Comparison of CT and DVT measurement results using the OTOPLAN software

Introduction Preoperative measurement of the cochlea to select the optimal electrode array length is now available prior to implantation. The OTOPLAN software allows to generate 3D models from both CT and DVT image datasets of patients and to perform a measurement of the cochlea. The aim of this retrospective study was to evaluate if CT and DVT imaging allow cochlear measurement comparably well, or if one of the imaging methods allows this measurement more accurately.

Method Data were analysed from patients who received a cochlear implant from 2018 to date and for whom DICOM records of preoperative computed tomography and postoperative digital volume tomography were available. The following measurements were collected: diameter (A), height (H), width (B) and cochlear duct length (CDL). The difference between CT and DVT measurement was considered significant if the p-value was <0.05. Results Data from 22 patients could be collected so far. The median deviation was -0.15mm for the diameter (A), 0mm for the height (H) and 0.15mm for the width (B). The median of the cochlear duct length (CDL) calculated by the programme varied by -0.20mm. There was a significant difference in the measurements for the parameters A, B and subsequently also CDL. This difference was not significant for height (p= 0.108).

Conclusion  Overall, there were predominantly significant differences in the measurements generated by CT and DVT. The difference is most likely explained by the fact that DVT imaging is more susceptible to motion artefacts. Therefore, the preoperative CT diagnosis is more reliable than the DVT for the OTOPLAN software-supported evaluation of the cochlear parameters.

Publication History

Article published online:
12 May 2023