Turning the Operating Room into a Mixed-Reality Environment: A Prospective Clinical Investigation for Cerebral Aneurysm Clipping
Transforming the Operating Room into a Mixed Reality Environment: A Prospective Clinical Study on Aneurysm Clipping
The surgical treatment of cerebral aneurysms is a highly complex and delicate process in neurosurgery. Researchers continue to explore new technologies and methods to improve surgical outcomes. In recent years, the development of Mixed Reality (MR) technology has brought new breakthroughs to the Operating Room (OR). Particularly with the use of Head-Mounted Displays (HMDs), surgeons can overlay virtual three-dimensional (3D) images onto the patient’s actual anatomical structures, thereby enhancing spatial orientation and intuitive operation.
Research Background and Objectives
This study aimed to evaluate the potential application of a novel Mixed Reality Head-Mounted Display (MR-HMD) in aneurysm clipping procedures, specifically in assisting surgeons with spatial orientation. Traditional surgical navigation systems typically rely on two-dimensional (2D) displays, requiring surgeons to mentally translate their hand movements from a 3D real environment. However, MR technology, by providing an immersive, holographic patient-specific anatomical model, can help surgeons better understand complex anatomical relationships and spatial layouts. Therefore, this study explored the advantages of mixed reality technology by comparing MR-HMD navigation with standard monitor navigation.
Paper Source
This research was co-authored by Matthias Gmeiner and others from the Department of Medicine at Kepler University Hospital and Johannes Kepler University, as well as Cortexplore GmbH. The article was published in the Journal of Neurosurgery, with an online publication date of June 7, 2024.
Research Methods
Experimental Setup and Workflow
This study was the first to apply a novel multi-camera navigation technology in the operating room environment, contrasting MR-HMD navigation and standard monitor navigation. The study subjects were 14 patients with unruptured middle cerebral artery aneurysms. In this process, the research team designed five different visual navigation conditions to evaluate the intuitiveness and effectiveness of surgical tools.
Surgical Planning: Using multimodal imaging data (such as CT, MRI, and Digital Subtraction Angiography, DSA) for surgical planning. The Cortexplore Med software was used to read, format, and merge the patient’s imaging data, generating a 3D digital model containing vessels, brain, skull, and skin layers.
Intraoperative Neuronavigation: Ten infrared cameras were installed in the operating room to monitor the surgical scene. These cameras emit and capture infrared light, determining the position and orientation of tools by tracking spherical reflective markers attached to them. Through this technology, surgeons can visualize and update the tool’s position relative to the patient’s anatomical model in real-time.
Clinical Survey: The clinical survey included 14 patients, 10 females and 4 males, with an average age of 51.3 years (standard deviation of 9.1 years), and middle cerebral artery aneurysm sizes ranging from 3 to 11 millimeters. The study was conducted under the approval of the Ethics Committee of Johannes Kepler University and the national competent authority.
Five Visual Navigation Conditions
The five visual navigation conditions were: 1. No Visual Assistance Navigation: Surgeons did not use any visual assistance tools (displays or MR-HMD), relying solely on their anatomical and spatial orientation skills to align the pointer. 2. Mixed Reality Navigation with Virtual Anatomical Structures: Using the MR-HMD to overlay virtual models of the brain, vessels, and aneurysm anatomy onto the patient, but without displaying a predefined surgical trajectory. 3. Mixed Reality Navigation with Virtual Anatomical Structures and Plan: Same as condition 2, but displaying a predefined surgical trajectory. 4. Monitor Navigation: Surgeons aligned the pointer on a 2D navigation computer, displaying a 3D digital replica of the anatomical model and the predefined surgical trajectory. 5. Multi-Planar Monitor Navigation: Same as condition 4, but displaying the anatomical layers and predefined surgical trajectory from three different angles: axial, sagittal, and coronal views.
Experimental Results
Preclinical and Intraoperative Tracking Accuracy
Two tests were conducted in the laboratory to evaluate the system’s accuracy: using a metal rod and a tumor model. In the metal rod measurement, the system’s error was 67±46 micrometers, demonstrating the feasibility of the multi-camera tracking technology before entering the clinical survey. Furthermore, intraoperatively, the Root Mean Square (RMS) registration accuracy across all patients and surgical segments was 0.72±0.19 millimeters, showing sub-millimeter biological accuracy.
Comparison of Different Navigation Strategies
Aneurysm localization with visual assistance tools (MR-HMD or monitors) was more accurate and reliable (errors ranging from 2.3 to 2.6 millimeters), significantly different from the no visual assistance condition (error of 10.5 millimeters). Specifically, when using the predefined surgical trajectory (conditions 3-5), significantly smaller angular deviations were formed, consistent with the surgical plan.
Efficiency and Intuitiveness of Mixed Reality Navigation
Mixed reality navigation in conditions 2 and 3 was notably faster than monitor navigation (conditions 4 and 5). The average navigation time for mixed reality visuals (19.2 seconds) was more than half that of monitor navigation, with no significant difference in accuracy.
Research Conclusions
The introduction of mixed reality technology marks a significant advancement in the field of neurosurgery. The application of MR-HMDs enables more intuitive and accurate intraoperative spatial orientation, potentially optimizing the execution of complex surgeries.
This study demonstrated the feasibility and efficiency of a novel multi-camera navigation system combined with mixed reality technology in a clinical environment. The results show that this innovative technology can significantly improve surgical speed and intuitiveness while maintaining accuracy levels comparable to traditional monitor navigation. The integration of this technology holds promise for further improving the execution and patient outcomes of neurosurgical procedures.