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| Incidence and morphological characteristics of paratracheal air cyst: a large sample study with 64-row spiral CT |
| FANG Chun, WANG Li-zhang, SUN Yan-bao, WANG Yan-chun |
| Department of Radiology, the First Hospital of Jiaxing, the First Affiliated Hospital of Jiaxing University, Jiaxing Zhejiang 314000, China |
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Abstract Objective: To evaluate the incidence and morphological characteristics of paratracheal air cyst(PTAC) with 64-row spiral CT, and to improve the recognition ability of PTAC. Methods: Five thousand and five patients underwent thoracic plain CT scan with 64-row spiral CT during a half-year at our institution were retrospectively enrolled to analyze for the presence of PTAC and their morphological characteristics. Results: Four hundred and thirty two patients had PTACs, and the general incidence was 8.63%. The incidence of male was 8.76%(245/2 797), and the incidence of female was 8.47%(187/2 208). There was no significant difference between the male and female(χ2=0.132, P=0.717). Among 432 patients, 404 patients(93.52%) had one air cyst, 23 patients(5.32%) had 2 air cysts, 5 patients(1.16%) had 3 air cysts, with the total of 465 air cysts. All air cysts were immediately adjacent to trachea within 3 mm. The air cysts ranged in size from 1 mm×1 mm to 37 mm×49 mm with mean long axis diameter of (5.6±5.2) mm and short axis diameter of (3.6±3.6) mm. Two hundred and fifty-three air cysts(54.41%) showed direct communication to trachea, and 164 air cysts(35.27%) had septations inside. All air cysts were located at C7~T4 vertebral level including 86.67% of them at T1~T2 vertebral level, meanwhile 96.35% of air cysts were next to the 6~8 o’clock position of trachea. The prevalence of right superior pleural thickening and fibers at right upper lung in patients with air cyst were slightly higher than that in patients without air cyst(42.36%, 44.44% vs 38.12%, 40.04%), but there was no significant statistical difference between them. Conclusion: The incidence of PTAC was quite high. Most of PTACs were single, immediately adjacent to the 6~8 o’clock position of trachea, and located at T1~T2 vertebral level. More than half of PTACs had thin communication to trachea and part of PTACs had septations inside. PTACs have no significant relation with local pleural thickening and fibers at right upper lung.
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Received: 07 January 2015
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2015, Vol. 26 
