RT Journal Article SR Electronic T1 Operated low grade astrocytomas: a long term PET study on the effect of radiotherapy JF Journal of Neurology, Neurosurgery & Psychiatry JO J Neurol Neurosurg Psychiatry FD BMJ Publishing Group Ltd SP 644 OP 647 DO 10.1136/jnnp.66.5.644 VO 66 IS 5 A1 U Roelcke A1 K von Ammon A1 O Hausmann A1 D L Kaech A1 W Vanloffeld A1 H Landolt A1 J A Rem A1 O Gratzl A1 E W Radü A1 K L Leenders YR 1999 UL http://jnnp.bmj.com/content/66/5/644.abstract AB The role of postoperative radiotherapy in patients with low grade gliomas is not established yet. PET with 11C methionine (MET) and 18F fluorodeoxyglucose (FDG) was used to perform cross sectional comparisons as well as within patient follow up studies in 30 operated patients with fibrillary astrocytoma WHO II. Uptake of tracer by tumour was quantified by radioactivity concentration ratios in tumour over contralateral brain (T/C). Comparing patients who did (n=13) or did not (n=17) receive external radiotherapy subsequent to first tumour resection, no differences in MET and FDG T/C between both groups were found during a postoperative period of 94 months (when recurrence and malignant progression of low grade astrocytomas are expected). Malignant progression occurred at a similar rate in both patient groups at a mean (SD) postoperative interval of 46 (26) months. Irrespective of whether radiotherapy was applied or not, malignant tumour recurrences showed higher T/C values (MET: 1.70 (0.64), FDG: 0.98 (0.23)) than recurrences without signs of malignancy (MET: 1.21 (0.21), FDG: 0.82 (0.08)) (Mann-Whitney: MET p=0.086, FDG p=0.035). The data show a relative lack of radiotherapy administered immediately after first tumour resection. In the course of disease, patients with tumours undergoing malignant progression may be identified with PET tracer methods.