Elsevier

European Journal of Radiology

Volume 81, Issue 11, November 2012, Pages 3557-3562
European Journal of Radiology

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

https://doi.org/10.1016/j.ejrad.2012.03.020Get rights and content

Abstract

Objective

To evaluate low-dose non-enhanced CT (ldCT) and full-dose contrast-enhanced CT (ceCT) in integrated 18F-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.

Section snippets

Objective

In approximately 20–30% of patients with early-stage ovarian cancer and 50–75% of those with advanced disease who obtain a complete response after therapy, disease will ultimately recur [1]. Few formal guidelines exist on the surveillance of these patients, and the type and timing of examinations to perform. The clinical follow-up generally includes measurement of the serum cancer antigen CA-125 level, physical examination, and imaging examinations.

Computed tomography (CT) and magnetic

Patients

One hundred and twenty patients (age range 32–87 years; mean 59 years) who had undergone treatment for histopathologically proven ovarian cancer underwent PET/CT examinations with intravenous contrast agent for suspected recurrence at PET Center, Institute of Biological Research and Innovation between December 2007 and July 2011 were included in this study. Informed consent was obtained from each patient after procedures were fully explained. Further details of these patients and their

Patient-based analysis

In 46 (38.3%) of the 120 patients, recurrence and/or distant metastasis was confirmed by pathologic examination and clinical follow-up study of imaging modality. In the other 74 patients (61.7%), no recurrence was confirmed by clinical follow-up study of tumor markers and imaging modality for periods than 6 months. The scales of detecting 46 patients with recurrence were N:4, E:2, and P:40 for PET/ceCT and N:4, E:6, and P:36 for PET/ldCT (Table 2). Four patients with equivocal findings by

Discussion

In our study, PET/ceCT is a more statistically accurate imaging modality for assessing ovarian cancer recurrence than PET/ldCT, reducing equivocal interpretations. Our results showed that patient-based sensitivity, specificity, and accuracy of PET/ceCT was 86.9%, 95.9%, and 92.5%, respectively, whereas those of PET/ldCT were 78.3%, 95.0%, and 88.3%, respectively. Moreover, with PET/ceCT, the proportion of equivocal findings on the per patient basis decreased by 4.2% (from 7 of 120 patients to 2

Conclusion

In conclusion, integrated FDG-PET/ceCT reduces the frequency of equivocal interpretations observed on PET/ldCT scan and is a more accurate imaging modality with higher confidence for assessing ovarian cancer recurrence than PET/ldCT. PET/ceCT may be a real “one-stop-shopping” examination.

Acknowledgments

We thank Hiroyoshi Okajima, Keita Miyamoto, Eiji Takeda, and Kazuhiro Kubo for their excellent technical assistance and generous support.

References (20)

There are more references available in the full text version of this article.

Cited by (39)

View all citing articles on Scopus
View full text