Ectopic Gas: A Sign for Potential Aortic Endoprosthesis Infection before Symptoms

Introduction

Abdominal aortic endoprosthesis (AAE) infection is the most dreaded complication of endovascular aortic repair (EVAR) for abdominal aortic aneurysm (AAA), with mortality rates reported as high as 51.8%. Recent meta-analyses emphasize that despite advances in surgical technique, the prognosis of AAE infection remains poor due to delayed diagnosis and the complexity of endoprosthesis explantation.^, The management of AAE infection is significantly hindered by diagnostic latency. Currently, computed tomography angiography (CTA) is typically reserved for evaluation only after the onset of infectious symptoms. Although periprosthetic exudation and ectopic gas are considered hallmark radiographic features, these signs are often subtle and minute during the early, pre-symptomatic stages of infection, rendering them easily overlooked. We present a case in which a radiologist detected minute periprosthetic ectopic gas via thin-section CT during a routine CTA follow-up, five days before the onset of infectious symptoms, thereby alerting clinicians to the possibility of AAE infection. Based on this case, we underscore the critical value of thin-section CT in the early identification of ectopic gas. Furthermore, we aim to demonstrate how advanced post-processing—specifically volume rendering (VR) and hyper-realistic rendering (HRR)—enhances the visualization of AAE infection, thereby enabling longitudinal monitoring of infection progression.

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