Native Aortic and Prosthetic Vascular Stent Infection on ^99mTc-Labeled White Blood Cell Scintigraphy

DISCUSSION

Scintigraphic visualization of infection in the native aorta itself has not been previously reported to our knowledge. In this patient, the images clearly indicated abnormal scintigraphic uptake in the native aortic aneurysm. The anterior and left lateral planar views of Figure 3 show increased white cell uptake in a spheric pattern outlining the wall of the native aneurysmal abdominal aorta tracking down into the right iliac artery.

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FIGURE 3.

Anterior (A) and left lateral (B) ^99mTc-labeled white blood cell scintigraphy planar images of abdomen demonstrating increased uptake (arrows) in vascular stent and in wall of native aorta

The findings are consistent with native abdominal aortic infection as well as infection of the prosthetic aortic stent. The sites of uptake on SPECT imaging (Figs. 1 and 2) correlated with the sites of previously deployed vascular stents. The increased uptake was clearly seen in the aortic stent extending into the right iliac stent as well as in the native aortic aneurysm wall. Laboratory investigations revealed leukocytosis (white cell count, 13,000 cm³) and elevated C-reactive protein (230 mg/L). A blood culture grew gram-negative Bacteroides fragilis (1), a pathogen previously reported to be associated with infected aortic aneurysm.

Endoluminal prosthetic graft infection is a rare, potentially life-threatening complication after reconstructive vascular surgery (2,3). Standard radiologic imaging may be unreliable in detection of early or low-grade infections (2,3) and demonstrate only secondary anatomic effects of inflammation caused by the graft infection (2,4). The use of ^99mTc-labeled white blood cell scintigraphy has been shown to be a reliable investigation regardless of the stage (early or late) or severity (low or high grade) of infection, with reported sensitivity and specificity values over 90% (2,5), and the results have been widely published. Whether multiple reconstructive vascular surgeries or the type of microorganism poses a risk of infection to the native aorta remains uncertain. The principal treatment for stent infection is total excision; however, because of the patient’s age and comorbidities he was treated conservatively with antibiotics and, thus, a follow-up scan was not indicated. The patient died 2 wk after the scan.