[Evaluation of various hepatic lesions with positron emission tomography]

[18F]FDG-PET is a functional imaging modality reflecting cellular glucose metabolism. In most malignant cells, accumulation and trapping of [18F]FDG allows the visualization of increased uptake compared with normal cells. The aim of this study was to assess the value of PET in differentiating benign from malignant hepatic lesions and to determine in which types of hepatic tumors PET can help evaluate stage, monitor response to therapy, and detect recurrence.

Eighty patients with liver lesions were enrolled (hepatocellular carcinoma 34, cholangiocarcinoma 8, metastatic liver cancer 25, hemangioma 6, liver abscess 7). Liver metastases were 22 adenocarcinoma, 2 lymphoma, 2 squamous cell carcinoma. The PET images of these patients were analyzed. SUV and lesion-to-normal liver background SUV ratio were obtained and compared among the disease groups.

All liver metastases and all cholangiocarcinomas had increased uptake value, with SUV ratios greater than 2. Hepatocellular carcinoma had SUV ratios greater than 2 in 20 of 34 patients (59%). All hemangiomas had poor uptake, a SUV ratio of less than 2. All liver abscesses showed definite uptake.

The PET technique using FDG static imaging was useful in differentiating malignant from benign lesions of the liver in limited situations. Limitations included false negative results in some patients with hepatocellular carcinoma. Liver abscesses raised problems in differential diagnosis from malignant liver tumors. The findings of this study suggest that the PET technique might be applied in tumor staging and the detection of recurrence, as well as monitoring responses to therapy for all adenocarcinomas and some hepatocellular carcinomas.