Estadificación locorregional por resonancia magnética del cáncer de recto: influencia de la imagen potenciada en difusión en la precisión diagnóstica

Objective To assess whether the accuracy in locoregional staging using magnetic resonance imaging (MRI) in rectal cancer (primary or post-chemoradiotherapy) improves by adding diffusion-weighted imaging, according to the radiologist's degree of experience. Method Retrospective study on 100 MRI records (1.5 T, 2011-2016) from patients with rectal cancer (reference standard: histology of surgical specimens). Ten radiologists (three experienced in rectal cancer, three specialized in other areas and four residents) individually reviewed each case twice: first, evaluating just high-resolution T2-weighted sequences; second, evaluation of diffusion-weighted plus high-resolution ones. The analysis focused on the differentiation between early (0-I) and advanced (II-IV) stages. Accuracy, sensitivity/specificity and predictive values were calculated. Results Experienced radiologists showed some worsening by adding diffusion-weighted imaging, mainly at primary staging (accuracy: 0.769 to 0.701). Inexperienced radiologists presented a post-chemoradiotherapy improvement (accuracy: 0.574 to 0.642; specificity of 19.1 to 29.8%), although with no other remarkable changes. Residents demonstrated a worsening at primary staging by adding diffusion (accuracy: 0.670 to 0.633; specificity: 45.8 to 39.6%), but post-chemoradiotherapy improvement (sensitivity: 80.6 to 87%). The differences between both reviews were not statistically significant. Conclusions No significant differences were found in the distinction between early and advanced rectal tumors secondary to adding diffusion-weighted imaging to high-resolution T2-weighted sequences.