Imaging features of mycotic aortic aneurysms

Abstract

Infectious aortitis (IA) is a rare and life-threatening cardiovascular disease. Early diagnosis and timely intervention are crucial for reducing mortality associated with mycotic aortic aneurysms (MAAs); however, early diagnosis is challenging due to the nonspecific symptoms. Some cases are diagnosed at an advanced stage or after developing complications, such as rupture or aortic fistula. Current state-of-theart imaging modalities-including computed tomography (CT), magnetic resonance imaging (MRI), and 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT-can detect infected aneurysms in clinically suspicious cases. MAA features on imaging include lobulated pseudoaneurysm, indistinct irregular arterial wall, perianeurysmal gas, perianeurysmal edema, perianeurysmal soft tissue mass, aneurysmal thrombosis, and high metabolic activity with increased uptake of FDG. Enlarged lymph nodes are often found adjacent to the aneurysm, while iliopsoas abscess (IPA), spondylitis, and aortic fistulas are commonly associated complications. After surgery or endovascular repair, radiological features-including ectopic gas, peri-graft fluid, thickening of adjacent bowel, pseudoaneurysm formed at the graft anastomosis, and increased uptake of FDG-may indicate an infection of aortic graft. This article provides an overview of the clinical and imaging features of MAAs. Thus, familiarity with the imaging appearances of MAAs may assist radiologists in the diagnosis and facilitation of timely treatment.

CT Imaging Manifestations of Tubercular Aortic Aneurysm

“…1B). No patients showed gas bubbles which may appear in and around MAAs which could be indicative of high diagnostic reliability of bacterial infection [10]. Although gas bubble is an important sign of arterial infection, it is too rare to make the differential diagnosis.…”

“…The contrast-enhanced CT can provide valuable information about the morphology of aortic aneurysm, aortic wall enhancement, and the relationship between the aneurysm and adjacent tissue because of the higher quality spatial resolution. TBAA typically appears on CT as a focal, contrast-enhancing, saccular lumen, lobulated, with an indistinct, irregular aortic wall [10]. Tuberculous aneurysms may occur anywhere along the arterial system [17] and usually occur as a solitary lesion [18].…”

“…The size of the aneurysm is neither a risk factor of rupture, nor of the necessity for in uencing treatment [22]. However, rapidly progressive growth of aneurysms (> 5 mm in 2 weeks) is suggestive of an infectious etiology [10]. CT is very sensitive to detect calci cation and gas bubbles.…”

“…The two radiologists assessed the images independently and they reached agreement in all of the image interpretation. As previously reported in literature [10], the following items were regarded as being predictive for mycotic aneurysms on CT images: the site of mycotic aneurysms, the atherosclerosis around aneurysms, the aneurysm wall enhanced or not, the air bubble around the aneurysm, the bone destruction of adjacent vertebra, soft tissue involved around the aneurysm(psoas abscess, retroperitoneal abscess or peritoneal abscess), enlarged lymph nodes near lesions, and other infectious foci outside the aorta.…”

Fatal Mycotic Aortic Aneurysmal Rupture Induced by Urosepsis From a Vesico-Enteric Fistula and/or Acute Pancreatitis

“…A mycotic (infectious) aortic aneurysm (iAA), is a rare, life-threatening disease of the aorta for which the chance of an early diagnosis may be missed due to a lack of specific clinical, radiological, and laboratory features [1,2]. Infectious abdominal aortic aneurysms usually occur in the elderly, predominantly affecting immunocompromised patients, including patients with diabetes mellitus, liver cirrhosis, end-stage renal disease, alcoholism, chronic glucocorticoid therapy, post-transplantation immunosuppression, human immunodeficiency virus infection, drug abuse, and malignancy [1,2]. An iAA is an acute inflammatory response to pathogenic infection, which induces neutrophilic infiltration at the arterial wall.…”