Evaluation of liver tumors with 18F-FDG PET

Objective: To evaluate diagnostic ability of 18F-2-fluoro-2-deoxy-D-glucose (FDG) PET in patients with liver tumors and its limitations. Methods: Ten patients with benign tumors and 28 patients with malignant tumors including 25 men and 3 women with a mean age of 58.1 +- 10.8 (40 - 85) years. There were 13 hepatocellular carcinomas (HCC) and 1 cholangio-cellular carcinomas (CCC), the tumor diameters were 1.2 - 3.8 cm, 14 patients with metastatic liver cancer. The PET study was performed using a Siemens ECAT EXACT HR+ PET. After the intravenous administration of FDG (5.55 MBq/kg), PET scan was performed in 3-7 bed positions with 2D acquisition and OSEM reconstruction. For quantitative evaluation, a region of interest (ROI) was placed over the tumor region, and a background ROI was placed over the nontumor region of liver, then the standardized uptake value (SUV) was calculated. On the basis of visual inspection, the tumors were divided into the following three types, type A: FDG uptake was increased; type B: FDG uptake was similar to the surrounding nontumor liver tissue and type C: FDG uptake was decreased or absent. Results: The SUV of nontumor region of liver was 1.86 +- 0.51. Tumors SUV of type A was 3.02 +- 1.33 (2.10 - 7.90) 9 of 13 HCC and 1 CCC fell in type A, and it was significantly different from the SUV of nontumor region (t = 1.44, P = 0.01); 3 patients with HCC fell in type B, 1 in type C. Nineteen metastatic lesions was found to be type A in 14 patients with metastatic liver cancer, while CT and MRI showed 11 and 13 metastatic lesions in the 14 patients, respectively. Conclusions: The PET technique using FDG is useful in localization and differentiation of liver lesions and metastatic liver cancer. The limitations include false-negative results in HCC