FAPI-PET/CT vs FDG-PET/CT: The Superior Imaging Technique for Liver Cancer Assessment

A recent study indicates that PET/CT imaging using a fibroblast activation protein inhibitor (FAPI) radiotracer is more effective than F-18 FDG-PET/CT for evaluating liver cancer patients. F-18 FAPI-04 appears to better characterize liver cancer subtypes and assess tumor growth.

Lead author Zhiying Liang, MD, from Guangzhou Medical University, noted that F-18 FAPI-04 could provide a noninvasive way to assess the proliferation of liver lesions, thereby offering useful insights into tumor behavior. This study was published in BMC Cancer on November 11.

Previous research highlighted the advantages of FAPI tracers, showing they have better uptake and contrast than F-18 FDG in various tumors, including liver tumors. However, studies focusing on FAPI-PET’s potential to reveal metabolic parameters and molecular characteristics of liver tumors have been limited.

To bridge this gap, 39 patients participated in a trial from September 2022 to February 2024, comprising 28 with hepatocellular carcinoma (HCC) and 11 with intrahepatic cholangiocarcinoma (ICC). Each patient underwent F-18 FDG and F-18 FAPI-04 PET/CT scans within a week. Experts analyzed the sensitivity, specificity, and accuracy of each tracer.

The results showed that F-18 FAPI-04 was more sensitive for tumor detection than F-18 FDG, with rates of 84.6% compared to 76.9%. Although the specificity of F-18 FDG was higher at 100%, F-18 FAPI-04’s accuracy was 81.8% versus 79.5% for F-18 FDG. F-18 FAPI-04 also demonstrated significantly higher maximum standardized uptake values (SUVmax) and tumor-to-background ratio (TBR).

In further analysis, F-18 FAPI-04 showed elevated SUVmax in benign lesions, HCCs, and ICCs. Higher SUVmax correlated with specific molecular characteristics, including hepatocyte negativity, CD34 negativity, and high Ki67 expression.

The researchers observed a notable correlation between F-18 FAPI-04 SUV and Ki67 expression, which is significant. This study emphasizes the importance of semiquantitative analysis using metabolic parameters in PET/CT tracer comparisons. It is one of the few studies to explore the link between FAPI metabolic parameters and immunohistochemical markers in liver cancers.

The researchers called for additional studies to validate these findings and their clinical relevance. The full study is available here.