Micro-CT study of the human cochlear aqueduct

The anatomic structure of the cochlear aqueduct (CA) in human temporal bone specimens was observed using micro-computed tomography (CT). Micro-CT scanning of 18-A mu m-thick slices was performed on 30 slides of human temporal bone specimens to observe the CA structure and its relationship with its surroundings. The length, internal and external apertures, and the narrowest width of the CA were measured. The differences in CAs were compared between high jugular bulb (HJB) specimens and normal specimens. A large number of CA images were acquired using Micro-CT scanning, which clearly displayed the basic anatomic structures, stereotactic localizations, and adjacent relationships of the CAs. The whole course of a CA was 12.31 +/- 3.60 mm, the diameter of the internal aperture was 465 +/- 242 A mu m, the diameter of the external aperture was 2.88 +/- 1.06 mm, the narrowest diameter was 601 +/- 335 A mu m, the diameter of the opening of inferior cochlear vein (ICV) was 151 +/- 50 A mu m, the distance between the internal aperture and ICV was 270 +/- 197 A mu m, and the distance between the inferior margin of the internal acoustic meatus (IAM) and the top most part of the external aperture of the CA was 6.783 +/- 2.15 mm. No bony obstruction of the CA or CA enlargement was observed in the specimens. A total of 28 CAs had one accompanying bony canal in the surroundings. The length and travelling of the CA were not affected by the level of the jugular bulb (JB). The variation of the travelling of the ICV was larger than that of the CA. Micro-CT adequately displayed the bony CA canal and provided a new method for anatomical studies of the CA and a basis for functional studies.