Quantitative F18-Fluorodeoxyglucose Positron Emission Tomography Accurately Characterizes Peripheral Nerve Sheath Tumors as Malignant or Benign

BACKGROUND: Correct pretreatment classification is critical for optimizing diagnosis and treatment of patients with peripheral nerve sheath tumors (PNSTs). The aim of this study was to evaluate whether F18-fluorodeoxyglucose positron emission tomography (FDG PET) can differentiate malignant (MPNST) from benign PNSTs. METHODS: Thirty-four adult patients presenting with PNST who underwent a presurgical FDG PET/computed tomography (CT) scan between February 2005 and November 2008 were included in the study. Tumors were characterized histologically, by FDG maximum standardized uptake value (SUVmax [g/mL]), and by CT size (tumor maximal diameter [cm]). The accuracy of FDG PET for differentiating MPNSTs from benign PNSTs (neurofibroma and schwannoma) was evaluated by receiver operating characteristic (ROC) curve analysis. RESULTS: SUVmax was measured in 34 patients with 40 tumors (MPNSTs: n = 17; neurofibromas: n = 9; schwannomas: n = 14). SUVmax was significantly higher in MPNST compared with benign PNST (12.0 +/- 7.1 vs 3.4 +/- 1.8; P < .001). An SUVmax cutoff point of >= 6.1 separated MPNSTs from BPSNTs with a sensitivity of 94% and a specificity of 91% (P < .001). By ROC curve analysis, SUVmax reliably differentiated between benign and malignant PNSTs (area under the ROC curve of 0.97). Interestingly, the difference between MPNSTs and schwannomas was less prominent than that between MPNSTs and neurofibromas. CONCLUSIONS: Quantitative FDG PET imaging distinguished between MPNSTs and neurofibromas with high accuracy. In contrast, MPNSTs and schwannomas were less reliably distinguished. Given the difficulties in clinically evaluating PNST and in distinguishing benign PNST from MPNST, FDG PET imaging should be used for diagnostic intervention planning and for optimizing treatment strategies. Cancer 2010;116:451-8. (C) 2070 American Cancer Society.