基于体素的颅面部锥形束CT三维重叠准确性及可靠性评估

Accuracy and reliability of three-dimensional craniofacial cone-beam CT superimposition method based on voxel registration

目的建立基于体素的颅面部锥形束CT三维重叠方法，评估不同基准区域重叠的准确性和可靠性。方法对一个完整干颅骨进行3次锥形束CT扫描，每次间隔2周；另对10名成年志愿者进行两次锥形束cT扫描，间隔1个月。使用Analyzel2．0软件，建立基于体素的锥形束cT三维重叠方法，并分别以双颧部和前颅底为基准区域进行重叠。重叠后使用GeomagicQualify2013软件对颅面部各区域进行面距测量，3位操作者重复3次。使用SPSS19．0软件分析重叠方法的准确性和可靠性。结果以双颧部为基准区域重叠时，干颅骨的面距均值为0．035～0．064mm，志愿者的面距均值为0．099—0．182mm；以前颅底为基准区域重叠时，干颅骨的面距均值为0．038—0．071mm，志愿者的面距均值为0．127—0．218mm；均显著小于锥形束CT体素尺寸0．25mm（P〈0．05）。3位操作者共9次操作的各面距测量值总体差异均无统计学意义（P〉0．05）。结论以颅面双颧部和前颅底为基准区域的基于体素的锥形束CT三维重叠方法有较高的准确性和可靠性，可用于颅面部治疗效果的三维评价。

Objective To set up a three-dimensional（3D） craniofacial cone-beam CT（CBCT） superimposition method based on voxel registration, and evaluate the accuracy and reliability of different reference superimposition areas. Methods CBCT scans were taken on a dry skull for three times with a time-interval of two weeks, and CBCT scans were taken on ten adult volunteers twice with a time-interval of one month. The 3D superimposition based on voxel registration was set up by means of Analyze 12.0. The bilateral-zygomatic bone and anterior cranial base were selected as different reference areas for voxel overlapping. The 3D overlapping images were output into Geomagie Qualify 2013, and the surface distances on different eraniofacial regions were measured. Three operators repeated three times of these superimposition and measurement. SPSS 19.0 were used to analyze the accuracy and reliability. Results When bilateral-zygomatic bone used as superimposition reference, the mean surface distance range of dry skull were from 0.035 to 0.064 mm, and volunteers from 0.099 to 0.182 mm. When the anterior cranial base used as superimposition reference, the mean surface distance range of dry skull were from 0.038 to 0.071 mm, and volunteers from 0.127 to 0.218 mm. All these mean values were less than the CBCT voxel size 0.25 mm（P〈0.05）, and got sub-pixel precision. No significant difference was found between the different operators at different times（P〉0.05）. Conclusions This study showed the high accuracy and reliability of 3D CBCT superimposition based on voxel registration, either the anterior cranial base or the bilateral-zygomatie bone as reference. This method could be used for evaluating 3D eraniofacial treatment effects.