Dependence of cochlear duct length measurement on the resolution of the imaging dataset

Introduction A precise information about the cochlear duct length (CDL) allows an individual selection and implantation of the CI-electrodes. It was shown in prior studies, that the measurement of the CDL in a flat-panel-Volume-Computed-Tomography (fpVCT) scan with secondary reconstruction (slice thickness 100µm) was not significantly different compared to experimental Micro-CT (slice thickness 18µm) scans. However, there was a significant difference in comparing it to a standard fpVCT imaging with a slice thickness of 450µm. Aim of the study was to evaluate the dependence of measurement of the CDL on the slice thickness of the imaging dataset.

Methods In this study fpVCT-scans of 10 human petrous bone specimens and measurement of the CDL with 3D-curved multiplanar reconstruction were performed. Secondary reconstruction were used in descending thickness from 450µm down to 100µm. A further aim of the study was to examine inter- and intraobserver variability.

Results In the measurement of the CDL by 3D-curved multiplanar reconstruction in fpVCT scans significant differences were found by using variant slice thickness. The smaller the slice thickness was chosen the longer the mean CDL was measured. In addition, an inter-observer variability when doing CDL measurement was seen while there was no evidence for large intra-observer variability.

Conclusion In the measurement of the CDL with 3D-curved multiplanar reconstruction preoperatively, a fpVCT with small slice thickness turned out to be most accurate measuring method despite of inter-observer variability. Further studies will show, how measurement of the CDL can be performed when using data sets of high-resolution CT scans of real patients with regard to higher susceptibility.

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Artikel online veröffentlicht:
13. Mai 2021