内耳CT形态学测量方法的探讨

Technique of radiologic measurements for the inner ear structures using computed tomography

目的寻找准确、可行的内耳CT形态学测量方法，评价不同测量者之间的一致性。方法对60例外、中、内耳结构正常者的颞骨高分辨力CT图像进行多平面重组（multi—planar reformations，MPR），在显示耳蜗最大剖面的MPR图像上测量耳蜗的高度和宽度，在可完整地显示半规管形态的MPR图像上测量各个半规管所环绕的骨岛面积。对两位测量者的结果进行统计学分析。结果MPR获得了良好的耳蜗和半规管的影像解剖学显示。配对t检验显示两位测量者的结果之间差异无统计学意义（P值均〉0．05），相关分析表明二者所测结果之间具有良好的一致性（r值均〉0．9）。其中耳蜗高度（x^-±s，下同）为（4．26±0．28）mm，耳蜗宽度为（7．03±0．39）mm，前半规管环绕骨岛面积为（25．49±3．84）mm^2，后半规管环绕骨岛面积为（20．07±2．93）mm^2，外半规管环绕骨岛面积为（11．50±1．94）mm^2。结论MPR可分别显示内耳各结构的中轴层面，在此基础上的测量具有良好的可重复性，可提供可靠的内耳形态学参数。

Objective The aim of this study was to find an accurate and feasible measurement technique for the inner ear structures using computed tomography and to check the inter-observer agreement. Methods Sixty patients without abnormal structure of temporal bones confirmed by means of high-resolution computed tomography were included in this study. The multi-planar reformations （MPR） were performed to show the maximum profile of cochlear, and to measure the height and width of cochlear. Areas of bony island encircled by three semicircular canals were measured on the MPR images that could show the whole canal. The data measured by two readers independently was compared to check the inter-observer agreement. Results The application of MPR yielded satisfactory anatomic presentation of inner ear for radiologic measurements. There was good inter-observer agreement revealed by the paired t-test and correlation analysis （ P 〉 0.05, r 〉 0. 9 ）. The height of cochlear（ x^-± s ） was （4. 26 ± 0. 28 ） mm while the width of cochlear was （7.03 ± 0. 39） mm. The areas of bony islands encircled by the anterior, posterior and lateral semicircular canals were （ 25.49 ± 3.84） mm^2, （ 20. 07 ± 2.93 ） mm^2 and （ 11.50 ± 1.94） mm^2, respectively. Conclusions MPR can display structures of cochlear and semicircular canals on planes along their central axis. Normative measurements on these MPR images derive excellent repeatability and provide reliable morphologic parameters of inner ear structures.