Department of Periodontology, Institute of Odontology, The Sahlgrenska Academy, University of Gothenburg, Sweden.
Dentomaxillofac Radiol. 2011 May;40(4):244-50. doi: 10.1259/dmfr/17432330.
The aim of this study was to assess the influence of inclination of the object on the reliability and reproducibility of linear measurements of anatomic structures of the mandible on images obtained using cone-beam CT (CBCT).
Ten linear dimensions between anatomical landmarks were measured in a dry mandible. The measurements were performed with a manual calliper three times by three observers. The mandible was scanned with Planmeca Promax 3D cone-beam CT (Planmeca Oy, Helsinki, Finland) with the base of the mandible parallel as well as tilted 45° to the horizontal plane. Computer measurements of the linear dimension were performed by three observers. The radiographic measurements were performed four times for each experimental setting. A total of 240 measurements were performed. Reproducibility was evaluated through comparison of standard deviation (SD) and estimation of intraclass correlation coefficient (ICC). The error was estimated as the absolute difference between the radiographic measurements and the mean manual calliper measurements.
The mean SD for the radiographic measurements was 0.36 mm for the horizontally positioned mandible and 0.48 mm for the inclined mandible. The ICC between examiners was 0.996 mm, between sessions was 0.990 mm and between CBCT measurements and calliper was 0.992 mm. The overall absolute mean measurement error was 0.40 mm (SD 0.39 mm). The percentage of errors that exceeded 1 mm was 6.7%.
The results revealed high reliability of measurements performed on CBCT images independently from object position, examiner's experience and high reproducibility in repeated measurements settings.
本研究旨在评估物体倾斜对使用锥形束 CT（CBCT）获得的下颌骨解剖结构线性测量的可靠性和可重复性的影响。
在干燥的下颌骨上测量了 10 个解剖标志之间的线性尺寸。由 3 名观察者使用手动卡尺进行了 3 次测量。使用 Planmeca Promax 3D 锥形束 CT（芬兰赫尔辛基 Planmeca Oy）对下颌骨进行扫描，下颌骨底部与水平面平行以及倾斜 45°。由 3 名观察者通过计算机进行线性尺寸的测量。对于每种实验设置，均进行了 4 次放射测量。总共进行了 240 次测量。通过比较标准偏差（SD）和估计组内相关系数（ICC）来评估可重复性。将放射测量与手动卡尺平均值之间的绝对差值作为误差进行估计。
水平放置的下颌骨的放射测量平均 SD 为 0.36mm，倾斜的下颌骨的 SD 为 0.48mm。观察者之间的 ICC 为 0.996mm，检查之间的 ICC 为 0.990mm，CBCT 测量值与卡尺之间的 ICC 为 0.992mm。总体平均绝对测量误差为 0.40mm（SD 为 0.39mm）。误差超过 1mm 的百分比为 6.7%。
结果表明，无论物体位置、检查者的经验如何，使用 CBCT 图像进行的测量均具有高度可靠性，并且在重复测量设置中具有高度可重复性。
