Evaluation of Coronal CT Scanning in Observing Vestibular Aqueduct

Objective To study the imaging features of the normal vestibular aqueduct (VA) on coronal CT scans, to provide further evidence for the diagnosis of sensorineural hearing loss of unknown reason.Materials and Methods Both axial and coronal CT scanning were performed in 52 cases (104 normal ears). The width and length of VA, as well as the angle between the long axis of VA and horizontal level were measured. The data thus obtained were statistically analyzed. Results On coronal plane, both the displaying rate and measurable rate of VA isthmus were 100%. On axial plane, the displaying rate of VA isthmus was 100%, while its measurable rate was only 88.3%. Both the displaying rate and measurable rate of the posterior part of VA were 61.5%. On coronal plane, the width and length of VA isthmus were (0.87±0.57) mm and (3.07±1.34) mm, while the width and length of the posterior part of VA were 1.23±0.51mm and (4.89±1.61) mm, respectively. The normal upper limit of VA isthmus was 4.4mm by 1.5mm (length by width).Conclusion On coronal plane, the VA course can be well demonstrated and the VA isthmus can be easily measured. The normal values of VA isthmus on coronal plane are proposed. Combination of coronal with axial images will improve the diagnostic accuracy of VA dilatation and, thus, help find out the etiology of sensorineural hearing loss.