Mixed Reality Assisted Radical Endoscopic Thyroidectomy

Our initial clinical study investigates the integration of mixed reality technology into endoscopic thyroidectomy, with the objective of establishing its practicality and efficacy. Mixed reality technology has been used for clinical training, preoperative evaluation, and interoperative navigation in various surgical procedures. However, there have been no similar reports of thyroidectomy.

Whether performed manually or automatically, registration between virtual and real anatomical structures is prone to inevitable discrepancies. Moreover, the complex environment and the intense lightening in the operating room can significantly affect the clarity and the visibility of holographic image. Compared to other technologies, mixed reality can achieve zero time visualization of visual 3D holographic models in real operating rooms with better presentation effects, stronger compatibility, lower cost, and operational difficulty.

To begin, on a computer, import the DICOM data from neck enhanced CT scans into 3D Slicer. Adjust the display settings to utilize a window width of 350 Hounsfield units, or HU, and a window level of 40 HU.Using the threshold and hollow functions, segment and reconstruct the skin. First, create a segmentation for CT values greater than minus 250 HU using the threshold function, then utilize the hollow function to remove the interior of the segmentation.

Next, segment and reconstruct the thyroid, lesion, trachea, and esophagus using the grow from seeds function based on either arterial or venous phase images. Manually delineate seeds within the target structures across cross-sectional, sagittal, and coronal images. Automatically generate the segmentation using the grow from seeds function.

Now, using the threshold function, segment and reconstruct the bone based on plane scanning images. Create a segmentation for CT values exceeding 200 HU.Segment and reconstruct the arteries using the local threshold function based on arterial phase images. Manually delineate seeds within the arteries in coronal images, then, create a segmentation consistent with the CT value range of the seeds using the local threshold function.

Repeat the procedure to gradually expand the segmentation. Segment and reconstruct veins using the local threshold function based on venous phase images. To begin on a computer, export the semi-automatically reconstructed neck 3D model from 3D Slicer as an OBJ file.

Create a new project in Unity 3D utilizing the Mixed Reality Toolkit and configure the necessary components. Add a control border using the box collider component. Implement a movable cursor using the cursor context object manipulator component.

Then, add movement, scaling, and rotation functions through the Object Manipulator, NearInteractionGrabbable, and MinMaxScaleConstraint components. Enable transparency control using the slider transparency controller component. Import the OBJ file into the Unity 3D project and associate the configured components, including the box collider, object manipulator, and transparency controller with the neck 3D model.

Debug the neck virtual hologram on the mixed reality or MR head-mounted device, or HMD, using the holographic remoting program. Package and export the project from Unity 3D. Wear the MRHMD before surgery.

Use the MRHMD to manipulate the neck virtual holograms. Using grab gesture, control the movement, scaling, and rotation of the neck virtual hologram, then, drag the corresponding virtual slider to adjust the transparency of the neck virtual hologram. Align the neck virtual hologram with the patient's position, ensuring proper alignment of anatomical markers, such as the mandible and clavicle.

Import clinical data, including neck CT images, ultrasonography, and laboratory examination results. into the MRHMD to allow access during surgery. Share the first person perspective through the MRHMD via a Wi-Fi connection.

Position the anesthetized patient in a split leg configuration and tilt their head back to extend their neck. Position the endoscope system at the front of the patient's head. After establishing an operating space, under 30 degree laparoscopic visualization, dissect the subcutaneous cavities on both sides of areolas with trocar needles.

Separate the cervical white line to free the thyroid gland. Suspend the ribbon muscles with sutures to extend the field of view. Inject carbon nanoparticles into the thyroid gland to stain both the thyroid and the cervical lymph nodes.

Next, disconnect the isthmus of the thyroid and excise the pyramidal lobe and prelaryngeal lymph nodes to expose the trachea and detach the ligaments of the thyroid. Identify the recurrent laryngeal nerve using the intraoperative neuromonitoring probe. Using the ultrasonic knife, coagulate the inferior thyroid artery and vein, inferior thyroid artery, and middle thyroid vein.

Identify and retain the left parathyroid gland. Secure and dissect the superior thyroid vessels with absorbable clamps. Carefully separate and excise the lesional thyroid gland.

Next, perform homolateral lymph adenectomy in the cervical central region, ensuring complete retrieval using a specimen bag. If necessary, perform contralateral thyroidectomy and lymph adenectomy in the same way. Use another specimen bag to remove the gland.

After ensuring all bleeding is thoroughly controlled, rinse the surgical field with sterile distilled water. Suture the incision layer by layer.