F-18-Fluorodeoxyglucose (FDG)-PET features of focal nodular hyperplasia (FNH) of the liver

Aim:. The aim of this paper is to describe the imaging pattern of focal nod ular hyperplasia (FNH) by F-18-fluorodeoxyglucose (18F-FDG) positron emissi on tomography (PET). Methods: Eight consecutive asymptomatic patients with histologic proof of FNH underwent 18F-FDG PET imaging. The lesions were fou nd incidentally. The 18F-FDG PET imaging was performed with a dedicated PET tomograph after intravenous injection of 300-370 MBq 18F-FDG. The 18F-FDG accumulation in the lesions was (semi)quantified by calculating the standar dized uptake value (SUV) and SUV has been corrected for the lean body mass (LBM). Eight patients with liver metastases spread from melanoma (n=2) and colorectal carcinoma (n=6) served as controls. The size of the FNH lesions and of the control group ranged from 2.0 to 8.5 cm (mean 4.83 cm+/-2.37) an d from 1.5 to 6 cm (mean 3.28+/-1.52), respectively. Results: While in mali gnant liver lesions the accumulation of 18F-FDG was significantly increased , all FNH lesions showed normal or even decreased accumulation of 18F-FDG. In FNH lesions, SUV ranged between 1.5 and 2.6 (mean 2.12+/-0.38), whereas all liver metastases showed an increased SW ranging between 6.20 and 16.00 (mean 10.07+/-3.79). The SUV corrected for LMB (SUVLBM) was similar to the SW and ranged between 0.9 and 2.2 (mean 1.81+/-0.41) for FNH and between 5. 9 and 16.3 (mean 9.15+/-4.03), respectively. Conclusion. In contrast to liv er metastases, there is no increased glucose metabolism in FNH in vivo. The imaging feature of FNH by 18F-FDG-PET imaging is not specific for FNH; how ever, it may be helpful to differentiate FNH from liver metastases in cance r patients if radiological methods are not diagnostic.