Diagnostic value of PET/CT is similar to that of conventional MRI and even better for detecting small peritoneal implants in patients with recurrent ovarian cancer

Abstract

Objective: The aim of this study was to evaluate the diagnostic value of 2-(fluorine-18)-fluoro-2-deoxy-D-glucose ((18)F-FDG) PET/CT in comparison with MRI for the detection of recurrent ovarian cancer.

Methods: Forty-seven patients with suspected ovarian cancer recurrence after total ablative or cytoreductive surgery, as well as neoadjuvant or adjuvant chemotherapy, who had undergone (18)F-FDG PET/CT imaging were recruited for the present study. All patients also underwent MRI within a month of (18)F-FDG PET/CT for the same purpose. Recurrent cancer in the abdomen and pelvis was evaluated in each of the 47 patients and classified as either distant metastasis or local pelvic recurrence involving the vaginal stump, peritoneal implants, supradiaphragmatic region, and/or abdominal and pelvic lymph nodes. Special attention was paid to peritoneal implants. These were divided into five groups according to size of the implants: less than 0.5 cm (group 1), 0.5-1 cm (group 2), 1-2 cm (group 3), 2-3 cm (group 4), and larger than 3 cm (group 5). PET/CT findings were compared with abdominopelvic MR findings. Statistical analysis was carried out using the Wilcoxon signed rank test.

Results: Thirty-nine of 47 patients were found to have recurrent ovarian cancer. Both PET/CT and MRI were negative for recurrence in six patients. Overall sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy of PET/CT were 97.5, 100, 100, 87.5, and 97.8%, respectively, whereas those of MRI were 95, 85.7, 97.4, 75, and 93.6%, respectively. For the peritoneal implants in groups 2 and 3, the sensitivity, negative predictive value, and diagnostic accuracy values of PET/CT were significantly better than those of MRI (P<0.05).

Conclusion: The present study revealed that PET/CT is similar to conventional MRI for the detection of recurrent ovarian cancer. PET/CT has greater accuracy in the detection of small-to-medium-sized (<2 cm) peritoneal implants compared with MRI. This may affect surgical decision making.