Differentiation of hepatocellular adenoma and focal nodular hyperplasia using 18F-fluorocholine PET/CT

The aim of this pilot study was to evaluate the use of PET/CT with 18F-fluorocholine in the differentiation of hepatocellular adenoma (HCA) from focal nodular hyperplasia (FNH). Patients with liver lesions larger than 2 cm suspicious for HCA or FNH were prospectively included. All patients underwent PET/CT with 18F-fluorocholine and histopathological diagnosis was obtained by either liver biopsy or surgery. The ratios between the maximum standardized uptake value (SUV) of the lesion and the mean SUV of normal liver parenchyma were calculated and a receiver operating characteristic (ROC) curve analysis was performed. Ten patients with FNH and 11 with HCA were included. The mean SUV ratio was 1.68±0.29 (±SD) for FNH and 0.88±0.18 for HCA (p<0.001). An SUV ratio cut-off value between 1.12 and 1.22 differentiated patients with FNH from those with HCA with 100% sensitivity and 100% specificity. This pilot study showed that PET/CT with 18F-fluorocholine can differentiate HCA from FNH

FDG and other radiopharmaceuticals in the evaluation of liver lesions

Liver nodules are common findings in medical practice, both in patients with and in those without chronic liver disease. These lesions have to be interpreted according to clinical history and biochemical findings. Conventional imaging (US, CT and MRI) is still the gold standard for evaluating liver nodules, while diagnostic flowcharts do not currently include PET/CT. Since the 1990s many studies have been conducted to assess a possible role for FDG PET or PET/CT in several liver pathologies. According to the literature, FDG PET (and later PET/CT) could be useful in detecting, staging and grading hepatocellular carcinoma, often leading to a change in therapy, and may even detect intrahepatic cholangiocarcinoma with adequate sensitivity. Moreover, FDG can allow more accurate staging of hepatic involvement deriving from other tumors (often underestimated by conventional imaging) and, therefore, more appropriate therapy in affected patients. Finally, FDG PET can also be used to evaluate 90Y microsphere therapy response. Other conditions (e.g., primary hepatic lymphoma when conventional imaging is inconclusive) may benefit from the use of FDG PET/CT, while benign lesions (e.g., focal nodular hyperplasia) show low FDG avidity. As regards non-FDG tracers, choline and acetate (ACE) have been evaluated in comparison with FDG and found to show good efficacy in detecting and staging well- or moderately differentiated HCC. However, their sensitivity in poorly differentiated HCC is very low, suggesting that dual-tracer investigation (FDG and choline/FDG and ACE) could be useful when non-invasive grading is required. Despite promising results, PET evaluation of liver nodules still seems to be far from routine application, mostly because of cost-related issues