Orthogonal Rings, Fiducial Markers, and Overlay Accuracy When Image Fusion is Used for EVAR Guidance

Area of Science:

• Medical Imaging
• Interventional Radiology
• Vascular Surgery

Background:

• Endovascular aortic repair (EVAR) relies on accurate intra-operative guidance.
• 3D image fusion offers potential for enhanced visualization during EVAR procedures.
• Assessing the accuracy of image fusion techniques is crucial for improving patient outcomes.

Purpose of the Study:

• To evaluate the accuracy of orthogonal rings, fiducial markers, and overlay in 3D image fusion for EVAR.
• To determine the effectiveness of different registration methods for intra-operative guidance during EVAR.
• To identify limitations and areas for improvement in 3D image fusion for EVAR.

Main Methods:

• Prospective single-center study involving 19 patients undergoing standard EVAR.
• Utilized 3D image fusion with pre-operative CT and intra-operative cone beam CT (CBCT).
• Employed orthogonal rings for marking renal arteries and stent graft positions, and fiducial markers for patient movement detection.

Main Results:

• Fiducial markers effectively detected intra-operative patient movement and misalignment.
• Automatic intensity-based registration alone was insufficient for EVAR guidance.
• Manual registration using vertebrae L1-L2 was sufficient in 37% of cases, with a median renal artery alignment error of 2 mm.
• The final overlay registration showed a median alignment error of 2 mm sideways and 2 mm longitudinally.

Conclusions:

• 3D image fusion is a valuable tool for intra-operative guidance in EVAR.
• Orthogonal rings and fiducial markers enhance visualization and aid in overlay correction.
• Current overlay accuracy is not consistently ideal, necessitating further technical advancements for improved EVAR procedures.