Utility of 18F-FDG positron emission tomography scanning on selection of patients for resection of hepatic colorectal metastases

Background: Hepatectomy represents a standard and potentially curative therapy for hepatic colorectal metastases. However, up to two thirds of patients explored for resection are found to have unsuspected disease, which precludes resection. Methods: In order to determine if 18F-FDG positron emission tomography (PET) scanning may prevent unnecessary surgery, a group of 40 patients being considered for hepatic resection but at high risk for unresectable disease by clinical criteria were subjected to whole body 18F-FDG-PET scanning. Effect on clinical outcome was evaluated. In addition, PET findings in the 25 patients who underwent resection of hepatic metastases were directly compared with the resected specimen to determine the sensitivity of 18F-FDG PET scanning in the liver. Results: Findings on 18F-FDG-PET scanning influenced the clinical management in 16 patients (40%) and directly altered management in 9 cases (23%). Six patients were spared laparotomy, and 3 others had PET-directed surgery that found extrahepatic tumor and spared the patient unwarranted liver resection. In 3 cases PET missed peritoneal metastases found on laparotomy. In these cases all missed tumors were less than 1 cm in size. Out of 52 resected hepatic lesions, 18F-FDG-PET detected 37. Within the liver, sensitivity of detection was also related to size. Only 25% of hepatic lesions smaller than 1 cm were detected by PET, while 85% of lesions larger than 1 cm were detected. Conclusions: FDG-PET is best for detecting extrahepatic disease. There are few false positives, and surgeons should carefully evaluate and biopsy extrahepatic positive sites. This test should be used for patients at high risk for extrahepatic disease and should be evaluated prospectively for all patients under consideration for liver resection.