Category: Augmented reality

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Transforming Neurosurgery With Spatial Computing: Enhancing Intraoperative Visualization and Precision Through Augmented Reality

Operative Neurosurgery 30:760–764, 2026

This technical note reports three neurosurgical cases using the Medivis surgical augmented reality platform with the Microsoft HoloLens 2 to overlay real-time 3D imaging, exoscopic, and endoscopic outputs intraoperatively. The workflow, registration method, hardware and software integration, and case-specific operative details are described, with all patients recovering without complications.

The report evaluates benefits and limitations of wearable XR in the operating room, highlighting improved visualization, surgical precision, and ergonomics, while addressing challenges such as registration accuracy, latency, cognitive overload, and avenues for future hardware and software improvements.

Goal Integrate wearable XR/AR and spatial computing into neurosurgical operating rooms to enhance intraoperative visualization, precision, and ergonomics.

System setup Three neurosurgical cases used the Medivis SurgicalAR platform paired with a Microsoft HoloLens 2 worn by the primary surgeon, enabling overlay of 3D volumes and intraoperative video in the surgeon’s field of view.

Imaging workflow Preoperative CT/MRI (including tractography/connectomic imaging when available) were uploaded from PACS, processed quickly (windowing/coloring/cropping/brightening), and stored for OR use, then linked to the HoloLens.

Registration approach Intraoperative holographic point-matching registration matched physical landmarks on the patient to virtual fiducials via an optical localizer recognized by HoloLens 2, with an FDA-approved navigation system also used in all cases for confirmation.

Video integration Exoscopic/endoscopic outputs were captured and streamed to the AR computer and transmitted to the HoloLens for real-time manipulation and interaction by the surgeon.

Observed benefits Combined overlays improved visualization and supported ergonomic operating posture, optimized sight lines, and reduced OR footprint while maintaining standard team visualization via the exoscope monitor.

Case outcomes All three patients recovered well postoperatively without complications; no critical intraoperative issues from latency/dropped frames prevented procedure completion.

Limitations & next steps Key challenges include potential cognitive overload/inattentional blindness, hologram registration accuracy, and technical issues like latency/dropped frames; future work targets improved/universal registration and broader overlayable data streams (e.g., conferencing, checklists).

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External Ventricular Drain Placement Using Active Augmented Reality Guidance

Operative Neurosurgery 30:414–421, 2026

This technical note presents a proof-of-concept augmented reality (AR) system that guides external ventricular drain (EVD) placement by integrating cloud-based automatic CT segmentation, PACS compatibility, trajectory planning, point-based image-to-patient registration, and real-time 3D AR guidance via an AR head-mounted display. The low-cost, end-to-end workflow and universal tracking tools aim to reduce attention shifts and improve accessibility compared with conventional neuronavigation.

The system was tested in a phantom study with 29 AR-guided EVD insertions by neurosurgical clinicians, yielding 69% optimal placements (Kakarla grade 1), a mean distance-to-target of 9.49 mm, mean angular deviation of 9.20°, an FRE of 4.00 mm, and mean procedural time of 22:45. Authors identify human–computer interaction, tracking fidelity, registration accuracy, and procedural time as primary areas for refinement before clinical adoption.

Augmented Reality (AR) Guidance: A low-cost, end-to-end AR system was developed for external ventricular drain (EVD) placement, integrating real-time 3D guidance, automated CT segmentation, and compatibility with standard hospital PACS infrastructure, all visualized through AR head-mounted displays (AR-HMDs).

Workflow Components: The system includes cloud-based image storage, automatic segmentation, trajectory planning, point-based image-to-patient registration, and real-time EVD tracking, aiming to reduce attention shifts and improve procedural integration.

Proof-of-Concept Results: In simulated procedures on anatomical phantoms with small ventricles, 69% of placements were optimal (Kakarla 1), with a mean distance to target of 9.49 mm and mean angular deviation of 9.20°, but accuracy is not yet at the level of best clinical standards.

Procedural Time: The mean workflow duration was nearly 23 minutes, which is longer than acceptable for emergency EVD placements, with most of the added time attributed to trajectory planning, marker attachment, and image-to-patient registration.

Usability and Interface Challenges: Users experienced difficulties with human-computer interaction, including issues with holographic controls, visual clutter, and marker tracking, which impacted both speed and accuracy.

Affordability and Accessibility: The AR-HMD system (approx. $4950) is significantly less expensive than traditional neuronavigation systems, potentially increasing access to advanced guidance in resource-limited settings

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Skull Base Anatomy Presented in 360° Photogrammetry 3-Dimensional Models

Operative Neurosurgery 30:124–136, 2026

This article presents the creation of seven photorealistic 360° photogrammetric 3D models of the central skull base derived from stepwise dissections of a formalin-fixed, vessel-injected cadaveric head. The workflow—dissection stages, smartphone-based image capture, cloud photogrammetry, refinement in Blender, and VR/MR upload—enables immersive visualization of cranial nerves, ICA/vertebral segments, and regional anatomy.

The models offer progressive exocranial-to-endocranial perspectives for education and preoperative planning, highlighting cavernous sinus, infratemporal and pterygopalatine fossae, petrous bone, and foraminal relationships. Limitations include a single-specimen dataset, color variations from fixation, and resolution constraints in deep cavities; nevertheless, the freely accessible VR models complement traditional dissection and anatomical atlases.

360° Photogrammetric 3D Models: Realistic, photogrammetry-based 3D models of the central skull base were created from cadaveric dissections, offering immersive 360° visualization of complex neuroanatomical structures for enhanced spatial understanding.

Stepwise Dissection and Scanning: Seven progressive anatomical models were generated by systematically dissecting and scanning a formalin-fixed, vessel-injected head specimen, documenting both exocranial and endocranial perspectives.

Key Structures Visualized: The models detail the courses of cranial nerves, major vessels (including all internal carotid artery segments), skull base foramina, infratemporal and pterygopalatine fossae, paranasal sinuses, and deep neck spaces.

Technical Workflow: High-resolution images were captured using a smartphone multi-camera system, processed via cloud-based photogrammetry, refined in 3D software, and made accessible through web, VR, and MR platforms.

Educational Value: The interactive models allow customizable, layered exploration of anatomy, overcoming limitations of traditional 2D images and static atlases, and are freely accessible for educational and preoperative planning purposes.

Limitations: The study used a single specimen, which may not represent anatomical variants; image quality in deep/narrow regions could be further improved with advanced imaging and fixation techniques.

Broad Accessibility: Smartphone-based and cloud photogrammetry methods make high-resolution anatomical modeling more accessible and less resource-intensive, facilitating widespread dissemination.

Conclusions: 360° photorealistic 3D models significantly enhance comprehension of skull base anatomy and are a valuable adjunct to traditional teaching, with potential to improve neurosurgical training and patient outcomes.

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Operative Microscope In-Field Visualization of Confocal Laser Endomicroscopy Interface (Zeiss CONVIVO )

Operative Neurosurgery 29:860–864, 2025

This study evaluates integrating the Zeiss CONVIVO confocal laser endomicroscopy interface into the operative microscope heads-up display to allow simultaneous visualization of the surgical field and real-time confocal laser endomicroscopy (CLE) images. A randomized cohort of 22 intra-axial tumor surgeries showed shorter CLE usage times, fewer total captures, and a trend toward higher usable-image proportion with heads-up integration.

The integration improved intraoperative ergonomics by reducing probe motion artifacts and image noninterpretability, streamlining workflow, and decreasing operative time while preserving diagnostic utility of CLE for margin assessment in gliomas and other brain lesions.

Confocal Laser Endomicroscopy (CLE): Provides real-time, in vivo microscopic imaging of brain tumors during neurosurgery, enabling identification of tumor margins without the need for traditional tissue extraction or frozen section analysis.

Zeiss CONVIVO® System: A CLE device recently introduced in neurosurgery, proven reliable for both ex vivo and in vivo applications, and undergoing further clinical refinement.

Technical Challenge: Standard CLE use requires the surgeon to shift attention from the operative field to a separate screen to assess image quality, potentially causing motion artifacts, prolonging surgery, and increasing the number of unusable images.

Heads-Up Display Integration: Visualization of the CONVIVO® interface was integrated as a picture-in-picture display inside the operative microscope, allowing simultaneous monitoring of the surgical field and CLE images without diverting gaze.

Study Findings: Use of the heads-up display significantly reduced CLE employment time (mean 61.1 vs. 201.6 seconds; P = .01), decreased the total number of images acquired, and increased the proportion of usable images, though the latter was not statistically significant (P = .06).

Workflow Efficiency: Direct intraoperative feedback enabled by the heads-up display led to fewer motion artifacts, more efficient image acquisition, and reduced overall operative time.

Clinical Implications: The integration supports more efficient and accurate intraoperative tumor assessment, potentially improving the extent of resection, especially in gliomas, and reducing reliance on frozen sections.

Limitations and Future Directions: Further refinement is needed for effortless image acquisition; artificial intelligence for artifact reduction and real-time interpretation by neurosurgeons are potential future improvements.

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High-Accuracy Augmented Reality Guidance for Intracranial Drain Placement Using a Standalone Head-Worn Navigation System

Neurosurgery 96:1217–1226, 2025

A standalone augmented reality (AR) headset navigation system was clinically validated for external ventricular drain (EVD) placement, demonstrating improved accuracy, higher first-attempt success, and reduced complications compared to freehand technique, supporting AR as a safe, effective, and ergonomic alternative for neurosurgical procedures.

• A standalone head-worn augmented reality (AR) navigation system was developed for external ventricular drain (EVD) placement.

• A prospective clinical pilot study compared AR-guided EVD placement to freehand technique in emergency/ICU settings.

• AR guidance achieved 100% functional first-attempt placements, significantly higher optimal placement rates, and lower complication and revision rates than freehand.

• Placement quality was evaluated with an extended modified Kakarla scale and all AR placements were functional on the first attempt.

• The AR system used high-accuracy inside-out infrared tracking and real-time 3D anatomical overlays for planning and guidance.

• Complications in the AR group were fewer and less severe, with errors attributed to hardware misuse rather than the AR guidance itself.

• Surgeons reported good acceptance and ease of use of the AR system, with minimal workflow disruption.

• A multicenter randomized controlled trial is planned to further validate these findings.

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Interactive microsurgical anatomy education using photogrammetry 3D models and an augmented reality cube

J Neurosurg 141:17–26, 2024

This study sought to assess the use of an augmented reality (AR) tool for neurosurgical anatomical education.

METHODS Three-dimensional models were created using advanced photogrammetry and registered onto a handheld AR foam cube imprinted with scannable quick response codes. A perspective analysis of the cube anatomical system was performed by loading a 3D photogrammetry model over a motorized turntable to analyze changes in the surgical window area according to the horizontal rotation. The use of the cube as an intraoperative reference guide for surgical trainees was tested during cadaveric dissection exercises. Neurosurgery trainees from international programs located in Ankara, Turkey; San Salvador, El Salvador; and Moshi, Tanzania, interacted with and assessed the 3D models and AR cube system and then completed a 17-item graded user experience survey.

RESULTS Seven photogrammetry 3D models were created and imported to the cube. Horizontal turntable rotation of the cube translated to measurable and realistic perspective changes in the surgical window area. The combined 3D models and cube system were used to engage trainees during cadaveric dissections, with satisfactory user experience. Thirty-five individuals (20 from Turkey, 10 from El Salvador, and 5 from Tanzania) agreed that the cube system could enhance the learning experience for neurosurgical anatomy.

CONCLUSIONS The AR cube combines tactile and visual sensations with high-resolution 3D models of cadaveric dissections. Inexpensive and lightweight, the cube can be effectively implemented to allow independent co-visualization of anatomical dissection and can potentially supplement neurosurgical education.

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A Low-Cost Mobile-Based Augmented Reality Neuronavigation System for Retrosigmoid Craniotomy

Operative Neurosurgery 26:695–701, 2024

The correct positioning of the transverse-sigmoid sinus junction (TSSJ) during retrosigmoid craniotomy (RC) is crucial for enhancing surgical efficiency and preventing complications. An augmented reality technology may provide low-cost guidance for the TSSJ position. The authors aimed to investigate the clinical application of a self-developed mobile augmented reality navigation system (MARNS) for TSSJ positioning during RC and present their findings.

METHODS: This observational research enrolled patients who underwent RC at Fujian Provincial Hospital from May 2023 to June 2023. All patients had their TSSJs located by MARNS. The surgical incision and skull “keyhole” for drilling were determined separately based on the projections of TSSJ on the 3-dimensional model displayed by MARNS. This method was assessed using matching error, positioning time, integrity of the bone flap, incidence of transversal sigmoid sinus injury, and other complications.

RESULTS: Seven patients diagnosed with acoustic neuroma, trigeminal neuralgia, and hemifacial spasm were enrolled in this study. The MARNS system exhibited a matching error with an average magnitude of 2.88 ± 0.69 mm. The positioning procedure necessitated an average duration of 279.71 ± 27.29 seconds. In every instance, the inner edge of the TSSJ was precisely identified and exposed while the bone flap was successfully formed and maintained an average integrity of 86.7%.

CONCLUSION: This study demonstrated the efficacy of MARNS in the precise placement of the TSSJ during RC procedures. It offers advantages for convenience, cost-effectiveness, and reliability for neurosurgical navigation.

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Mixed Reality for Cranial Neurosurgical Planning

Operative Neurosurgery 26:551–558, 2024

Mixed reality (MxR) benefits neurosurgery by improving anatomic visualization, surgical planning and training. We aim to validate the usability of a dedicated certified system for this purpose.

METHODS: All cases prepared with MxR in our center in 2022 were prospectively collected. Holographic rendering was achieved using an incorporated fully automatic algorithm in the MxR application, combined with contrast-based semiautomatic rendering and/or manual segmentation where necessary. Hologram segmentation times were documented. Visualization during surgical preparation (defined as the interval between finalized anesthesiological induction and sterile draping) was performed using MxR glasses and direct streaming to a side screen. Surgical preparation times were compared with a matched historical cohort of 2021. Modifications of the surgical approach after 3-dimensional (3D) visualization were noted. Usability was assessed by evaluating 7 neurosurgeons with more than 3 months of experience with the system using a Usefulness, Satisfaction and Ease of use (USE) questionnaire.

RESULTS: One hundred-seven neurosurgical cases prepared with a 3D hologram were collected. Surgical indications were oncologic (63/107, 59%), cerebrovascular (27/107, 25%), and carotid endarterectomy (17/107, 16%). Mean hologram segmentation time was 39.4 ± 20.4 minutes. Average surgical preparation time was 48.0 ± 17.3 minutes for MxR cases vs 52 ± 17 minutes in the matched 2021 cohort without MxR (mean difference 4, 95% CI 1.7527-9.7527). Based on the 3D hologram, the surgical approach was modified in 3 cases. Good usability was found by 57% of the users.

CONCLUSION: The perioperative use of 3D holograms improved direct anatomic visualization while not significantly increasing intraoperative surgical preparation time. Usability of the system was adequate. Further technological development is necessary to improve the automatic algorithms and reduce the preparation time by circumventing manual and semiautomatic segmentation. Future studies should focus on quantifying the potential benefits in teaching, training, and the impact on surgical and functional outcomes.

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Preoperative Microsoft HoloLens 2 planning‑assisted surgical clipping of a fetal posterior cerebral artery aneurysm

Acta Neurochirurgica (2023) 165:3371–3374

The treatment of intracranial aneurysms has predominantly shifted towards endovascular strategies, but complex cases still necessitate microsurgery. Preoperative stimulation can be beneficial for inexperienced young neurosurgeons in preparing for safe microsurgery.

Method A 72-year-old female with a left irregular fetal posterior cerebral artery (PCA) aneurysm underwent clipping repair. Microsoft HoloLens 2, utilizing mixed reality technology, was employed for preoperative stimulation and anatomical study. During the operation, we successfully identified the planned relationship between the aneurysm and the fetal PCA. The patient was cured without any complications.

Conclusion We hope that this report will highlight the significance of Microsoft HoloLens 2 in microsurgical planning and education.

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Augmented Reality in Minimally Invasive Spinal Surgery

World Neurosurg. (2023) 176:35-42

Spine surgery has undergone significant changes in approach and technique. With the adoption of intraoperative navigation, minimally invasive spinal surgery (MISS) has arguably become the gold standard. Augmented reality (AR) has now emerged as a front-runner in anatomical visualization and narrower operative corridors. In effect, AR is poised to revolutionize surgical training and operative outcomes. Our study examines the current literature on AR-assisted MISS, synthesizes findings, and creates a narrative highlighting the history and future of AR in spine surgery.

MATERIAL AND METHODS: Relevant literature was gathered using the PubMed (Medline) database from 1975 to 2023. Pedicle screw placement models were the primary intervention in AR. These were compared to the outcomes of traditional MISS

RESULTS: We found that AR devices on the market show promising clinical outcomes in preoperative training and intraoperative use. Three prominent systems were as follows: XVision, HoloLens, and ImmersiveTouch. In the studies, surgeons, residents, and medical students had opportunities to operate AR systems, showcasing their educational potential across each phase of learning. Specifically, one facet described training with cadaver models to gauge accuracy in pedicle screw placement. AR-MISS exceeded free-hand methods without unique complications or contraindications.

CONCLUSIONS: While still in its infancy, AR has already proven beneficial for educational training and intraoperative MISS applications. We believe that with continued research and advancement of this technology, AR is poised to become a dominant player within the fundamentals of surgical education and MISS operative technique.

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Augmented Reality–Assisted Percutaneous Rhizotomy for Trigeminal Neuralgia

Operative Neurosurgery 24:665–669, 2023

Percutaneous rhizotomy of the trigeminal nerve is a common surgery to manage medically refractory trigeminal neuralgia. Traditionally, these procedures have been performed based on anatomic landmarks with fluoroscopic guidance. Augmented reality (AR) relays virtual content on the real world and has the potential to improve localization of surgical targets based on preoperative imaging.

OBJECTIVE: To study the potential application and benefits of AR as an adjunct to traditional fluoroscopy-guided glycerol rhizotomy (GR).

METHODS: We used traditional fluoroscopy-guided percutaneous GR technique as previously described, performed under general anesthesia. Anatomic registration to the Medivis SurgicalAR system was performed based on the patient’s preoperative computerized tomography, and the surgeon was equipped with the system’s AR goggles. AR was used as an adjunct to fluoroscopy for trajectory planning to place a spinal needle into the medial aspect of the foramen ovale.

RESULTS: A 50-year-old woman with multiple sclerosis–related right-sided classical trigeminal neuralgia had persistent pain, refractory to medications, previous gamma knife stereotactic radiosurgery, and percutaneous radiofrequency rhizotomy performed elsewhere. The patient underwent AR-assisted fluoroscopy-guided percutaneous GR. The needle was placed into the right trigeminal cistern within seconds. She was discharged home after a few hours of observation with no complications and reported pain relief.

CONCLUSION: AR-assisted percutaneous rhizotomy may enhance the learning curve of these types of procedures and decrease surgery duration and radiation exposure. This allowed rapid and correct placement of a spinal needle through the foramen ovale.

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A Sensorised Surgical Glove to Analyze Forces During Neurosurgery

Neurosurgery 92:639–646, 2023

Measuring intraoperative forces in real time can provide feedback mechanisms to improve patient safety and surgical training. Previous force monitoring has been achieved through the development of specialized and adapted instruments or use designs that are incompatible with neurosurgical workflow.

OBJECTIVE: To design a universal sensorised surgical glove to detect intraoperative forces, applicable to any surgical procedure, and any surgical instrument in either hand.

METHODS: We created a sensorised surgical glove that was calibrated across 0 to 10 N. A laboratory experiment demonstrated that the sensorised glove was able to determine instrument-tissue forces. Six expert and 6 novice neurosurgeons completed a validated grape dissection task 20 times consecutively wearing the sensorised glove. The primary outcome was median and maximum force (N).

RESULTS: The sensorised glove was able to determine instrument-tissue forces reliably. The average force applied by experts (2.14 N) was significantly lower than the average force exerted by novices (7.15 N) (P = .002). The maximum force applied by experts (6.32 N) was also significantly lower than the maximum force exerted by novices (9.80 N) (P = .004). The sensorised surgical glove’s introduction to operative workflow was feasible and did not impede on task performance.

CONCLUSION: We demonstrate a novel and scalable technique to detect forces during neurosurgery. Force analysis can provide real-time data to optimize intraoperative tissue forces, reduce the risk of tissue injury, and provide objective metrics for training and assessment.

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Invention of an Online Interactive Virtual Neurosurgery Simulator With Audiovisual Capture for Tactile Feedback

Operative Neurosurgery 24:194–200, 2023

BACKGROUND: Present neurosurgical simulators are not portable.

OBJECTIVE: To maximize portability of a virtual surgical simulator by providing online learning and to validate a unique psychometric method (“audiovisual capture”) to provide tactile information without force feedback probes.

METHODS: An online interactive neurosurgical simulator of a posterior petrosectomy was developed. The difference in the hardness of compact vs cancellous bone was presented with audiovisual effects as inclinations of the drilling speed and sound based on engineering perspectives. Three training methods (the developed simulator, lectures and review of slides, and dissection of a 3-dimensional printed temporal bone model [D3DPM]) were evaluated by 10 neurosurgical residents. They all first attended a lecture and were randomly allocated to 2 groups by the training D3DPM (A: simulator; B: review of slides, no simulator). In D3DPM, objective measures (required time, quality of completion, injury scores of important structures, and the number of instructions provided) were compared between groups. Finally, the residents answered questionnaires.

RESULTS: The objective measures were not significantly different between groups despite a younger tendency in group A (graduate year À2.4 years, 95% confidence interval À5.3 to 0.5, P = .081). The mean perceived hardness of cancellous bone on the simulator was 70% of that of compact bone, matching the intended profile. The simulator was superior to lectures and review of slides in feedback and repeated practices and to D3DPM in adaptability to multiple learning environments.

CONCLUSION: A novel online interactive neurosurgical simulator was developed, and satisfactory validity was shown. Audiovisual capture successfully transmitted the tactile information.

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Three-Dimensional Modeling and Augmented Reality and Virtual Reality Simulation of Fiber Dissection of the Cerebellum and Brainstem

Surgeons must understand the complex anatomy of the cerebellum and brainstem and their 3-dimensional (3D) relationships with each other for surgery to be successful. To the best of our knowledge, there have been no fiber dissection studies combined with 3D models, augmented reality (AR), and virtual reality (VR) of the structure of the cerebellum and brainstem. In this study, we created freely accessible AR and VR simulations and 3D models of the cerebellum and brainstem.

OBJECTIVE: To create 3D models and AR and VR simulations of cadaveric dissections of the human cerebellum and brainstem and to examine the 3D relationships of these structures.

METHODS: Ten cadaveric cerebellum and brainstem specimens were prepared in accordance with the Klingler’s method. The cerebellum and brainstem were dissected under the operating microscope, and 2-dimensional and 3D images were captured at every stage. With a photogrammetry tool (Qlone, EyeCue Vision Technologies, Ltd.), AR and VR simulations and 3D models were created by combining several 2-dimensional pictures.

RESULTS: For the first time reported in the literature, high-resolution, easily accessible, free 3D models and AR and VR simulations of cerebellum and brainstem dissections were created.

CONCLUSION: Fiber dissection of the cerebellum-brainstem complex and 3D models with AR and VR simulations are a useful addition to the goal of training neurosurgeons worldwide.

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Current status of augmented reality in cerebrovascular surgery: a systematic review

Neurosurgical Review (2022) 45:1951–1964

Augmented reality (AR) is an adjuvant tool in neuronavigation to improve spatial and anatomic understanding. The present review aims to describe the current status of intraoperative AR for the treatment of cerebrovascular pathology.

A systematic review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The following databases were searched: PubMed, Science Direct, Web of Science, and EMBASE up to December, 2020. The search strategy consisted of “augmented reality,” “AR,” “cerebrovascular,” “navigation,” “neurovascular,” “neurosurgery,” and “endovascular” in both AND and OR combinations. Studies included were original research articles with intraoperative application. The manuscripts were thoroughly examined for study design, outcomes, and results.

Sixteen studies were identified describing the use of intraoperative AR in the treatment of cerebrovascular pathology. A total of 172 patients were treated for 190 cerebrovascular lesions using intraoperative AR. The most common treated pathology was intracranial aneurysms. Most studies were cases and there was only a case–control study. A head-up display system in the microscope was the most common AR display. AR was found to be useful for tailoring the craniotomy, dura opening, and proper identification of donor and recipient vessels in vascular bypass. Most AR systems were unable to account for tissue deformation.

This systematic review suggests that intraoperative AR is becoming a promising and feasible adjunct in the treatment of cerebrovascular pathology. It has been found to be a useful tool in the preoperative planning and intraoperative guidance. However, its clinical benefits remain to be seen.

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Real‐time augmented reality application in presurgical planning and lesion scalp localization by a smartphone

Acta Neurochirurgica (2022) 164:1069–1078

Objective A smartphone augmented reality (AR) application (app) was explored for clinical use in presurgical planning and lesion scalp localization.

Methods We programmed an AR App on a smartphone. The accuracy of the AR app was tested on a 3D-printed head model, using the Euclidean distance of displacement of virtual objects. For clinical validation, 14 patients with brain tumors were included in the study. Preoperative MRI images were used to generate 3D models for AR contents. The 3D models were then transferred to the smartphone AR app. Tumor scalp localization was marked, and a surgical corridor was planned on the patient’s head by viewing AR images on the smartphone screen. Standard neuronavigation was applied to evaluate the accuracy of the smartphone. Max-margin distance (MMD) and area overlap ratio (AOR) were measured to quantitatively validate the clinical accuracy of the smartphone AR technique.

Results In model validation, the total mean Euclidean distance of virtual object displacement using the smartphone AR app was 4.7 ± 2.3 mm. In clinical validation, the mean duration of AR app usage was 168.5 ± 73.9 s. The total mean MMD was 6.7 ± 3.7 mm, and total mean AOR was 79%.

Conclusions The smartphone AR app provides a new way of experience to observe intracranial anatomy in situ, and it makes surgical planning more intuitive and efficient. Localization accuracy is satisfactory with lesions larger than 15 mm.

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Clinical accuracy and initial experience with augmented reality–assisted pedicle screw placement

J Neurosurg Spine 36:351–357, 2022

Augmented reality (AR) is a novel technology which, when applied to spine surgery, offers the potential for efficient, safe, and accurate placement of spinal instrumentation. The authors report the accuracy of the first 205 pedicle screws consecutively placed at their institution by using AR assistance with a unique head-mounted display (HMD) navigation system.

METHODS A retrospective review was performed of the first 28 consecutive patients who underwent AR-assisted pedicle screw placement in the thoracic, lumbar, and/or sacral spine at the authors’ institution. Clinical accuracy for each pedicle screw was graded using the Gertzbein-Robbins scale by an independent neuroradiologist working in a blinded fashion.

RESULTS Twenty-eight consecutive patients underwent thoracic, lumbar, or sacral pedicle screw placement with AR assistance. The median age at the time of surgery was 62.5 (IQR 13.8) years and the median body mass index was 31 (IQR 8.6) kg/m2. Indications for surgery included degenerative disease (n = 12, 43%); deformity correction (n = 12, 43%); tumor (n = 3, 11%); and trauma (n = 1, 4%). The majority of patients (n = 26, 93%) presented with low-back pain, 19 (68%) patients presented with radicular leg pain, and 10 (36%) patients had documented lower extremity weakness. A total of 205 screws were consecutively placed, with 112 (55%) placed in the lumbar spine, 67 (33%) in the thoracic spine, and 26 (13%) at S1. Screw placement accuracy was 98.5% for thoracic screws, 97.8% for lumbar/S1 screws, and 98.0% overall.

CONCLUSIONS AR depicted through a unique HMD is a novel and clinically accurate technology for the navigated insertion of pedicle screws. The authors describe the first 205 AR-assisted thoracic, lumbar, and sacral pedicle screws consecutively placed at their institution with an accuracy of 98.0% as determined by a Gertzbein-Robbins grade of A or B.

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Augmented reality visualization in brain lesions: a prospective randomized controlled evaluation of its potential and current limitations in navigated microneurosurgery

Acta Neurochirurgica (2022) 26:3–14

Augmented reality (AR) has the potential to support complex neurosurgical interventions by including visual information seamlessly. This study examines intraoperative visualization parameters and clinical impact of AR in brain tumor surgery.

Methods Fifty-five intracranial lesions, operated either with AR-navigated microscope (n = 39) or conventional neuronavigation (n = 16) after randomization, have been included prospectively. Surgical resection time, duration/type/mode of AR, displayed objects (n, type), pointer-based navigation checks (n), usability of control, quality indicators, and overall surgical usefulness of AR have been assessed.

Results AR display has been used in 44.4% of resection time. Predominant AR type was navigation view (75.7%), followed by target volumes (20.1%). Predominant AR mode was picture-in-picture (PiP) (72.5%), followed by 23.3% overlay display. In 43.6% of cases, vision of important anatomical structures has been partially or entirely blocked by AR information. A total of 7.7% of cases used MRI navigation only, 30.8% used one, 23.1% used two, and 38.5% used three or more object segmentations in AR navigation. A total of 66.7% of surgeons found AR visualization helpful in the individual surgical case. AR depth information and accuracy have been rated acceptable (median 3.0 vs. median 5.0 in conventional neuronavigation). The mean utilization of the navigation pointer was 2.6   /resection hour (AR) vs. 9.7   /resection hour (neuronavigation); navigation effort was significantly reduced in AR (P < 0.001).

Conclusions The main benefit of HUD-based AR visualization in brain tumor surgery is the integrated continuous display allowing for pointer-less navigation. Navigation view (PiP) provides the highest usability while blocking the operative field less frequently. Visualization quality will benefit from improvements in registration accuracy and depth impression.

German clinical trials registration number. DRKS00016955.

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The effect of augmented reality on the accuracy and learning curve of external ventricular drain placement

Neurosurg Focus 51 (2):E8, 2021

The traditional freehand technique for external ventricular drain (EVD) placement is most frequently used, but remains the primary risk factor for inaccurate drain placement. As this procedure could benefit from image guidance, the authors set forth to demonstrate the impact of augmented-reality (AR) assistance on the accuracy and learning curve of EVD placement compared with the freehand technique.

METHODS Sixteen medical students performed a total of 128 EVD placements on a custom-made phantom head, both before and after receiving a standardized training session. They were guided by either the freehand technique or by AR, which provided an anatomical overlay and tailored guidance for EVD placement through inside-out infrared tracking. The outcome was quantified by the metric accuracy of EVD placement as well as by its clinical quality.

RESULTS The mean target error was significantly impacted by either AR (p = 0.003) or training (p = 0.02) in a direct comparison with the untrained freehand performance. Both untrained (11.9 ± 4.5 mm) and trained (12.2 ± 4.7 mm) AR performances were significantly better than the untrained freehand performance (19.9 ± 4.2 mm), which improved after training (13.5 ± 4.7 mm). The quality of EVD placement as assessed by the modified Kakarla scale (mKS) was significantly impacted by AR guidance (p = 0.005) but not by training (p = 0.07). Both untrained and trained AR performances (59.4% mKS grade 1 for both) were significantly better than the untrained freehand performance (25.0% mKS grade 1). Spatial aptitude testing revealed a correlation between perceptual ability and untrained AR-guided performance (r = 0.63).

CONCLUSIONS Compared with the freehand technique, AR guidance for EVD placement yielded a higher outcome accuracy and quality for procedure novices. With AR, untrained individuals performed as well as trained individuals, which indicates that AR guidance not only improved performance but also positively impacted the learning curve. Future efforts will focus on the translation and evaluation of AR for EVD placement in the clinical setting.

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Microsurgical clipping of middle cerebral artery aneurysms: preoperative planning using virtual reality to reduce procedure time

Neurosurg Focus 51 (2):E12, 2021

The authors sought to evaluate the impact of virtual reality (VR) applications for preoperative planning and rehearsal on the total procedure time of microsurgical clipping of middle cerebral artery (MCA) ruptured and unruptured aneurysms compared with standard surgical planning.

METHODS A retrospective review of 21 patients from 2016 to 2019 was conducted to determine the impact on the procedure time of MCA aneurysm clipping after implementing VR for preoperative planning and rehearsal. The control group consisted of patients whose procedures were planned with standard CTA and DSA scans (n = 11). The VR group consisted of patients whose procedures were planned with a patient-specific 360° VR (360VR) model (n = 10). The 360VR model was rendered using CTA and DSA data when available. Each patient was analyzed and scored with a case complexity (CC) 5-point grading scale accounting for aneurysm size, incorporation of M2 branches, and aspect ratio, with 1 being the least complex and 5 being the most complex. The mean procedure times were compared between the VR group and the control group, as were the mean CC score between the groups. Comorbidities and aneurysm conduction (ruptured vs unruptured) were also taken into consideration for the comparison.

RESULTS The mean CC scores for the control group and VR group were 2.45 ± 1.13 and 2.30 ± 0.48, respectively. CC was not significantly different between the two groups (p = 0.69). The mean procedure time was significantly lower for the VR group compared with the control group (247.80 minutes vs 328.27 minutes; p = 0.0115), particularly for the patients with a CC score of 2 (95% CI, p = 0.0064). A Charlson Comorbidity Index score was also calculated for each group, but no statistical significance was found (VR group, 2.8 vs control group, 1.8, p = 0.14).

CONCLUSIONS In this study, usage of 360VR models for planning the craniotomy and rehearsing with various clip sizes and configurations resulted in an 80-minute decrease in procedure time. These findings have suggested the potential of VR technology in improving surgical efficiency for aneurysm clipping procedures regardless of complexity, while making the procedure faster and safer.

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