Rosenberg DS et al. (2005) [11C]-methionine PET: dysembryoplastic neuroepithelial tumours compared with other epileptogenic brain neoplasms. J Neurol Neurosurg Psychiatry 76: 1686–1692

Drug-resistant partial epilepsy arises from epileptogenic tumors, many of which are nonprogressive dysembryoplastic neuroepithelial tumors (DNTs). Preoperative DNTs are difficult to define, and misclassifications can result in unnecessary and potentially hazardous therapy. In a prospective study of 27 patients who had shown epileptic symptoms for at least 6 months, Rosenberg et al. tested whether [11C]-methionine (MET)-PET could distinguish DNTs from gliomas and gangliogliomas.

In each study patient, tumor [11C]-MET uptake was compared with uptake in the surrounding and contralateral homotopic regions of the brain, and was graded as normal, moderately increased, or markedly increased. MET-PET analysis showed significant differences between the DNT (n = 11), ganglioglioma (n = 5) and glioma (n = 11) tumor types (P <0.0002): moderately or markedly increased [11C]-MET uptake was observed in all gliomas and gangliogliomas, whereas 7/11 DNTs had normal uptake and 4/11 DNTs had moderate uptake.

The data indicate that nonprogressive epileptogenic tumors with normal MET-PET readings are likely to be DNTs, whereas those with markedly increased [11C]-MET uptake readings are likely to be of a different tumor type. MET-PET might therefore be a clinically useful tool for identifying DNTs and for obtaining reliable information on the pathology of epileptogenic brain tumors. MET-PET could help pathologists to diagnose difficult DNT cases and might assist in making decisions as to whether surgical removal of tumors is necessary.