A comparison between in vivo and ex vivo HR-MAS 1H MR spectra of a pediatric posterior fossa lesion

The present case report was aimed at identifying the molecular profile characteristic of a primitive neuroectodermal tumor(PNET) in a 3-year-old child affected by a lesion localized in the cerebellar region. The histological diagnosis was medulloblastoma. In vivosingle voxel 1 H magnetic resonance spectroscopy (MRS) shows high specificity in detecting the main metabolic alterations in the primitive cerebellar lesion; a very high amount of the choline-containing compounds and very low level of creatine derivatives and N-acetylaspartate. Ex vivohigh resolution magic angle spinning(HR-MAS) 1 H magnetic resonance spectroscopy, performed at 9.4 Tesla on the neoplastic specimen collected during surgery, allows for the unambiguous identification of several metabolites giving a more in-depth evaluation of the metabolic pattern of the lesion. The ex vivoHR-MAS MR spectra show that the spectral detail is much higher than that obtained in vivoand that, for example, myo-inositol, taurine and phosphorylethanolaminecontribute to the in vivosignal at 3.2 ppm, usually attributed to choline-containing compounds. In addition, the spectroscopic data appear to correlate with some morphological features of the medulloblastoma. Consequently, the present study shows that ex vivoHR-MAS 'H MRS is able to strongly improve the clinical possibility of in vivoMRS and can be used in conjunction with in vivospectroscopy for clinical purposes.