Is diffusion-weighted MRI superior to FDG-PET or FDG-PET/CT in evaluating and predicting pathological response to preoperative neoadjuvant therapy in patients with rectal cancer?

Objective This meta‐analysis aimed to compare the diagnostic accuracy of diffusion‐weighted magnetic resonance imaging (DW‐MRI) and fluorodeoxyglucose‐positron emission tomography (FDG‐PET) or FDG‐PET/computed tomography (CT) in evaluating and predicting pathological response to preoperative neoadjuvant chemoradiotherapy (NCRT) in patients with rectal cancer. Methods A comprehensive literature research was conducted to identify the relevant studies for this meta‐analysis. Combined sensitivity, specificity, positive (PPV) and negative predictive values (NPV) were calculated. Results A total of 33 studies including 1564 patients met the inclusion criteria. The pooled sensitivity (81% [95% CI 74–86%] vs 85% [95% CI 75–91%]) and NPV (80% [95% CI 68–89%] vs 91% [95% CI 80–95%]) for FDG‐PET or FDG‐PET/CT were significantly lower than those for DW‐MRI (P