Subtentorial primitive neuroectodermal tumors (PNET) - imaging diagnostics and MR spectroscopy

Primitive neuroectodermal tumors (PNET) belong to embryonal tumors. They often comprise the highly malignant and invasive neoplasms of childhood. The classification of PNET includes medulloblastoma, the most important tumor of posterior fossa and supratentorial primitive neuroepithelial tumor, known as S-PNET. These tumors have a tendency to disseminate throughout CSF and cause subarachnoid metastases, which is associated with low survival rate. We present epidemiologic, clinical and pathogenic aspects of these tumors groups. Computer tomography is the initial modality in diagnosis of PNET, but magnetic resonance imaging is of primary significance. The information about MR spectroscopy application in patients with neuroectodermal neoplasms is scarce. Only in a few articles, based on MRS in vitro and in vivo studies, there was elevated concentration of taurine in spectra of PNETs. Literature data suggest, that MR spectroscopy has relevant value in differential diagnosis and could be useful in assessment of prognosis. In our article we attempt to review the literature concerning neuroectodermal tumors and take ours clinical cases into account. (author)