头颅侧位片2D和CBCT 3D头影测量的可靠性及精确度比较

Comparison of reliability and accuracy of 2D lateral cephalometric and 3D cephalometric on CBCT scans

目的:比较Cone beam CT(CBCT)三维头影测量和X线片二维头影测量线距及角度的可靠度和精确度。方法:30个研究对象同时拍摄X线头颅侧位片和CBCT。用winceph 7.0软件对X线头颅侧位片进行2D头影测量,用Simplant Pro 13.0软件对CBCT图像用MPR法定点(轴向、矢状向、冠状向联合定点)和3D头影测量。两种方法均测量41个项目值,由3位测量者每人测2遍,2遍时间间隔1个星期。采用组内相关系数(ICC)比较2D和3D操作者内和操作者间的测量信度,用配对t检验分析2D测量和3D测量的差异。结果:对于操作者内ICC,58.5%2D测量项目ICC>0.9(24/41),65.9%3D测量项目ICC>0.9(27/41),2D和3D差异有统计学意义(P=0.028)。对于操作者间ICC,90.2%2D测量项目ICC>0.9(37/41),85.4%3D测量项目ICC>0.9(35/41),2D和3D差异无统计学意义(P=0.302)。2D测量和3D测量差异比较中,角度测量值除L1 to Go-Gn角外,差异均有统计学意义;线距测量值Ar-Go、Go-Me、S-Go、B-Go、ANS-PNS、Go-PNS、PNS-B差异有统计学意义;比例测量值PFH/AFH 2D明显小于3D,差异有统计学意义。结论:CBCT 3D头影测量可靠度和精确度优于X线片2D头影测量。CBCT 3D头影测量有较大的临床应用价值和前景,但某些点的定位有待统一。

Objective： To compare the reliability and accuracy of linear and angular measurements made on lateral cephalograms and on cone beam computed tomography（CBCT） images.Methods： CBCT scans and conventional lateral headfilms were subsequently taken in 30 target patients.Standard cephalometric software winceph 7.0 was used to identify landmarks on 2D images and Simplant Pro 13.0 was used to identify landmarks in the sagittal,coronal,and axial slices on 3D images.Forty one linear and angular cephalometric measure-ments were registered on the lateral cephalogram and compared to the same measurements on the 3D CBCT scans.Three observers independently repeated two times with a time-interval of 1 week.Intraclass Correlations（ICC） and paired t tests（P0.05） were used to analyze vari-ability differences.Results： The intra-observer Correlations（ICC） was 0.9 for 58.5% of 2D assessments and 65.9% of 3D assessments,and a statistically significant difference（P 0.05） was observed.The inter-observer Correlations（ICC） was 0.9 for 90.2% of 2D assessments and 85.4% of 3D assessments,and no statistically significant difference was found.All angular measurements,except for angle L1 to Go-Gn,were significantly different statistically be-tween 2D and 3D.Linear measurements Ar-Go,Go-Me,S-Go,B-Go,ANS-PNS,Go-PNS,PNS-B were significantly dif-ferent statistically between 2D and 3D.Conclusion： The reliability of 3D measurement was better than that of 2D measurement.CBCT 3D cephalometric has great potential to be promoted and applied in clinic.