Early Prediction of Volumetric Progression in Sellar-Parasellar Meningiomas Using Delta Radiomics on 6-Month MRI...

Background/Objectives: This study aimed to develop and internally validate multiparametric MRI radiomics models for predicting volumetric progression following Gamma Knife radiosurgery (GKRS) in sellar-parasellar meningiomas and to evaluate the incremental value of diffusion-derived features beyond contrast-enhanced imaging. Methods: Fifty-four patients underwent pretreatment and approximately 6-month post-treatment MRI, including contrast-enhanced T1-weighted imaging (T1C-WI) and apparent diffusion coefficient (ADC) maps. Whole-tumor segmentations were reviewed by two neuroradiologists by consensus. Radiomic features were extracted using PyRadiomics, and delta features were calculated as post-treatment minus pretreatment values. Elastic-net logistic regression models were evaluated using repeated nested cross-validation with five-fold inner and outer loops repeated 10 times. The primary endpoint was volumetric progression, defined as a >20% volume increase at 3 years. Results: At 3 years, 9 tumors (16.7%) progressed, 25 (46.3%) remained stable, and 20 (37.0%) regressed. The ΔT1C-WI model showed the highest repeated nested cross-validation performance, with a mean AUC of 0.861 ± 0.065, an accuracy of 0.846 ± 0.037, and an F1 score of 0.579 ± 0.097. Averaged patient-level out-of-fold predictions yielded an AUC of 0.914 (95% CI, 0.822-0.980), a sensitivity of 77.8%, and a specificity of 88.9%. The ΔADC model showed moderate discrimination, whereas combining ΔT1C-WI and ΔADC features did not improve performance. Conclusions: Delta radiomics derived from 6-month post-treatment T1C-WI may help identify sellar-parasellar meningiomas at risk of 3-year volumetric progression after GKRS. These findings suggest that 6-month ΔT1C-WI radiomics may support early risk stratification, but its clinical value requires external validation and prospective evaluation.