胸廓入口区气管旁含气囊肿的CT及临床表现

CLINICAL AND CT MANIFESTATIONS OF PARATRACHEAL AIR CYSTS IN THE THORACIC INLET

目的探讨胸廓入口区气管旁含气囊肿的CT及临床表现。方法总结45例胸部常规CT扫描中发现的胸廓入口区气管旁含气囊肿，分析其部位、大小、形态、边缘、临床症状及肺部CT表现。以40例非患有胸廓入口区气管旁含气囊肿的病例作为对照组，对比分析两组肺功能、气管指数及肺气肿计数。结果45例胸廓入口区气管旁含气囊肿均位于胸腔入口区的气管旁右后外侧，其中20例（44％）位于第2胸椎水平，38例（84％）位于气管旁右侧。CT均表现为不规则形或卵圆形的含气囊肿，囊内有不规则线状、索条状分隔（53％），平均大小为1cm×1cm×2cm，外缘多呈不规则分叶状，壁厚薄不一（16％）。薄层扫描可见到囊肿和气管间的含气交通细管，三维重建图像可见到软组织密度的交通管道和在气管内壁上的开口。病例组FEV1／FVC和FEF25％～75％显著低于对照组（F=5．474、11．355，P〈0．05），而两组FVC％、FEV1％差异无统计学意义。病例组与对照组的气管指数及肺气肿计数的差别有显著的统计学意义（F=32．600、29．740，P〈0．01）。结论位于胸腔入口处气管右外后侧和气管间有细管状交通的含气囊肿影是本病最可靠的CT征象。它的发生与慢性肺疾患密切相关。

Objective To discuss the CT and clinical manifestations of paratracheal air cysts in the thoracic inlet. Methods Data of 45 cases of paratracheal air cysts （PAC） in the thoracic inlet found with conventional CT examination were analyzed for their location, size, form, margin, clinical symptoms and the manifestations in lung. Forty patients with non-PAC were enrolled and served as controls. Pulmonary function, tracheal and emphysema indices were compared. Results All the cysts were situated on the right posterolateral aspect of the trachea of the thoracic inlet, of which, 20 lesions （44%） located at T2 level and 38 （84%） at the right trachea. On CT scans, all cysts displayed as irregular or round air-containing lesions, with irregular linear septal （53%） within the cyst and irregular lobulated outline （16%）. The mean size of the lesions was about 1 cm× 1 cm×2 cm. On thin-section scans, a fine communicating channel between the cyst and trachea was found in 14 cases. Clinically, 36 patients （80%） showed respiratory symptoms. FEV1/FVC and FEF25%- 75% in the patients with this problem were significantly lower than that in the control group （P〈0.05）. However, FVC%, FEV1%, and proportion of obstructive pattern between the two groups were not significantly different. The differences between the tracheal indices and CT-determined emphysema scores were significant （P〈0.01）. Conclusion A paratracheal air cyst situated at the thoracic inlet with a fine communicating channel with the trachea is the most reliable CT sign of the disease, which is closely related to the pathogenesis of chronic pulmonary diseases.