Response to neoadjuvant chemoradiotherapy for locally advanced rectum cancer: Texture analysis of dynamic contrast-enhanced MRI

Abstract

Background: Tumor heterogeneity can be assessed by texture analysis (TA). TA has been applied using diffusion-weighted imaging and apparent diffusion coefficient maps to predict pathological responses to preoperative chemoradiation therapy (CRT) in patients with locally advanced rectal cancer (LARC).

Purpose: To evaluate the texture parameters obtained from K ^trans maps derived from dynamic contrast-enhanced (DCE)-MRI for predicting pathological responses to preoperative CRT for LARCs.

Study type: Retrospective.

Population: Altogether, 83 patients (26 women, 57 men) with rectal cancer met the inclusion criteria.

Field strength/sequence: 3.0T/T₁ -weighted DCE-MRI sequence.

Assessment: After CRT, each tumor was assessed by a pathologist who assigned a tumor regression grade (TRG), thereby identifying pathologically complete responders (pCR; TRG 1) and good responders (GR; TRG1 + TRG2). TA was then applied to the DCE-MRI K ^trans maps. The K ^trans value, several TA parameters, and tumor volumes were calculated.

Statistical tests: The Shapiro-Wilk test was used to verify that the data had normal distribution. Results of parameters measured before and after CRT were compared using paired-sample t-tests. Value changes of each parameter in the combined pCR/GR group were compared using independent sample t-tests. Receiver operating characteristic curves and areas under the curve (AUC) were calculated to assess the diagnostic performance of each parameter related to CRT effectiveness.

Results: There were 15 pCR (16.9%) and 21 GR (25.3%) patients. Tumor volume, mean K ^trans , entropy, and correlation decreased and energy values increased significantly in these groups compared with those of the non-PCR and non-GR groups. ΔCorrelation (Δcorrelation = postcorrelation - precorrelation) was found to be a valuable parameter for identifying pCR/GR patients (AUC 0.895, sensitivity 86.7%, specificity 81.8%).

Data conclusion: TA parameters from the DCE-MRI K ^trans map can predict the efficacy of CRT for treating LARCs. Also, Δcorrelation may be useful for identifying patients who will be responsive to CRT.

Level of evidence: 4 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2019;49:885-893.

Keywords: K trans map; dynamic contrast-enhanced; neoadjuvant chemoradiotherapy; rectal cancer; texture analysis.