Can IVIM MRI be superior to ADC in predicting aggressive subtypes of endometrial carcinoma: new insights into FIGO 2023 classification

Abstract Background MRI is a valuable imaging modality for pre-operative evaluation and staging of endometrial carcinoma (EC). However, with the introduction of the updated 2023 FIGO staging system, MRI faces a new challenge: not only accurately diagnosing and anatomically staging EC but also predicting its aggressive subtypes. Growing interest in advanced diffusion imaging methods, like IVIM, has emerged to improve MRI's diagnostic and prognostic value. This prospective study investigated the potential of IVIM MRI (D, D*, pf) of 34 cases of pathologically proven endometrial carcinoma to predict aggressive EC subtypes, a key component of the FIGO 2023 staging system. Associations between IVIM-derived parameters and the two histological subtypes based on the FIGO 2023 classification, including aggressive group (high grade endometroid, papillary serous, clear cell, carcinosarcoma, and undifferentiated carcinoma) and non-aggressive group (low grade endometrioid carcinoma) were evaluated. Statistical analysis to validate the ability of IVIM metrics to discriminate aggressive subtypes from less aggressive counterparts. Results Aggressive endometrial carcinoma showed reduced D, ADC, and f values, with D (cut-off = 0.56, AUC = 0.87) achieving the highest diagnostic accuracy (79.4%) in distinguishing aggressive from non-aggressive subtypes, followed by ADC (cut-off = 0.53) and f (cut-off = 0.14). Conclusions While both D and ADC were lower in aggressive tumors, IVIM-derived D showed superior diagnostic accuracy compared to ADC for predicting aggressive endometrial carcinoma (79.4% vs. 73.5%). These findings support D as a promising non-invasive biomarker for preoperative risk stratification.