Enrico Martin

113 Abstract Background Malignant peripheral nerve sheath tumors (MPNST) carry a dismal prognosis and require early detection and complete resection. However, MPNSTs are prone to sampling errors and biopsies or resections are cumbersome and possibly damaging in benign PNST (BPNST). This study aimed to systematically review and quantify diagnostic accuracy of non-invasive tests for distinguishing MPNST from BPNST. Methods Studies on accuracy of MRI, FDG-PET, and liquid biopsies were identified in PubMed and Embase from 2000-2019. Pooled accuracies were calculated using Bayesian bivariate meta-analyses. Individual level-patient data was analyzed for ideal maximum standardized uptake volume (SUVmax) threshold on FDG-PET. Results Forty-three studies were selected for qualitative synthesis including data on 1875 patients and 2939 lesions. Thirty-five studies were included for meta-analyses. For MRI, absence of target sign showed highest sensitivity (0.99, 95% CI: 0.94-1.00); ill-defined margins (0.94, 95% CI: 0.88-0.98) and perilesional edema (0.95, 95% CI: 0.83-1.00) showed highest specificity. For FDG-PET, SUVmax and tumor-to-liver ratio show similar accuracy; sensitivity 0.94, 95% CI: 0.91-0.97 and 0.93, 95% CI: 0.87-0.97 respectively, specificity 0.81, 95% CI: 0.76-0.87 and 0.79, 95% CI: 0.70-0.86 respectively. SUVmax ≥3.5 yielded the best accuracy with a sensitivity of 0.99 (95% CI: 0.93-1.00) and specificity of 0.75 (95% CI: 0.56-0.90). Conclusion Biopsies may be omitted in the presence of a target sign and the absence of ill-defined margins or perilesional edema. Because of diverse radiological characteristics of MPNST, biopsies will still commonly be required. In NF1, FDG-PET scans may further reduce biopsies. Ideal SUVmax threshold is ≥3.5. 6