Purpose: The authors' goal was to determine the sensitivity and specificity of F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) for identifying patients with hepatic metastases from colorectal cancer and the accuracy of PET for determining the number and distribution of lesions within the liver. Intraoperative sonography and surgical inspection and palpation were used as the reference standard.
Methods: Twenty-three patients being evaluated for surgical resection of hepatic metastases from colorectal carcinoma underwent FDG PET before operation. Findings of the PET studies were reviewed in a blinded, retrospective manner, with the results compared with the findings of intraoperative sonography and surgical exploration. Lesions of all sizes were considered in the analysis.
Results: The FDG-PET results were positive in 21 of the 22 patients ultimately found to have metastatic disease to the liver, and they were negative in the single patient without metastases. Therefore, for identification of patients with hepatic metastatic disease, PET has a sensitivity of 95% and a specificity of 100%. In all, 48 metastatic lesions were identified in these patients, of which 38 (79%) were identified on PET images. The probability of lesion detection by PET was directly correlated with lesion size (P < 0.01). The assessment of lobar disease distribution in the liver was discordant between PET and surgery in 3 of 23 (13%) patients.
Conclusions: In patients being evaluated for potential curative resection of hepatic metastases from colorectal cancer, FDG PET is accurate for the identification of the presence or absence of metastatic disease to the liver. However, detection of individual lesions depends on their size, and determination of lesion number and distribution within the liver is more accurately accomplished with intraoperative sonography.