Differential diagnosis of benign and malignant peripheral nerve sheath tumors using [¹⁸F]FDG PET/CT

Malignant peripheral nerve sheath tumors (MPNSTs) are rare tumors that show high metastatic potential and have a poor prognosis. [¹⁸F]fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) is helpful for diagnosing MPNSTs, but the ideal parameters and threshold values remain unclear. The purpose of our study was to evaluate visual assessment and quantitative analysis of [¹⁸F]FDG PET/CT for differentiating between benign peripheral nerve sheath tumors (BPNSTs) and MPNSTs.

This retrospective analysis included patients with pathologically-proven BPNSTs or MPNSTs who underwent [¹⁸F]FDG PET/CT. The visual parameters of [¹⁸F]FDG PET/CT were uptake intensity and heterogeneity, while the quantitative parameters were standardized uptake values (SUVmax, SUVpeak, SUVmean), tumor-to-liver ratio (TLR), metabolic tumor volume (MTV), total lesion glycolysis (TLG), and tumor size.

A total of 69 patients (median age = 41 years, M:F = 30:39) with 95 lesions (39 BPNSTs and 59 MPNSTs) were finally included. Among the visual parameters, uptake intensity greater than liver (P = 0.001) and heterogenous uptake (P = 0.004) were significant parameters for diagnosing MPNSTs. All of the quantitative parameters analysed were significant for diagnosing MPNSTs, with SUVmax showing the largest area under the curve (AUC) of 0.87 (P < 0.001) with an optimal threshold of > 6.9 (sensitivity 76.8% and specificity 87.2%). In addition, the SUVmax of high-grade MPNSTs were significantly higher than those of low-grade MPNSTs (P = 0.039).

Of the [¹⁸F]FDG PET/CT measures investigated, SUVmax showed the highest accuracy for diagnosing MPNSTs, and also showed an association with the grade of MPNSTs.