Proton magnetic resonance spectroscopy of brain lesions in children with neurofibromatosis type 1

Two of the recognized cranial MRI findings in children with neurofibromatosis type 1 (NF1) are neurofibromatosis bright objects (NBO) and brain glioma. Their differential diagnosis can be problematic. This study aimed to determine the features of these abnormalities on short echo-time in-vivo proton magnetic resonance spectroscopy. Twenty children under the age of 16 with NF1 were studied. A single voxel, short echo-time technique (TE = 20 ms; TR = 5000 ms) was used to obtain proton spectra of typical NBO and any regions suggestive of atypical bright objects or tumor. Nine children without neurofibromatosis with no structural brain abnormality acted as aged-matched comparisons. A semi-quantitative analysis indicated significant increase in choline and myo-inisitol in tumors compared to typical NBO (p < 0.05) and compared to controls (p < 0.05); reduction in the levels of N-acetyl moieties in NBO compared to controls (p < 0.05); reduction in N-acetyl in tumors compared to controls (p < 0.001); and reduction in glutamate/glutamine in tumors compared to controls (p < 0.05). This cross-sectional data suggests that proton spectroscopy can aid differentiating between NBO and brain (non-optic/hypothalamic) glioma. Typical NBO have different short echo-time spectroscopic appearances compared to normal brain.