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Abstract Background Right heart failure (RHF) is a complication of pulmonary hypertension (PH) and increases the mortality independently of the underlying disease. However, the process of RHF development and progression is not fully understood. We aimed to develop effective approaches for early diagnosis and precise evaluation of RHF. Methods Right ventricle (RV) pressure overload was performed via pulmonary artery banding (PAB) surgery in Sprague–Dawley (SD) rats to induce RHF. Echocardiography, right heart catheterization, histological staining, fibroblast activation protein (FAP) immunofluorescence and 18 F-labelled FAP inhibitor-42 ([18 F] -FAPI-42) positron emission tomography/computed tomography (PET/CT) were performed at day 3, week 1, 2, 4 and 8 after PAB. RNA sequencing was performed to explore molecular alterations between PAB and sham group at week 2 and week 4 after PAB respectively. Results RV hemodynamic disorders were aggravated, and RV function was declined based on right heart catheterization and echocardiography at week 2, 4 and 8 after PAB. Progressive cardiac hypertrophy, fibrosis and capillary rarefaction could be observed in RV from 2 to 8 weeks after PAB. RNA sequencing indicated 80 upregulated genes and 43 downregulated genes in the RV at both week 2 and week 4 after PAB; Gene Ontology (GO) analysis revealed that fibrosis as the most significant biological process in the RV under pressure overload. Immunofluorescence indicated that FAP was upregulated in the RV from week 2 to week 8 after PAB; and [18 F] -FAPI-42 PET/CT revealed FAPI uptake was significantly higher in RV at week 2 and further increased at week 4 and 8 after PAB. Conclusion RV function is progressively declined with fibrosis as the most prominent molecular change after pressure overload, and [18 F] -FAPI-42 PET/CT is as sensitive and accurate as histopathology in RV fibrosis evaluation.

Background: Right heart failure (RHF) is a complication of pulmonary hypertension (PH) and increases the mortality independently of the underlying disease. However, the process of RHF development and progression is not fully understood. We aimed to develop effective approaches for early diagnosis and precise evaluation of RHF. Methods: Right ventricle (RV) pressure overload was performed via pulmonary artery banding (PAB) surgery in Sprague–Dawley (SD) rats to induce RHF. Echocardiography, right heart catheterization, histological staining, fibroblast activation protein (FAP) immunofluorescence and 18 F-labelled FAP inhibitor-42 ([18 F] -FAPI-42) positron emission tomography/computed tomography (PET/CT) were performed at day 3, week 1, 2, 4 and 8 after PAB. RNA sequencing was performed to explore molecular alterations between PAB and sham group at week 2 and week 4 after PAB respectively. Results: RV hemodynamic disorders were aggravated, and RV function was declined based on right heart catheterization and echocardiography at week 2, 4 and 8 after PAB. Progressive cardiac hypertrophy, fibrosis and capillary rarefaction could be observed in RV from 2 to 8 weeks after PAB. RNA sequencing indicated 80 upregulated genes and 43 downregulated genes in the RV at both week 2 and week 4 after PAB; Gene Ontology (GO) analysis revealed that fibrosis as the most significant biological process in the RV under pressure overload. Immunofluorescence indicated that FAP was upregulated in the RV from week 2 to week 8 after PAB; and [18 F] -FAPI-42 PET/CT revealed FAPI uptake was significantly higher in RV at week 2 and further increased at week 4 and 8 after PAB. Conclusion: RV function is progressively declined with fibrosis as the most prominent molecular change after pressure overload, and [18 F] -FAPI-42 PET/CT is as sensitive and accurate as histopathology in RV fibrosis evaluation. [ABSTRACT FROM AUTHOR]

The review is devoted to the application of the new perspective class of radionuclide tracers, based on inhibitors of the fibroblast activation protein (FAP), which is a marker of cancer-associated fibroblasts of microenvironment of most malignant tumors. FAP inhibitors (FAPI) can be labeled by a wide spectrum of radionuclides, which can pro& vide both radionuclide diagnostics and radionuclide therapy. It was showed, that the diagnostic efficacy of FAPI positron emission tomography/computed tomography (PET/CT) in various cancers is similar to 18F-fluorodesoxyglucose-PET/CT or superior. The FAPI radiopharmaceuticals (RP) have some advantage compared to 18F-fluorodesoxyglucose (FDG): no need for special preparation and diet, fast imaging with high contrast, and increased sensitivity in region with high glucose metabolism. FAPI-PET/CT may be an important addition to conventional methods in all stages of diagnostic process in oncology, especially when 18F-FDG cannot be used. It is need to further wide prospective investigations for assessing of diagnostic efficacy of FAPI-RP and determination of indications for its using. [ABSTRACT FROM AUTHOR]