Correlation of Intraoperative 5-ALA-Induced Fluorescence Intensity and Preoperative 11C-Methionine PET Uptake in Glioma Surgery
K. Shimizu, Kaoru Tamura, Shoko Hara, Motoki Inaji, Yoji Tanaka, Daisuke Kobayashi, Takashi Sugawara, Hiroaki Wakimoto, Tadashi Nariai, Kenji Ishii, Ichiro Sakuma, Taketoshi Maehara
Abstract
BACKGROUND: C-methionine (MET-PET) represents the activity of brain tumors with precise boundaries but is not readily available. We hypothesized that quantitative 5-ALA-induced fluorescence intensity might correlate with MET-PET uptake in gliomas. METHODS: Adult patients with supratentorial astrocytic gliomas who underwent preoperative MET-PET and surgical tumor resection using 5-ALA were enrolled in this prospective study. The regional tumor uptake of MET-PET was expressed as the ratio of standardized uptake volume max to that of the normal contralateral frontal lobe. A spectrometric fluorescence detection system measured tumor specimens' ex vivo fluorescence intensity at 635 nm. Ki-67 index and IDH mutation status were assessed by histopathological analysis. Use of an antiepileptic drug (AED) and contrast enhancement pattern on MRI were also investigated. RESULTS: Thirty-two patients, mostly with Glioblastoma IDH wild type (46.9%) and anaplastic astrocytoma IDH mutant (21.9%), were analyzed. When the fluorescence intensity was ranked into four groups, the strongest fluorescence group exhibited the highest mean MET-PET uptake and Ki-67 index values. When rearranged into fluorescence Visible or Non-visible groups, the Visible group had significantly higher MET-PET uptake and Ki-67 index compared to the Non-visible group. Contrast enhancement on MRI and IDH wild type tumors were more frequent among the Visible group. AED use did not correlate with 5-ALA-induced fluorescence intensity. CONCLUSIONS: In astrocytic glioma surgery, visible 5-ALA-induced fluorescence correlated with high MET-PET uptake, along with a high Ki-67 index.