Traditional imaging modalities used to monitor the diameter of aortic aneurysms (AAs) often fail to follow pathological progression. Fibroblast activation protein (FAP), a key regulator of extracellular matrix (ECM) remodeling, plays a pivotal role in aortic disease. However, its expression in the aortic wall during aneurysm progression and its potential correlation with disease severity remains unexplored. Here, utilizing histology the levels of FAP are higher in the aortic wall of patients with AA compared to healthy controls. In three distinct animal models of AA, a progressive increase in FAP expression, coincides with the advancement of ECM remodeling. Notably, the levels of