Objectives: The purpose of this study was to evaluate the performance of F-fluorodeoxy-D-glucose (FDG)-PET/computed tomography (CT) and contrast-enhanced CT (CECT) in the detection and characterization of hepatic metastases.
Methods: Forty-five patients harboring an extrahepatic primary malignancy, with suspected hepatic metastases on clinical or ultrasonographic examination were enroled prospectively. Each patient underwent contrast-enhanced abdominal CT and F-FDG-PET/CT within 72 h of each other, reported by an experienced radiologist and nuclear medicine specialist, respectively in a blinded manner. CECT and PET-CT findings were compared and analyzed. Final diagnosis was based on histology and/or follow-up (ranging from 6 to 12 months).
Results: The sensitivity and specificity of CECT in the detection of hepatic metastases was 87.9 and 16.7%, respectively, whereas that of PET/CT was 97 and 75%, respectively. This study showed the superiority of PET/CT over CECT in the detection of hepatic metastases, irrespective of the primary site. This was especially owing to the latter's inability to reliably distinguish small (less than 15 mm) lesions as benign or malignant.
Conclusion: Many studies have been conducted on the impact of FDG-PET/CT in the evaluation of hepatic metastases, especially from colorectal primary. Very few prospective studies, however, have been conducted on its role in evaluation of hepatic metastases from nongastrointestinal primaries. Despite its superior performance, it cannot replace CECT for this purpose, owing to the low but definite risk of false positivity based on PET-CT findings alone. Inclusion of CECT in PET/CT protocols may enable us to achieve a higher diagnostic accuracy. This suggests the need for a large prospective study with serial evaluations and pathological correlation.