Metabolic imaging of patients with intracranial tumors: H-1 MR spectroscopic imaging and PET

Hydrogen-1 magnetic resonance (MR) spectroscopic images of patients with intracranial tumors were obtained. Metabolite maps of N-acetyl aspartate, choline, lactate, and creatine concentrations were reconstructed with a nominal spatial resolution of 7 mm and a section thickness of 25 mm. The metabolite maps showed variations in metabolite concentrations across the tumor. In one patient, it was observed that choline concentration was increased in one part of the tumor but decreased in another part. In another patient, the concentration of N-acetyl aspartate was extremely low in one part of the tumor but only slightly increased in another part of the tumor. Lactate was observed in all patients. In one patient, a combined measurement made with positron emission tomography (PET) and MR spectroscopic imaging was performed. This demonstrated that increased lactate concentration measured with H-1 MR spectroscopic imaging corresponded topographically with increased glucose uptake measured with fluorine-18 fluoro-2-deoxyglucose PET. Combined MR spectroscopic and PET measurements provide an opportunity to investigate, in greater detail than before, glucose uptake and catabolism by intracranial tumors.