Differentiation of MPNSTs from benign neurofibromas in neurofibromatosis patients using ADC and SUV biomarkers in children and young adults.

PURPOSE: This study evaluated the sensitivity and specificity of the apparent diffusion coefficient (ADC) and standardized uptake value (SUV) to differentiate malignant peripheral nerve sheath tumors (MPNSTs) from benign neurofibromas in children and young adults with NF1.

METHODS

We included 31 patients (19 male, 12 female, age 1-24 years) with 33 nerve sheath tumors, including 11 MPNSTs and 22 benign neurofibromas underwent MRI with diffusion-weighted imaging (DWI, n = 30 lesions, 22 benign, 8 malignant) or 18F-FDG PET (n= 22 lesions, 11 benign, 11 malignant). Tumor apparent diffusion coefficients (ADCmean, ADCmin, and ADCmax) and standardized uptake values (SUVmax) were compared between benign and malignant lesions using Wilcoxon rank-sum tests. In addition, ROC curves were generated to determine optimal cutoffs for each parameter and their respective area under the curve (AUC), sensitivity and specificity. We used Spearman's rank correlation to assess the correlation between ADCmin and SUVmax.

RESULTS

Mean ADCmin and ADCmean were significantly lower in MPNST compared to benign neurofibromas (p<0.001). Mean SUVmax was significantly higher in MPNSTs (11.05±4.80) compared to benign lesions (2.21±0.68, p<0.001). An ADCmin cutoff of 1.1×10⁻³ mm²/s differentiated MPNST from benign neurofibromas with a sensitivity of 87%, specificity of 100%, and AUC of 0.97. A SUVmax threshold of 4.9 yielded a sensitivity of 91%, specificity of 100%, and AUC of 0.99. ADCmin correlated inversely with SUVmax (rho= -0.81, p < 0.0001). Longitudinal clustered regression showed progressive declines in ADCmean, ADCmax, and ADCmin in benign neurofibromas, with significant reductions in ADCmean and ADCmax at 2 and 3 years and in ADCmin at 3 years relative to baseline.

CONCLUSION

Either ADC metrics or SUVmax could differentiate MPNSTs from benign neurofibromas in children and young adults with high sensitivity and specificity.