PMC

A 67-year old glioblastoma patient prior to adjuvant chemotherapy (images on the left). After two cycles of temozolomide chemotherapy (images on the right), a clear decrease of both the metabolically active tumor volume and tumor/brain ratios can be observed whereas conventional MRI shows no change of contrast enhancement (“stable disease” according to RANO criteria).

A 52-year-old patient with a progressive anaplastic oligoastrocytoma according to the WHO classification 2007 (top row). During follow-up after 8 and 12 months (middle and bottom row) of biweekly bevacizumab therapy, MRI shows a markedly reduction of contrast enhancement and T2 hyperintensity. Correspondingly, FET PET shows a decrease of metabolic activity by means of maximum tumor/brain ratio reduction (TBR_max).

Patient with a newly diagnosed glioblastoma. After resection and chemoradiation with temozolomide, MR and FET PET images show residual tumor in the left frontal lobe (baseline imaging for radiotherapy planning) with complete metabolic response 10 weeks after radiotherapy. The residual contrast-enhancing lesion is metabolically inactive (arrows) indicating a post-treatment effect. This is confirmed 22 months later with complete resolution of this lesion.