Integrated FDG PET-CT in patients with persistent ovarian cancer: Correlation with histologic findings

PURPOSE: To prospectively evaluate the accuracy of integrated positron emission tomography (PET) and computed tomography (CT) for depiction of persistent ovarian carcinoma after first-line treatment, with use of histologic findings as the reference standard. MATERIALS AND METHODS: Thirty-one women (mean age, 55.9 years) with ovarian carcinoma treated with primary cytoreductive surgery and followed up with platinum regimen chemotherapy were included. All 31 patients were scheduled for surgical second-look. Before surgical second-look, all patients underwent fluorodeoxyglucose (FDG) PET/CT. At PET/CT, three main categories of persistent disease were considered for data analysis: lymph nodal lesion, peritoneal lesion, and pelvic lesion. In all patients, imaging findings were compared with results of histologic examination after surgical second-look to determine the diagnostic accuracy of PET/CT in the evaluation of disease status. The kappa statistic (Cohen kappa) was used for statistical analysis. RESULTS: Seventeen (55%) of 31 patients had persistent tumor at histologic analysis after surgical second-look, and fourteen (45%) had no histologically proved tumor. The total number of lesions that was positive for tumor cells at histologic analysis was 41 (lymph nodes, n = 16; peritoneal lesions, n = 21; pelvic lesions, n = 4); maximum diameter of these lesions was 0.3-3.2 cm (mean, 1.7 cm). A correlation was found between PET/CT and histologic analysis (kappa = 0.48). The overall lesion-based sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of PET/CT were 78%, 75%, 77%, 89% and 57%, respectively. In the detection of a tumor, a size threshold could be set at 0.5 cm, as this was the largest diameter of a lesion missed at PET/CT. CONCLUSION: Integrated PET/CT depicts persistent ovarian carcinoma with a high positive predictive value.