Morphologic measurements of 3D Eustachian tube model and their diagnostic value regarding Eustachian tube dysfunction - A cross-sectional observational study.

PURPOSE

To investigate the diagnostic value of three-dimensional morphologic measurements of the Eustachian tube on computed tomography in Eustachian tube dysfunction.

METHOD

This prospective cross-sectional observational study includes forty patients with unilateral Eustachian tube dysfunction. The clinical diagnosis is verified using the Eustachian tube score - 7 and the Eustachian tube dysfunction questionnaire - 7. Computed tomography scans of the temporal bone are acquired while performing a Valsalva manoeuvre to improve the visualization of the air-filled Eustachian tube lumen. The Eustachian tubes are delineated on curved planar reconstructions, and three-dimensional models are constructed. Seven morphological parameters are measured for each Eustachian tube: the cross-sectional size of the tympanic and pharyngeal orifice; the visualization length; the inclination angles, and the curvature angles. Morphological measurements and Eustachian tube scores are correlated.

RESULTS

The mean value of the visualization length of the complete Eustachian tube and in its bony segment is significantly higher in healthy sides than in pathological sides (p = 0.034 and p = 0.029, respectively). There is a significant correlation between the Eustachian tube score - 7 and the cross-sectional size of the tympanic orifice (r = 0.361; p = 0.022). The Eustachian tube score - 7 correlates significantly with the visualization length of complete Eustachian tube (r = 0.436; p = 0.005) and its bony segment (r = 0.598; p < 0.0001), respectively.

CONCLUSIONS

The cross-sectional size of the tympanic orifice may be a specific imaging feature indicating the obstructive Eustachian tube. However, 3D morphologic measurements of the Eustachian tube are insufficient to yield useful data about its function.