Non-invasive evaluation of early liver fibrosis process by targeting αvβ6 integrin PET imaging.

Liver fibrosis is a key pathological stage in the progression of chronic liver diseases. Current diagnostic methods for early fibrosis detection are still limited. Therefore, there is an urgent need to develop non-invasive strategies that can detect and dynamically monitor early liver fibrosis. The integrin αvβ6 is significantly upregulated during fibrogenesis and has become a promising target for molecular imaging. In this study, we evaluated the potency of gallium-68-labeled αvβ6‑targeted probe, [68Ga]Ga-DOTA-αvβ6-BP, in liver fibrosis progression visualization and monitoring. In a CCl4-induced murine model, [68Ga]Ga-DOTA-αvβ6-BP PET/CT imaging demonstrated hepatic uptake that correlated positively with fibrosis stage, as confirmed by histopathology and serum biochemistry. Significant uptake (2.32 ± 0.33%ID/g, *p = 0.0435) was detected as early as week 3 and increased with prolonged injury-well before changes on ultrasound elastography or FAPI-04 PET. Immunofluorescence revealed αvβ6 predominantly on CK19-positive cholangiocytes, with later spread to α-SMA-positive myofibroblasts, confirming its cellular source. Furthermore, in pirfenidone-treated mice, [68Ga]Ga-DOTA-αvβ6-BP uptake declined markedly from 4.27 ± 0.13%ID/g to 1.47 ± 0.13%ID/g (p < 0.01) after 3 weeks, accompanied by histological improvement. To test cross-etiology utility, we validated the probe in MASH and MASH + CCl4 models; uptake was 2.34 ± 0.23%ID/g in MASH alone and increased to 2.51 ± 0.13%ID/g with CCl4 challenge (***p = 0.0006), matching histological severity. These findings establish [68Ga]Ga-DOTA-αvβ6-BP PET/CT as a sensitive, non-invasive tool for early detection and therapy monitoring across fibrotic etiologies, with dose estimates supporting clinical translation.