SESSION TITLE: Imaging Student/Resident Case Report Posters
SESSION TYPE: Student/Resident Case Report Poster
PRESENTED ON: Tuesday, October 27, 2015 at 01:30 PM - 02:30 PM
INTRODUCTION: Aortic graft infections are an exceedingly difficult diagnosis, given their non specific signs and symptoms. There is general confusion in determining which imaging modalities to utilize initially. Here we present such a case, and attempt to clarify this topic.
CASE PRESENTATION: An 84 year old male with a past medical history of axillary to bifemoral artery bypass complicated by ureteral to aortic fistula status post repair presented with complaints of fatigue and subjective fever for three days. Given his complex surgical history, a CT abdomen was obtained which demonstrated gas within the abdominal aorta. This finding was suspicious for repeated fistula formation or possibly infection. A white blood cell (WBC) scan was done, confirming arterial stent infection. Given the location, cultures could not be obtained and the risks of surgery for removal of the graft were discussed with the patient. The decision was made to proceed with chronic antibiotic therapy and he was discharged home on six weeks of intravenous daptomycin and meropenem, followed by chronic moxifloxacin therapy.
DISCUSSION: The reported incidence of aortic graft infection is 2-6% (1). The time period for development of infections is varied, and can range from the immediate post operative period until several years later. However, infections tend to occur later, with a mean presenting interval of 25 months (1). The presence of gas in the bed of the graft greater than two weeks post operatively is pathognomonic of aortic graft infection (1). A prospective study comparing CT scan and WBC scan in making the diagnosis of aortic graft infections suggested that CT was more sensitive in evaluating the extent of the infection (1). This is due to the fact that WBC scans were inferior to CT in proving retroperitoneal extension, and that CT has the ability to demonstrate perigraft fluid or air (1).
CONCLUSIONS: This case highlights the importance of obtaining proper imaging studies in order to determine the extent of aortic graft infection. The finding of gas in the aorta was concerning for multiple etiologies including infection, surgical changes, or repeated fistula formation. However, after reviewing the literature, it appears this presentation is very specific for infection. Studies have shown that CT is superior to WBC scan in determining the extent and involvement of graft infection, and have the additional benefit of assessing free air or fluid, such as in this case. These findings demonstrate that CT imaging can aid the physician in making the diagnosis of graft infection much more confidently.
Reference #1: Mark Alexander S, McCarthy Shirley M, Moss Albert A, Price David. Detection of Abdominal Aortic Graft Infection: Comparison of CT and In-Labeled White Blood Cell Scans. American Journal of Roentgenology 1985;144:315-318.
DISCLOSURE: The following authors have nothing to disclose: Michael Kosters, Anshu Giri, Naveen Gnanabakthan, Ibrahim Katerji
No Product/Research Disclosure Information