Hybrid retargeting for high-speed targeted optical biopsies

Abstract

With the increasing maturity of optical biopsy techniques, routine clinical use has become more widespread. This wider adoption of the technique demands effective tracking and retargeting of the biopsy sites, as no visible markers are left following examination. This study presents a high-speed framework for intra-procedural retargeting of probe-based optical biopsies in gastrointestinal endoscopy. A probe tip localisation method using active shape models and geometric heuristics, which eliminates the traditional dependency on shaft visibility, is proposed for automated initialisation. Partial occlusion and tissue deformation are addressed by exploiting the benefits of indirect and direct tracking through a novel combination of geometric association and online learning. Robustness to rapid endoscope motion and improvements in computational efficiency are achieved by restricting processing to the automatically detected video content area and through a feature-based rejection of non-informative frames. Performance evaluation in phantom and in-vivo environments demonstrates accurate biopsy site initialisation, robust retargeting and significant improvements over the state-of-the- art in processing time and memory usage.