One autoradiography study demonstrated that 18F-fluciclatide detects areas of angiogenesis in AAA in vitro.47 18F-FMISO (fluoromisonidazole) and 18F-HX4 are radiotracers that selectively identify areas of hypoxia and have been used to localise high-risk carotid artery plaque reflecting increased macrophage activity.48 Proteolytic degradation of collagen and elastin in the extracellular matrix is another key component in AAA formation. This evidence concerns the gene ELN and triple-A syndrome.