Multimodal neuroimaging of gliomatosis cerebri: a case series of four patients

In the latest World Health Organization classification of brain tumors, gliomatosis cerebri has been redefined to varying subsets of diffuse gliomas; however, the term is still used to describe gliomas with infiltrative growth into three or more cerebral lobes. These tumors are frequently misdiagnosed and difficult to treat due to their atypical presentation using structural imaging modalities including computed tomography and T1/T2-weighted magnetic resonance imaging (MRI). In this retrospective case series, we compared clinical MRI to amino acid positron emission tomography (PET) to assess the potential value of PET in the assessment of the extent of tumor involvement and in monitoring disease progression. We report the clinical course and serial multimodal imaging findings of four patients. Each patient presented at varying points in disease progression with widespread glioma brain involvement and was evaluated at least once by amino acid PET using alpha-[(11)C]methyl-L-tryptophan ([(11)C]-AMT). Increased uptake of [(11)C]-AMT was detected in a subset of non-enhancing brain lesions and detected tumor invasion before MRI signs of tumor in some regions. Increased uptake of [(11)C]-AMT was also detected in tumorous regions not detected by perfusion MRI or MR spectroscopy. Metabolic response to treatment was also observed in two patients. Overall, these data are consistent with and expand upon previous reports using other amino acid PET tracers in gliomatosis and show the potential added value of this imaging modality to clinical MRI in the detection and monitoring of these diffusely infiltrative tumors.