CT imaging-based approaches to cochlear duct length estimation—a human temporal bone study

Abstract Objectives Knowledge about cochlear duct length (CDL) may assist electrode choice in cochlear implantation (CI). However, no gold standard for clinical applicable estimation of CDL exists. The aim of this study is (1) to determine the most reliable radiological imaging method and imaging processing software for measuring CDL from clinical routine imaging and (2) to accurately predict the insertion depth of the CI electrode. Methods Twenty human temporal bones were examined using different sectional imaging techniques (high-resolution computed tomography [HRCT] and cone beam computed tomography [CBCT]). CDL was measured using three methods: length estimation using (1) a dedicated preclinical 3D reconstruction software, (2) the established A-value method, and (3) a clinically approved otosurgical planning software. Temporal bones were implanted with a 31.5-mm CI electrode and measurements were compared to a reference based on the CI electrode insertion angle measured by radiographs in Stenvers projection (CDLreference). Results A mean cochlear coverage of 74% (SD 7.4%) was found. The CDLreference showed significant differences to each other method (p < 0.001). The strongest correlation to the CDLreference was found for the otosurgical planning software-based method obtained from HRCT (CDLSW-HRCT; r = 0.87, p < 0.001) and from CBCT (CDLSW-CBCT; r = 0.76, p < 0.001). Overall, CDL was underestimated by each applied method. The inter-rater reliability was fair for the CDL estimation based on 3D reconstruction from CBCT (CDL3D-CBCT; intra-class correlation coefficient [ICC] = 0.43), good for CDL estimation based on 3D reconstruction from HRCT (CDL3D-HRCT; ICC = 0.71), poor for CDL estimation based on the A-value method from HRCT (CDLA-HRCT; ICC = 0.29), and excellent for CDL estimation based on the A-value method from CBCT (CDLA-CBCT; ICC = 0.87) as well as for the CDLSW-HRCT (ICC = 0.94), CDLSW-CBCT (ICC = 0.94) and CDLreference (ICC = 0.87). Conclusions All approaches would have led to an electrode choice of rather too short electrodes. Concerning treatment decisions based on CDL measurements, the otosurgical planning software-based method has to be recommended. The best inter-rater reliability was found for CDLA-CBCT, for CDLSW-HRCT, for CDLSW-CBCT, and for CDLreference. Key Points • Clinically applicable calculations using high-resolution CT and cone beam CT underestimate the cochlear size. • Ten percent of cochlear duct length need to be added to current calculations in order to predict the postoperative CI electrode position. • The clinically approved otosurgical planning software-based method software is the most suitable to estimate the cochlear duct length and shows an excellent inter-rater reliability.

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Cone beam CT for perioperative imaging in hearing preservation Cochlear implantation – a human cadaveric study

Journal of Otolaryngology - Head and Neck Surgery ◽

10.1186/s40463-019-0388-x ◽

2019 ◽

Vol 48 (1) ◽

Cited By ~ 2

Author(s):

Kayvan Nateghifard ◽

David Low ◽

Lola Awofala ◽

Dilakshan Srikanthan ◽

Jafri Kuthubutheen ◽

...

Keyword(s):

Radiation Dose ◽

Cochlear Implantation ◽

Lateral Wall ◽

Cone Beam ◽

Insertion Depth ◽

Cochlear Duct ◽

Low Radiation Dose ◽

A Value ◽

Cochlear Duct Length ◽

Temporal Bones

Abstract Background Knowledge of the cochlear implant array’s precise position is important because of the correlation between electrode position and speech understanding. Several groups have provided recent image processing evidence to determine scalar translocation, angular insertion depth, and cochlear duct length (CDL); all of which are being used for patient-specific programming. Cone beam computed tomography (CBCT) is increasingly used in otology due to its superior resolution and low radiation dose. Our objectives are as followed: Validate CBCT by measuring cochlear metrics, including basal turn diameter (A-value) and lateral wall cochlear duct length at different angular intervals and comparing it against microcomputed CT (uCT).Explore the relationship between measured lateral wall cochlear duct length at different angular intervals and insertion depth among 3 different length electrodes using CBCT. Methods The study was performed using fixed human cadaveric temporal bones in a tertiary academic centre. Ten temporal bones were subjected to the standard facial recess approach for cochlear implantation and imaged by CBCT followed by uCT. Measurements were performed on a three-dimensional reconstructed model of the cochlea. Sequential insertion of 3 electrodes (Med-El Flex24, 28 and Soft) was then performed in 5 bones and reimaged by CBCT. Statistical analysis was performed using Pearson’s correlation. Results There was good agreement between CBCT and uCT for cochlear metrics, validating the precision of CBCT against the current gold standard uCT in imaging. The A-value recorded by both modalities showed a high degree of linear correlation and did not differ by more than 0.23 mm in absolute values. For the measurement of lateral wall CDL at various points along the cochlea, there was a good correlation between both modalities at 360 deg and 720 deg (r = 0.85, p < 0.01 and r = 0.79, p < 0.01). The Flex24 electrode displayed consistent insertion depth across different bones. Conclusions CBCT reliably performs cochlear metrics and measures electrode insertion depth. The low radiation dose, fast acquisition time, diminished metallic artifacts and portability of CBCT make it a valid option for imaging in cochlear implant surgery.

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An automated A-value measurement tool for accurate cochlear duct length estimation

Journal of Otolaryngology - Head and Neck Surgery ◽

10.1186/s40463-018-0253-3 ◽

2018 ◽

Vol 47 (1) ◽

Cited By ~ 10

Author(s):

John E. Iyaniwura ◽

Mai Elfarnawany ◽

Hanif M. Ladak ◽

Sumit K. Agrawal

Keyword(s):

Measurement Tool ◽

Cochlear Duct ◽

Length Estimation ◽

A Value ◽

Cochlear Duct Length ◽

Value Measurement

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Determination of Cochlear Duct Length With 3D Versus Two-dimensional Methods: A Retrospective Clinical Study of Imaging by Computed Tomography and Cone Beam Computed Tomography

In Vivo ◽

10.21873/invivo.12631 ◽

2021 ◽

Vol 35 (6) ◽

pp. 3339-3344

Author(s):

STEPHAN WALDECK ◽

CHRISTIAN VON FALCK ◽

RENE CHAPOT ◽

MARC BROCKMANN ◽

DANIEL OVERHOFF

Keyword(s):

Computed Tomography ◽

Clinical Study ◽

Cone Beam Computed Tomography ◽

Cone Beam ◽

Two Dimensional ◽

Cochlear Duct ◽

Retrospective Clinical Study ◽

Cochlear Duct Length

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3D reconstruction algorithm for cone-beam differential phase contrast computed tomography

2008 IEEE Nuclear Science Symposium Conference Record ◽

10.1109/nssmic.2008.4774206 ◽

2008 ◽

Cited By ~ 2

Author(s):

Li Zhang ◽

Qiaoguang Fang ◽

Zhifeng Huang

Keyword(s):

Computed Tomography ◽

3D Reconstruction ◽

Phase Contrast ◽

Reconstruction Algorithm ◽

Cone Beam ◽

Differential Phase ◽

Differential Phase Contrast

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Assessment of Inter- and Intra-Rater Reliability of Tablet-Based Software to Measure Cochlear Duct Length

Otology & Neurotology ◽

10.1097/mao.0000000000003015 ◽

2021 ◽

Vol Publish Ahead of Print ◽

Author(s):

Shayna P. Cooperman ◽

Ksenia A. Aaron ◽

Ayman Fouad ◽

Emma Tran ◽

Nikolas H. Blevins ◽

...

Keyword(s):

Rater Reliability ◽

Cochlear Duct ◽

Cochlear Duct Length

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A study on modelling cochlear duct mid-scalar length based on high-resolution computed tomography, and its effect on peri-modiolar and mid-scalar implant selection

The Journal of Laryngology & Otology ◽

10.1017/s0022215119001671 ◽

2019 ◽

Vol 133 (09) ◽

pp. 764-769

Author(s):

G Pamuk ◽

A E Pamuk ◽

A Akgöz ◽

E Öztürk ◽

M D Bajin ◽

...

Keyword(s):

Computed Tomography ◽

High Resolution ◽

Round Window ◽

Chronic Otitis Media ◽

Lateral Wall ◽

High Resolution Computed Tomography ◽

Cochlear Duct ◽

Implant Selection ◽

Cochlear Duct Length ◽

Implant Length

AbstractObjectiveTo determine cochlear duct mid-scalar length in normal cochleae and its role in selecting the correct peri-modiolar and mid-scalar implant length.MethodsThe study included 40 patients with chronic otitis media who underwent high-resolution computed tomography of the temporal bone. The length and height of the basal turn, mid-modiolar height of the cochlea, mid-scalar and lateral wall length of the cochlear duct, and the ‘X’ line (the largest distance from mid-point of the round window to the mid-scalar point of the cochlear canal) were measured.ResultsCochlear duct lateral wall length (28.88 mm) was higher than cochlear duct mid-scalar length (20.08 mm) (p < 0.001). The simple linear regression equation for estimating complete cochlear duct length was: cochlear duct length = 0.2 + 2.85 × X line.ConclusionUsing the mid-scalar point as the reference point (rather than the lateral wall) for measuring cochlear duct mid-scalar length, when deciding on the length of mid-scalar or peri-modiolar electrode, increases measurement accuracy. Mean cochlear duct mid-scalar length was compatible with peri-modiolar and mid-scalar implant lengths. The measurement method described herein may be useful for pre-operative peri-modiolar or mid-scalar implant selection.

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Cone Beam Computed Tomography 3D Reconstruction of the Mandibular Condyle

The Angle Orthodontist ◽

10.2319/072007-339.1 ◽

2008 ◽

Vol 78 (5) ◽

pp. 880-888 ◽

Cited By ~ 37

Author(s):

Brian Schlueter ◽

Ki Beom Kim ◽

Donald Oliver ◽

Gus Sortiropoulos

Keyword(s):

Computed Tomography ◽

Soft Tissue ◽

3D Reconstruction ◽

Cone Beam Computed Tomography ◽

Three Dimensional ◽

Mandibular Condyle ◽

Cone Beam ◽

Low Density ◽

Mineral Density ◽

Linear Measurements

Abstract Objective: To determine the ideal window level and width needed for cone beam computed three-dimensional (3D) reconstruction of the condyle. Materials and Methods: Linear dimensions were measured with a digital caliper to assess the anatomic truth for 50 dry human mandibular condyles. Condyles were scanned with the i-CAT cone beam computed tomography (CBCT) and 3D-models were reconstructed. Three linear three-dimensional measurements were made on each of the 50 condyles at 8 different Hounsfield unit (HU) windows. These measurements were compared with the anatomic truth. Volumetric measurements were also completed on all 50 condyles, at 23 different window levels, to define the volumetric distribution of bone mineral density (BMD) within the condyle. Results: Significant differences were found in two of the three linear measurement groups at and below the recommended viewing window for osseous structures. The most accurate measurements were made within the soft tissue range for HU window levels. Volumetric distribution measurements revealed that the condyles were mostly comprised of low-density bone, and that condyles exhibiting significant changes in linear measurements were shown to have higher percentages of low-density bone than those condyles with little change from the anatomic truth. Conclusions: CBCT assessment of the mandibular condyle, using the 3D reconstruction, is most accurate when accomplished at density levels below that recommended for osseous examination. However, utilizing lower window levels which extend into the soft tissue range, may compromise one's capacity to view the bony topography.

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Impacts of Thresholds of Gray Value for Cone-Beam Computed Tomography 3D Reconstruction on the Accuracy of Image Matching with Optical Scan

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph17176375 ◽

2020 ◽

Vol 17 (17) ◽

pp. 6375 ◽

Cited By ~ 2

Author(s):

Se-Won Park ◽

Ra Gyoung Yoon ◽

Hyunwoo Lee ◽

Heon-Jin Lee ◽

Yong-Do Choi ◽

...

Keyword(s):

Computed Tomography ◽

Image Registration ◽

3D Reconstruction ◽

Cone Beam Computed Tomography ◽

Cone Beam ◽

Dental Arch ◽

Arch Model ◽

3D Mesh ◽

Optical Scan ◽

Reconstruction Model

In cone-beam computed tomography (CBCT), the minimum threshold of the gray value of segmentation is set to convert the CBCT images to the 3D mesh reconstruction model. This study aimed to assess the accuracy of image registration of optical scans to 3D CBCT reconstructions created by different thresholds of grey values of segmentation in partial edentulous jaw conditions. CBCT of a dentate jaw was reconstructed to 3D mesh models using three different thresholds of gray value (−500, 500, and 1500), and three partially edentulous models with different numbers of remaining teeth (4, 8, and 12) were made from each 3D reconstruction model. To merge CBCT and optical scan data, optical scan images were registered to respective 3D reconstruction CBCT images using a point-based best-fit algorithm. The accuracy of image registration was assessed by measuring the positional deviation between the matched 3D images. The Kruskal–Wallis test and a post hoc Mann–Whitney U test with Bonferroni correction were used to compare the results between groups (α = 0.05). The correlations between the experimental factors were calculated using the two-way analysis of variance test. The positional deviations were lowest with the threshold of 500, followed by the threshold of 1500, and then −500. A significant interaction was found between the threshold of gray values and the number of remaining teeth on the registration accuracy. The most significant deviation was observed in the arch model with four teeth reconstructed with a gray-value threshold of −500. The threshold for the gray value of CBCT segmentation affects the accuracy of image registration of optical scans to the 3D reconstruction model of CBCT. The appropriate gray value that can visualize the anatomical structure should be set, especially when few teeth remain in the dental arch.

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