Clinical Study
Source of Errors and Accuracy of a Two-Dimensional/Three-Dimensional Fusion Road Map for Endovascular Aneurysm Repair of Abdominal Aortic Aneurysm

https://doi.org/10.1016/j.jvir.2014.12.019Get rights and content

Abstract

Purpose

To evaluate the accuracy and source of errors using a two-dimensional (2D)/three-dimensional (3D) fusion road map for endovascular aneurysm repair (EVAR) of abdominal aortic aneurysm.

Materials and Methods

A rigid 2D/3D road map was tested in 16 patients undergoing EVAR. After 3D/3D manual registration of preoperative multidetector computed tomography (CT) and cone beam CT, abdominal aortic aneurysm outlines were overlaid on live fluoroscopy/digital subtraction angiography (DSA). Patient motion was evaluated using bone landmarks. The misregistration of renal and internal iliac arteries were estimated by 3 readers along head-feet and right-left coordinates (z-axis and x-axis, respectively) before and after bone and DSA corrections centered on the lowest renal artery. Iliac deformation was evaluated by comparing centerlines before and during intervention. A score of clinical added value was estimated as high (z-axis < 3 mm), good (3 mm ≤ z-axis ≤ 5 mm), and low (z-axis > 5 mm). Interobserver reproducibility was calculated by the intraclass correlation coefficient.

Results

The lowest renal artery misregistration was estimated at x-axis = 10.6 mm ± 11.1 and z-axis = 7.4 mm ± 5.3 before correction and at x-axis = 3.5 mm ± 2.5 and z-axis = 4.6 mm ± 3.7 after bone correction (P = .08), and at 0 after DSA correction (P < .001). After DSA correction, residual misregistration on the contralateral renal artery was estimated at x-axis = 2.4 mm ± 2.0 and z-axis = 2.2 mm ± 2.0. Score of clinical added value was low (n = 11), good (n= 0), and high (n= 5) before correction and low (n = 5), good (n = 4), and high (n = 7) after bone correction. Interobserver intraclass correlation coefficient for misregistration measurements was estimated at 0.99. Patient motion before stent graft delivery was estimated at x-axis = 8 mm ± 5.8 and z-axis = 3.0 mm ± 2.7. The internal iliac artery misregistration measurements were estimated at x-axis = 6.1 mm ± 3.5 and z-axis = 5.6 mm ± 4.0, and iliac centerline deformation was estimated at 38.3 mm ± 15.6.

Conclusions

Rigid registration is feasible and fairly accurate. Only a partial reduction of vascular misregistration was observed after bone correction; minimal DSA acquisition is still required.

Section snippets

Study Design and Patient Population

This study was compliant with the Health Insurance Portability and Accountability Act and was approved by the institutional review boards of the participating hospitals. All patients signed an informed consent form. The study included 16 subjects (12 men and 4 women) with a mean age of 77 years (range, 66–85 y) undergoing EVAR (between August 2011 and April 2013) in the interventional suite where the AAA interventional guidance tool prototype was installed.

Preoperative Multidetector CT Protocols and Image Segmentation and Registration

The 16 multidetector CT examinations

Technical Success

All main steps of the AAA guidance tool for EVAR workflow were performed successfully for the 16 patients. The mean volume of contrast agent injected and fluoroscopy time were 110 mL and 26.4 minutes for standard EVAR and 156 mL and 176 minutes for FEVAR and branched graft (thoracoabdominal) EVAR (Table 2).

Renal and Bone Displacements

Before correction, the mean absolute misregistration on the lowest renal artery was estimated at x-axis = 10.6 mm ± 11.1/z-axis = 7.4 mm ± 5.3 for R1, x-axis = 10.6 mm ± 11.1/z-axis = 7.5 mm

Discussion

Our study results show that rigid 3D fusion of cone beam CT and CT angiography is feasible and fairly accurate for EVAR guidance. The correction tool based on DSA acquisition improves significantly the misregistration and the SCAV. However, to achieve this correction, a limited contrast agent injection before delivering the stent graft is needed.

Before any correction, the SCAV was low for more than half of the patients owing to a cumulative error combining patient displacement mainly at the

Acknowledgment

This work was supported by a joint grant from the Canadian Institute of Health Research, Object Research System, and Siemens AG Healthcare Sector, Forchheim Germany (CIHR-UI Industry Partnered Collaborative Research, Grant No. ISO-93328). G.S. holds a national scientist award from the Fonds de la Recherche en Santé du Québec.

References (24)

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M.P. is funded by Siemens Medical.

None of the other authors have identified a conflict of interest.

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