[THE function and morphology study of eustachian tube based on sonotubometry and multi-slice spiral CT in normal...

Objective: In order to assess ET more comprehensively, sonotubometry (STM)combined with CT images were applied to investigate the opening features of eustachian tube (ET) in normal subjects. STM was also used as a monitor training ET opening maneuver and optimizing CT scan parameters. Methods: Following ET opening training monitored by STM, STM data of ET opening duration and maximum sound pressure from 13 healthy volunteers (10 males and 3 females, 22 to 26 years old) were acquired using maneuvers of swallowing and Valsalva in standing and supine positions. Two trials of CT scan, setting A (slice thickness 6.0 mm, manually simulated to 0.6 mm, reconstruction thickness 0.6 mm) for normal and Valsalva scans and setting B(slice thickness 0.4 mm,reconstruction thickness 0.4 mm)for Valsalva scan, were conducted in each subject. The bone area and cartilage area of ET were measured respectively in reconstructed CT images. Statistical software SPSS 19.0 was employed in data analysis. Results: The duration of ET opening and maximum sound pressure by Valsalva were longer and stronger than those by swallowing in both positions. For Valsalva maneuver, standing position resulted in longer ET opening duration compared to supine position (P<0.05). Under setting A, ET cartilage area was measured larger by Valsalva scan than by normal scan (P<0.05). By Valsalva scan, setting A captured larger ET cartilage area compared to setting B (P<0.05). CT setting B resulted in longer scan time in comparison to setting A (P<0.05). Conclusions: Techniques of STM in supine position plus CT scan under setting A can be combined by Valsalva passive ET opening. Not only the invisible ET lumen through routine CT scan can be illustrated, but also relevant ET open-close process is shown, therefore, this study provides the technique for ET research of function and structure.