A Technique to Improve the Confidence of Color Duplex Ultrasound assessment of Aortic Endografts: The use of Contrast Agents

Abstract

Introduction Color duplex ultrasound (CDU) is routinely used in the evaluation of aortic endografts in many centers. CDU compliments computed tomography (CT) and selective angiography in the identification of persistent endoleaks in these grafts. Because of the complexity of these procedures and the subtle nature of endoleaks, CDU can be time-consuming and challenging. Contrast agents can improve the ease of imaging by rapidly detecting low flow endoleaks. The application of ultrasound contrast agents has been studied in other specialties, such as cardiac echocardiography. This article describes our technique and early experience using contrast-enhanced CDU in aortic endograft assessment. Methods Nineteen patients being seen for a routine CDU examination after endovascular aortic aneurysm repair were evaluated according to published protocol. An initial CDU examination was completed, thoroughly assessing for the presence of graft patency, limb dysfunction, and endoleak. After patient consent, a focused ultrasound was performed using a Food and Drug Administration–approved contrast agent (Optison). The residual aneurysm sac was closely inspected after a 0.3-ml intravenous injection. A maximum of three injections were given in 10-min intervals, with careful evaluation in transverse and sagittal views of the residual aortic sac. Contrast was used to confirm endoleaks noted on the baseline study and help clarify subtle perigraft flow, especially on suboptimal examinations. Results Of the 19 patients given the contrast agent, none had side effects, and all tolerated contrast well. In 9 of 19 examinations, contrast-enhanced CDU confirmed the baseline results positive for perigraft endoleak. Six of nine studies had improved ease of identification of endoleak with contrast. Six of 19 studies were negative for endoleak before and after contrast. Three of 19 studies were indeterminate for endoleak by CDU only secondary to bowel gas and body habitus. The contrast agent was given and was negative for endoleak in these three cases. One study was initially negative for endoleak by CDU, and contrast revealed a small lumber artery leaking into the aneurysm sac. The contrast was easily identified within the endograft and leak sites in all patients. Conclusions CDU is a valuable modality in the postoperative evaluation of endovascular aortic aneurysm repairs. These examinations can be challenging and subject to limitations including bowel gas and body habitus, even when performed by experienced technologists. Color artifacts within the residual aneurysm sac can be difficult to differentiate from true endoleak. Contrast-enhanced CDU can improve the technologist's confidence in the detection of endoleaks.