The Role of Dynamic Computed Tomography Angiography in Endoleak Detection and Classification After Endovascular Aneurysm Repair: A Comprehensive Review

Abstract

Backgroud: The use of dynamic computed tomography angiography (dCTA) for the detection of endoleaks in patients who underwent endovascular repair of abdominal aortic aneurysms is gaining interest. This study aims to provide an overview of the current applications of dCTA technologies in vascular surgery. Methods: We performed a comprehensive review by searching in the PubMed database and Cochrane Library (last search: 1 November 2024). We included studies considering endoleak investigation after endovascular aneurysm repair (EVAR). We included papers that reported the outcome of applications of dCTA, excluding case reports or very limited case series (≤4). Finally, 14 studies regarding 377 computed tomography angiographies (CTA) were included and evaluated. Results: Persistent perfusion of the aneurysm sac is the most common complication after EVAR. Imaging-based surveillance post-EVAR is essential with the aim of early detection, characterization, and localization of endoleaks to guide therapeutic intervention or follow-up. dCTA detected 36 type I endoleaks versus 16 identified with standard CTA and 138 versus 95 type II endoleaks. Conclusions: The emergence of dCTA offers a promising solution through enhanced temporal resolution, allowing the visualization of real-time flow dynamics within the aneurysmal sac essential to establishing endoleak treatment or post-EVAR follow-up.

Keywords: 4D; EVAR; dynamic computed tomography; endoleak; four-dimensional computed tomography.

Figure 1

PRISMA flow diagram showing the identification process of the included studies. PRISMA, Preferred Reporting Items for Systematic Reviews and Meta-Analysis.

Figure 2

(A). 3D CT angiography (CTA) image of a 57-year-old man who underwent three-stage thoraco-abdominal stent-graft aortic repair (TEVAR and BEVAR) for symptomatic Type B aortic dissection. (B). At 3 month-follow-up, a CTA was performed for abdominal pain in the emergency setting demonstrating the presence of a large endoleak with a significant increase in sac size from 53 mm to 71 mm in maximum anterior–posterior diameter. However, the standard static CTA, including arterial and venous acquisitions ((B1) and (B2), respectively), was insufficient to further characterize the endoleak type. (C). Dynamic or 4D CTA (4D-CTA) was performed using a second-generation CT scanner (Somatom Definition Flash^®, Siemens Healthineers, Forchheim, Germany), which acquired multiple time-resolved contrast enhanced scans (11 scans in this specific case) during table movement in shuttle mode. 4D-CTA three-dimensional reconstructions revealed a large type-2 endoleak (arrows) from the third lumbar arteries (arrowheads in (C1) and (C2)). Note that the contrast opacification occurs earlier and is more pronounced in the right lumbar artery (arrowheads in (C1)) compared to the left lumbar artery (arrowheads in (C2)). Additionally, observe the large type II endoleak extending to the anterior aspect of the aneurysmal sac (arrows in (C1) and (C2)). (D,E). 4D-CTA image dataset was evaluated qualitatively and quantitatively after motion correction and 3D noise reduction using dedicated software VB60A_HF06 (syngo.via^®, Siemens Healthineers, Forchheim, Germany) that generates time-attenuation curves (TACs) for the analysis of the resulting temporal changes in contrast enhancement within regions of interest (D). In (E), note the different phenotype of the aortic TAC (orange curve) compared to the endoleak TACs (yellow and green curves), the latter presenting a gradual upslope, a wide plateau, a low peak value, and gradual endoleak washout due to slow outflow. TAC analysis, incorporating the peak value and time-to-peak parameters, enhances the characterization of endoleaks type and their inflow and outflow patterns. This approach overcomes the limitations of the standard thriphasic (non-contrast, arterial, and delayed phases) CTA improving the sensitivity and specificity for the detection and characterization of endoleaks, with a comparable or lower radiation dose profile (dose length product [DLP] of the static thriphasic CTA acquisition of 1329 mGy*cm and of the 11-phase 4D-CTA of 835 mGy*cm).