PET-METHIONINE OF SKULL BASE NEUROMAS AND MENINGIOMAS

Eighteen patients with intracranial skull base tumours diagnosed at CT or MR as neuromas or meningiomas were studied with positron emission tomography (PET) using L-(methyl-C-11) methionine. Compared with norma l cerebellar tissue, the uptake of methionine in the tumours increased more rapidly and reached a higher level, and showed a slow decline af ter a peak occurring about 5 min after the injection. All the meningio mas exhibited considerably higher accumulation of the tracer compared with the surrounding cerebellar tissue, which made the tumour easy to identify and to demarcate from the surrounding cerebellar tissue, whic h made the tumour easy to identify and to demarcate from the surroundi ng structures (tumour to cerebellum ratios 2.62-5.37, mean 3.63). The uptake was homogeneous in all meningiomas, which were all of the syncy tial type. The neuromas showed lower contrast against the cerebellum ( tumour to cerebellum ratios 1.1-1.87, mean 1.48). Some neuromas displa yed an irregular pattern with regions of decreased tracer uptake corre sponding to small cystic areas within the neuroma. There was no overla p in methionine uptake between the two tumour groups. The results indi cate that PET-methionine may contribute to the evaluation, treatment p lanning and follow-up of patients with skull base meningiomas and neur omas.