18F-FDG PET/CT usefulness vs Tc99m-Tetrofosmin in the assessment of malignant brain gliomas: Report of two cases

Gliomas account for almost 80% of primary malignant brain tumors in adults. Magnetic Resonance imaging (MRI) is still the gold standard for diagnosis of brain tumors and brain 99mTc-tetrofosmin Single Photon Emission Computed Tomography (99mTc-tetrofosmin-SPECT) has been established as a useful tool for their evaluation. Fluorine-18-2-fluoro-2-deoxy-dglucose positron emission tomography/computed tomography (18F-FDG PET/CT) provides non-invasive information for staging, clinical assessment and prognosis of glial tumors. We report 2 cases of patients with brain lesions described on MRI suspected for malignancy, however 99mTc-tetrofosmin-SPECT that didn't show any lesion, 18F-FDG PET/CT revealed radiotracer uptake that supported the hypothesis of malignant gliomas, confirmed later by biopsy. Our cases confirm 18FFDG PET/CT may be useful for differentiating common enhancing malignant brain tumors and is recommended when differential diagnoses are difficult to narrow using MRI and 99mTc-tetrofosmin-SPECT. 18F-FDG PET/CT can be used to characterize their aggressiveness and to detect a more feasible site for a stereotaxic biopsy. It yields supplementary noninvasive information to conventional imaging useful in the clinical decision-making.