薛氏位X线片与矢状位CT颞下颌关节骨性结构关系测量

STUDY ON THE TEMPOROMANDIBULAR JOINT BONY RELATIONSHIPS BY TRANSCRANIAL RADIOGRAPHY AND SAGITTAL COMPUTED TOMOGRAPHY

目的：了解不同影像检查和不同解剖层次上颞下颌关节骨性结构位置关系情况。方法：对３０名健康成年志愿者的６０侧颞下颌关节在牙尖交错位拍摄薛氏位Ｘ线片并行轴向位ＣＴ扫描，用计算机图像分析仪分别对薛氏位Ｘ线片和ＣＴ矢状位３个层面上颞下颌关节间隙进行线性测量和面积测量。结果：不同图像上应用不同测量方法所得左右两侧颞下颌关节相应的关节间隙基本对称。线性测量显示，薛矢位Ｘ线片上在０°和１８０°方向上髁状突基本处于中位，而在其它方向上髁状突则多处于关节窝的后位；ＣＴ矢状面外１／３层面上髁状突基本处于中位；中１／３层面０°和１８０°方向上髁状突多处于后位，而在其它方向上髁状突则分布于前位或中位；内１／３层面上０°和１８０°方向上髁状突位置多居中。面积测量结果显示薛氏位Ｘ线片上髁状突略处后位，而ＣＴ矢状面外１／３层面上髁状突位置稍偏前，中和内１／３层面上髁状突则多处于中位。结论：在不同影像检查方式、不同关节层面、不同定点测量方法和不同取值标准条件下，髁状突和关节窝的位置关系表达并不一致，在颞下颌关节疾病的临床诊断和基础研究中应予以注意。

Objective: The different expression of temporomandibular joint(TMJ) bony relationships on different imaging methods and different cut of the joints were studied and analysed.Method:Sixty temporomandibular joints from 30 adult healthy volunteeres were selected for taking transcranial radiogram and computed tomogram at intercuspal position.Three dimensional reconstruction were made by using computed tomography examining data to obtain sagittal outside, middle and inside 1/3 tomograms of TMJ.Linear measurements and area measurements of TMJ space as a means of determining condyle positions were performed on transcranial radiograph and three sagittal computed tomography sections with computed digital image analysis techniques. Results:The data obtained from different measuring methods on different images indicated that the both left and right TMJ spaces were about the same.Linear joint space measuring in transcranial radiogram showed that the condyle is normally in the center in 0° and 180° directions and posterior in other directions. There was statistically significant difference between the condyle/fossa relationship at various depts of cut.In outside 1/3 cut,the condyle is in the center of the joint.In middle 1/3 cut,the condyle is in the posterior in 0° and 180° directions and anterior or middle in other directions.In inside 1/3 cut,the majority of condyles were in the center in 0° and 180° directions. Area measurements of the joint spaces suggested that condyle was slightly posterior in the joint in transcranial images,slightly anterior in the joint in outside 1/3 cut computed tomograph and in the center in middle and inside 1/3 cuts.Conclusion:Expression of condyle/fossa relationship is not identical under different imaging methods,different cuts of the joint,different measuring means,and different judging criteria.Attention should be paid to this variety in clinical diagnosis and basic study of TMJ diseases.