gms | German Medical Science

Objective: Positron emission tomography (PET) is able to depict accurately the metabolic properties of brain tumors and the localization of eloquent areas for speech and motor function. The aim of our study was to present the potentials of PET-guided neuronavigation in glioma surgery, especially concerning tumors in eloquent areas, ill-defined lesions and tumor recurrences.

Methods: In twelve patients with intrinsic brain tumors, intraoperative neuronavigation (BrainLAB) was based on the coregistration of [¹¹C]methionine PET and thin-sliced MRI scans, and [¹⁵O]water PET for the spatial localization of motorcortex and speech areas. In all cases, the tumor and its “hot spot” (i.e. the area of highest [¹¹C]methionine uptake) were defined by setting arbitratry thresholds of metabolic tumor activity. In lesions bordering on eloquent areas, the operation was performed under local anesthesia with continuous neuropsychologial monitoring and by the use of brain-mapping techniques.

Results: Although the tumor border was not clearly defined in the MRI, [¹¹C]methionine PET demonstrated clear tumor margins in all cases. By the simultaneous use of PET-guided neuronavigation by coregistrating metabolic and functional data, the application of electrophysiological techniques and neuropsychological monitoring, all tumors could be resected safely even in highly eloquent areas, i.e. gliomas in the precentral gyrus or Wernicke´s area. Three patients showed a widespread and diffusely infiltrating glioma not amenable to surgery by conventional means. By selectively resecting those regions of highest metabolic acitivity in these cases determined by the quantitative tracer-uptake in [¹¹C]methionine PET, the tumors could be depleted of their prognostically most significant components. In cases of a recurrence and an ill-defined tumor delinement on MRI, [¹¹C]methionine PET was particularly useful in differentiating between tumor and gliosis, thus being indispensible for defining the tumor margins for neuronavigation.

Conclusions: PET-guided neuronavigation in glioma surgery makes it possible to resect the metabolically active tumor components and simultaneously preserve relevant functional brain areas, even in ill-defined lesions. The approach may decrease perioperative morbidity and optimize the extent of tumor resection.