Background: diffusion-weighted magnetic resonance imaging (DW-MRI) permits non-invasive assessment of tumor characteristics.
Aim of the work: this study was aimed to emphasize the role of DWI in assessing aggressiveness of rectal cancer with the histopathological correlation.
Patients and methods: this was a prospective study that included thirty patients with histopathological proved rectal carcinoma referred from the Surgical Department, Ain Shams University Hospitals to the MRI Radiology Unit for Rectal Cancer Staging.
Pelvic MRI study with conventional sequences and DWI were performed.
Results: 81% of moderately differentiated adenocarcinoma (ADC) (grade II) showed restricted diffusion with low signals in ADC sequence, while none of the poorly differentiated adenocarcinoma (grade III) showed restricted diffusion with high signals in ADC sequence (T2 shin-through). There was a high statistically significant difference in characterization of poorly (grade III) and moderately differentiated adenocarcinomas (grade II).
Conclusion: significant correlations were detected between mean ADC values and differentiation grade. ADC may be useful as an imaging tool for re-staging of tumor aggressiveness, but it cannot serve as an independent tool for primary staging of rectal cancer.