Role of diffusion-weighted MRI in diagnosis and post therapeutic follow up of colorectal cancer.

Abstract

MRI plays now a major role in patients with colorectal cancer regarding tumor staging, surgical planning, therapeutic decision, and assessment of tumor response to chemoradiotherapy and surveillance of rectal cancer. DW-MRI is a functional imaging tool that is now part of the standard MRI protocol for the investigation of patients with colorectal cancer. DW-MRI reflects micro-displacements of water molecules in tissues and conveys high degrees of accuracy to discriminate between benign and malignant colorectal conditions. This study found that: 1. The DW MR has high sensitivity for detection of colorectal cancer reaching up to 92.5%. 2. There is significant correlation between the ADC value and the histological grade of the tumor. The ADC value is significantly lower in the poor differentiated tumors. 3. Adding DW MR imaging to conventional MR imaging yields better diagnostic accuracy than use of conventional MR imaging alone in the evaluation of CR to Neoadjuvant CRT in patients with locally advanced colo-rectal cancer. In view of limited number of cases and other limitations of the study larger studies are needed to confirm these results. We recommend using DWI in conjunction to conventional imaging as a useful modality that aids in assessment of colorectal neoplasms and follow up after chemoradiotherapy to assess response.