The differential diagnosis by 18F-FDG PET between WHO grades III/IV gliomas and brain metastases is limited, since considerable overlap of SUVmax exists between these tumor types 1)
18F-FDG PET also has limited specificity for distinguishing glioma from other nonneoplastic lesions, such as brain abscesses, demyelinating tumefactive (“tumor-like”) lesions, fungal infections, and neurosarcoidosis 2) due to increased 18F-FDG metabolism in inflammatory tissue.
The precise definition of the post-operative resection status in high-grade gliomas (HGG) is crucial for further management. We aimed to assess the feasibility of assessment of the resection status with early post-operative positron emission tomography (PET) using [18F]O-(2-[18F]-fluoroethyl)-L-tyrosine ([18F]FET).
25 patients with the suspicion of primary HGG were enrolled. All patients underwent pre-operative [18F]FET-PET and magnetic resonance imaging (MRI). Intra-operatively, resection status was assessed using 5-aminolevulinic acid (5-ALA). Imaging was repeated within 72h after neurosurgery. Post-operative [18F]FET-PET was compared with MRI, intra-operative assessment and clinical follow-up.
[18F]FET-PET, MRI and intra-operative assessment consistently revealed complete resection in 12/25 (48%) patients and incomplete resection in 6/25 cases (24%). In 7 patients, PET revealed discordant findings. One patient was re-resected. 3/7 experienced tumor recurrence, 3/7 died shortly after brain surgery.
Early assessment of the resection status in HGG with [18F]FET-PET seems to be feasible 3).