Benavides E, Bilgen M, Al-Hafez B, Alrefae T, Wang Y, Spencer P
Department of Periodontics and Oral Medicine, University of Michigan, School of Dentistry Office 2029A, 1011 North University Avenue, Ann Arbor, MI 48109-1078, USA.
Dentomaxillofac Radiol. 2009 Mar;38(3):148-55. doi: 10.1259/dmfr/19195745.
Diffusion tensor imaging (DTI) is an MRI modality for characterizing the property, microstructural organization and function in tissues such as the brain and spinal cord. Prior to this investigation, DTI had not been adapted for studies of the temporomandibular joint (TMJ) disc. Objectives were to test the feasibility of DTI to evaluate the porcine TMJ disc and to use DTI to observe differences in magnitude of anisotropy of water diffusion between TMJ disc regions.
Five adult pig TMJs were scanned on a 9.4 Tesla horizontal bore MRI scanner using an inductively coupled surface coil. High-resolution gradient-echo and diffusion-weighted spin-echo based images were obtained. The mean diffusivity and fractional anisotropy (FA) were computed in different regions of the disc. Two observers were calibrated to review the two-dimensional and three-dimensional images. Polarized light microscopy was used as the gold standard for collagen fibre orientation.
In the sagittal plane, the mean diffusivity was higher in the posterior (1.28+/-0.10 x 10(-3) mm(-2) s(-1)) and anterior (1.27+/-0.08 x 10(-3) mm(-2) s(-1)) bands compared with the intermediate zone (0.96+/-0.01 x 10(-3) mm(-2) s(-1)), and the FA index was also lowest in the intermediate zone. In the coronal plane, the mean diffusivity was higher in the medial (1.42+/-0.01 x 10(-3) mm(-2) s(-1)) and lateral (1.21+/-0.12 x 10(-3) mm(-2) s(-1)) aspects than in the centre (1.09+/-0.08 x 10(-3) mm(-2) s(-1)), and the FA index was also lowest in the centre.
DTI is a useful method for non-invasively characterizing the structure/property relationships of the porcine TMJ disc.
扩散张量成像（DTI）是一种磁共振成像方式，用于表征大脑和脊髓等组织的特性、微观结构组织及功能。在本研究之前，DTI尚未应用于颞下颌关节（TMJ）盘的研究。目的是测试DTI评估猪TMJ盘的可行性，并使用DTI观察TMJ盘各区域水扩散各向异性大小的差异。
使用感应耦合表面线圈在9.4特斯拉水平孔径磁共振成像扫描仪上对5个成年猪的颞下颌关节进行扫描。获得了基于高分辨率梯度回波和扩散加权自旋回波的图像。计算了盘不同区域的平均扩散率和分数各向异性（FA）。校准了两名观察者以查看二维和三维图像。偏振光显微镜用作胶原纤维取向的金标准。
在矢状面中，与中间区（0.96±0.01×10⁻³mm⁻²s⁻¹）相比，后带（1.28±0.10×10⁻³mm⁻²s⁻¹）和前带（1.27±0.08×10⁻³mm⁻²s⁻¹）的平均扩散率更高，并且FA指数在中间区也最低。在冠状面中，内侧（1.42±0.01×10⁻³mm⁻²s⁻¹）和外侧（1.21±0.12×10⁻³mm⁻²s⁻¹）的平均扩散率高于中心（1.09±0.08×10⁻³mm⁻²s⁻¹），并且FA指数在中心也最低。
DTI是一种用于非侵入性表征猪TMJ盘结构/特性关系的有用方法。
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