Fluorine-18 FDG positron emission tomography for imaging of hepatocellular carcinoma

The detection of increased fluorine-18 fluorodeoxyglucose (18F-FDG) uptake by positron emission tomography (PET) is based on the enhanced glucose metabolism of tumor cells. Because the detection and staging of hepatocellular carcinoma (HCC) in patients with liver cirrhosis can be difficult, we prospectively evaluated the sensitivity of 18F-FDG PET in 14 consecutive patients with HCC.

Whole body and regional 18F-FDG PET of the liver were obtained. The results were compared with ultrasonography, contrast-enhanced, helical CT, histological grading, p53 protein expression of HCC, and serum alpha-fetoprotein (AFP) level.

In 7 patients PET demonstrated increased tumor 18F-FDG uptake, whereas HCC was not distinguishable from nonmalignant liver tissue in 7 other patients. Hepatic lesions were detected by ultrasonography in all patients, whereas only 11 of 14 HCCs could be identified by CT. In 3 patients extrahepatic spread was demonstrated by 18F-FDG PET. Patients with increased tumor 18F-FDG uptake had significantly larger hepatic lesions and higher serum AFP levels than those with normal 18F-FDG uptake. Lesions could be visualized by 18F-FDG PET in 7 of 8 patients with moderately or poorly differentiated HCC, whereas none of the six well-differentiated tumors was detected. Two patients with strong p53 expression demonstrated increased tumor 18F-FDG uptake and extrahepatic metastases.

The sensitivity of 18F-FDG PET for the imaging of HCC is low. Nevertheless, in patients with moderately or poorly differentiated HCC, tumors >5 cm, or with markedly elevated AFP levels 18F-FDG PET may contribute to an effective noninvasive staging.