Functional MRI of the pharyngeal airway

超出所提供的空间。咽气道的通畅性取决于咽横截面积、顺应性和形状。舌外肌和咽壁的肌肉在调节这些机械特性中起主要作用。咽部似乎是最易塌陷的区域，最近的数据表明，顺应性和临界塌陷压力（Pcrit）在人类和低等哺乳动物中沿咽部的喙尾侧范围沿着变化。分离大鼠咽部，系统地改变咽部压力，同时获得磁共振图像。将获得最多15个1.0 mm轴向切片，通过鼻咽和尾侧口咽，并计算每个切片的横截面积。然后将获得每个切片的压力：面积关系，这将允许导出局部咽顺应性和Pcrit。咽肌活动对这些变量的影响进行评估，通过比较控制图像，而得到的舌头或咽壁肌肉电刺激。几何分析将允许我们描述每个轴向切片的侧径与前后径的比率（即，气道的“椭圆率”）和咽的限流段（FLS）的位置。假设是：1）顺应性是区域依赖性的，其中最高值在咽部; 2）FLS位于咽部; 3）咽部的形状在FLS处最椭圆; 4）舌或咽收缩肌的激活将降低区域顺应性和Pcrit，并使气道不那么椭圆（即，将使气道“弯曲”）。这些实验将提供关于咽部的几何形状和内在机械特性以及咽肌收缩所发生的变化的独特信息。这些数据可能有助于指导旨在使用气道压力变化和/或植入式咽肌神经刺激器来缓解睡眠期间气道阻塞的治疗策略。性能现场=

EXCEED THE SPACE PROVIDED. The patency of the pharyngeal airway depends on pharyngeal cross-sectional area, compliance and shape. The extrinsic tongue muscles and the muscles of the pharyngeal wall play a major role in modulating these mechanical properties. The velopharynx appears to be the region most isusceptible to collapse, and recent data suggest that compliance and the critical collapsing pressure (Pcrit) vary along the rostral-caudal extent of the velopharynx in humans and lower mammals. The rat pharynx will be isolated and pharyngeal pressure will be changed systematically while magnetic resonance images are obtained. Up to 15, 1.0 mm axial slices through the velopharynx and caudal oropharynx will be obtained, and the cross-sectional area of each slice computed. The pressure:area relation will then be obtained for each slice, which will allow derivation of regional pharyngeal compliance and Pcrit. The influence of pharyngeal muscle activity on these variables is evaluated by comparing control images with those obtained while the tongue or pharyngeal wall muscles are stimulated electrically. Geometric analyses will allow us to describe the ratio of the lateral to the anterior-posterior diameters of each axial slice (i.e., the "ellipticity" of the airway), and the location of the flow-limiting segment (FLS) of the pharynx. The hypotheses are: 1) compliance is regionally dependent, with the highest values in the velopharynx; 2) the FLS is located in the velopharynx; 3) the shape of the velopharynx is most elliptical at the FLS; 4) activation of tongue or pharyngeal constrictor muscles will decrease regional compliance and Pcrit, and make the airway less elliptical (i.e, will "stiffen" the airway). These experiments will provide unique information on the geometry and intrinsic mechanical properties of the pharynx, and the changes that occur with pharyngeal muscle contraction. The data may help to guide treatment strategies that are aimed at using airway pressure changes and/or implantable pharyngeal muscle nerve stimulators to alleviate airway obstruction during sleep. PERFORMANCE SITE ========================================Section End===========================================