Use of [¹⁸F]fluorodeoxyglucose positron emission tomography in patients with primary malignant brain tumors

In patients with malignant gliomas, [¹⁸F]fluorodeoxyglucose positron emission tomography (FDG‐PET) may discriminate tumor progression from radionecrosis. We evaluated data from 50 patients undergoing FDG‐PET for suspicion of tumor progression. Forty‐nine were treated with surgery, 48 with radiotherapy, and 37 with chemotherapy. Twenty‐one had intensive radiotherapy with either three daily treatments in two 5‐day periods and intravenous carboplatin (17) or interstitial brachytherapy or stereotactic radiotherapy. Twenty underwent surgery after magnetic resonance imaging/FDG‐PET; 9 demonstrated increased uptake of FDG and evidence of tumor, whereas 6 had decreased uptake and no evidence of tumor. In 5 patients, there was no correlation (all had intensive radiotherapy). In 17 patients who received bromodeoxyuridine intravenously just before surgery, the bromodeoxyuridine labeling index corresponded to the histological appearance in all but 2 patients (both had received intensive radiotherapy). In 30 patients without surgery, decreased uptake of FDG suggested prolonged survival; increased uptake of FDG did not predict survival. Eight of 10 with intensive radiotherapy had decreased label uptake. We conclude FDG‐PET for evaluation of patients with possible recurrent tumors requires more study. In patients with intensive radiotherapy, FDG‐PET results cannot be correlated accurately with tumor progression.