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Accuracy of preoperative cochlear length determination using CBCT and HR MR imaging
18 April 2018 (online)
In the present study, the accuracy of cochlear length measurement based on CBCT and 3 Tesla MR imaging was examined. The validation was carried out with corrosion casts of the same human cochlea.
Five human temporal bones were scanned with CBCT and 3 Tesla MRI (high-resolution T2-weighted VFA-TSE sequence). Subsequently, corrosion casts were made. The cochlear length was determined on both clinically available imaging modalities using curved three-dimensional multiplanar reconstruction. The corrosion casts were measured with computer-based planimetry.
The difference between the cochlear length on CBCT or MRI and the respective length of the casts was on average -1 mm (-0.3 mm to -2.1 mm) and 0.6 mm (-0.8 mm to 1.6 mm). The reproducibility of the method was checked by two observers. The interobserver reproducibility for both image modalities together averaged 0.8 mm (0.1 mm to 2.7 mm). The intraobserver reproducibility for each of the observer averaged 0.8 mm (0.1 mm to 1.7 mm) and 0.5 mm (0 to 1.2 mm).
The preoperative determination of the cochlear length has a varying accuracy on both CBCT and 3T MRI data. Nevertheless, taking into account the deviations determined, these measurements can support the selection of the optimal electrode length with good accuracy.