Introduction Achieving a complete cytoreductive surgery (CRS) is crucial in ovarian cancer patients, making preoperative assessment of surgical feasibility essential. MRI has shown promising results in predicting the peritoneal cancer index (PCI) and the extent of peritoneal disease. We aimed to prospectively determine the performance of MRI in predicting PCI and feasibility of complete CRS.

Methods The MISSION study (ClinicalTrial registry, NCT03399344) was a prospective, multicentre trial conducted in four Dutch referral hospitals. Inclusion criteria were aged > 18 years and newly diagnosed Stage III/IV ovarian cancer. Two readers scored the mrPCI. The predictive performance of DW-MRI for the PCI and resectability is investigated based on Youden’s index in terms of positive predictive value, negative predictive value and bootstrapped area under the receiver operating characteristic curve (AUC), as well as intraclass correlation coefficients for inter-observer reproducibility. The surgical PCI (sPCI) and result of CRS were used as reference standard.

Results Between June 2018 and June 2023, 270 patients were recruited, of whom 220 (193 interval and 27 primary CRS) were eligible for the current analysis. The mrPCI and sPCI were strongly correlated (ICC=0.71, p<0.0001). The AUC for predicting a complete primary CRS or interval CRS were 0.9 and 0.83 respectively. A very strong correlation was found between both readers for the mrPCI (ICC=0.81, p<0.0001).

Conclusion/Implications MRI is an accurate and robust tool for predicting the extent of peritoneal metastases and is able to predict whether complete CRS can be achieved in patients with advanced ovarian cancer.