J Korean Neurosurg Soc.  2014 Nov;56(5):400-404. 10.3340/jkns.2014.56.5.400.

Quantitative Analysis of Factors Affecting Cobalt Alloy Clip Artifacts in Computed Tomography

• Sim SY
• Choi CH

• KMID: 2018098
• DOI: http://doi.org/10.3340/jkns.2014.56.5.400

Abstract

OBJECTIVE
Clip artifacts limit the visualization of intracranial structures in CT scans from patients after aneurysmal clipping with cobalt alloy clips. This study is to analyze the parameters influencing the degree of clip artifacts.
METHODS
Postoperative CT scans of 60 patients with straight cobalt alloy-clipped aneurysms were analyzed for the maximal diameter of white artifacts and the angle and number of streak artifacts in axial images, and the maximal diameter of artifacts in three-dimensional (3-D) volume-rendered images. The correlation coefficient (CC) was determined between each clip artifact type and the clip blade length and clip orientation to the CT scan (angle a, lateral clip inclination in axial images; angle b, clip gradient to scan plane in lateral scout images).
RESULTS
Angle b correlated negatively with white artifacts (r=-0.589, p<0.001) and positively with the angle (r=0.636, p<0.001) and number (r=0.505, p<0.001) of streak artifacts. Artifacts in 3-D images correlated with clip blade length (r=0.454, p=0.004). Multiple linear regression analysis revealed that angle b was the major parameter influencing white artifacts and the angle and number of streak artifacts in axial images (p<0.001), whereas clip blade length was a major factor in 3-D images (p=0.034).
CONCLUSION
Use of a clip orientation perpendicular to the scan gantry angle decreased the amount of white artifacts and allowed better visualization of the clip site.

Keyword

Artifacts; Clip; Intracranial aneurysm; Multidetector computed tomography

MeSH Terms

Alloys*
Aneurysm
Artifacts*
Cobalt*
Humans
Imaging, Three-Dimensional
Intracranial Aneurysm
Linear Models
Multidetector Computed Tomography
Tomography, X-Ray Computed
Alloys
Cobalt

Figure

• 

  Fig. 1 Measurement of influencing factors and clip artifacts. Degree of lateral inclination of clip blade to CT axial scan (angle a) (A), degree of gradient of clip blade to scan gantry angle in lateral scout view (angle b) (B), and angle of streak artifacts (C) are measured as shown in the pictures.

• 

  Fig. 2 Correlation analysis between each type of clip artifacts and influencing factors. White artifacts in axial images and angle b (A). Angle of streak artifacts and angle b (B). Number of streak artifacts and angle b (C). Artifacts in volume-rendered images and diameter of the clip blade (D).

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