Pulmonary and renal involvement are the most common clinical manifestations of antineutrophil cytoplasmic antibody(ANCA)-associated vasculitis (AAV). Studies have shown that both interstitial lung disease (ILD) and renal dysfunction are closely associated with poor prognosis in patients with AAV. Therefore, early identification of whether AAV patients have concomitant ILD and renal involvement is of great clinical importance for assessing disease severity, stratifying prognostic risk, and developing individualized treatment strategies. Positron emission tomography (PET) is a noninvasive molecular imaging technique that can provide decision-making support for early and accurate diagnosis, timely intervention, as well as evaluation of treatment response and prognosis. In the same individual, PET enables whole-body localization of disease in a single examination, overcoming the limitation of conventional diagnostic methods that typically assess only one region at a time, thereby facilitating patient benefit. In recent years, many novel PET tracers have been developed and introduced into clinical practice. 68Ga-Fibroblast Activation Protein Inhibitor (FAPI) has been studied in the diagnosis of various malignant and nonmalignant diseases; it targets fibroblast activation protein (FAP) and thus reflects the distribution of cancer-associated fibroblasts (CAFs). However, its clinical significance in AAV remains to be further investigated. This study aims to use a CAF-targeted novel PET tracer to conveniently and noninvasively detect the real-time distribution of lesions in patients, providing valuable information for personalized diagnosis and treatment.