Article
Certified prototype of an OCT – integrated operating microscope for intraoperative optical tissue analysis
CE-zertifizierter Prototyp eines OCT-integrierten Operationsmikroskops zur intraoperativen Gewebeanalyse
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Authors
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A. Giese
- Neurochirurgische Klinik, Universitätsklinikum Göttingen
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S. R. Kantelhardt
- Neurochirurgische Klinik, Universitätsklinikum Göttingen
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S. Oelckers
- Möller-Wedel, Wedel
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E. Lankenau
- Institut für Biomedizinische Optik, Universität Lübeck
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G. Hüttmann
- Institut für Biomedizinische Optik, Universität Lübeck
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V. Rohde
- Neurochirurgische Klinik, Universitätsklinikum Göttingen
| Published: | May 30, 2008 |
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Outline
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Objective: Optical coherence tomography (OCT) is a non-invasive imaging technique with a micrometer resolution, which can operate with no tissue contact and generate 2, 3, and 4 dimensional image data arrays based on the reflection of infrared laser light. Preclinical studies have demonstrated that OCT may detect tumor during surgical removal of gliomas. We have developed a clinical prototype of an OCT integrated operating microscope in which the OCT laser utilizes the optical path of a modified surgical microscope now suitable for clinical routine use.
Methods: The optical path of the light router of a HR-1000 Möller-Wedel operating microscope was optimized for both the near-infrared and conventional light spectrum. The difference of the refractions of laser and visible light was corrected by adaptation of a dedicated lens system, which maintains full use of zoom and auto-focus function of the microscope. A coherence tomography was integrated into the microscope, which may be fully operated by the neurosurgeon.
Results: OCT imaging of tumor tissue depending on the cellularity of the specimen showed a loss of the light attenuation profile of normal brain. Based on this parameter and the microstructure of the tumor tissue, which was entirely absent in normal tissue, OCT analysis allowed the discrimination of normal brain tissue, invaded brain, solid tumor tissue, and necrosis. In a clinical pilot study OCT analysis of the resection cavity demonstrated residual tumor tissue following macroscopically complete resections, which was confirmed by histological analysis. The OCT integrated microscope remained fully functional for microsurgery and allowed OCT analysis of a 3–50 mm scan line at a zoom factor 2–14.3. OCT – Doppler allowed none-contact measurements of blood flow in capillaries and major vessels.
Conclusions: Integration of optical coherence tomography into an operating microscope allows continuous and immediate tissue analysis of the resection edge during neurosurgical resection of brain tumors and identifies residual tumor prior to secondary changes such as induced by tissue contusion. OCT-Doppler integration further offers functional analysis of blood flow and tissue perfusion through the microscope and therefore extents the information provided beyond conventional operating microscopes today.
