PC026. Type II Endoleak on Computed Tomography Angiography After Endovascular Abdominal Aortic Aneurysm Repair: Density and Volume Versus Sac Growth

Abstract

The objective of this study was to evaluate the changes in density and volume of type II endoleak (T2EL) nidus on arterial and delayed phases of computed tomography angiography (CTA) and their relationships with aneurysm sac change in patients with abdominal aortic aneurysm who underwent endovascular aneurysm repair (EVAR). A total of 82 patients (mean age, 72 ± 8 years; range, 56-88 years; male to female ratio, 63:19) with abdominal aortic aneurysm who underwent EVAR (n = 48) or fenestrated EVAR (n = 34) and had T2EL on follow-up CTA between June 2005 and July 2018 were retrospectively reviewed. Patients were divided into two groups, without (group A, n = 37) and with (group B, n = 45) aneurysmal sac enlargement on follow-up CTA. Volume and density of T2EL were measured on each phase of CTA for first and last CTA studies to evaluate changes. Mean follow-up duration was 34.4 ± 28.4 months (range, 3-163.8 months), and mean number of CTA studies was 4.1 ± 1.7 (range, 2-10). Statistical analysis was performed for parametric variables using Student t-test and χ2 test to determine statistically significant differences between groups, defined as P <.05. Patients' demographics and baseline characteristics were not significantly different. Persistent T2EL on the last follow-up CTA was identified in 17 (46%) and 19 (42%) patients in group A and group B respectively, as seen in Table I (P = .74). Embolization was required in 60% of group B as opposed to 36.8% of group A (P = .046). Endoleak volumes on arterial and delayed phases on the initial CTA study were not significantly different between group A and group B. On the last follow-up CTA, endoleak volumes in arterial phase were significantly different between group A vs group B. Endoleak volume is significantly greater in delayed phase compared with arterial phase in both groups on the last CTA (Table II). Changes in endoleak volumes and densities between arterial and delayed phases and the number of branch vessels were not significantly different between group A and group B on both initial and last CTAs. Although T2EL volumes are increased overall on delayed phase of CTA compared with those on arterial phase, changes in volumes between phases may not be directly associated with aneurysmal sac enlargement. Endoleak volume is significantly greater in those with greater sac volumes, especially on arterial phase of the last CTA. This may have resulted from increased arterial pressure in the endoleak nidus over time in the group of patients with aneurysmal sac enlargement.Table IComparison of endoleak (EL) and aneurysm sac parameters measured in group A vs group BGroup A (n = 37)Group B (n = 45)P valueAneurysm sac diameter, mm Initial CTA5.9 ± 1.2 (4.1-8.7)6.9 ± 1.6 (3.2-10).64 Last CTA5.6 ± 1.1 (3.1-7.6)6.8 ±1.9 (3.7-13.9).001*Persistent EL17 (46)19 (42).74EL embolization14 (36.8)27 (60).046*EL volume, cm3 Initial CTAAP1.9 ± 1.5 (0.4-6.9)3.6 ± 4.9 (0.2-27).057DP2.8 ± 2.4 (0.6-11.1)4.8 ± 5.9 (0.3-33.8).07 Last CTAAP1.8 ± 1.6 (0.2-8.1)3.8 ± 4.2 (0.2-21.8).009*DP3.2 ± 3.7 (0.1-19.1)5.5 ± 6.2 (0.2-36.8).054Change in EL volume, % Initial CTA45.4 ± 52.7 (−35.7 to 175.4)78 ± 164.1 (−44.5 to 883.1).28 Last CTA125.6 ± 242.9 (−74.6 to 942)90.3 ± 143.9 (−49.6 to 622.3).43Volume of EL within sac, % Initial CTAAP1.2 ± 0.9 (0.1-4.1)2.9 ± (0.1-39.4).13DP1.7 ± 1.6 (0.2-6.4)3.8 ± 7.8 (0.2-48.3).14 Last CTAAP1.4 ± 1.9 (0.03-9.9)2.6 ± 3.4 (0.1-14.5).05DP2.1 ± 2.4 (0.1-9.5)3.7 ± 4.7 (0.1-23.9).06EL density, HU Initial CTAAP237.9 ± 65.6 (107-386)245 ± 70 (111-515).64DP150 ± 29.9 (105-218)152 ± 49.9 (0.4-270).83 Last CTAAP210 ± 57.3 (113-326)219 ± 70 (120-406).49DP151.9 ± 47.3 (1.7-245)167.9 ± 46.9 (111-330).13Change in EL density, % Initial CTA31.6 ± 21.1 (−25.2 to 60.1)35.1 ± 22.6 (−7.4 to 99.9).49 Last CTA24.1 ± 25.3 (−15.4 to 98.9)17.5 ± 26.1 (−48.3 to 54.9).25No. of branch vessels1.7 ± 0.8 (1-4)1.9 ± 0.7 (1-4).13ChangeinELvolume(%)=ELvolumeondelayedphase−ELvolumeonarterialphaseELvolumeonarterialphasex100ChangeinELdensity(%)=ELvolumeonarterialphase−ELdensityondelayedphaseELdensityonarterialphasex100VolumeofELwithinsac(%)=Endoleakvolume/excludedsacvolumex100AP, Arterial phase; CTA, Computed tomography angiography; DP, delayed phase.Categorical variables are presented as number (%). Continuous variables are presented as mean ± standard deviation (range). Open table in a new tab Table IIComparison between arterial and delayed phases in group A and group BCTAGroup A (n = 37)Group B (n = 45)Arterial phaseDelayed phaseP valueArterial phaseDelayed phaseP valueEL volume, cm3 Initial1.9 ± 1.5 (0.4-6.9)2.8 ± 2.4 (0.6-11.1).073.6 ± 4.9 (0.2-27)4.8 ± 5.9 (0.3-33.8).32 Last1.8 ± 1.6 (0.2-8.1)3.2 ± 3.7 (0.1-19.1).02*3.8 ± 4.2 (0.2-21.8)5.5 ± 6.2 (0.2-36.8).14Volume of EL within sac, % Initial1.2 ± 0.9 (0.1-4.1)1.7 ± 1.6 (0.2-6.5).12.9 ± 6.3 (0.1-39.4)3.8 ± 7.4 (0.2-48.3).56 Last1.4 ±1.9 (0.03-9.9)2.1 ± 2.4 (0.1-9.5).172.6 ± 3.4 (0.1-14.5)3.7 ± 4.7 (0.1-23.9).21EL density, HU Initial237.9 ± 65.6 (107-386)150 ± 29.9 (105-218)<.001*245 ± 70 (111-515)152 ± 49.9 (0.4-270)<.001* Last210 ± 57.3 (113-326)151.9 ± 47.3 (1.7-245)<.001*219 ± 70 (120-406)167.9 ± 46.9 (111-330)<.001*CTA, Computed tomography angiography; EL, endoleak.Values are presented as mean ± standard deviation (range).Boldface entries indicate statistical significance. Open table in a new tab