Comparative analysis of 5-ALA-induced fluorescence intensity and 11C-Methionine PET uptake in glioma surgery

摘要

Background: 5-aminolevulinic acid (5-ALA) induces red fluorescence in malignant brain tumors that has been used forintraoperative guidance for tumor removal. Positron emission tomography with 11C-Methionine (Met-PET) is apromising imaging modality to depict clear boundary of infiltrating glioma. We studied the correlation betweenpreoperative Met-PET uptake and intraoperative 5-ALA fluorescence.Method: Patients who underwent preoperative Met-PET study and tumor removal using 5-ALA over a period of twoyears were analyzed. The regional uptake of Met-PET was expressed as the ratio of the maximum of standardized uptakevalue (SUV-max) to the contralateral normal brain. 5-ALA fluorescence from tumor sample was immediately measuredduring surgery using blue laser and spectrometer. Fluorescence intensity was categorized into four groups (None, Weak,Moderate, Strong) with ten-hold differences.Results: 16 cases with pathological diagnosis of astrocytic tumors were analyzed. Met-PET uptake was markedly high in“Strong” fluorescence group (3.81±0.77). Particularly, among 11 newly-diagnosed cases, the difference was statisticallysignificant (p=0.017, Kruskal-Wallis test). “Strong” fluorescence group still showed significant difference whencompared with other groups together, in all cases and newly-diagnosed cases (p=0.01 and p=0.004, respectively, Mann-Whitney U test).Discussion/Conclusion: There are limited number of reports regarding 5-ALA and Met-PET, stating that Met-PET and 5-ALA fluorescence should be considered separately. However, the fluorescence was grossly distinguished whetherpositive or negative. Our study utilized objective spectroscopic measurement of fluorescence intensity. The resultssuggested that strong fluorescence intensity induced by 5-ALA reflects high Met-PET uptake. This could indicate theimportance of bright fluorescence by 5-ALA in glioma surgery.