Mycotic Aneurysm

Mycotic Aneurysm

US – Color Doppler images show turbulent flow within a large infrarenal aortic and smaller right iliac artery aneurysms.

CT – Multiplanar and volume rendered 3D images further characterize the aneurysms.

Infected aneurysms are uncommon but can affect any artery; the aorta, peripheral arteries, cerebral arteries, and visceral arteries are involved in descending order of frequency. The prevalence of infected aortic aneurysms is 0.7%–1% of all surgically treated aortic aneurysms. Synchronous or metachronous infected aneurysms occur in 20%–36% of cases. Staphylococcus and Streptococcus species are the most common causes of infected aneurysms. Sterile blood cultures occur in 18%–50% of patients with infected aneurysms. Infected aneurysms can develop from a) hematogenous spread of infectious microemboli into the vasa vasorum of a normal-caliber artery or a preexisting aneurysm, b) infection of a preexisting intimal defect by circulating infectious agent, c) contiguous involvement of the vessel from an adjacent source of sepsis, or d) direct infectious inoculation of the vessel wall at the time of vascular trauma. Infected aneurysms have high morbidity and mortality which increase with delay in diagnosis related to hemorrhage and sepsis.

Lee WK, Mossop PJ, Little AF, et al. Infected (Mycotic) Aneurysms: Spectrum of Imaging Appearances and Management
RadioGraphics (2008); 28:1853-1868.