18F-FDGal PET/CT and PET/MRI in Patients With Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the most common primary liver tumor and the fourth leading cause of cancer-related death worldwide. In Denmark, the incidence of HCC is 5.2 per 100.000 population per year with a dismal prognosis as the median survival time is just 7.7 months.

Extrahepatic spread of HCC is common at advanced stages with haematogenous spread to lungs, bones and adrenal glands or lymphatic spread to regional lymph nodes.

The majority of patients who develop HCC have cirrhosis of the liver and in these patients, diagnosis can be made non-invasively with characteristic contrast-enhancement pattern on computed tomography (CT) and/or magnetic resonance imaging (MRI). Although contrast-enhanced CT and MRI are considered equal in current guidelines, MRI may have a better sensitivity especially for small lesions.

Positron emission tomography (PET) is a molecular imaging technique based on the injection of a very small dose of a tracer substance labelled with a positron emitting radioisotope. PET with the glucose tracer 18F-2-fluoro-2-deoxy-D-glucose fluorodeoxyglucose (18F-FDG) is an important tool in the staging of many cancer forms, but it is not included in the international guidelines for management of HCC because of suboptimal sensitivity of only up to 50-60 % for HCC situated in the liver.

In Aarhus, the liver specific tracer 18F-FDGal has been developed. It is a fluorine-18 labelled galactose analogue which in the human body is trapped in hepatocytes by phosphorylation by galactokinase. The first study of the diagnostic use of 18F-FDGal PET/CT in patients suspected of having HCC was published in 2011. The study showed good clinical potential for 18F-FDGal as a tracer for detection of intra- as well as extrahepatic HCC.

The aim of the present project is to establish the clinical impact and utilization of 18F-FDGal PET/CT and PET/MRI in patients suspected of having HCC or diagnosed with HCC, for staging and evaluation of treatment response including effect of treatment on liver function.

Hypotheses:

I. Adding 18F-FDGal PET/CT or PET/MRI to diagnostic work-up of patients suspected of or diagnosed with HCC will add to the establishment of a definitive diagnosis and improve staging and thus choice of treatment.

II. The uptake pattern of 18F-FDGal in HCC provides prognostic information and can be used to evaluate regional metabolic liver function before and after loco-regional treatment.