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Clinical value of F-FDG PET/CT in assessing suspicious relapse after rectal cancer resection.

AIM
To evaluate the value of (18)F-fluorodeoxyglucose positron emission tomography/computed tomography ((18)F-FDG PET/CT) in the restaging of resected rectal cancer.


METHODS
From January 2007 to Sep 2008, 21 patients who had undergone curative surgery resection for rectal carcinoma with suspicious relapse in conventional imaging or clinical findings were retrospectively enrolled in our study. The patients underwent 28 PET/CT scans (two patients had two scans, one patient had three and one had four scans). Locoregional recurrences and/or distant metastases were confirmed by histological analysis or clinical and imaging follow-up.


RESULTS
Final diagnosis was confirmed by histopathological diagnosis in 12 patients (57.1%) and by clinical and imaging follow-up in nine patients (42.9%). Eight patients had extrapelvic metastases with no evidence of pelvic recurrence. Seven patients had both pelvic recurrence and extrapelvic metastases, and two patients had pelvic recurrence only. (18)F-FDG PET/CT was negative in two patients and positive in 19 patients. (18)F-FDG PET/CT was true positive in 17 patients and false positive in two. The accuracy of (18)F-FDG PET/CT was 90.5%, negative predictive value was 100%, and positive predictive value was 89.5%. Five patients with perirectal recurrence underwent (18)F-FDG PET/CT image guided tissue core biopsy. (18)F-FDG PET/CT also guided surgical resection of pulmonary metastases in three patients and monitored the response to salvage chemotherapy and/or radiotherapy in four patients.


CONCLUSION
(18)F-FDG PET/CT is useful for evaluating suspicious locoregional recurrence and distant metastases in the restaging of rectal cancer after curative resection.