Detection of Abdominal Aortic Graft Infection: Comparison of Magnetic Resonance Imaging and Indium-Labeled White Blood Cell Scanning

Abstract

Infected abdominal aortic grafts rank as one of the most severe complications of vascular surgery, with high mortality and morbidity. The incidence of infection after prosthetic aortic reconstruction is 1-3%. Diagnosis of vascular graft infection can be occasionally difficult. Clinical manifestations and assessment of the extent of graft infection are usually nonspecific, and their detection by radiographic methods, such as computed tomography (CT), magnetic resonance imaging (MRI), and leukocyte -imaging, can be difficult. The purpose of this study was to evaluate the predictive value (PV) of indium-111-labeled white blood cell scanning (WBCS) and MRI in patients who were suspected of having intracavitary vascular graft infection (IGF). The study was done as a cross-control retrospective, single-center study. Fifty-eight In-111-labeled WBC scans and 59 MRIs were performed in suspected patients between January 1995 and January 2005. Among the 40 suspected patients, 35 cases of aorta graft infection were identified intraoperatively. The diagnosis of IGF was based on clinical signs, microbiological and histological examination, MRI and leukocyte imaging, and lack of graft incorporation with surrounding fluid observed intraoperatively. The positive PV (PPV) of MRI was 95% (95% confidence interval [CI] 84-105%) compared to In-111-labeled WBCS, which was 80% (95% CI 62-96%). The negative PV (NPV) of MRI was 80% (95% CI 68-92%) compared to 82% (95% CI 69-94%) for In-111-labeled WBCS. MRI showed a nonsignificant but better PPV for detecting IGF compared to In-111 leukocyte imaging. The NPVs for MRI and In-111-labeled WBCS were very near each other, with a very small advantage for In-111-WBCS. This comparison study suggested MRI as a primary diagnostic modality to investigate patients suspected of having aortic graft infections before In-111-labeled WBCS.