Burnett K R, Davis C L, Read J
Long Beach Medical Imaging Clinic, CA 90804.
AJR Am J Roentgenol. 1987 Nov;149(5):959-62. doi: 10.2214/ajr.149.5.959.
In order to display temporomandibular joint (TMJ) images as a dynamic or motion study, a protocol was developed to obtain MR images of the TMJ in multiple phases of opening by using the "fast-scanning" capabilities of the GE Signa MR scanner. To facilitate this procedure a prototype device was also developed to passively open the patient's mouth from resting (closed) to fully open in user-defined increments (minimum 1 mm). MR imaging (surface coil) was carried out at each successive station using the GRASS, pulse-sequence data base of the GE Signa system operating at 1.5 T. Image-acquisition parameters were optimized in studies of cadavers and volunteers to obtain the clearest delineation of the TMJ meniscus and to determine any potential tradeoffs between total imaging time per slice (image quality), patient tolerance, and other practical considerations. For viewing, the images were sequentially placed in the video memory of the operating console and displayed in a back-and-forth-closed cine loop or "movie" mode at variable (operator-selectable) speeds. The dynamic sequences in four individuals were compared with static open- and closed-mouth views obtained with routine pulse sequences. Any single image from the dynamic display lacked the high resolution of the routine static images because of technical limitations of the pulse-sequence data base. However, in the movie mode the pertinent joint structures (such as meniscus and condyle) were clearly delineated, as were several of the important muscles of mastication. The anterior motion (translation) of the meniscus during jaw opening is particularly evident and suggests great potential for functional evaluation. These results show the feasibility of dynamic TMJ imaging with MR. The added information of the cine display potentially complements the routine static images and may prove extremely valuable in the assessment of TMJ dysfunction.
为了将颞下颌关节（TMJ）图像显示为动态或运动研究，我们制定了一项方案，利用GE Signa MR扫描仪的“快速扫描”功能，在开口的多个阶段获取TMJ的MR图像。为便于进行此操作，还开发了一种原型设备，以用户定义的增量（最小1毫米）被动地将患者的嘴从静止（闭合）状态张开至完全张开。使用在1.5 T运行的GE Signa系统的GRASS脉冲序列数据库，在每个连续位置进行MR成像（表面线圈）。在尸体和志愿者研究中优化了图像采集参数，以获得TMJ半月板最清晰的描绘，并确定每层总成像时间（图像质量）、患者耐受性和其他实际因素之间的任何潜在权衡。为了进行观察，将图像顺序放入操作控制台的视频内存中，并以可变（操作员可选）速度在来回闭合的电影循环或“电影”模式下显示。将4名个体的动态序列与用常规脉冲序列获得的静态开口和闭口视图进行比较。由于脉冲序列数据库的技术限制，动态显示中的任何单幅图像都缺乏常规静态图像的高分辨率。然而，在电影模式下，相关的关节结构（如半月板和髁突）以及几块重要的咀嚼肌都清晰可辨。半月板在张口时的向前运动（平移）尤为明显，显示出在功能评估方面具有巨大潜力。这些结果表明了用MR进行动态TMJ成像的可行性。电影显示所提供的额外信息可能补充常规静态图像，并可能在评估TMJ功能障碍方面被证明极具价值。
