PET/CT in patients with ovarian cancer: Change in confidence levels and added benefits

643 Objectives: T and PET alone have been used in the past to evaluate patients with ovarian cancer. Although both modalities often provide useful information, the interpretation often lacks confidence. We hypothesized that combined PET/CT would allow a greater degree of confidence than either CT alone or PET alone. Methods: Ninety-nine consecutive patients with suspected recurrent ovarian carcinoma were evaluated with combined PET/CT. A radiologist with extensive experience in women’s imaging prospectively reviewed the CT images without the PET data. A nuclear medicine physician with extensive PET experience reviewed the PET images without the CT data. The two reviewers then evaluated the fused PET-CT images and rendered a consensus interpretation. Thus, each study had three interpretations: CT alone, PET alone, and consensus PET/CT. Each lesion was assigned a number from 0-5 indicating degrees of certainty: malignant (5), probably malignant (4), equivocal (3), probably benign (2), benign (1), or not detected (0). Results: There were a total of 244 potential lesions in 72 patients (27 had negative CT and PET). Of the 72 patients, there was discordance between PET and CT in 36. 50 lesions (20%) were in the neck or chest, an area not routinely scanned in this patient population. 48 lesions on CT and 27 lesions on PET were changed from category 0 (not detected) to malignant or probably malignant (4 or 5) on PET/CT. 7 CT lesions and 13 PET lesions were initially classified as probably malignant or malignant and reclassified as benign on PET/CT. PET/CT offered no additional information in 92 lesions and offered additional information as follows: improved lesion localization in 43 lesions, improved lesion characterization (benign from pathology) in 36 lesions and 39 potential lesions (category 4 or 5) were reclassified as benign after viewing the fused images. Conclusions: These data support our hypothesis that fused PET/CT images allows a greater degree of confidence than either CT alone or PET alone. Furthermore, the combined modality can prevent misinterpretation, particularly compared to CT alone.