Morphological aberration of the Eustachian tube is a significant factor of various middle ear diseases.
Traditionally, cadaveric specimens have been used for studies on the morphology of Eustachian tubes.However, this approach was not too efficient, as samples were limited in number as they were difficult to obtain, and biological conditions were not reflected due to rigor mortis and atrophy during specimen preparation.
We thus decided to use Multi-Slice CT (MSCT) to perform 3-D anatomic measurements of the Eustachiantube. MSCT has benefits of isotropy and high resolution, and it is useful in preparing images of any plane.
Forty-eight adults were studied. For the purpose of measurement, various anatomic indices were carefullyand precisely defined to identify each area on the image. Calculations based on each coordinate value enabledthe measurement of length, diameter and angle of the Eustachian tube of normal adults.
Therefore, measurements of the Eustachian tube, which were traditionally difficult as it is located in the deeppart of the cranium, were simplified in many specimens.
Mean value of total length was 39. 2±3. 2 mm, cartilage part length of the tube 30.0±2.7mm and bony part9.2±1.6mm. Mean values of diameter of tympanic orifice were 5.2×3.2mm, and pharyngeal orifice 9.7×4.4mm. Mean value of angle between bony part and cartilage part was 160.9-13.6 degrees.
This approach to anatomic measurement is expected to contribute greatly to investigation on various middleear diseases.
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