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

Mario Petrillo,Biagio Pecori,Antonella Petrillo,Roberta Fusco,Fabiana Tatangelo,Mario Sansone,Paolo Delrio,Orlando Catalano,Antonio Avallone

doi:10.1155/2015/514740

Abstract

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.

Highlights

Rectal cancer is a frequent malignancy in both men and women, accounting for 40.290 new cases in the USA in 2012 [1]
Wilcoxon’s test findings reported significant decreases in volumetric measures, between preand posttreatment, assessed with all methods (Table 3): V(C) median value decreased from 36.9 cm3 to 16.7 cm3; V(DCE) median value decreased from 30.9 cm3 to 16.5 cm3; V(DWI) median value decreased from 14.59 cm3 to 6.0 cm3 (p < 0.01)
The focus of this study was to clarify the association between manual tumor volume estimations obtained by T2-weigthed imaging, diffusion weighted imaging (DWI), DCEMRI images, and tumor regression grade (TRG) to predict locally advanced rectal cancer (LARC) response after preoperative radiation therapy and concurrent chemotherapy (pCRT)

Summary

Introduction

Rectal cancer is a frequent malignancy in both men and women, accounting for 40.290 new cases in the USA in 2012 [1]. A further conservative strategy has been to adopt a “wait and see” policy, omitting surgery when a complete clinical response is obtained after pCRT This strategy has the advantage of reducing morbidity and provides a “true” organ-sparing approach, considering that sphincter preservation without adequate function has questionable benefit. In various oncology fields, researchers have recently suggested that diffusion-weighted imaging (DWI) can potentially be used to identify biomarkers of treatment response [3]. These assertions are based on the fact that DWI could provide individual tumor apparent diffusion coefficient (ADC) increase rates during the course of CRT, which could reflect biological tumor changes

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