正常成人胸内气管动态CT扫描

Investigation of normal intrathoracic trachea during dynamic CT sanning

目的研究正常成人胸内气管在用力呼吸时的横断面面积、径线及形态的改变。材料与方法用电子束ＣＴ对２５例正常男性主动脉弓上方２ｃｍ处的胸内气管做了动态扫描。在被检者用力做深吸、呼气的５．５秒钟内做１０次扫描，每次１００毫秒，间隔５００毫秒，层厚３ｍｍ。结果气管的平均横断面面积、矢状径及冠状径在吸气末和呼气末时分别为２２８．３６ｍｍ２、１８．２８ｍｍ、１６．９７ｍｍ和１９１．２４ｍｍ２、１５．６２ｍｍ、１６．１９ｍｍ。横断面面积于呼气末时较吸气末减少１５．４８％±９．６％。气管形态在吸气末呈圆形、卵圆形，至呼气末时可呈马鞍形。结论动态ＣＴ是在呼吸状态下研究气管的形态和径线的理想工具，在中国人中，若呼气末时气管横断面面积较吸气末时减少５０％以上时，可考虑有气管软化。

Purpose To study the diameters and cross sectional areas, as well as the shape of normal adult intrathoracic thachea during forced respiration in the Chinese. Materials and methods 25 male volunteers were studied with dynamic CT, using electron beam CT scanner, at a level 2 cm above aortic arch, with 3 mm collimation. Ten 100 msec dynamic scans were obtained at 500 msec intervals during 5.5 second peroid as the volunteers performed forced inspiration and expiration vital capacity maneuvers. Results The mean cross sectional area, sagittal and coronal diameter of the trachea decreased dynamically from 228.36 mm 2, 18.28 mm and 16.97 mm at end insperation to 191.24 mm 2, 15.62 mm and 16.19 mm at end expiration respectively. The average cross section area decreased by 15.48%± 9.6% between inspiration and expiration. The shape of trachea was rounded or elliptical on inspiration image and horseshoe shaped on end of expiration. Conclusion The dynamic CT is ideally suited for the study of tracheal dimensions and shape during respiration maneuvers. Among the Chinese, if the cross sectional area of trachea decrease by more than 50% from inspiration to expiration, diagnosis of tracheomalacia can be established.