Abstract INTRODUCTION IDH-mutant glioma subtypes share similarities on MRI and histopathology but have distinct differences in survival based on their molecular subtypes. Radiomic features provide novel analysis of glioma imaging phenotypes that may not appear in clinical evaluations. We evaluated whether clustering of radiomic features of IDH-mutant gliomas could identify different subtypes based on the 2021 WHO classification. METHODS We extracted up to 5,763 radiomic features per case from pretreatment FLAIR and T1 post-contrast tumor segmentations of 206 patients with IDH-mutant gliomas WHO grade 2-4 using a standardized Pyradiomics 3.1.0 pipeline. Segmentations were performed using a semiautomatic workflow with a UNETR algorithm trained on the BRaTS 2021 dataset. To visualize high-dimensional feature space, we evaluated the following unsupervised clustering algorithms to differentiate tumor subtypes: PCA, t-SNE, UMAP, and PHATE. We performed redundancy reduction by calculating a Pearson correlation-matrix, and removed highly correlated features above a threshold of 0.7. Significant features were selected using the L1-norm regularization (LASSO). RESULTS The dataset of 206 patients included 19 grade 4, 28 grade 3, and 36 grade 2 astrocytomas as well as 23 grade 3 and 58 grade 2 oligodendrogliomas. The UNETR algorithm performed with a 0.85 Dice score on the segmentations. Clustering of the extracted 2D radiomic features from FLAIR and T1postgad using PCA, tSNE, UMAP, and PHATE did not identify distinct classes. To further analyze the two tumor entities, we applied XGBOOST, RandomForest, and KNN classifiers and found them to have AUCs < 0.5. CONCLUSIONS We showed that the spectrum of imaging features of IDH-mutant gliomas has a significant overlap on FLAIR and T1 post-contrast imaging. We propose that standard anatomical imaging does not provide sufficient information on these two sequences. To further identify specific subtypes of IDH-mutant gliomas, additional sequences, such as T2, ADC, SWI, and T1, can provide additional information.