18F FDG PET/CT evaluation of patients with ovarian carcinoma

Abstract

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Objectives: 18F FDG PET/CT is becoming widely available as a powerful imaging modality, combining the ability to detect active metabolic processes and their morphologic features in a single exam. The role of 18F FDG PET was studied in a variety of cancers, including ovarian carcinoma, but its sensitivity and specificity calculations are based on dedicated PET acquisitions, not PET/CT in the majority of the published studies. Therefore, we were prompted to review our experience with PET/CT in the management of patients with ovarian carcinoma. Methods: This is a retrospective study of 43 women with ovarian carcinoma, 27-80 years old (average: 53.9 ± 7.8), who had whole-body PET/CT at our institution from Jan 1st, 2003 to Aug 31st, 2006. Reinterpretation of the imaging studies for accuracy and data analysis from medical records were performed. Sensitivity and specificity were calculated using a 2 × 2 table with pathology results (79.1% of the patients) or clinical follow-up (20.9% of the cases) as the gold standard. Confidence interval (CI) estimations were performed using the Wilson score method. Results: All patients had advanced stage ovarian cancer and the study requested for disease re-staging. A total of 60 scans were performed: 30 pts had 1 scan, 9 pts had 2 scans and 4 pts had 3 scans. The administered doses of 18F FDG ranged 10.3 - 20.8 mCi (average: 15.4 ± 1.98). PET/CT had a sensitivity of 88.4% (95% CI: 75.1-95.4) and a specificity of 88.2% (95% CI: 64.4-97.9) for detection of ovarian cancer. The SUV max of the detected lesions ranged 3-27 (average: 9.4±5.9). The CA-125 tumor marker ranged 3-935 kU/ml (average: 265.2) in patients with positive scans and 4-139 kU/ml (average: 17.1) in patients with negative scans. This difference was statistically significant (P value: 0.0242). Conclusions: This study confirms the good results of 18F FDG PET/CT for identification of residual/recurrent ovarian cancer, as well as for distant metastases localization. PET/CT should be an integral part in evaluation of patients with high risk ovarian cancer or rising values of tumor markers (CA-125), prior to selection of the most appropriate therapy.