Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37235, USA.
IEEE Trans Biomed Eng. 2013 Apr;60(4):1090-9. doi: 10.1109/TBME.2012.2215033. Epub 2012 Aug 23.
Soft-tissue image-guided interventions often require the digitization of organ surfaces for providing correspondence from medical images to the physical patient in the operating room. In this paper, the effect of several inexpensive surface acquisition techniques on target registration error and surface registration error (SRE) for soft tissue is investigated. A systematic approach is provided to compare image-to-physical registrations using three different methods of organ spatial digitization: 1) a tracked laser-range scanner (LRS), 2) a tracked pointer, and 3) a tracked conoscopic holography sensor (called a conoprobe). For each digitization method, surfaces of phantoms and biological tissues were acquired and registered to CT image volume counterparts. A comparison among these alignments demonstrated that registration errors were statistically smaller with the conoprobe than the tracked pointer and LRS (p<0.01). In all acquisitions, the conoprobe outperformed the LRS and tracked pointer: for example, the arithmetic means of the SRE over all data acquisitions with a porcine liver were 1.73 ± 0.77 mm, 3.25 ± 0.78 mm, and 4.44 ± 1.19 mm for the conoprobe, LRS, and tracked pointer, respectively. In a cadaveric kidney specimen, the arithmetic means of the SRE over all trials of the conoprobe and tracked pointer were 1.50 ± 0.50 mm and 3.51 ± 0.82 mm, respectively. Our results suggest that tissue displacements due to contact force and attempts to maintain contact with tissue, compromise registrations that are dependent on data acquired from a tracked surgical instrument and we provide an alternative method (tracked conoscopic holography) of digitizing surfaces for clinical usage. The tracked conoscopic holography device outperforms LRS acquisitions with respect to registration accuracy.
软组织影像引导介入通常需要对器官表面进行数字化，以便将医学图像与手术室中的物理患者进行对应。本文研究了几种廉价的表面采集技术对软组织的目标注册误差和表面注册误差（SRE）的影响。提供了一种系统的方法来比较使用三种不同器官空间数字化方法的图像到物理注册：1）跟踪激光测距扫描仪（LRS），2）跟踪指针，和 3）跟踪锥光全息传感器（称为锥光探头）。对于每种数字化方法，采集了幻影和生物组织的表面，并将其与 CT 图像体积对应物进行注册。这些对齐方式的比较表明，与跟踪指针和 LRS 相比，注册误差在统计上更小（p<0.01）。在所有采集过程中，锥光探头都优于 LRS 和跟踪指针：例如，在对猪肝进行的所有数据采集过程中，SRE 的算术平均值分别为 1.73 ± 0.77mm、3.25 ± 0.78mm 和 4.44 ± 1.19mm。在一个尸体肾脏标本中，锥光探头和跟踪指针的所有试验的 SRE 的算术平均值分别为 1.50 ± 0.50mm 和 3.51 ± 0.82mm。我们的结果表明，由于接触力和试图与组织保持接触而导致的组织位移，会影响依赖于从跟踪手术器械获取的数据的注册，我们提供了一种替代方法（跟踪锥光全息术）来数字化表面以供临床使用。与 LRS 采集相比，跟踪锥光全息术设备在注册精度方面表现更好。
