Additive value of whole abdomen FDG PET/MRI to standard whole body PET/CT for detection of peritoneal recurrence of ovarian cancer

Presence of peritoneal metastasis in ovarian cancer is one of the most important factors affecting the prognosis of the disease. In this study we aimed to investigate the additive value of dedicated abdomen 18 F-FDG PET/MR imaging to whole body 18 F-FDG PET/CT in the detection of peritoneal recurrence in ovarian cancer patients with elevated serum Ca-125 levels. This prospective study included 45 ovarian cancer patients with elevated serum Ca-125 levels during postoperative follow-up, all of whom underwent whole-body 18 F-FDG PET/CT followed by dedicated abdominal PET/MRI. With the addition of PET/MR imaging to PET/CT, peritoneal recurrence was detected in 35 patients (78%), whereas PET/CT alone detected recurrence in 26 patients (57%) ( p = 0.012). The total number of regions with peritoneal uptake was 100 with PET/CT alone, but increased to 170 when PET/MRI was added ( p < 0.001). Furthermore, distant organ metastases that were not detected on PET/CT were identified in 3 patients with the addition of PET/MRI. In our study, additional findings from PET/MRI led to changes in the treatment strategy for 15 patients (33%). The addition of dedicated abdominal PET/MRI to whole-body PET/CT enhances the detection of peritoneal metastases in patients with recurrent ovarian cancer and elevated Ca-125 levels. This combined imaging approach provides complementary information, improving diagnostic accuracy and aiding in the selection of optimal treatment strategies.