RESUMO
Objective To evaluate the clinical value of 18F-FDG PET/CT for detecting tumor on physical examination people with unexplained elevated serum carcinoembryonic antigen (CEA). Methods A total of 100 physical examination people with unexplained elevated serum levels of CEA in our hospital from June 2010 to December 2014 were involved in the study. All the people were detected with 18F-FDG PET/CT. The pathology, clinical follow ups and conventional medical imaging results were combined to evaluate the value of 18F-FDG PET/CT in diagnosing tumor. The doubling time (DT) of CEA was calculated in the patients who were received more than twice of serum CEA detection. The relationships between serum CEA levels, CEA DT and 18F-FDG PET/CT imaging were analyzed. The receiver operating characteristic (ROC) curve was used to assess the diagnostic efficiency of serum CEA. Results Twenty-seven patients were confirmed with malignant tumor, and the rest of 73 cases were excluded. The 18F-FDG PET/CT reported one false positive and one false negative respectively. The sensitivity, specificity, accuracy, positive and negative predictive values of 18F-FDG PET/CT in diagnosing malignant tumors were 96.3%, 98.6%, 98.0%, 96.3% and 98.6% respectively. The median serum CEA levels were significantly higher in the positive 18F-FDG PET/CT patients than those in the negative patients (Z=5.796, P180 d and DT180 d and patients with DT0.05). The area under the curve (AUC) of serum CEA was 0.894, the optimal diagnostic cutoff value was 14.24μg/L. Conclusion 18F-FDG PET/CT is a useful image modality for detecting malignant tumors in patients with unexplained elevated serum CEA, especially for patients with CEA≥14.24μg/L and increase progressively.