High incidence of peritoneal implants in recurrence of intra-abdominal cancer revealed by 18F-FDG PET/CT in patients with increased tumor markers and negative findings on conventional imaging.

OBJECTIVE

The aim of this prospective study was to investigate the role of 18F-fluorodeoxyglucose (18F-FDG) PET/CT in the diagnosis of recurrent intra-abdominal cancer in patients with increased tumor markers and negative findings on conventional imaging studies.

METHODS

Seventy-three patients (30 men; age 61.1 ± 11.5 years) with intra-abdominal cancer (colorectal, n=32; ovarian, n=18; gastric, n=7; pancreatic, n=7; cervical, n=4; endometrial, n=3; duodenal, n=1; and small bowel, n=1) and increasing levels of tumor markers during follow-up and negative CT, MRI or both underwent 125 18F-FDG PET/CT examinations. The final diagnosis was confirmed by histopathological findings in 22 patients, clinical follow-up (median of 12 months) in 13 patients,and repeated imaging with 18F-FDG PET/CT examinations in 38 patients.

RESULTS

Of 73 cancer patients, 18F-FDG PET/CT identified recurrent disease in 52 patients and ruled out in 21 patients. 18F-FDG PET/CT scan was true positive (TP) in 49 patients, false positive in three patients, false negative in four patients, and true negative in 17 patients. In our study, the 18F-FDG-PET/CT scan had a sensitivity of 92.4%, a specificity of 85%, and an accuracy of 91%. Fourteen of 49 TP studies (28.5%) showed peritoneal implants only. Moreover, peritoneal implants were detected in additional nine of 49 TP studies (18.3%) presented with multiple lesions. Thus, half of the true-positive examination revealed peritoneal implants that CT or MRI had not depicted.

CONCLUSION

The results of this study indicate a high incidence of peritoneal implants revealed by 18F-FDG PET/CT in the diagnosis of recurrent intra-abdominal cancer in patients with increasing tumor markers and negative findings on conventional imaging studies.