title: Infected aortic aneurysms: imaging findings.
abstract: OBJECTIVE
  To determine the imaging characteristics of infected aortic aneurysms.
  
  
  METHODS
  Review of records of patients with surgical and/or microbiologic proof of infected aortic aneurysm obtained over a 25-year period revealed 31 aneurysms in 29 patients. This study included 21 men and eight women (mean age, 70 years). One radiologist reviewed 28 computed tomographic (CT) studies (22 patients underwent CT once and three patients underwent CT twice), 12 arteriograms (12 patients underwent arteriography once), eight nuclear medicine studies (six patients underwent nuclear medicine imaging once and one patient underwent nuclear medicine imaging twice), and three magnetic resonance (MR) studies (three patients underwent MR imaging once). Features evaluated included aneurysm size, shape, and location; branch involvement; aortic wall calcification; gas; radiotracer uptake on nuclear medicine studies; and periaortic and associated findings. The location of infected aortic aneurysms was compared with that of arteriosclerotic aneurysms.
  
  
  RESULTS
  Aneurysms were located in the ascending aorta (n = 2, 6%), descending thoracic aorta (n = 7, 23%), thoracoabdominal aorta (n = 6, 19%), paravisceral aorta (n = 2, 6%), juxtarenal aorta (n = 3, 10%), infrarenal aorta (n = 10, 32%), and renal artery (n = 1, 3%). Two patients had two infected aortic aneurysms. CT revealed 25 saccular (93%) and two fusiform (7%) aneurysms with a mean diameter at initial discovery of 5.4 cm (range, 1-11 cm). Paraaortic soft-tissue mass, stranding, and/or fluid was present in 13 (48%) of 27 aneurysms, and early periaortic edema with rapid aneurysm progression and development was present in three (100%) patients with sequential studies. Other findings included adjacent vertebral body destruction with psoas muscle abscess (n = 1, 4%), kidney infarct (n = 1, 4%), absence of calcification in the aortic wall (n = 2, 7%), and periaortic gas (n = 2, 7%). Angiography showed 13 saccular aneurysms with lobulated contour in 10 (77%). Nuclear medicine imaging showed increased activity consistent with infection in six (86%) of seven aneurysms. MR imaging showed three saccular aneurysms. Adjacent abnormal vertebral body marrow signal intensity was seen in one (33%) of three patients.
  
  
  CONCLUSIONS
  Saccular aneurysms (especially those with lobulated contour) with rapid expansion or development and adjacent mass, stranding, and/or fluid in an unusual location are highly suspicious for an infected aneurysm.
authors.affiliation: Department of Radiology and Division of Vascular Surgery, Mayo Clinic and Foundation, 200 First St SW, Rochester, MN 55905, USA. macedo.thanila@mayo.edu
authors.forename: Thanila A
authors.initials: TA
authors.lastname: Macedo
authors.forename: Anthony W
authors.initials: AW
authors.lastname: Stanson
authors.forename: Gustavo S
authors.initials: GS
authors.lastname: Oderich
authors.forename: C Michael
authors.initials: CM
authors.lastname: Johnson
authors.forename: Jean M
authors.initials: JM
authors.lastname: Panneton
authors.forename: Mark L
authors.initials: ML
authors.lastname: Tie
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000785:Aneurysm, Infected / Q000145:classification / Q000175:diagnosis* / Q000382:microbiology; D017544:Aortic Aneurysm, Abdominal / Q000145:classification / Q000175:diagnosis* / Q000382:microbiology; D017545:Aortic Aneurysm, Thoracic / Q000145:classification / Q000175:diagnosis* / Q000382:microbiology; D002445:Celiac Artery / Q000000981:diagnostic imaging / Q000382:microbiology; D004927:Escherichia coli Infections / Q000145:classification / Q000175:diagnosis* / Q000382:microbiology; D005260:Female; D006192:Haemophilus Infections / Q000145:classification / Q000175:diagnosis* / Q000382:microbiology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008088:Listeriosis / Q000145:classification / Q000175:diagnosis* / Q000382:microbiology; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008638:Mesenteric Arteries / Q000000981:diagnostic imaging / Q000382:microbiology; D008875:Middle Aged; D008910:Minnesota; D012077:Renal Artery / Q000000981:diagnostic imaging / Q000382:microbiology; D012480:Salmonella Infections / Q000145:classification / Q000175:diagnosis* / Q000382:microbiology; D013203:Staphylococcal Infections / Q000145:classification / Q000175:diagnosis* / Q000382:microbiology; D013290:Streptococcal Infections / Q000145:classification / Q000175:diagnosis* / Q000382:microbiology; D014057:Tomography, X-Ray Computed