Low-dose non-enhanced CT versus full-dose contrast-enhanced CT in integrated PET/CT scans for diagnosing ovarian cancer recurrence

Objective: To evaluate low-dose non-enhanced CT (ldCT) and full-dose contrast-enhanced CT (ceCT) in integrated F-18-fluorodeoxyglucose (FDG)-PET/CT studies for restaging of ovarian cancer. Materials and methods: One hundred and twenty women who had undergone treatment for ovarian cancer underwent a conventional PET/CT scans with ldCT, and then ceCT. Two observers interpreted and decided in consensus on the PET/ldCT and PET/ceCT images by a 3-point scale (N: negative, E: equivocal, P: positive) per patient and lesion site. Final diagnoses were obtained by histopathological examinations, or clinical follow-up for at least 6 months. Results: Patient-based analysis showed that the sensitivity, specificity, and accuracy of PET/ceCT was 86.9% (40/46), 95.9% (71/74), and 92.5% (111/120), respectively, whereas those of PET/ldCT were 78.3% (36/46), 95.0% (70/74), and 88.3% (106/120), respectively. All sensitivity, specificity, and accuracy significantly differed between two methods (McNemar test, p < 0.0005, p = 0.023, and p < 0.0001, respectively). The scales of detecting 104 recurrent lesion sites were N: 14, E: 6, P: 84 for PET/ceCT, and N: 15, E: 17, P: 72 for PET/ldCT, respectively. Eleven equivocal and one negative regions by PET/ldCT were correctly interpreted as positive by PET/ceCT. Conclusion: PET/ceCT is a more accurate imaging modality with higher confidence for assessing ovarian cancer recurrence than PET/ldCT. Crown Copyright (C) 2012 Published by Elsevier Ireland Ltd. All rights reserved.