Comparison of Diffusion-Weighted Magnetic Resonance Imaging and 18F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography for Detection of Peritoneal Carcinomatoses in Advanced Epithelial Ovarian Cancer

Objectives: To compare the diagnostic accuracy of diffusion-weighted magnetic resonance imaging (DW-MRI) and 18F-fluorodeoxyglucose combined positron emission tomography combined with computed tomography(FDG-PET/CT) in detecting peritoneal carcinomatoses in advanced epithelial ovarian cancer (EOC). Methods: This prospective study enrolled patients with stage III-IV EOC consecutively from October 2020 to February 2023. Participants underwent both DW-MRI and FDG-PET/CT. Three radiologists independently evaluated the radiological images using peritoneal cancer index (PCI) scoring systems. Clinical data, preoperative imaging assessments, and cytoreductive surgical outcomes were recorded. Univariate and multivariate analyses were performed to determine the critical regions for surgery associated with incomplete resection. The diagnostic performance of each imaging modality was calculated for each site. The interobserver agreement was assessed. Results: Forty-eight patients were enrolled in this study. No statistically significant differences were found between the imaging modalities ( p ≥0.142) based on the PCI scoring evaluation system. Omental lesions extend to the hepatic flexure or splenic flexure ( p =0.045, OR=20.891), and small bowel mesentery involvement ( p =0.039, OR=21.814) were identified as surgically critical regions associated with incomplete resection. DW-MRI demonstrated significantly higher accuracy than FDG-PET/CT ( p =0.049) in diagnosis at omental lesions extend to the hepatic flexure or splenic flexure and diaphragmatic peritoneum, with sensitivity and specificity of 0.773 and 0.792 for DW-MRI, and 0.619 and 0.696 for FDG-PET/CT, respectively. DW-MRI also showed higher interobservers agreement (k=0.654-0.782) compared to moderate agreement (k=0.515-0.745) in FDG-PET/CT. Conclusion: DW-MRI and FDG-PET/CT were comparable in assessing the entire abdominopelvic tumor burden based on PCI scoring system. DW-MRI has an advantage in detecting omental lesions extending to the hepatic flexure or splenic flexure, which is predictive of incomplete resection.