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

Abstract

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 AE 0.365, 6.6 1 AE 0 .35 9, an d 2.9 1 AE 0.312 mm) and cMPR (9.32 AE 0.314, 6.59 AE 0.342, and 2.93 AE 0.250 mm). The average cochlear duct length calculated by Otoplan was 34.37 AE 1.481 mm, which was not significantly different from that calculated by cMPR (34.55 AE 1.903mm, p ¼ 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 AE 0.69 min, significantly shorter than that by cMPR (9.3 AE 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.

Intra- and Interrater Reliability of CT- versus MRI-Based Cochlear Duct Length Measurement in Pediatric Cochlear Implant Candidates and Its Impact on Personalized Electrode Array Selection

“…Müller-Graff et al found a mean CDL of the organ of Corti (CDL OC ) of 34.55 mm ± 1.6 mm using the same Otoplan version 2.0 with multi-slice CT data of 20 subjects aged 64 ± 14.9 years [49]. Chen et al found a mean CDL of 34.37 ± 1.481 in 68 cochleae of 34 subjects with a mean age of 16.6 years (range: 0.6-63.6) without any statistical differences in age or side of the ear [32].…”

“…In addition to the impact of different radiological diagnostic procedures, the fact that interindividual rater-related differences might also influence the selection of the optimal electrode array must also be taken into account when assessing the reliability of radiological measurement of the CDL. In previous studies, comparative evaluations of CDL measurements using Otoplan were mostly performed by two raters based on CT scans [32,36,37,55,56] and in one case based on an MRI scan [53].…”

“…Currently, preoperative CDL measurement is usually performed radiologically by using high-resolution computed tomography (HR-CT) data of the temporal bone. For this, different options are available [28]: direct measurements of the CDL by projecting the cochlear duct onto a 2D plane [29] and using contouring techniques [30]; 3D reconstructions of the cochlea [26]; measurement of spiral coefficients with cochlear parameters calculating the CDL [31,32]. However, correct CDL measurement is not feasible in candidates with any type of cochlear dysplasia.…”

“…Chen et al used Otoplan version 2.0 and found no significant difference in the CDL, the diameters A and B, or the height H between both methods, whereas time of measurement significantly decreased to 5.9 ± 0.69 min by using the Otoplan system compared to 9.3 ± 0.72 min by using the curved multiplanar reconstruction method. In addition, the intraindividual reliability of repetitive measurements using the same evaluation method was better with Otoplan than with the curved multiplanar reconstruction method [32]. Breitsprecher et al compared Otoplan version 3.0 to a specifically designed preclinical 3D reconstruction software and to the established A-value method.…”

Validation of Automatic Cochlear Measurements Using OTOPLAN® Software

“…OTOPLAN ® (CASCINATION AG, Bern, Switzerland, in corporation with MED-EL, Innsbruck, Austria) is the surgical planning software for otological procedures. The software has dedicated manual, semi-automatic, and automatic planning tools for application in general otology [ 29 ] and pre-operative surgical planning and reconstruction [ 30 , 31 , 32 , 33 , 34 , 35 ], as well as in post-operative image analysis [ 23 , 36 ] in hearing implant patients. For cochlear measurements specifically, the software requires a user to manually define the cochlear view and measure the cochlea’s diameter, width, and height, resulting in automatically calculated Cochlear Duct Length (CDL OC ) at the level of the Organ of Corti/Basilar membrane.…”