18 F-FAPI PET/CT in chronic liver disease: myocardial fibroblast activation and its correlates.

Objectives: This study investigated the relationship between cardiac fibroblast activation and clinical parameters, electrophysiological findings, serum fibrosis markers, and hepatic fibroblast activation in patients with chronic liver disease.

Methods: In this prospective study conducted from December 2021 to April 2022, 46 patients with chronic liver disease underwent fluorine-18 ( 18 F)-labeled fibroblast activation protein inhibitor (FAPI) PET/computed tomography (CT) imaging and 12-lead electrocardiogram (ECG). Abnormal cardiac 18 F-FAPI uptake was defined as uptake greater than that of the blood pool.

Results: Among 46 patients with chronic liver disease analyzed, 14 showed positive myocardial FAPI uptake and 32 were negative. Significant differences were observed between positive and negative myocardial 18 F-FAPI PET/CT imaging groups in terms of age ( P = 0.006), epicardial fat volume (EFV) ( P = 0.004), Cornell voltage QRS amplitude ( P = 0.022), and QRS duration ( P = 0.032). The multivariable logistic regression analysis demonstrated a significant association between EFV [odds ratio (OR) = 1.019; P = 0.024] and age (OR = 1.162; P = 0.019) and positive myocardial FAPI uptake. Myocardial maximum target-to-background ratio (TBR max ) was positively correlated with hepatic TBR max ( r = 0.405; P = 0.005) and hepatic TBR mean ( r = 0.412, P = 0.004). Moreover, myocardial maximum standardized uptake value was positively correlated with serum laminin levels ( r = 0.367; P = 0.042).

Conclusions: In patients with chronic liver disease, FAPI PET/CT imaging observed cardiac fibroblast activation, which was associated with electrophysiological parameters, hepatic FAPI uptake, and serum liver fibrosis markers. These findings suggest that 18 F-FAPI PET/CT imaging may offer a noninvasive approach for identifying early myocardial changes in chronic liver disease.