Three-dimensional CT-guided bronchoscopy with a real-time electromagnetic position sensor: a comparison of two image registration methods.
Three-dimensional CT-guided bronchoscopy with a real-time electromagnetic position sensor: a comparison of two image registration methods.
复制标题
具有实时电磁位置传感器的三维 CT 引导支气管镜检查：两种图像配准方法的比较。
作者：
S. Solomon;P. White;C. Wiener;J. Orens;Ko
研究目标
比较两种不同的图像配准方法，以便在支气管镜检查过程中在先前获得的三维CT扫描上准确地显示柔性支气管镜的位置。
设置
某大学医院的支气管镜检查套间。
病人
15例成人患者接受非急诊支气管镜检查。
方法
在柔性支气管镜的尖端放置了一个微型电磁位置传感器。先前获得的三维CT扫描与患者在支气管镜检查套间中登记。配准方法1使用多个皮肤基准标记。配准方法2使用气管本身的内表面进行配准。方法1通过测量真实皮肤标记位置与计算机显示位置之间的误差距离来客观评估。方法1、2由支气管镜医师将支气管镜下的直观解剖位置与CT图像上的计算机显示位置相关联，对1、2进行主观评价。
结果
对于配准方法1，距已知点的误差距离(+/-SD)为5.6+/-2.7 mm。对于方法2，由于支气管镜传感器的准确位置不能与CT位置相关联，所以没有测量客观误差距离。主观上，与纤维支气管镜下的气管切面相比，方法2比方法1更准确。此外，方法2的优点是在CT扫描前不需要放置基准标记。呼吸运动导致3.6+/-2.6 mm的误差，这一误差被放置在患者胸部的第二个跟踪传感器部分补偿。
结论
对于支气管镜检查中柔性支气管镜的位置的配准，主观上判断表面贴合气管的图像配准方法2优于基准标记的图像配准方法1。方法2也更实用，因为在支气管镜检查前不需要特殊的CT扫描技术。
STUDY OBJECTIVES
To compare two different image registration methods for accurately displaying the position of a flexible bronchoscope on a previously acquired three-dimensional CT scan during bronchoscopy.
SETTING
Bronchoscopy suite of a university hospital.
PATIENTS
Fifteen adult patients scheduled for nonemergent bronchoscopy.
METHODS
A miniature electromagnetic position sensor was placed at the tip of a flexible bronchoscope. Previously acquired three-dimensional CT scans were registered with the patient in the bronchoscopy suite. Registration method 1 used multiple skin fiducial markers. Registration method 2 used the inner surface of the trachea itself for registration. Method 1 was objectively assessed by measuring the error distance between the real skin marker position and the computer display position. Methods 1 and 2 were subjectively assessed by the bronchoscopist correlating visual bronchoscopic anatomic location with the computer display position on the CT image.
RESULTS
The error distance (+/- SD) from known points for registration method 1 was 5.6 +/- 2.7 mm. Objective error distances were not measured for method 2 because no accurate placement of the bronchoscope sensor could be correlated with CT position. Subjectively, method 2 was judged more accurate than method 1 when compared with the fiberoptic view of the airways through the bronchoscope. Additionally, method 2 had the advantage of not requiring placement of fiducial markers before the CT scan. Respiratory motion contributed an error of 3.6 +/- 2.6 mm, which was partially compensated for by a second tracking sensor placed on the patient's chest.
CONCLUSION
Image registration method 2 of surface fitting the trachea rather than method 1 of fiducial markers was subjectively judged to be superior for registering the position of a flexible bronchoscope during bronchoscopy. Method 2 was also more practical inasmuch as no special CT scanning technique was required before bronchoscopy.