Mycotic aneurysms in the abdominal aorta and iliac arteries: CT-based grading and correlation with surgical outcomes

Background: Computed tomography (CT) is the modality of choice in the diagnosis of mycotic aneurysms. The present study aimed to classify the CT findings of mycotic aneurysms, and to assess their predictive value based on the correlation of a CT-based grading system with prognostic factors and outcomes. Methods: Over the past 21 years, 40 consecutive patients underwent open surgery for mycotic aneurysms of the abdominal aorta and iliac arteries in our hospital. The CT appearances of mycotic aneurysms were categorized into four grades: grade 1, periarterial changes without destruction of the arterial wall; grade 2, presence of saccular outpouching; grade 3, extensive retroperitoneal infection; and grade 4, massive perianeurysmal hemorrhage. Clinical data were recorded for analysis. Results: The surgical mortality and overall aneurysm-related mortality rates were 17.5 and 25 %, respectively. The poor prognostic predictors were shock, rupture, and concomitant gastrointestinal procedures. The increasing proportions of shock and rupture status corresponded to mycotic aneurysms of higher grades in the CT-based grading. In addition, one patient in grades 1 and 2, versus five in grades 3 and 4 (P = 0.02), required concomitant gastrointestinal procedures. The CT-based grading exhibited a strong association with surgical mortality (Cramer's V coefficient = 0.65; P = 0.002) and a relatively strong association with overall aneurysm-related mortality (Cramer's V coefficient = 0.53; P = 0.01). Conclusions: For patients surgically treated for abdominal mycotic aneurysms, the CT-based grading is correlated with clinical severity, surgical complexity, and outcomes, and thus it may serve as a simple scale for risk classification.