側面測顱界標點判讀之觀察者內可信度研究:錐狀射源電腦斷層合成影像與傳統測顱影像之比較

目的：本實驗是以同一觀察者內方法探討同一觀察者(intraobserver)，分別使用錐狀射源電腦斷層掃描合成二維側面測顱影像(cone beam computed tomography (CBCT)-synthesized two-dimensional (2D) lateral cephalograms)和傳統數位側面測顱影像(conventional digital cephalograms)兩種方法在界標點判讀(landmark identification)之可信度的比較。材料與方法：隨機選擇20位病患CBCT之影像，以及其所對應的傳統數位側面測顱影像。2D的測顱影像是從3D的CBCT掃描中，將整體體積的體素(voxels)堆疊加總，再將影像匯入Winceph 8.0。這兩種影像，由一位有經驗的矯正專科醫師在電腦螢幕上直接進行界標點判讀，並在兩週後重複一次。檢測每個界標點的x和y座標，來評估同一觀察者內的可信度。兩種方法當中，界標點再現性(reproducibility)的差別，由配對型student’s t-test進行評估。結果：兩種測顱分析方式的水平和垂直方向的誤差範圍，介於0.18~1.67 mm。在CBCT測顱分析中，少部分界標點有超過1 mm的觀察者內誤差；；界標點Me(menton)、LIE(lower central incisor edge)、LIA(lower central incisor root apex)，及Pog(pogonion)、Gn(gnathion)、Me(menton)、UIA(upper central incisor root apex)、LIA(lower central incisor root apex)、LM(lower molar)分別在水平方向與垂直方向之可信度較佳。散佈圖(scatter-plots)顯示，每個界標點有特別的誤差分布模式。結論：在本實驗中發現利用CBCT合成二維側面測顱影像的測顱分析在矯正學診斷上可以取代數位傳統側面測顱分析。

關鍵字

矯正診斷；數位傳統側面測顱影像；錐狀射源電腦斷層；界標點判讀

並列摘要

Object: The aim of the study was to examine the intraobserver reliability of landmark identification in cone beam computed tomography (CBCT)-synthesized two-dimensional (2D) lateral cephalograms versus conventional digital cephalograms. Materials and methods: Twenty CBCT scans and the corresponding conventional lateral cephalgrams were randomly selected. Two-dimensional lateral cephalograms were constructed from the three-dimensional (3D) CBCT scans by summing the voxels of the entire volume. All the images were imported into Winceph 8.0. Twenty landmarks in the CBCT-synthesized 2D cephalograms and conventional cephalograms were identified directly on the computer screen by an experienced orthodontist and the operation was repeated two weeks later. The x- and y-coordinates of each landmark were examined for intraobserver reliability. The differences in landmark reproducibility between the two modalities were analyzed with paired Student’s t-test. Results: The horizontal and vertical errors of landmark identification by the two modalities of cephalometry ranged from 0.18 to 1.67 mm. Fewer landmarks in CBCT-synthesized cephalograms had intraobserver error greater than 1 mm. Significantly better reliability was observed in CBCT-synthesized cephalograms at Me, LIE and LIA in the horizontal dimension and at Pog, Gn, Me, UIA, LIA and LM in the vertical dimension. Scatter-plots revealed a characteristic pattern of error distribution for each landmark. Conclusions: CBCT-synthesized lateral cephalograms is a promising method to replace conventional cephalograms for orthodontic diagnosis.

並列關鍵字

orthodontic diagnosis ； digital cephalogram ； cone-beam computed tomography ； landmark identification

參考文獻

1. Sukovic P. Cone beam computed tomography in craniofacial imaging. Orthod Craniofac Res 2003;6 Suppl. 1:31-6. (discussion 179-82).

2. Swennen GR, Schutyser F. Three-dimensional cephalometry: spiral multi-slice vs cone-beam computed tomography. Am J Orthod Dentofacial Orthop 2006;130:410-6.

3. Chien PC, Parks ET, Eraso F, Hartsfield JK, Roberts WE, Ofner S. Comparison of reliability in anatomical landmark identification using two-dimensional digital cephalometrics and three-dimensional cone beam computed tomography in vivo. Dentomaxillofac Radiol 2009;38:262-73.

4. de Oliveira AE, Cevidanes LHS, Phillips C, Motta A, Burke B, Tyndall D. Observer reliability of three-dimensional cephalometric landmark identification on cone-beam computerized tomography. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2009;107:256-65.

5. Lagravere MO, Low C, Flores-Mir C, et al. Intraexaminer and interexaminer reliabilities of landmark identification on digitized lateral cephalograms and formatted 3-dimensional cone-beam computerized tomography images. Am J Orthod Dentofacial Orthop 2010;137:598-604.

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側面測顱界標點判讀之觀察者內可信度研究:錐狀射源電腦斷層合成影像與傳統測顱影像之比較

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