Brain tumors: L-[1-C-11]tyrosine PET for visualization and quantification of protein synthesis rate.

Abstract

Positron emission tomography (PET) with the amino acid tracer L-[1-C-11]-tyrosine was evaluated in 27 patients with primary and recurrent brain tumors. Patients underwent either static (n = 14) or dynamic PET (n = 13), with quantification of protein synthesis rate (PSR) and tumor-to-background ratio. Findings were compared with histologic findings. Primary brain tumor was proved in 22 patients histologically, as well as metastatic cancer of unknown origin, primary non-Hodgkin lymphoma, meningioma, atypical infarction, and vasculitis in one patient each. At PET, 20 of 22 primary tumors, the metastasis, and non-Hodgkin lymphoma were correctly depicted. A false-positive finding was obtained with the infarction, and the meningioma and vasculitis were not depicted. The calculated sensitivity was 92%; specificity, 67%; and accuracy, 89%. There were no statistically significant relationships between histologic findings, PSR, and tumor-to-background ratio. L-[1-C-11]-tyrosine is a valid tracer for diagnosis of brain tumors and allowed quantification of PSR.