Sim Sook Young, Choi Chi Hoon
Department of Neurosurgery, Inje University Seoul Paik Hospital, Seoul, Korea.
Department of Radiology, National Medical Center, Seoul, Korea.
J Korean Neurosurg Soc. 2014 Nov;56(5):400-4. doi: 10.3340/jkns.2014.56.5.400. Epub 2014 Nov 30.
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.
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).
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).
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.
在使用钴合金夹进行动脉瘤夹闭的患者的CT扫描中，夹子伪影会限制颅内结构的可视化。本研究旨在分析影响夹子伪影程度的参数。
对60例使用直钴合金夹夹闭动脉瘤的患者的术后CT扫描进行分析，测量轴向图像中白色伪影的最大直径、条纹伪影的角度和数量，以及三维（3-D）容积再现图像中伪影的最大直径。确定每种夹子伪影类型与夹片长度以及夹子相对于CT扫描的方向（角度a，轴向图像中夹子的横向倾斜度；角度b，侧位定位像中夹子与扫描平面的梯度）之间的相关系数（CC）。
角度b与白色伪影呈负相关（r = -0.589，p < 0.001），与条纹伪影的角度（r = 0.636，p < 0.001）和数量（r = 0.505，p < 0.001）呈正相关。三维图像中的伪影与夹片长度相关（r = 0.454，p = 0.004）。多元线性回归分析显示，角度b是影响轴向图像中白色伪影以及条纹伪影的角度和数量的主要参数（p < 0.001），而夹片长度是三维图像中的主要因素（p = 0.034）。
使用与扫描机架角度垂直的夹子方向可减少白色伪影的数量，并能更好地显示夹子部位。
