Measurement of the cochlear duct length (CDL) using the flat-panel volume CT

Introduction Cochlea implants (CI) can restore speech perception in patients with severe hearing loss or deafness. Studies have shown that the length and type of the electrode array and the anatomy of the cochlea have an impact on the clinical outcome. Hence, a preoperative exact measurement of the cochlear length (CDL) to select the optimal CI electrode array becomes more important.

Methods This study compares a flat panel volume CT (fpVCT) with a High Resolution CT (HRCT) of temporal bones for CDL-measurements. It was investigated if a manual measurement after 3D-curved multiplanar reconstruction improves accuracy over common formulas for CDL-calculation. For reference control, images were taken in a µ-CT.

Results The determination of the CDL in fpVCT compared to HRCT did not differ significantly. Compared to the reference measurement in µ-CT, the errors increase from basal to apical turns of the cochlea in both modalities and can be reduced by measuring 2 turns (2TL). A manual 2TL- or CDL-measurement provides acceptable to excellent intraobserver-variability regardless of the modality. Manual measurements in fpVCT and HRCT produce systematic errors compared to the reference, while formulas are more likely to produce random errors.

Conclusion Manual CDL-measurement using 3D-curved multiplanar reconstruction provides a clinically methodological benefit over formulas for CDL-calculation. At the moment, fpVCT cannot further improve accuracy compared to HRCT. However, using fpVCT radiation dose is reduced, acquisition times are shorter and a better reduction of metal artifacts can be achieved in postoperative quality control.

Poster-PDF A-1139.PDF

Publication History

Article published online:
10 June 2020