IRM apres radiochimiotherapie neoadjuvante du cancer du rectum: Magnetic Resonance Imaging after neoadjuvant radiochemotherapy for rectal cancer

摘要

MRI is the optimal imaging technique to restage rectal cancer after neoadjuvant treatment, which is becoming a very relevant issue for tailoring of treatment. For optimal MRI, no bowel preparation is required; a standard protocol comprises T2-weighted sequences without fat suppression in three planes, and diffusion-weighted sequences. Gadolinium contrast administration has not proven to be beneficial. Interpretation criteria are morphologic, volumetric and functional (diffusion-weighted sequences). Overstaging is the most encountered problem because fibrosis cannot be distinguished from residual tumor. Especially, accuracy of identification of complete responders is only 30-35%, and MRI has to be correlated to clinical examination and endoscopy.