Video Object Segmentation with Optimal Frame Auto-selection Based on Prior Knowledge for Midbrain Assessment in Transcranial Ultrasound

Transcranial sonography (TCS) provides a non-invasive means of assessing movement disorders such as Parkinson's disease (PD). However, current TCS-based evaluations rely heavily on manual operation by experienced physicians, making the process time-consuming and physician-dependent. For the first time, we aimed to develop a hybrid pipeline for real-time video object segmentation (VOS) and automatic optimal frame selection. Eighty-three standardized TCS real-time data comprising 1,992 midbrain frames from Beijing Tiantan Hospital were collected. We adopted three state-of-the-art VOS models (STCN, RDE-VOS, and XMEM) and incorporated anatomical priors to guide optimal frame selection. Specifically, we leveraged the anatomical trend of midbrain morphology to estimate the midbrain radius at the optimal frame and selected the frame where the VOS-segmented midbrain best matched this estimate. The XMEM-based pipeline achieved high segmentation performance (Jaccard: 0.85, Boundary Accuracy: 0.95, Dice: 0.92) and optimal frame selection (Distance: 4.87; Jaccard: 0.92), with efficiency (51.05 FPS, 0.56 s/patient, 661.55 MB). Subgroup analyses confirmed robustness across image quality and PD conditions. Assessment of a junior physician's selection suggests potential to reduce the expertise gap in optimal frame selection. The proposed hybrid pipeline offers an automated tool for midbrain assessment using TCS, which may help reduce physicians' workload and minimize subjectivity, particularly supporting junior physicians in mitigating the expertise-demanding nature of TCS. This approach may serve as a foundation for more promising TCS-based assessments in the future, contributing to broader adoption of non-invasive ultrasound techniques in PD evaluation.