BackgroundThis pilot study is aimed to perform a pilot visualization study to investigate in vivo fibroblast activation in non-ischemic cardiomyopathies by68Ga-FAPI-04 PET/CT.MethodsTwenty-nine consecutive patients with symptomatic non-ischemic cardiomyopathies who underwent68Ga-FAPI-04 PET/CT were prospectively recruited. Clinical characteristics and echocardiographic parameters were recorded. Cardiac uptake was quantified by standardized uptake values (SUVmax,SUVmean, SUVR) and left ventricular metabolism volume. The relationship between68Ga-FAPI-04 uptake with clinical and echocardiography parameters was investigated.ResultsHeterogeneous68Ga-FAPI-04 uptake was observed in different subtypes of non-ischemic cardiomyopathies. Twenty-two (75.9%) patients showed elevated68Ga-FAPI-04 uptake in the left ventricle, and 10 (34.5%) patients also showed slightly diffuse elevated uptake in the right ventricle. Cardiac uptake values were significantly correlated with enlarged ventricular volume evaluated by echocardiography.ConclusionFAPI PET/CT presents a potential value for in vivo visualization and quantification of fibroblast activation on the molecular level. Further study is warranted for investigating the theranostic and prognostic value of elevated FAP signal.