# 68Ga-FAPI-04 PET/CT in the Diagnosis of Hepatocellular Carcinoma Associated with Cirrhosis: Diagnostic Value, Correlation Between PET Parameters of the Tumor and Its Size, and PIVKA-II Levels

## TL;DR

This study shows that 68Ga-FAPI-04 PET/CT is effective for detecting liver cancer, especially in non-cirrhotic patients, but has limitations in cirrhotic livers due to high background uptake.

## Contribution

The study evaluates the diagnostic performance of 68Ga-FAPI-04 PET/CT in hepatocellular carcinoma with and without cirrhosis and explores correlations with tumor size and PIVKA-II levels.

## Key findings

- 68Ga-FAPI-04 PET/CT showed 89.8% sensitivity for HCC detection.
- Cirrhotic patients had higher liver background uptake and lower tumor-to-background ratios.
- SUVmax correlated with tumor size in non-cirrhotic patients and with PIVKA-II levels in cirrhotic patients.

## Abstract

Background/Objectives: Hepatocellular carcinoma remains a major cause of death from cancer globally. While 18F-FDG PET/CT is commonly used for tumor imaging, its sensitivity is limited, especially due to high liver background uptake. Recently, 68Ga-FAPI PET/CT, which targets fibroblast activation protein in tumor stroma, has emerged as a promising diagnostic tool. In this study, we aimed to assess the diagnostic performance of 68Ga-FAPI-04 PET/CT in HCC patients with and without liver cirrhosis and to explore the relationship between PET metrics, tumor size, and PIVKA-II serum marker. Methods: In this prospective single-center study, 59 patients with confirmed HCC (37 with cirrhosis, 22 without) underwent 68Ga-FAPI-04 PET/CT. The standard dose (1.5–2.0 MBq/kg) was administered intravenously, and imaging was carried out 60 min post-injection. Semi-quantitative parameters including SUVmax, SUVmean, and tumor-to-background ratio were calculated. Diagnostic performance was assessed using histopathology and multimodal imaging. Statistical analyses included the Mann–Whitney U test and Spearman correlation. Results: The overall sensitivity for HCC detection was 89.8%, with a specificity of 60% and accuracy of 87%. Sensitivity and specificity showed a tendency to be lower in cirrhotic compared with non-cirrhotic patients, with a notably higher background liver uptake in cirrhosis (SUVmax 3.60 vs. 1.3, p < 0.001), resulting in lower TBR values (3.7 vs. 7.0, p < 0.001). A strong correlation between SUVmax and tumor size was seen in non-cirrhotic HCC, while a moderate association between SUVmax and PIVKA-II levels was observed in cirrhotic patients. Conclusions:
68Ga-FAPI-04 PET/CT demonstrates high sensitivity for HCC detection and may serve as a complementary imaging modality, particularly when interpreted through conventional cross-sectional imaging. Image interpretation in cirrhotic livers may be challenging due to increased background uptake and reduced TBR. Associations between PET-derived parameters, tumor size, and serum PIVKA-II levels should be considered hypothesis-generating and require validation in larger, multicenter studies with clinical outcome data.