A nomogram strategy for identifying the subclassification of IDH mutation and ATRX expression loss in lower-grade gliomas

Objectives To construct a radiomics nomogram based on multiparametric MRI data for predicting isocitrate dehydrogenase 1 mutation (IDH +) and loss of nuclear alpha thalassemia/mental retardation syndrome X‐linked expression (ATRX −) in patients with lower‐grade gliomas (LrGG; World Health Organization [WHO] 2016 grades II and III). Methods A total of 111 LrGG patients (76 mutated IDH and 35 wild-type IDH) were enrolled, divided into a training set ( n = 78) and a validation set ( n = 33) for predicting IDH mutation. IDH + LrGG patients were further stratified into the ATRX − ( n = 38) and ATRX + ( n = 38) subtypes. A total of 250 radiomics features were extracted from the region of interest of each tumor, including that from T 2 fluid-attenuated inversion recovery (T 2 FLAIR), contrast-enhanced T 1 WI, ASL-derived cerebral blood flow (CBF), DWI-derived ADC, and exponential ADC (eADC). A radiomics signature was selected using the Elastic Net regression model, and a radiomics nomogram was finally constructed using the age, gender information, and above features. Results The radiomics nomogram identified LrGG patients for IDH mutation (C-index: training sets = 0.881, validation sets = 0.900) and ATRX loss (C-index: training sets = 0.863, validation sets = 0.840) with good calibration. Decision curve analysis further confirmed the clinical usefulness of the two nomograms for predicting IDH and ATRX status. Conclusions The nomogram incorporating age, gender, and the radiomics signature provided a clinically useful approach in noninvasively predicting IDH and ATRX mutation status for LrGG patients. The proposed method could facilitate MRI-based clinical decision-making for the LrGG patients. Key Points • Non-invasive determination of IDH and ATRX gene status of LrGG patients can be obtained with a radiomics nomogram. • The proposed nomogram is constructed by radiomics signature selected from 250 radiomics features, combined with age and gender. • The proposed radiomics nomogram exhibited good calibration and discrimination for IDH and ATRX gene mutation stratification of LrGG patients in both training and validation sets.