Functional MRI of the pharyngeal airway

描述（由申请人提供）：咽气道的通畅取决于咽的横截面积、顺应性和形状。舌外肌和咽壁肌在调节这些力学特性中起主要作用。腭咽似乎是最容易塌陷的区域，最近的数据表明，在人类和低等哺乳动物中，腭咽的顺应性和临界塌陷压力（Pcrit）沿着腭咽的喙端-尾端范围变化。分离大鼠咽部，系统地改变咽压，同时获得磁共振图像。通过腭咽和尾口咽获得最多15,1.0 mm的轴向切片，并计算每个切片的横截面积。压力：面积关系将得到每个切片，这将允许推导区域咽顺应性和Pcrit。咽肌活动对这些变量的影响是通过比较对照图像与电刺激舌头或咽壁肌肉时获得的图像来评估的。几何分析将使我们能够描述每个轴向片的外侧直径与前后直径的比例（即气道的“椭圆性”），以及咽的限流段（FLS）的位置。假设是：1)顺应性是区域性的，腭咽的顺应性最高；2) FLS位于腭咽；(3)舌咽部在前侧翼处呈椭圆形；4)舌头或咽部收缩肌的激活会降低局部顺应性和Pcrit，使气道不那么椭圆（即使气道“僵硬”）。这些实验将提供咽的几何形状和内在力学特性的独特信息，以及咽肌肉收缩时发生的变化。这些数据可能有助于指导旨在使用气道压力改变和/或植入式咽肌神经刺激器减轻睡眠期间气道阻塞的治疗策略。

DESCRIPTION (provided by applicant): 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 susceptible 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.