18F-FAPI PET/CT Imaging in Pneumoconiosis: a new tool for early diagnosis and guiding treatment of pulmonary fibrosis

PurposePneumoconiosis is characterized by pulmonary fibrosis. The activation of fibroblasts play an important role in the pathological development of pulmonary fibrosis. Chest CT, as a conventional examination to diagnose pulmonary fibrosis of pneumoconiosis, cannot evaluate the fibrosis activity. The application value of 18F-FAPI in pneumoconiosis is unclear. This study aimed to clarify the feasibility of 18F-FAPI PET/CT in non-invasively monitoring the activity evolution of pulmonary fibrosis in pneumoconiosis and the anti-fibrotic treatment. Materials and MethodsA preliminary clinical study was conducted on 6 pneumoconiosis patients and 4 healthy control individuals, correlation analysis was performed between the 18F-FAPI uptake in pulmonary fibrosis areas and the pulmonary diffusing function. Sprague-Dawley rat experiments were performed on three groups concluding pneumoconiosis model, pirfenidone-treated, and normal control groups. 18F-FAPI and 18F-FDG PET/CT, histopathologic, and hematological analysis were assessed monthly from modeling until 6 months. Results18F-FAPI uptake in fibrotic areas was found in the pneumoconiosis patients, and negatively correlated with the diffusing function (r = -0.929, P = 0.022). In the pneumoconiosis model, 18F-FAPI activity preceded one month earlier than relative collagen content (%) in Masson trichrome staining and the level of connective tissue growth factor in plasma, an indicator reflecting the fibroblast activation. The uptake of 18F-FAPI, rather than 18F-FDG, significantly decreased in the pirfenidone-treated group compared to the pneumoconiosis group (P < 0.05). Conclusion18F-FAPI PET/CT imaging holds promise for the early identification of pulmonary fibrosis activity and monitoring its evolution in pneumoconiosis, offering a precise clinical opportunity for targeted anti-fibrotic treatment.