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Integrated PET-CT Best for Detecting Recurrent Ovarian Ca


 

CHICAGO — The accuracy of PET-CT for detecting recurrent ovarian cancer is high, Dr. Sunit Sebastian said at the annual meeting of the Radiological Society of North America.

The diagnosis of early recurrence is challenging due to the small size of peritoneal metastases, he said.

In a retrospective study, integrated PET-CT imaging proved to be more accurate than CT alone or PET alone for detecting ovarian cancer recurrence either above or below the diaphragm, reported Dr. Sebastian, who was at Massachusetts General Hospital in Boston at the time of the study.

The analysis included 54 consecutive CT, PET, and PET-CT examinations that were performed at the hospital on 53 women for tumor recurrence after primary debulking surgery for histologically proven ovarian cancer.

One patient underwent PET-CT examination twice.

PET-CT scans of the neck, chest, abdomen, and pelvis were performed with negative oral contrast on a fusion PET-CT scanner.

Delayed PET images were obtained 1 hour later. Finally, a diagnostic CT scan was performed with intravenous contrast and negative oral contrast.

A nuclear medicine radiologist and an abdominal radiologist independently reviewed the diagnostic CT and PET scans, and then reviewed the PET-CT fusion study together.

A gynecologic oncologist provided the standard for recurrent disease based on a clinical record review that took place 3 months after the scans.

The gynecologic oncologist and the readers were blinded to each others' reports, Dr. Sebastian said.

Sensitivity, specificity, and accuracy were each calculated with 95% confidence intervals.

For the entire body, the sensitivity for CT was 35/38 (92%), 31/38 (82%) for PET, and 37/38 (97%) for PET-CT.

Specificity for CT was 9/15 (60%), 10/15 (67%) for PET, and 12/15 (80%) for PET-CT.

Accuracy for CT was 44/53 (83%), 41/53 (77%) for PET, and 49/53 (92%) for PET-CT, said Dr. Sebastian, now a senior research associate in the division of radiology, Emory University School of Medicine, Atlanta.

For the neck and chest, the accuracy was 47/53 (89%) for CT, 48/53 (91%) for PET, and 51/53 (96%) for PET-CT. For the abdomen and pelvis, the accuracy was 42/53 (79%), 42/53 (79%) for PET, and 48/53 (91%) for PET-CT.

Dr. Sebastian suggested that women with ovarian cancer should be routinely evaluated with PET-CT 4–6 months after surgery.

Ideally, a CT scan of the chest should be included as part of the work-up because about 5% of patients with recurrent ovarian cancer will have metastatic disease in the chest without identifiable recurrence in the abdomen and pelvis. For economic reasons, a chest x-ray at least would be helpful, he said.

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