Diagnostic Accuracy of APTw and NOEw MRI Metrics for IDH Mutation and 1p/19q Codeletion Prediction in Gliomas.

Isocitrate dehydrogenase (IDH) mutation and 1p/19q codeletion are key molecular markers for glioma classification. Amide proton transfer weighted (APTw) and nuclear Overhauser effect-weighted (NOEw) markers showed promise for glioma characterization, by probing protein-related tissue properties. However, their interpretation is confounded by direct water saturation, macromolecules (semi-solid magnetization transfer-ssMT), and T1 relaxation. Here, we aimed to assess the performance of three APTw and NOEw metrics-uncorrected, spillover/ssMT-corrected (FMC), and fully spillover/ssMT- and T1-corrected (FMTC)-for glioma stratification. Fifty patients with suspected gliomas were prospectively enrolled (12 IDH-wild-type, 38 IDH-mutant, of which 21 with 1p/19q codeletion). Acquisitions were performed at 3 T using a 3D gradient echo readout with chemical exchange saturation transfer (B1 = 2 μT for APTw, 0.6 μT for NOEw; T1sat = 2 s), WASABI (WAter Shift And B1) for B0/B1 mapping, and saturation recovery for T1 mapping. Glioma subtypes were compared using metrics extracted from manually segmented masks, using two-tailed Mann-Whitney U tests, and the Benjamini-Hochberg false discovery rate (FDR) correction. Effect sizes were quantified using Cliff's δ with 95% bootstrap confidence intervals and classification performance was assessed by receiver operating characteristic analyses (area under the curve, AUC). IDH-mutant and wild-type gliomas differed significantly for the uncorrected APTw metric (p = 0.005, AUC = 0.79), with stronger discrimination following correction-APTw-FMC (p < 0.001, AUC = 0.94) and APTw-FMTC (p < 0.001, AUC = 0.96), both with large effect sizes. Only APTw-FMTC distinguished 1p/19q codeleted from non-codeleted gliomas before FDR correction (uncorrected p = 0.01, AUC = 0.74). The NOEw metrics did not differ between any molecular subgroups, likely due to limited sensitivity of this contrast at 3 T. These results suggest that correcting for fluid, ssMT, and T1 effects enhances the accuracy of APTw metrics, offering a more robust and biophysically grounded approach to noninvasive glioma diagnosis.