MRI for Assessing Response to Neoadjuvant Therapy in Locally Advanced Rectal Cancer Using DCE-MR and DW-MR Data Sets: A Preliminary Report

Abstract EN

To evaluate MRI for neoadjuvant therapy response assessment in locally advanced rectal cancer (LARC) using dynamic contrast enhanced-MRI (DCE-MRI) and diffusion weighted imaging (DWI), we have compared magnetic resonance volumetry based on DCE-MRI (V(DCE)) and on DWI (V(DWI)) scans with conventional T2-weighted volumetry (V(C)) in LARC patients after neoadjuvant therapy.

Twenty-nine patients with LARC underwent MR examination before and after neoadjuvant therapy.

A manual segmentation was performed on DCE-MR postcontrast images, on DWI (b-value 800 s/mm2), and on conventional T2-weighted images by two radiologists.

DCE-MRI, DWI, and T2-weigthed volumetric changes before and after treatment were evaluated.

Nonparametric sample tests, interobserver agreement, and receiver operating characteristic curve (ROC) were performed.

Diagnostic performance linked to DCE-MRI volumetric change was superior to T2-w and DW-MRI volumetric changes performance (specificity 86%, sensitivity 93%, and accuracy 93%).

Area Under ROC (AUC) of V(DCE) was greater than AUCs of V(C) and V(DWI) resulting in an increase of 15.6% and 11.1%, respectively.

Interobserver agreement between two radiologists was 0.977, 0.864, and 0.756 for V(C), V(DCE), and V(DWI), respectively.

V(DCE) seems to be a promising tool for therapy response assessment in LARC.

Further studies on large series of patients are needed to refine technique and evaluate its potential value.