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 (Delta L-least and Delta glnu) 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. Receiver Operating Characteristic (ROC) curve analysis was performed on the 16 cases of the original study and the best cut-off value was identified. The performance of Delta L-least and Delta glnu was evaluated at the best cut-off value. Results: On the original dataset of 16 patients, Delta L-least reported an AUC of 0.81 for cCR and 0.93 for pCR, while Delta glnu 0.72 and 0.54 respectively. The best cut-off values of.Lleast was 0.73 for both outcomes, while Delta glnu reported 0.54 for cCR and 0.93 for pCR. At the external validation, Delta L-least showed an accuracy of 81% for cCR and 79% for pCR, while Delta glnu reported 63% for cCR and 40% for pCR. Conclusion: The accuracy of.Lleast in predicting cCR and pCR is significantly higher than those obtained considering.glnu, but inferior if compared with other image-based biomarker, such as the early-regression index. Studies with larger cohorts of patients are recommended to further investigate the role of delta radiomic features in MRgRT.

Automated summary

The study confirmed the predictive value of ΔL-least and Δglnu features for clinical and pathological complete response in LARC patients, emphasizing the potential role of radiomics in MRgRT treatment.