Combination of Multiple MRI Parameters Related to Signal Intensity and Volume for Predicting Response to Neoadjuvant Chemoradiotherapy by Patients with Locally Advanced Rectal Cancer

Abstract

Background:: MRI of patients with locally advanced rectal cancer (LARC) can predict the pathological complete response (pCR) to preoperative chemoradiation therapy (CRT). Our purpose was to use MRI results to evaluate the diagnostic value of combined changes in signal intensity (SI) and volume (V) of patients with LARC for predicting pCR to CRT. Methods:: This retrospective study on 100 patients with LARC analyzed clinical and imaging data that were collected from March, 2018, to March, 2020. Before and after CRT, T2-weighted (T2W), apparent diffusion coefficient (ADC), and contrast-enhanced T1-weighted (ceT1W) data were analyzed. Percent changes of V (%ΔV) and relative SI ratio (%ΔSIR) on different sequences were calculated. After CRT, patients had pathological confirmation as pCR or non-pCR. Data were analyzed using nonparametric tests and receiver operating characteristic (ROC) analysis. Results:: There were 34 pCR and 66 non-pCR patients. Except for ADC-%ΔSIR, the combined parameters and single parameters had a greater decrease in the pCR group. The combination of ADC-%ΔV and T2W-%ΔSIR had the greatest diagnostic value (AUC=0.85,cutoff=0.23%) and the combination of ADC-%ΔV% and ΔSIR had the best accuracy (89%, cutoff=44.11%). Except for T2W-%ΔV and T2W-%ΔSIR, the different sequences had moderate differences in diagnostic performance. The diagnostic performance of combined parameters or single parameters on ADC and T2W was significantly better than those on ceT1W (p<0.01). Conclusion:: All sequences except ADC-%ΔSIR provided reliable predictions of pCR, although ceT1W data had limited usefulness.