Changes in Apposition of Endograft Limbs in the Iliac Arteries After Endovascular Aneurysm Repair: Determination With New Computed Tomography–Applied Software

Abstract

Purpose: To validate new computed tomography (CT)–applied software used to determine endograft limb position and apposition after endovascular aneurysm repair (EVAR). Materials and Methods: Twelve EVAR patients (mean age 81±6 years; 10 men) with distal stent-graft extensions for 15 (3 bilateral) type Ib endoleaks during follow-up were selected based on the availability of the following CT studies: pre-EVAR, 1 month, and the penultimate scan prior to the scan disclosing the type Ib endoleak. Twelve patients (mean age 82±7 years; 11 men) without endoleak and a similar interval between the primary EVAR procedure and the penultimate CT scan of the endoleak group were selected as controls using measurements from both endograft limbs (n=21, 3 excluded). Prototype Vascular Imaging Analysis software was adapted to calculate 6 parameters for the distal apposition zone: fabric distance, shortest apposition length, endograft diameter, iliac seal surface (ISS), iliac endograft apposition surface (IEAS), and percentage of iliac surface coverage (IEAS/ISS × 100). Measurements were performed on the preoperative, first postoperative, and penultimate/matched follow-up CT scans. Interobserver variability was assessed with the intraclass correlation coefficient (ICC). Continuous data are presented as the median [interquartile range (IQR) Q1, Q3]. Results: CTA follow-up was not significantly different between the endoleak and control groups [30 months (IQR 18, 58) vs 36 months (IQR 21, 59), p=0.843]. Interobserver agreement was good to excellent for all parameters (ICC 0.879–0.985). Preoperative anatomy and endograft dimensions on the first follow-up CTA scan did not differ significantly between the groups. When the penultimate CTA scan was compared with the first postoperative CT scan, endograft dimensions had significantly changed in the endoleak group; importantly, apposition was significantly decreased, and fabric distance was significantly increased, indicating limb retraction. Differences in changes in endograft dimensions were significant between the groups. Conclusion: New CT-applied software was introduced to visualize apposition and position changes of endograft limbs during follow-up. The software demonstrated good-to-excellent interobserver agreement and enabled accurate analysis of post-EVAR endograft dimensions. Significant changes in apposition and position were observed with the software on the penultimate CT scan prior to diagnosis of type Ib endoleak.

Commentary: Sealing the Deal: Easier Methods Are on the Horizon for Postoperative Evaluation of Stent-Graft Seal Zones

“…However, less attention is typically given to the iliac segments in EVAR planning, and a suboptimal result is more frequently accepted at the distal end. The pertinence of the article by Goudeketting et al 5 is therefore high.…”

“…However, less attention is typically given to the iliac segments in EVAR planning, and a suboptimal result is more frequently accepted at the distal end. The pertinence of the article by Goudeketting et al 5 is therefore high. Although the studied population was small, there were statistically relevant results indicating the effectiveness of the proposed VIA software.…”

“…In the December 2019 issue of the JEVT, Goudeketting et al 5 have validated a CT-applied prototype Vascular Imaging Analysis (VIA) software used to determine endograft limb position and apposition after EVAR, following their earlier work using this software to assess proximal sealing. 6 It would be interesting to compare in a large cohort of patients the predictive capacity of the method presented by Goudeketting et al 5 to the one proposed by our group based on CLL reconstruction and measurement of 1-mm intervals of circumferential graft-wall apposition. 7,8 While the majority of research on the subject has focused on the proximal neck, the importance of the iliac sealing zone has long been known, and its dynamics are of upmost importance.…”

“…In conclusion, Goudeketting et al 5 provide a user-friendly tool based on an interesting concept that may facilitate serial evaluation of sealing zones (including iliac arteries), therefore having the capacity to predict complications and lead to appropriate preventive action. It is also likely that the tool will aid in stratifying the frequency of and modality used in subsequent follow-up.…”