18F-FDG PET/CT prediction of malignant versus benign lesion in patients presenting with adnexal mass

Objectives: The purpose was to evaluate the accuracy of preoperative 18F-FDG PET/CT in the prediction of malignancy in patients with adnexal masses versus the clinical pathological staging. Our study compared the results of preoperative 18F-FDG PET/CT findings with the intra-operative and histopathological findings consecutively from January 2008 to April 2010.

Methods: 104 patients (mean age 62 years, range: 32-89 years), with adnexal masses suspicious of ovarian cancer and elevated RMI > 200 underwent 18F-FDG PET/CT with intravenous contrast prior to surgery. The 18F-FDG PET/CT findings were classified as benign or malignant and the results were compared with the registered intra-operative findings and the final histopathological examination. Preoperative 18F-FDG PET/CT-based staging was compared to the final histopathological staging according to FIGO 2003.

Results: The preliminary results indicated that 18F-FDG PET/CT description of malignant and benign was correct in 86 percent of patients. The correlation between the preoperative18F-FDG PET/CT-report, the intra-operative findings and the histopathological staging was satisfying. 18F-FDG PET/CT demonstrated areas of abnormally metabolic activity highly suspicious for malignant tumors in 60 patients. Tumor were considered benign on 18F-FDG PET/CT in 44 patients. Histopathology showed malignant tumors in 53 patients and benign tumors in 51 patients. The diagnostic 18F-FDG PET/CT-scan showed a sensitivity of 91 % CI: [79; 97%] and a specificity of 76 % CI: [63; 87%].

Conclusions: 18F-FDG PET/CT-scanning can be useful for preoperative differentiation between benign and malignant adnexal masses. Furthermore, as a whole-body examination with intravenous contrast, it gives useful information of metastasis extent of malignant diseases and other concomitant pathologies