Computed tomographic imaging of stapes implants.
OBJECTIVE
Computed tomographic (CT) imaging of stapes prostheses is inaccurate.


BACKGROUND
Clinical situations arise in which it would be helpful to determine the depth of penetration of a stapes prosthesis into the vestibule. The accuracy of CT imaging for this purpose has not been defined. This study was aimed to determine the accuracy of CT imaging to predict the depth of intrusion of stapes prostheses into the vestibule.


METHODS
The measurement of stapes prostheses by CT scan was compared with physical measurements in 8 cadaveric temporal bones.


RESULTS
The depth of intrusion into the vestibule of the piston was underestimated in specimens with the fluoroplastic piston by a mean of 0.5 mm when compared with the measurements obtained in the temporal bones. The depth of penetration of the stainless steel implant was overestimated by 0.5 mm when compared with that in the temporal bone.


CONCLUSIONS
The type of implant must be taken into consideration when estimating the depth of penetration into the vestibule using CT scanning because the imaging characteristics of the implanted materials differ. The position of fluoroplastic pistons cannot be accurately measured in the vestibule. Metallic implants are well visualized, and measurements exceeding 2.2 mm increase the suspicion of otolithic impingement. Special reconstructions along the length of the piston may be more accurate in estimating the position of stapes implants.
Division of Otolaryngology, University of Utah, Salt Lake City, Utah, USA. frank.warren@earthlink.net
Frank M
FM
Warren
Sterling
S
Riggs
Richard H
RH
Wiggins
D006319:Hearing Loss, Sensorineural / Q000453:epidemiology / Q000503:physiopathology / Q000601:surgery; D006801:Humans; D010040:Otosclerosis / Q000453:epidemiology / Q000503:physiopathology / Q000601:surgery; D019736:Prostheses and Implants; D019919:Prosthesis Implantation; D012444:Saccule and Utricle / Q000503:physiopathology; D013199:Stapes / Q000503:physiopathology; D013201:Stapes Surgery; D013701:Temporal Bone / Q000000981:diagnostic imaging* / Q000601:surgery*; D014057:Tomography, X-Ray Computed; D014717:Vertigo / Q000453:epidemiology