Proton magnetic resonance spectroscopic imaging in pediatric pilomyxoid astrocytoma.

Objects: A pilomyxoid astrocytoma (PmA) is considered to be either a more aggressive variant of a pediatric pilocytic astrocytoma (PA) or a tumor of a separate entity. Methods: We present two cases of pediatric optic-chiasmatic PmA. Proton magnetic resonance spectroscopic imaging (MRSI) of the PmA revealed decreased concentrations of total choline (Cho), creatine (Cr), and N-acetyl aspartate (NAA). In contrast, proton MR spectra of PAs showed elevated Cho and decreased Cr and NAA signals. Conclusion: Low metabolite concentrations in PmAs detected by MRSI may therefore help to distinguish PmAs from PAs preoperatively. [ABSTRACT FROM AUTHOR]