Direct measurement of cochlear parameters for automatic calculation of the cochlear duct length

BACKGROUND: Cochlear morphology and cochlear duct length (CDL) play important roles in the selection of appropriate electrodes. Cochlear parameters such as diameter (A value) and width (B value) are used as inputs for calculating the CDL. Current measurements of these parameters are inefficient and time consuming. Recently developed otological planning software (OTOPLAN) allows surgeons to directly measure these parameters and then automatically calculate the CDL. OBJECTIVES: The primary objective was to validate this new software for measuring the cochlear parameters and CDL. The secondary aim was to investigate the correlation between each cochlear parameter with the calculated CDL. DESIGN: Retrospective. SETTINGS: Ear specialist hospital. PATIENTS AND METHODS: The measurement of cochlear diameter (A value) was chosen as the validation parameter. To do this, the A value was measured by a neurotologist on the new OTOPLAN planning software and was validated to the one measured on the currently used DICOM viewer. Upon the validation of the OTOPLAN software, the other two cochlear parameters, namely width (B value) and height (H value) were measured, and CDL was automatically calculated. Finally, the correlation of all parameters with the CDL was statistically analyzed. MAIN OUTCOME MEASURES: Validation of OTOPLAN and CDL estimation. SAMPLE SIZE: 88 ears. RESULTS: There was no significant difference between the A-value measured on the DICOM viewing software and that on the new planning software by the two independent neurotologists (P=.27). Both Aand B-values showed a high positive correlation to the CDL. However, the B-value showed a stronger correlation to the CDL than the A-value (r=0.63 for A, and r=0.96 for B). CONCLUSION: The direct measurement of cochlea parameters and automatic calculation of the CDL could improve the efficiency of clinical workflow and make otology surgeons more independent. Moreover, the cochlear width (B) has a strong correlation to the CDL. Thus, we suggest using the combination of A and B to accurately estimate the CDL rather than using only one. LIMITATIONS: Single center and small sample size.