Differentiation of choroid plexus tumors by advanced magnetic resonance spectroscopy.

OBJECT: The management of pediatric intraventricular tumors is highly dependent on identification of the tumor type. Choroid plexus papillomas, a common intraventricular tumor in children, can be difficult to distinguish radiographically from choroid plexus carcinomas and other common pediatric central nervous system (CNS) tumors. In this study to overcome the limitations of current noninvasive imaging modalities, the authors use novel magnetic resonance (MR) spectroscopy techniques in vivo to elucidate the identifying biochemical features of choroid plexus tumors that may facilitate diagnosis and treatment. METHODS: Based on an Internal Review Board-approved protocol, six children with newly diagnosed, untreated intraventricular brain tumors were identified. On retrospective review, this series included three choroid plexus papillomas and three choroid plexus carcinomas. Single-voxel proton MR spectroscopy with a short echo time was performed, and absolute metabolite concentrations (in mmol/kg) were determined using fully automated quantitation. These results were compared with MR spectroscopy profiles obtained in 54 other untreated CNS neoplasms in children. The myo-inositol (mI) level was significantly higher in choroid plexus papillomas (> 10 mmol/kg), uniquely distinguishing these tumors from choroid plexus carcinomas and all other tumors. Choroid plexus carcinomas, on the other hand, had significantly elevated levels of choline when compared with choroid plexus papillomas. CONCLUSIONS: In this study the authors find that mI is a biochemical constituent that uniquely identifies choroid plexus papillomas and can be used as a noninvasive means of diagnosis and for follow-up evaluations in patients with this disease.