Purpose
Microscope-integrated optical coherence tomography (MIOCT) allows intraoperative visualization of tissue microstructure and provides real-time feedback for clinical decision making during surgery. However, the potential for OCT-guided surgical maneuvers has been limited by imaging speed, which can only display single cross-sectional images at video-rates. While recent advances in laser technology have been used to image several 3D volumes per second, the acquisition and image rendering rates are still insufficient for unguided intraoperative use. We demonstrate real-time tracking of conventional ophthalmic surgical instruments and a feedback system for guided video-rate cross-section imaging using a MIOCT system.
Methods
A digital tracking system was designed using HSV-masked feature extraction. Conventional ophthalmic surgical instruments were modified using retro-reflective materials, which provided consistent contrast and tracking markers on the documentation camera video stream of a surgical microscope. An open-loop control circuit was built to introduce positional offsets to the scanning mirrors of the MIOCT based on the position of the tracked instrument (Fig. 1). Instrument tracked MIOCT was assessed with cadaveric porcine eyes.
Results
Successful implementation of the tracking system allowed for real-time positioning of MIOCT cross-sectional scans at the instrument tip with an optimal scan orientation (e.g., parallel and/or perpendicular to the instrument axis) (Fig. 1). This system allows for rapid visualization of tissue-instrument interactions at the point of contact, providing feedback on positioning, depth of penetration, and tissue compression.
Conclusions
Real-time instrument tracked MIOCT imaging can provide valuable feedback during surgical maneuvers. This is a critical milestone for seamless integration of intraoperative OCT into the surgical environment. Cross-sectional imaging at the point of contact between the tissue and surgical instrument can potentially help guide surgical decision-making and allow for novel surgical techniques that require precision manipulation of specific tissue layers and microstructures. Our implementation is agnostic to the underlying OCT technology, which simplifies its clinical translation and integration with the current clinical systems.
Keywords: 551 imaging/image analysis: non-clinical •
552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)