Nomogram for distinguishing glioblastoma from solitary brain metastasis involving the subependymal zone based on apparent diffusion coefficient and conventional MRI features

Background Accurately distinguishing glioblastoma (GBM) from solitary brain metastasis (SBM) involving the subventricular zone (SVZ) preoperatively is highly important but challenging in actual clinical practice. This study investigated the value of the relative apparent diffusion coefficient (rADC) of the SVZ and peritumoral edema, in combination with conventional magnetic resonance imaging (MRI) features, for distinguishing between these two diseases. Methods A total of 119 patients with GBM and SBM showing SVZ (+) on T2-weighted fluid-attenuated inversion recovery (T2-FLAIR) images were included. These patients were further categorized into two subgroups: subgroup 1 (T2-FLAIR and T1CE SVZ (+)) and subgroup 2 (T2-FLAIR SVZ (+) but T1CE SVZ (-)). The conventional MRI features and rADC values of the SVZ and peritumoral edema were compared. Diagnostic efficacy was evaluated by calculating the area under the receiver operating characteristic curves, whereas clinical applicability was analysed using nomograms. Results Combining rADC values from the SVZ and peritumoral edema with conventional MRI features demonstrated good predictive performance, with areas under the curve (AUC) of 0.879 for the entire group, 0.869 for subgroup 1, and 0.886 for subgroup 2. The C-indices for the nomograms were 0.859 for the entire group, 0.819 for subgroup 1, and 0.886 for subgroup 2. The calibration curves of the nomograms closely aligned with the ideal curves, and the decision curve analysis indicated a greater overall net benefit. Conclusion Combining rADC values from the SVZ and peritumoral edema with conventional MRI features enables noninvasive preoperative differentiation between GBM and SBM with SVZ (+). The nomograms are useful tools for predicting GBM and SBM with SVZ (+).