Cochlear Duct Length Calculation: Comparison Between Using Otoplan and Curved Multiplanar Reconstruction in Nonmalformed Cochlea.

OBJECTIVE

To describe a new method to measure the cochlear parameters using Otoplan software, and to compare it with the traditional method using curved multiplanar reconstruction (cMPR).

STUDY DESIGN

Retrospective analysis using internal consistency reliability and paired sample t test.

SETTING

Tertiary referral center.

PATIENTS

Thirty-four patients including 68 ears from a clinical trial were retrospectively reviewed.

MAIN OUTCOME MEASURES

The length, width, height (distances A, B, H), and cochlear duct length of each cochlea were measured independently using two modalities: Otoplan and cMPR. Internal consistency reliability of the two modalities was analyzed. The time spent on each measurement was also recorded.

RESULTS

Otoplan software was compatible with all radiological data in this series. Distances A, B, and H showed no significant differences between Otoplan (9.33 ± 0.365, 6.61 ± 0.359, and 2.91 ± 0.312 mm) and cMPR (9.32 ± 0.314, 6.59 ± 0.342, and 2.93 ± 0.250 mm). The average cochlear duct length calculated by Otoplan was 34.37 ± 1.481 mm, which was not significantly different from that calculated by cMPR (34.55 ± 1.903mm, p = 0.215). The measurements with Otoplan had better internal consistency reliability compared with those by cMPR, and measurements with a higher peak kilovoltage (140 kVp) CT scan showed further higher internal consistency reliability. Time spent on each cochlea by Otoplan was 5.9 ± 0.69 min, significantly shorter than that by cMPR (9.3 ± 0.72 min).

CONCLUSION

Otoplan provides more rapid and reliable measurement of the cochlea than cMPR. Furthermore, it can be easily used in the laptop computer.