Analysis of the accuracy of high-resolution computed tomography techniques for the measurement of stapes prostheses.
OBJECTIVE
Severe cochleovestibulopathy is a complication after stapes plasty and CT may be needed to assess intravestibular intrusion depth of the stapes piston. The accuracy of modern CT systems in this task has not been established.


METHODS
Stapes plasty was performed on six cadaver ears, and Soft CliP titanium pistons were inserted. Specimens were then examined using three different CT systems: single source 64-row, dual source 64-row and flat-panel computed tomography (FD-CT). Piston length, width and intravestibular intrusion were measured by four independent observers. Temporal bone dissection was then performed and vestibular piston intrusion measured microscopically.


RESULTS
Piston dimensions were overestimated by all observers and CT systems. Intravestibular penetration as assessed by CT was consistently greater than the value found on cadaveric anatomical dissection. On average, the CT measurement of width was 0.176 mm (44%) greater, length 0.125 mm (6.25%) greater and intrusion 0.333 mm (39.2%) greater than the anatomical measurements. FD-CT showed better image quality and partly less bias in several measurements, but penetration depth was still variably overestimated.


CONCLUSIONS
CT measurement consistently overestimated intravestibular piston dimensions and vestibular intrusion. Modern temporal bone imaging systems are not yet able to depict the stapes piston position with a sufficient degree of accuracy.
Bozzato
Alessandro
A
Department of Otorhinolaryngology, Head & Neck Surgery, University of Erlangen-Nuremberg, FAU Medical School, Waldstrasse 1, 91054 Erlangen, Germany. alessandro.bozzato@uk-erlangen.de
Struffert
Tobias
T
Hertel
Victoria
V
Iro
Heinrich
H
Hornung
Joachim
J
D002102:Cadaver; D006801:Humans; D019736:Prostheses and Implants; D019919:Prosthesis Implantation / Q000379:methods*; D011856:Radiographic Image Enhancement / Q000379:methods*; D015641:Radiography, Interventional / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013201:Stapes Surgery / Q000295:instrumentation* / Q000379:methods*; D014057:Tomography, X-Ray Computed / Q000379:methods*