Step-wise identification of ultrasound-visible anatomical landmarks for 3D visualization of scoliotic spine

摘要

PURPOSE: Identification of vertebral landmarks with ultrasound is a challenging task. We propose a step-wisecomputer-guided landmark identification method for developing 3D spine visualizations from tracked ultrasound images.METHODS: Transverse process bone patches were identified to generate an initial spine segmentation in real -time from live ultrasound images. A modified k-means algorithm was adapted to provide an initial estimate of landmarklocations from the ultrasound image segmentation. The initial estimations using the modified k-means algorithm do notalways provide a landmark on every segmented image patch. As such, further processing may improve the result capturedfrom the sequences, owing to the spine’s symmetries. Five healthy subjects received thoracolumbar US scans. Their realtimeultrasound image segmentations were used to create 3D visualizations for initial validation of the method.RESULTS: The resulting visualizations conform to the parasagittal curvature of the ultrasound images. Our processingcan correct the initial estimation to reveal the underlying structure and curvature of the spine from each subject. However,the visualizations are typically truncated and suffer from dilation or expansion near their superior and inferior-most points.CONCLUSION: Our methods encompass a step-wise approach to bridge the gap between ultrasound scans, and 3Dvisualization of the scoliotic spine, generated using vertebral landmarks. Though a lack of ground-truth imaging preventedcomplete validation of the workflow, patient-specific deformation is clearly captured in the anterior-posterior curvatures.The frequency of user-interaction required for completing the correction methods presents a challenge in moving towardsfull automation and requires further attention.