32. Detection of Recurrence of Ovarian Cancer using [F-18]-FDG Scan Performed on a Dual-Head Coincidence Gamma Camera (CDET)

Purpose: The aim of this preliminary study was to evaluate the role of FDG-CDET in detection of recurrence of ovarian cancer.

Methods and patients: After a fast of 6 hours, the patient (pt) was injected I. V. with 150–250 MBq of [F-18]-FDG and imaging (whole-body scan and at least a tomoscintigram) was started 45 min. later, using a PICKER Prism XP 2000 CDET gamma camera. Between July 1997 and December 1999, 40 patients were studied for ovarian carcinoma. To date, the results of 23 patients are evaluable with reference to histology after surgery or long-term follow-up. From these 23 patients, 18 pts were referred for suspected recurrence of ovarian carcinoma: occult recurrence (OR) defined by an increase in serum CA-125 levels with negative conventional imaging (13 pts) or equivocal aspect at conventional imaging (5 pts).

Results: In 13 pts referred for suspicion of OR, FDG-CDET was true positive (TP) in 11 cases all confirmed by histology after surgery and was true negative (TN) in the remaining 2 cases as confirmed by spontaneous normalization of CA-125 levels and no events during a 20-month follow-up. In the 5 pts with equivocal aspect on CT, 4 were (TP) with recurrent foci at FDG-CDET in 1 case and 1 was (TN) corresponding to a leı̈omyoma on histology after surgery. In summary, the overall sensitivity and accuracy on a per patient basis were 18/18 for FDG-CDET while sensitivity and accuracy of conventional imaging was only 6/18.

Conclusion: These preliminary results in a clinical setting, which is not frequently evaluated on CDET gamma cameras, seem very promising.