Measurement of cochlear length using the 'A' value for cochlea basal diameter: A feasibility study

Area of Science:

• Radiology
• Otolaryngology
• Anatomy

Background:

• Accurate cochlear length estimation is crucial for successful cochlear implantation.
• Current methods for cochlear length measurement may lack precision.
• High-resolution imaging offers potential for improved anatomical assessment.

Purpose of the Study:

• To assess the reliability and consistency of measuring cochlear basal diameter (A value) from high-resolution temporal bone CT scans.
• To determine the feasibility of using this measurement for cochlear length estimation in patients undergoing cochlear implantation.

Main Methods:

• A feasibility study involving high-resolution temporal bone CT scans from 40 consecutive patients (80 cochleae).
• Measurement of the distance from the round window to the lateral cochlear wall by two independent reviewers (neuroradiologist and otolaryngologist).
• Interrater reliability assessed using the intraclass correlation coefficient (ICC) and Bland-Altman plot.

Main Results:

• High interrater reliability was observed for cochlear measurements, with ICCs of 0.90 for the left ear and 0.96 for the right ear.
• Bland-Altman analysis confirmed reliability, with 96% of measurements falling within the 95% limits of agreement.
• The measurement between the round window and lateral cochlear wall demonstrated a high level of agreement between reviewers.

Conclusions:

• Measurement of the distance between the round window and lateral cochlear wall is consistently and reliably obtainable from high-resolution temporal bone CT scans.
• This imaging-based method is feasible for estimating cochlear length in patients considered for cochlear implantation.
• The findings support the use of this technique to enhance pre-surgical planning for cochlear implant procedures.