Augmented Reality Visualization for Image-Guided Surgery: A Validation Study Using a Three-Dimensional Printed Phantom.

BACKGROUND: Oral and maxillofacial surgery currently relies on virtual surgery planning based on image data (CT, MRI). Three-dimensional (3D) visualizations are typically used to plan and predict the outcome of complex surgical procedures. To translate the virtual surgical plan to the operating room, it is either converted into physical 3D-printed guides or directly translated using real-time navigation systems. PURPOSE: This study aims to improve the translation of the virtual surgery plan to a surgical procedure, such as oncologic or trauma surgery, in terms of accuracy and speed. Here we report an augmented reality visualization technique for image-guided surgery. It describes how surgeons can visualize and interact with the virtual surgery plan and navigation data while in the operating room. The user friendliness and usability is objectified by a formal user study that compared our augmented reality assisted technique to the gold standard setup of a perioperative navigation system (Brainlab). Moreover, accuracy of typical navigation tasks as reaching landmarks and following trajectories is compared. RESULTS: Overall completion time of navigation tasks was 1.71 times faster using augmented reality (P = .034). Accuracy improved significantly using augmented reality (P < .001), for reaching physical landmarks a less strong correlation was found (P = .087). Although the participants were relatively unfamiliar with VR/AR (rated 2.25/5) and gesture-based interaction (rated 2/5), they reported that navigation tasks become easier to perform using augmented reality (difficulty Brainlab rated 3.25/5, HoloLens 2.4/5). CONCLUSION: The proposed workflow can be used in a wide range of image-guided surgery procedures as an addition to existing verified image guidance systems. Results of this user study imply that our technique enables typical navigation tasks to be performed faster and more accurately compared to the current gold standard. In addition, qualitative feedback on our augmented reality assisted technique was more positive compared to the standard setup.?>.

Immediate implant-retained prosthetic obturation after maxillectomy based on zygomatic implant placement by 3D-guided surgery: a cadaver study.

BACKGROUND: The aim of this study was to introduce a complete 3D workflow for immediate implant retained prosthetic rehabilitation following maxillectomy in cancer surgery. The workflow consists of a 3D virtual surgical planning for tumor resection, zygomatic implant placement, and for an implant-retained prosthetic-obturator to fit the planned outcome situation for immediate loading. MATERIALS AND METHODS: In this study, 3D virtual surgical planning and resection of the maxilla, followed by guided placement of 10 zygomatic implants, using custom cutting and drill/placement-guides, was performed on 5 fresh frozen human cadavers. A preoperatively digitally designed and printed obturator prosthesis was placed and connected to the zygomatic implants. The accuracy of the implant positioning was obtained using 3D deviation analysis by merging the pre- and post-operative CT scan datasets. RESULTS: The preoperatively designed and manufactured obturator prostheses matched accurately the per-operative implant positions. All five obturators could be placed and fixated for immediate loading. The mean prosthetic point deviation on the cadavers was 1.03 ± 0.85 mm; the mean entry point deviation was 1.20 ± 0.62 mm; and the 3D angle deviation was 2.97 ± 1.44°. CONCLUSIONS: It is possible to 3D plan and accurately execute the ablative surgery, placement of zygomatic implants, and immediate placement of an implant-retained obturator prosthesis with 3D virtual surgical planning.The next step is to apply the workflow in the operating room in patients planned for maxillectomy.

Patient-specific pre-contouring of osteosynthesis plates for mandibular reconstruction: Using a three-dimensional key printed solution.

PURPOSE: In mandibular reconstructive surgery, the osteosynthesis plates require contouring according to the patients' individual anatomical situation. These plates are frequently contoured around a three-dimensional (3D) printed model. However, the translation to the actual patient can introduce inaccuracies and unwanted rotations in the condyles and mandibular ramus, due to malpositioning of the pre-contoured plate. MATERIALS AND METHODS: This article describes an easy-access method for exact translation of the pre-contoured plate to the patient's mandible. This is done by using 3D printed guides that allow pre-drilling of screw holes in both the contour model and the patients' mandible. The accuracy of the Key Printed Solution was analysed by comparing the anatomical landmarks on both the 3D planned and post-operative models. RESULTS: The method was applied to 4 cases. All landmarks were identified on both the 3D planning and post-operative computed tomographic data. This showed an average deviation of 1.0 mm between planning and the post-operative result. The inter-observer variation was 0.6 mm (intra-class correlation, 0.75). CONCLUSION: This article presents an easy-to-use method for pre-bending the osteosynthesis plate and subsequent accurate translation of the intended contour with corresponding screw hole locations. The method was proved to be accurate and time-efficient.

Accuracy and reproducibility of a newly developed tool for volume measurements of the arm using 3D stereophotogrammetry.

BACKGROUND: Lymph edema of the arm is a common complication after breast cancer treatment. To evaluate lymph edema volume and treatment outcome, an easy to use, objective quantification method of arm volume is necessary. Most often, water displacement is used to measure arm volume, as it is an easy and robust method that can be performed at any place with a simple equipment. However, when using water displacement, no exact localization of volume difference can be seen. To accurately measure hand and forearm volumes separately, an in-house-developed device was constructed for an accurate landmark placement. METHOD: An in-house developed measurement tool was used for placing artificial landmarks proximal to the wrist crease on ten healthy subjects. Three-dimensional (3D) images of the hand and forearm were acquired, and volume measurements of the hand and forearm were performed. Measurements were repeated to investigate the intra- and inter-rater variability caused by the landmark placement. RESULTS: Measuring volume of the hand and forearm while using artificially placed landmarks turned out to be a highly reproducible, quick, and easy procedure. Both intra- and inter-rater variability showed high reproducibility for hand (ICC = 0.96 and 0.98, respectively) and forearm (ICC = 0.99 and 0.99, respectively) volumes. CONCLUSION: Measuring volumes of the hand and forearm while using artificially placed landmarks was found to be a highly reproducible, quick, and easy procedure. The device enables to analyze the localization of lymph edema in greater details.