Retrospective Cohort Study on Vessel Deformation During Fenestrated or Branched Endovascular Aortic Repair; Traditional CTA Roadmaps Provide Insufficient and Inadequate Guidance During Target Vessel Cannulation

Introduction: Optimal visualization of target vessels in
three-dimensions (3D) plays a key role in complex endovascular
procedures, such as fenestrated and branched
endovascular aortic repair (EVAR). A popular imaging
technique to enhance target vessel visualization is image
fusion. Image fusion combines real-time fluoroscopy with
static preprocedural anatomical images, typically computed
tomography angiography (CTA) to create an arterial roadmap.
However, the introduction of stiff endovascular devices
cause the arteries to stretch, leading to a mismatch
between the actual position of the (origin of the) artery and
its representation on the image fusion roadmap.
This retrospective study assesses vessel deformation of the
aorta and its side branches due to the introduction of a stiff
endovascular devices, during fenestrated and branched
EVAR. Furthermore, the influence of vascular tortuosity on
the extent of vessel deformation was analysed.
Methods: Patients that underwent fenestrated or branched
EVAR between January 2015 and January 2018 were retrospectively
included in this study. Two imaging datasets were
collected from each patient: 1) the preoperative CTA and 2)
the intraoperative contrast-enhanced cone beam computed
tomography (ce-CBCT), acquired after the insertion of the
stiff guidewire and stent delivery device (Zenith custom
made, Cook, Bloomington IN, USA) . Manual registration of
both datasets was performed, using the bony landmarks of
the vertebrae. Subsequently, the ostium of the celiac artery
(CA), superior mesenteric artery (SMA), left renal artery (LRA)
and right renal artery (RRA) were marked in both the CTA and
ce-CBCTreconstructions.The ostium displacement of the four
target vessels was reported as a 3D vector as well as a 2D
vector in the coronal plane (RRA and LRA) or sagittal plane (CA
and SMA). The tortuosity index of the iliac and the abdominal
aortic segment were calculated. The effect of the tortuosity
index on the extent of vessel deformation was assessed using
linear regression.
Results: In total 77 target vessels from 20 patients were
included in this study. The 3D mean displacement vector of
the ostium of the CA, SMA, RRA and LRA were respectively
8.73.8mm, 7.42.7mm, 7.92.7mm and 7.64.4mm. The
2D mean displacement vector for the SMA and CA in the
sagittal viewing plane was 4.92.9mm and 6.53.0mm
respectively. The 2D mean displacement vector of the RRA
and LRA in the coronal viewing plane was 7.02.8mm
6.24.3mm respectively. An example of the 2D displacement
of the RRA in the coronal plane is shown in Figure 1. In total,
74% of the target vessels had a 2D vector displacement of
more than 50% of the diameter of the vessel.
The mean tortuosity index of the abdominal aortic segment
and the iliac segment was 1.10 and 1.34 respectively. Linear
regression showed no association between the extend of
vessel displacement and the tortuosity index of the abdominal
aortic segment (p¼0.37), nor the iliac segment (p¼0.11).
Conclusion: There is significant vessel displacement of the
ostium of the target vessels, during fenestrated and
branched EVARs caused by the introduction of stiff endovascular
devices. Consequently, preoperative CTA roadmaps
are inadequate to guide target vessel cannulation during
fenestrated or branched EVAR.