follow-up IVUS pullback pairs based on 3D graph-based optimization [18]. Validation on 29 IVUS pullback pairs demonstrated registration performance statistically identical to that of human experts [18], [19]. This registration method is employed here, enabling focal studies of coronary atherosclerosis development.…”

Novel quantitative description approaches assessing coronary morphology and development

“…However, this cannot be ensured in reality and both pullbacks need to be matched to provide accurate temporal changes of plaque. Using our recently reported 3D graph optimization approach [77], pairs of serial IVUS pullbacks of the same vessel were registered by implementing a cost function that jointly reflects similarity of vessel/plaque morphology and perivascular image appearance, which included shadow after calcified plaque, coronary branches, passing micro vessels etc.…”