Delta radiomics for rectal cancer response prediction using low field magnetic resonance guided radiotherapy: an external validation.

Introduction: A recent study performed on 16 locally advanced rectal cancer (LARC) patients treated using magnetic resonance guided radiotherapy (MRgRT) has identified two delta radiomics features as predictors of clinical complete response (cCR) after neoadjuvant radio-chemotherapy (nCRT). This study aims to validate these features (ΔL and Δglnu) on an external larger dataset, expanding the analysis also for pathological complete response (pCR) prediction.

Methods: A total of 43 LARC patients were enrolled: Gross Tumour Volume (GTV) was delineated on T2/T1* MR images acquired during MRgRT and the two delta features were calculated.

External Validation of Early Regression Index (ERI) as Predictor of Pathologic Complete Response in Rectal Cancer Using Magnetic Resonance-Guided Radiation Therapy.

Purpose: Tumor control probability (TCP)-based early regression index (ERI) is a radiobiological parameter that showed promising results in predicting pathologic complete response (pCR) on T2-weighted 1.5 T magnetic resonance (MR) images of patients with locally advanced rectal cancer. This study aims to validate the ERI in the context of low-tesla MR-guided radiation therapy, using images acquired with different magnetic field strength (0.