Article
Intraoperative localization of stimulated functional brain areas by optical imaging
Intraoperative Lokalisation stimulierter Hirnareale durch Optical Imaging
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Authors
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S.B. Sobottka
- Klinik für Neurochirurgie, Universitätsklinikum Dresden
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T. Meyer
- Institut für Biomedizinische Technik, Technische Universität Dresden
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E. Koch
- Klinisches Sensoring und Monitoring, Technische Universität Dresden
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R. Steinmeier
- Klinikum Chemnitz gGmbH
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U. Morgenstern
- Institut für Biomedizinische Technik, Technische Universität Dresden
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G. Schackert
- Klinik für Neurochirurgie, Universitätsklinikum Dresden
| Published: | April 11, 2007 |
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Outline
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Objective: Optical imaging of cortical activity is a new method for a fast and contact free visualization of stimulated eloquent brain areas during neurosurgical interventions.
Methods: The intensity of the light reflected by the cortical tissue was measured in 13 patients with lesions around the somatosensory, visual or speech cortex using a high resolution CDD camera (Hamamatsu Photonics: EB-CCD C7190-13W and C4742-96) mounted to an operating microscope. Using adequate stimulation methods, the difference in the spectral absorption was used to differentiate between activated and non-activated brain areas. The data acquisition time was 9 minutes with alternating 30 seconds with and without stimulation. The difference between averaged frames was calculated and overlaid over an image of the operative site. Brain movements associated with heartbeat and respiration were compensated using a deformable registration algorithm.
Results: An EB-CCD camera turned out to be unsuitable for intraoperative optical imaging due to its high photosensitivity and the resulting reflection highlights. A C4742 camera was more suitable, however, the exposure time per frame had to be increased, which sometimes led to blurred images caused by the movement artefacts. The intraoperative numerical analysis of the acquired image data sets showed the localized activation of cortical tissue. The calculated location and the size of the activated region corresponded to the results derived by electrophysiological examinations and confirmed the estimation of the neurosurgeon. Most successful were the stimulations of the somatosensory and visual cortex. In some patients no activation of cortical tissue could be deciphered.
Conclusions: Optical imaging provides an intraoperative high spatial resolution image of brain surface activation, allowing the localization of eleoquent brain areas during surgery. Interestingly, the type of pathology seems to influence the perfusion of the surrounding tissue, so that changes between activation and rest may not be detectable in some cases.
