Artikel
Intraoperative optical imaging – possibilities and limitations of the method during awake surgery
Intraoperative optische Bildgebung – Möglichkeiten und Grenzen der Methode bei Wachoperationen
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Veröffentlicht: | 26. Juni 2020 |
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Gliederung
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Objective: Intraoperative Optical Imaging (IOI) is a marker free and non-invasive imaging technique that can be utilized for visualization of metabolic changes within the cerebral cortex. In the past, we used the technique for the identification of functional brain areas while the patients were under general anesthesia. In this work, we investigated the potential of the method for surgical decision-making during awake surgery.
Methods: Measurements in 10 patients that underwent surgical resection of lesions near or within cortical language or motor processing sites were performed. IOI was applied in three different scenarios: identification of motor areas using finger tapping tasks, identification of language areas using speech tasks (overt and silent speech), and a novel approach - the application of IOI as a visual feedback tool during direct electrical stimulation (DES) mapping of language. The functional maps (activity maps), calculated from the IOI data for the speech and motor tasks were qualitatively compared towards the preoperative acquired fMRI and the electrophysiological testing results during the surgical procedure. Additionally, the extent of activation during language mapping with DES was quantized.
Results: The results reveal that the intraoperative identification of motor sites is possible in good agreement to fMRI and the intraoperative electrophysiological measurements. The identification of language processing sites with IOI was also possible, but in the majority of cases, significant differences between fMRI, IOI, and DES were visible. During language mapping procedure with DES, we were able to visualize and calculate the spatial extent of activation for each single stimulation. A high inter-stimulation variability was observed (range of activated area: Amin = 44mm2 to Amax = 155mm2, no. of stimulations n=15).
Conclusion: A promising new application of IOI is the combined use with DES during the standard language mapping procedure. Here, IOI is able to provide visual feedback about the extent of each single stimulated area. This might enable the surgeon to optimize the mapping process in the future. The application of the technique for motor site identification seems to be also promising and beneficial for the surgery. According to our findings, the results of the speech tasks are too unspecific to be useful for intraoperative decision-making in respect to exact language localization. Here DES mapping will remain the method of choice.