Review question / Objective: To assess the diagnostic efficacy of 18F-FDG PET/MRI for lymph node metastasis primary staging in patients with colorectal cancer (CRC). Condition being studied: Recent studies found that 18F-FDG PET/MRI also grants CT extra effect in the identification of m e t a s t a s e s a n d d i s c r i m i n a t i o n o fambiguous lesions, which improves diagnostic accuracy and efficiency. To date, there is no systematic review conducted to further validate the diagnostic performance of 18F-FDG PET/MRI for lymph node metastatic primary staging in CRC patients. We present this systematic review and meta-analysis expecting to provide evidence-based reference for its clinical application.

Objective To assess the diagnostic efficacy of 18F-FDG PET/MRI for lymph node (LN) metastasis primary staging in patients with colorectal cancer (CRC). Methods This study was conducted and reported in accordance with the PRISMA-DTA statement. Electronic databases (PubMed, Embase, Cochrane Library) were searched for studies on 18F-FDG PET/MRI for diagnosing LN metastasis. The pooled sensitivity (SEN), specificity (SPE), and area under the curve (AUC) were applied to assess the diagnostic performance. Heterogeneity was identified and processed using meta-regression and sensitivity analysis. All data analyses were performed via STATA 15 and Meta-Disc 1.4 software. Results There were finally 7 studies included, involving a total of 184 patients. The Spearman rank correlation coefficient was 0.108 (P = 0.818), with no threshold-effect observed. The pooled SEN was 0.81 (95%CI 0.66–0.90) and the SPE was 0.89 (95% CI 0.73–0.96). In sub-groups, prospective groups demonstrated to have the highest SEN of 0.92 (95%CI 0.79–1.00). The studies conducted by Catalano et al. and Kang et al. were considered to be potential sources of heterogeneity. Conclusion 18F-FDG PET/MRI has shown remarkable diagnostic performance in identification of LN metastases in newly diagnosed CRC patients. It would be of great application value for the primary staging of CRC lymph node metastases.