FAP and interstitial lung disease: It had been reported that FAP inhibitor (FAPI) labeled by radionuclide could reveal the FAP expression in patients with ILD, (Bergmann et al., 2021; Rohrich et al., 2022) positron emission tomography computed tomography (PET/CT) used FAPI as a tracer maybe is a promising imaging modality for ILDs to detect lesion earlier than CT, because CT only focuses on the change of structure, but FAPI PET/CT can observe the metabolism of the fibroblast before the change of anatomy.