[O-15]-WATER PET AND INTRAOPERATIVE BRAIN MAPPING - A COMPARISON IN THE LOCALIZATION OF ELOQUENT CORTEX

[O-15]-water PET was performed on 12 patients with structural lesions for localization of the motor (n = 5), language (receptive and express ive; n=6), and visual cortex (n=1). All these patients underwent inter active image-guided surgery using an infrared digitizer and intraopera tive electrical stimulation mapping for motor, sensory, language, and visual cortex location. MRI-PET coregistration was performed using a s urface matching approach that integrated functional information with i nteractive image guidance during the surgical procedure. An a wake cra niotomy with motor and sensory intraoperative stimulation was performe d using a registered bipolar electrode that was tracked on real-time d uring the surgical procedure. Intraoperative functional findings were displayed and saved on the registered MRI images. The sires of functio nal PET activation during the performance of motor, visual and languag e tasks were then compared to the results of intraoperative cortical s timulation in 11 patients and visual evoked potentials in one. The res ults of the PET activation studies were concordant with the findings o f intraoperative stimulation in all cases. During resection of the str uctural lesions, intraoperative stimulation was continued in the subco rtical pathways, and five patients had positive responses on areas not identified by the functional PET. Furthermore, 3 patients showed tran sitory changes in function (speech arrest 1, naming difficulty 1, and motor weakness 1) that were reversible after changing the dissection t echnique or a brain retractor. [O-15]-water PET was reliable in identi fying the motor, visual, and language cortex. Language-related rCBF in creases were highly distributive, although only part of these activati ons were subjected to intraoperative stimulation. We conclude that [O- 15]-water PET can be used for preoperative noninvasive identification of functional cortex and may be useful in neurosurgical preplanning. I ntraoperative mapping still remains the main means to avoid neurologic al damage as it can be performed during the entire surgical procedure to avoid damage to cortex, pathways, and damage secondary to ischemia or edema (brain retraction).