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Biomedical Imaging and Instrumentation

Biomedical Imaging and Instrumentation - Poster Session A

Poster F2 - 3D Printed Temporal Bone Model for Patient Education before Cochlear Implant Surgery

Thursday, October 24, 2024
10:00 AM – 11:00 AM EST
Location: Exhibit Hall E, F & G

Introduction:  Patient education is a continued challenge in the healthcare system. Proper education not only benefits the patient-physician relationship but also provides patients with better information before making decisions about their health. A shortage in materials, language barriers, and a lack of time dedicated to patient education during healthcare visits are all reasons that can be attributed to poor patient education in their conditions or procedures. The use of 3D models of patient anatomy has improved patient education in pre-surgical cases, improving knowledge of risks involved and overall surgical procedure.
Cochlear implantation is a complex procedure involving drilling into the temporal bone and forming a passageway for an electrode lead wire to be inserted through the bone into the cochlea in the inner ear. The procedure and risks involved, such as sensory issues due to facial nerve damage, can be difficult to comprehend for patients outside of the field of otology or for children, who make up a large population of cochlear implantation patients. In this study, a 3D model of the temporal bone, along with other desired anatomical features, was created to demonstrate the path of the electrode lead in cochlear implantation surgery using the round window approach to the cochlea. Polyjet printing technology was the selected method for 3D printing due to its ability for multi-color printing and high-resolution capability. This model can be used in preoperative settings, providing improved education for patients undergoing the procedure.

Materials and

Methods:  The model was created using 3D segmentation of publicly available, anonymized computed tomography (CT) scans of the human head in the open-source software ITK-Snap. The cochlea and semicircular canals were segmented using automatic and manual segmentation methods. The facial nerve and temporal bone were segmented manually, and the porous regions of the mastoid were left hollowed for easier visualization of the desired organs. The ossicle bones were also segmented and left intact, along with the pathway of the electrode lead wire through the facial recess of the middle ear, reflected by a hole. The segmented 3D model was exported to MeshMixer, another open-source software, for model processing. The model was color-coded so bony features are colored white, the facial nerve in magenta, and the cochlear labyrinth in yellow. Two models were then printed, one at actual anatomical size and another at 3x size, using polyjet printing (Stratasys J5 Medijet) with resin material. Post-processing of the physical model was performed by power washing the model using water to remove the support material from the anatomical model. The procedure for creating the models is shown in Figure 1.
The models were validated via measurements of the facial nerve diameter, aditus ad antrum, bone height, and mastoid tegmen length taken from the raw CT imaging data, the computational model, and the physical model. The electrode pathway was validated using imaging data of patients with the device presently implanted, following the same pathway shown in publicly available data.

Results, Conclusions, and Discussions: The composite model created contains the outer portions of the temporal bone, ossicle bones, cochlea, facial nerve, vestibulocochlear nerve, and semicircular canals. During post-processing of the physical model, the inferior portion of the facial nerve’s mastoid segment was damaged during support material removal, and thus was not included in the final model. This loss is not significant for understanding of the procedure and was lost due to the small diameter of the feature. With this exception, all other desired anatomical markers were included in the final model without any noticeable loss of size or anatomical features. All measurements between the imaging data, computational model, and physical model were within 1mm difference. The hole through the facial recess of the middle ear demonstrates the path of the cochlear implant electrode leading through the temporal bone and towards the round window, where the electrode is inserted into the cochlea. The completed model and hole for the electrode pathway are shown in Figure 2. A wire can demonstrate the lead for patients to view. This method for creating composite models to demonstrate surgery for patient education is cost-effective and reproducible. All software used for the generation of the model is open-source. This method of 3D modeling for patient education can be applied to other surgical procedures of the temporal bone, as well as procedures for other parts of the body. Additionally, the computational models created via this method can be used for finite element analysis in other software. Given previous successes with 3D modeling in patient education, this patient-specific model for cochlear implantation via the round window approach is a possible option to improve preoperative patient education in cochlear implant surgery, helping patients feel more comfortable with the procedure and make better-informed decisions regarding their health. The future direction for this project includes quantifying the improvement in public understanding of the cochlear implant procedure achieved through preoperative explanation alone, compared to preoperative explanation combined with the use of the custom patient education model.

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