3.01] 3-D intraoperative imaging combining an operating microscope with optical coherence tomography (OCT)

Abstract

Objective Optical coherence tomography (OCT) allows non-contact/non-invasive analysis of tissues with a penetration depth of 2–3 mm reaching a spatial resolution of approximately 4–15 μm. This resolution is compatible with the resolution of modern operation microscopes. Aim of this work was to provide a three-dimensional (3D) intraoperative visualization of tissue structures. Material and methods A high-speed spectral domain OCT (a modified version of the Ganymed, Thorlabs HL) was adapted to a motorized operation microscope (HR 1000, Moller-Wedel). Via a specially designed two axis-scanner, the 840 nm OCT was adapted directly to a camera port of the operation microscope. Group velocity dispersion of the microscope optics was compensated successfully to provide bandwidth-limited depth resolution. Together with a step motor-controlled reference arm, an automatic control of the working distance (232–290 mm), the scan field (4–24 mm) and the position of the OCT focus within the sample is possible. Results The system allows a 3-D visualization of OCT imaged during the surgical procedure. The OCT images were provide to the surgeon via a special video ocular in the surgical microscope. This new device was tested successfully in a preclinical setting with different ENT tissues to evaluate the principle. Conclusion It may be used during brain tumor surgery, tumor surgery of the vocal cords, the placement of cochlear transplants or during bone surgery in the middle ear.