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 (rP = 0.361; p = 0.022). The Eustachian tube score - 7 correlates significantly with the visualization length of complete Eustachian tube (rP = 0.436; p = 0.005) and its bony segment (rS = 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.
Keywords: CT; Computed tomography; Eustachian tube; Morphologic measurements; Tuba auditiva; Valsalva.
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