gms | German Medical Science

Objective: PET using ¹⁸F FET (fluoroethyl-L-tyrosine) and ¹⁸F-FDG (fluoro- desoxyglucose) are widely used for non-invasive preoperative grading of glial brain tumors. However, the correlation of FDG and amino acid PET uptake with histological grade in pure oligodendrogliomas is discussed controversially. Thus, we retrospectively investigated this relationship in patients suffering from pure oligodendrogliomas

Method: Altogether, twelve patients (8 female, 4 male, mean age 37, from 21–69) surgically treated during the last 4 years had pure oligodendrogliomas. Preoperative ¹⁸F-FET PET and ¹⁸F-FDG PET uptake areas were correlated to the histological grading of intraoperatively collected tissue samples during resection using image fusion and navigation.

Results: Out of 12 patients harboring pure oligodendrogliomas, 5 were graded as low-grade tumors (WHO II) and 7 as anaplastic tumors (WHO III). All tumors but one (11/12) had a strong FET uptake, irrespective of the histological grade. Standard uptake values (SUV) of grade II tumors were 1.5 mean (1.3–1.7), in grade III tumors 2.1 mean (1.6–2.6), differences not significant (p=0.06). Only one oligodendroglioma III showed FDG uptake, 6 out of 7 anaplastic oligodendrogliomas (grade III) and all low-grade tumors were FDG negative.

Conclusions: Pure oligodendrogliomas in our series demonstrated strong FET uptake, irrespective of the histological grading, whereas FDG PET was not useful in separating high-grade pure oligodendrogliomas from low-grade tumors.