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

HoloDIEP-Faster and More Accurate Intraoperative DIEA Perforator Mapping Using a Novel Mixed Reality Tool

BACKGROUND

 Microsurgical breast reconstruction using abdominal tissue is a complex procedure, in part, due to variable vascular/perforator anatomy. Preoperative computed tomography angiography (CTA) has mitigated this challenge to some degree; yet it continues to pose certain challenges. The ability to map perforators with Mixed Reality has been demonstrated in case studies, but its accuracy has not been studied intraoperatively. Here, we compare the accuracy of "HoloDIEP" in identifying perforator location (vs. Doppler ultrasound) by using holographic 3D models derived from preoperative CTA.

METHODS

 Using a custom application on HoloLens, the deep inferior epigastric artery vascular tree was traced in 15 patients who underwent microsurgical breast reconstruction. Perforator markings were compared against the 3D model in a coordinate system centered on the umbilicus. Holographic- and Doppler-identified markings were compared using a perspective-corrected photo technique against the 3D model along with measurement of duration of perforator mapping for each technique.

RESULTS

 Vascular points in HoloDIEP skin markings were -0.97 ± 6.2 mm (perforators: -0.62 ± 6.13 mm) away from 3D-model ground-truth in radial length from the umbilicus at a true distance of 10.81 ± 6.14 mm (perforators: 11.40 ± 6.15 mm). Absolute difference in radial distance was twice as high for Doppler markings compared with Holo-markings (9.71 ± 6.16 and 4.02 ± 3.20 mm, respectively). Only in half of all cases (7/14), more than 50% of the Doppler-identified points were reasonably close (<30 mm) to 3D-model ground-truth. HoloDIEP was twice as fast as Doppler ultrasound (76.9s vs. 150.4 s per abdomen).

CONCLUSION

 HoloDIEP allows for faster and more accurate intraoperative perforator mapping than Doppler ultrasound.

Determination of rotation center and diameter of femoral heads using off-the-shelf augmented reality hardware for navigation

In total hip arthroplasty (THA), determining the center of rotation (COR) and diameter of the hip joint (acetabulum and femoral head) is essential to restore patient biomechanics. This study investigates on-the-fly determination of hip COR and size, using off-the-shelf augmented reality (AR) hardware. An AR head-mounted device (HMD) was configured with inside-out infrared tracking enabling the determination of surface coordinates using a handheld stylus. Two investigators examined 10 prosthetic femoral heads and cups, and 10 human femurs. The HMD calculated the diameter and COR through sphere fitting. Results were compared to data obtained from either verified prosthetic geometry or post-hoc CT analysis. Repeated single-observer measurements showed a mean diameter error of 0.63 mm ± 0.48 mm for the prosthetic heads and 0.54 mm ± 0.39 mm for the cups. Inter-observer comparison yielded mean diameter errors of 0.28 mm ± 0.71 mm and 1.82 mm ± 1.42 mm for the heads and cups, respectively. Cadaver testing found a mean COR error of 3.09 mm ± 1.18 mm and a diameter error of 1.10 mm ± 0.90 mm. Intra- and inter-observer reliability averaged below 2 mm. AR-based surface mapping using HMD proved accurate and reliable in determining the diameter of THA components with promise in identifying COR and diameter of osteoarthritic femoral heads.

Augmented Reality-Guided External Ventricular Drain Placement: A Case Report

The placement of an external ventricular drain (EVD) is a critical neurosurgical procedure used to relieve intracranial pressure in patients with conditions such as hydrocephalus, traumatic brain injury, and intracranial hemorrhage. Traditional methods rely heavily on anatomical landmarks and the surgeon's experience, which can lead to variability in outcomes and increased risk of complications. Neuronavigation, while available, is infrequently used due to the size, cost, and set-up times associated with these devices. This report explores the use of a headset-based augmented reality (AR) system for guidance during the EVD placement procedure. We describe an AR system that overlays a 3D model of the patient's cranial anatomy, derived from preoperative imaging, onto the patient's head. This system is a head-mounted display and utilizes a rapid fiducial-less registration to provide the surgeon with visualization of 3D anatomy, and targeted trajectories. The system was used with a 32-year-old patient undergoing EVD placement prior to a cranioplasty. Due to the atypical cranial anatomy and due to prior procedures and midline shift, this relatively high-risk catheter placement was an ideal circumstance for the use of AR guidance during the EVD placement. This report described an early use of AR for EVD placement and represents a substantial advancement in neurosurgical practice, offering enhanced precision, efficiency, and safety. Further large-scale studies are warranted to validate these findings and explore the broader applicability of AR in other neurosurgical procedures.

Virtual and Augmented Reality in Ventriculostomy: A Systematic Review

BACKGROUND

Ventriculostomy, one of the most common neurosurgical procedures, involves inserting a draining catheter into the brain's ventricular system to alleviate excessive cerebrospinal fluid accumulation. Traditionally, this procedure has relied on freehand techniques guided by anatomical landmarks, which have shown a high rate of misplacement. Recent advancements in virtual reality (VR) and augmented reality (AR) technologies have opened up new possibilities in the field. This comprehensive review aims to analyze the existing literature, examine the diverse applications of VR and AR in ventriculostomy procedures, address their limitations, and propose potential future directions.

METHODS

A systematic search was conducted in Web of Science and PubMed databases to identify studies employing VR and AR technologies in ventriculostomy procedures. Review papers, non-English records, studies unrelated to VR/AR technologies in ventriculostomy, and supplementary documents were excluded. In total 29 papers were included in the review.

RESULTS

The development of various VR and AR systems aimed at enhancing the ventriculostomy procedure are categorized according to the Data, Visualization and View taxonomy. The study investigates the data utilized by these systems, the visualizations employed, and the virtual or augmented environments created. Furthermore, the surgical scenarios and applications of each method, as well as the validation and evaluation metrics used, are discussed.

DISCUSSION

The review delves into the fundamental challenges encountered in the implementation of VR and AR systems in ventriculostomy. Additionally, potential future directions and areas for improvement are proposed, addressing the identified limitations and paving the way for further advancements in the field.

Augmented Reality Registration System for Visualization of Skull Landmarks

BACKGROUND

Augmented reality (AR) is an emerging technology in neurosurgery with the potential to become a strategic tool in the delivery of care and education for trainees. Advances in technology have demonstrated promising use for improving visualization and spatial awareness of critical neuroanatomic structures. In this report, we employ a novel AR registration system for the visualization and targeting of skull landmarks.

METHODS

A markerless AR system was used to register 3-dimensional reconstructions of suture lines onto the head via a head-mounted display. Participants were required to identify craniometric points with and without AR assistance. Targeting error was measured as the Euclidian distance between the user-defined location and the true craniometric point on the subjects' heads.

RESULTS

All participants successfully registered 3-dimensional reconstructions onto the subjects' heads. Targeting accuracy was significantly improved with AR (3.59 ± 1.29 mm). Across all target points, AR increased accuracy by an average of 19.96 ± 3.80 mm. Posttest surveys revealed that participants felt the technology increased their confidence in identifying landmarks (4.6/5) and that the technology will be useful for clinical care (4.2/5).

CONCLUSIONS

While several areas of improvement and innovation can further enhance the use of AR in neurosurgery, this report demonstrates the feasibility of a markerless headset-based AR system for visualizing craniometric points on the skull. As the technology continues to advance, AR is expected to play an increasingly significant role in neurosurgery, transforming how surgeries are performed and improving patient care.

Does Extended Reality Simulation Improve Surgical/Procedural Learning and Patient Outcomes When Compared With Standard Training Methods?: A Systematic Review

INTRODUCTION

The use of extended reality (XR) technologies, including virtual, augmented, and mixed reality, has increased within surgical and procedural training programs. Few studies have assessed experiential learning- and patient-based outcomes using XR compared with standard training methods.

METHODS

As a working group for the Society for Simulation in Healthcare, we used Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and a PICO strategy to perform a systematic review of 4238 articles to assess the effectiveness of XR technologies compared with standard training methods. Outcomes were grouped into knowledge, time-to-completion, technical proficiency, reactions, and patient outcomes. Because of study heterogeneity, a meta-analysis was not feasible.

RESULTS

Thirty-two studies met eligibility criteria: 18 randomized controlled trials, 7 comparative studies, and 7 systematic reviews. Outcomes of most studies included Kirkpatrick levels of evidence I-III (reactions, knowledge, and behavior), while few reported level IV outcomes (patient). The overall risk of bias was low. With few exceptions, included studies showed XR technology to be more effective than standard training methods in improving objective skills and performance, shortening procedure time, and receiving more positive learner ratings. However, XR use did not show significant differences in gained knowledge.

CONCLUSIONS

Surgical or procedural XR training may improve technical skill development among trainees and is generally favored over standard training methods. However, there should be an additional focus on how skill development translates to clinically relevant outcomes. We recommend longitudinal studies to examine retention and transfer of training to clinical settings, methods to improve timely, adaptive feedback for deliberate practice, and cost analyses.

Evaluation Metrics for Augmented Reality in Neurosurgical Preoperative Planning, Surgical Navigation, and Surgical Treatment Guidance: A Systematic Review

BACKGROUND AND OBJECTIVE

Recent years have shown an advancement in the development of augmented reality (AR) technologies for preoperative visualization, surgical navigation, and intraoperative guidance for neurosurgery. However, proving added value for AR in clinical practice is challenging, partly because of a lack of standardized evaluation metrics. We performed a systematic review to provide an overview of the reported evaluation metrics for AR technologies in neurosurgical practice and to establish a foundation for assessment and comparison of such technologies.

METHODS

PubMed, Embase, and Cochrane were searched systematically for publications on assessment of AR for cranial neurosurgery on September 22, 2022. The findings were reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

RESULTS

The systematic search yielded 830 publications; 114 were screened full text, and 80 were included for analysis. Among the included studies, 5% dealt with preoperative visualization using AR, with user perception as the most frequently reported metric. The majority (75%) researched AR technology for surgical navigation, with registration accuracy, clinical outcome, and time measurements as the most frequently reported metrics. In addition, 20% studied the use of AR for intraoperative guidance, with registration accuracy, task outcome, and user perception as the most frequently reported metrics.

CONCLUSION

For quality benchmarking of AR technologies in neurosurgery, evaluation metrics should be specific to the risk profile and clinical objectives of the technology. A key focus should be on using validated questionnaires to assess user perception; ensuring clear and unambiguous reporting of registration accuracy, precision, robustness, and system stability; and accurately measuring task performance in clinical studies. We provided an overview suggesting which evaluation metrics to use per AR application and innovation phase, aiming to improve the assessment of added value of AR for neurosurgical practice and to facilitate the integration in the clinical workflow.

Augmented reality for intracranial meningioma resection: a mini-review

Augmented reality (AR) integrates computer-generated content and real-world scenarios. Artificial intelligence's continuous development has allowed AR to be integrated into medicine. Neurosurgery has progressively introduced image-guided technologies. Integration of AR into the operating room has permitted a new perception of neurosurgical diseases, not only for neurosurgical planning, patient positioning, and incision design but also for intraoperative maneuvering and identification of critical neurovascular structures and tumor boundaries. Implementing AR, virtual reality, and mixed reality has introduced neurosurgeons into a new era of artificial interfaces. Meningiomas are the most frequent primary benign tumors commonly related to paramount neurovascular structures and bone landmarks. Integration of preoperative 3D reconstructions used for surgical planning into AR can now be inserted into the microsurgical field, injecting information into head-up displays and microscopes with integrated head-up displays, aiming to guide neurosurgeons intraoperatively to prevent potential injuries. This manuscript aims to provide a mini-review of the usage of AR for intracranial meningioma resection.

Augmented Reality-Assisted versus Freehand Ventriculostomy in a Head Model

BACKGROUND

 Ventriculostomy (VST) is a frequent neurosurgical procedure. Freehand catheter placement represents the standard current practice. However, multiple attempts are often required. We present augmented reality (AR) headset guided VST with in-house developed head models. We conducted a proof of concept study in which we tested AR-guided as well as freehand VST. Repeated AR punctures were conducted to investigate if a learning curve can be derived.

METHODS

 Five custom-made 3D-printed head models, each holding an anatomically different ventricular system, were filled with agarose gel. Eleven surgeons placed two AR-guided as well as two freehand ventricular drains per head. A subgroup of four surgeons did a total of three series of AR-guided punctures each to test for a learning curve. A Microsoft HoloLens served as the hardware platform. The marker-based tracking did not require rigid head fixation. Catheter tip position was evaluated in computed tomography scans.

RESULTS

 Marker-tracking, image segmentation, and holographic display worked satisfactorily. In freehand VST, a success rate of 72.7% was achieved, which was higher than under AR guidance (68.2%, difference not statistically significant). Repeated AR-guided punctures increased the success rate from 65 to 95%. We assume a steep learning curve as repeated AR-guided punctures led to an increase in successful attempts. Overall user experience showed positive feedback.

CONCLUSIONS

 We achieved promising results that encourage the continued development and technical improvement. However, several more developmental steps have to be taken before an application in humans can be considered. In the future, AR headset-based holograms have the potential to serve as a compact navigational help inside and outside the operating room.

External Ventricular Drain Training in Medical Students Improves Procedural Accuracy and Attitudes Toward Virtual Reality

OBJECTIVE

Neurosurgery residents face a learning curve at the beginning of residency. Virtual reality (VR) training may alleviate challenges through an accessible, reusable, anatomical model.

METHODS

Medical students performed external ventricular drain placements in VR to characterize the learning curve from novice to proficient. Distance from catheter to foramen of Monro and location with respect to ventricle were recorded. Changes in attitudes toward VR were assessed. Neurosurgery residents performed external ventricular drain placements to validate proficiency benchmarks. Resident and student impressions of the VR model were compared.

RESULTS

Twenty-one students with no neurosurgical experience and 8 neurosurgery residents participated. Student performance improved significantly from trial 1 to 3 (15 mm [12.1-20.70] vs. 9.7 [5.8-15.3], P = 0.02). Student attitudes regarding VR utility improved significantly posttrial. The distance to foramen of Monro was significantly shorter for residents than for students in trial 1 (9.05 [8.25-10.73] vs. 15 [12.1-20.70], P = 0.007) and trial 2 (7.45 [6.43-8.3] vs. 19.5 [10.9-27.6], P = 0.002). By trial 3 there was no significant difference (10.1 [8.63-10.95 vs. 9.7 [5.8-15.3], P = 0.62). Residents and students provided similarly positive feedback for VR in resident curricula, patient consent, preoperative practice and planning. Residents provided more neutral-to-negative feedback regarding skill development, model fidelity, instrument movement, and haptic feedback.

CONCLUSIONS

Students showed significant improvement in procedural efficacy which may simulate resident experiential learning. Improvements in fidelity are needed before VR can become a preferred training technique in neurosurgery.

External ventricular drains and risk of freehand placement: A systematic review and meta-analysis

OBJECTIVE

External ventricular drains (EVDs) are used to monitor and treat elevated intracranial pressure. EVDs are often placed blindly without the use of imaging guidance, and successful placement with respect to pass attempts and final catheter location may suffer as a result of this freehand technique.

METHODS

A systematic literature search was conducted in PubMed, Embase, Web of Science, and Cochrane databases to identify studies pertaining to freehand EVD placement through March 30, 2022. Studies were included if they reported percentage of EVDs placed successfully on the first pass attempt, or final catheter location as defined by the Kakarla Grading System. Pooled weighted incidence estimates and 95% confidence intervals (95%CI) were calculated using a random effects model.

RESULTS

Of the 2964 results returned from the literature search, 39 studies were included in this meta-analysis. These studies reported on 6313 EVDs placed via freehand technique in 6070 patients with the following respective incidence: successful EVD placement on the first attempt (78%, 95%CI: 67-86%); placement with a Kakarla Grade of 1 (optimal location) (72%, 95%CI: 66-77%); hemorrhage (7%, 95%CI: 6-10%), and infection (5%, 95%CI: 3-8%).

CONCLUSIONS

Only 78% of EVDs in this meta-analysis were placed successfully on the first pass, and only 72% of final placements were deemed optimal. This represents a relatively high rate of suboptimal outcomes with respect to EVD placement, which could potentially be avoided with the use of navigation-assisted placement techniques.

Improved Accuracy and Lowered Learning Curve of Ventricular Targeting Using Augmented Reality-Phantom and Cadaveric Model Testing

BACKGROUND

Augmented reality (AR) has demonstrated significant potential in neurosurgical cranial, spine, and teaching applications. External ventricular drain (EVD) placement remains a common procedure, but with error rates in targeting between 10% and 40%.

OBJECTIVE

To evaluate Novarad VisAR guidance system for the placement of EVDs in phantom and cadaveric models.

METHODS

Two synthetic ventricular phantom models and a third cadaver model underwent computerized tomography imaging and registration with the VisAR system (Novarad). Root mean square (RMS), angular error (γ), and Euclidian distance were measured by multiple methods for various standard EVD placements.

RESULTS

Computerized tomography measurements on a phantom model (0.5-mm targets showed a mean Euclidean distance error of 1.20 ± 0.98 mm and γ of 1.25° ± 1.02°. Eight participants placed EVDs in lateral and occipital burr holes using VisAR in a second phantom anatomic ventricular model (mean RMS: 3.9 ± 1.8 mm, γ: 3.95° ± 1.78°). There were no statistically significant differences in accuracy for postgraduate year level, prior AR experience, prior EVD experience, or experience with video games ( P > .05). In comparing EVDs placed with anatomic landmarks vs VisAR navigation in a cadaver, VisAR demonstrated significantly better RMS and γ, 7.47 ± 0.94 mm and 7.12° ± 0.97°, respectively ( P ≤ .05).

CONCLUSION

The novel VisAR AR system resulted in accurate placement of EVDs with a rapid learning curve, which may improve clinical treatment and patient safety. Future applications of VisAR can be expanded to other cranial procedures.

The HoloLens in medicine: A systematic review and taxonomy

The HoloLens (Microsoft Corp., Redmond, WA), a head-worn, optically see-through augmented reality (AR) display, is the main player in the recent boost in medical AR research. In this systematic review, we provide a comprehensive overview of the usage of the first-generation HoloLens within the medical domain, from its release in March 2016, until the year of 2021. We identified 217 relevant publications through a systematic search of the PubMed, Scopus, IEEE Xplore and SpringerLink databases. We propose a new taxonomy including use case, technical methodology for registration and tracking, data sources, visualization as well as validation and evaluation, and analyze the retrieved publications accordingly. We find that the bulk of research focuses on supporting physicians during interventions, where the HoloLens is promising for procedures usually performed without image guidance. However, the consensus is that accuracy and reliability are still too low to replace conventional guidance systems. Medical students are the second most common target group, where AR-enhanced medical simulators emerge as a promising technology. While concerns about human-computer interactions, usability and perception are frequently mentioned, hardly any concepts to overcome these issues have been proposed. Instead, registration and tracking lie at the core of most reviewed publications, nevertheless only few of them propose innovative concepts in this direction. Finally, we find that the validation of HoloLens applications suffers from a lack of standardized and rigorous evaluation protocols. We hope that this review can advance medical AR research by identifying gaps in the current literature, to pave the way for novel, innovative directions and translation into the medical routine.

Neuro-oncological augmented reality planning for intracranial tumor resection

Background

Before starting surgery for the resection of an intracranial tumor, its outlines are typically marked on the skin of the patient. This allows for the planning of the optimal skin incision, craniotomy, and angle of approach. Conventionally, the surgeon determines tumor borders using neuronavigation with a tracked pointer. However, interpretation errors can lead to important deviations, especially for deep-seated tumors, potentially resulting in a suboptimal approach with incomplete exposure. Augmented reality (AR) allows displaying of the tumor and critical structures directly on the patient, which can simplify and improve surgical preparation.

Methods

We developed an AR-based workflow for intracranial tumor resection planning deployed on the Microsoft HoloLens II, which exploits the built-in infrared-camera for tracking the patient. We initially performed a phantom study to assess the accuracy of the registration and tracking. Following this, we evaluated the AR-based planning step in a prospective clinical study for patients undergoing resection of a brain tumor. This planning step was performed by 12 surgeons and trainees with varying degrees of experience. After patient registration, tumor outlines were marked on the patient's skin by different investigators, consecutively using a conventional neuronavigation system and an AR-based system. Their performance in both registration and delineation was measured in terms of accuracy and duration and compared.

Results

During phantom testing, registration errors remained below 2.0 mm and 2.0° for both AR-based navigation and conventional neuronavigation, with no significant difference between both systems. In the prospective clinical trial, 20 patients underwent tumor resection planning. Registration accuracy was independent of user experience for both AR-based navigation and the commercial neuronavigation system. AR-guided tumor delineation was deemed superior in 65% of cases, equally good in 30% of cases, and inferior in 5% of cases when compared to the conventional navigation system. The overall planning time (AR = 119 ± 44 s, conventional = 187 ± 56 s) was significantly reduced through the adoption of the AR workflow (p &lt; 0.001), with an average time reduction of 39%.

Conclusion

By providing a more intuitive visualization of relevant data to the surgeon, AR navigation provides an accurate method for tumor resection planning that is quicker and more intuitive than conventional neuronavigation. Further research should focus on intraoperative implementations.

Evaluation of AR visualization approaches for catheter insertion into the ventricle cavity

Augmented reality (AR) has shown potential in computer-aided surgery. It allows for the visualization of hidden anatomical structures as well as assists in navigating and locating surgical instruments at the surgical site. Various modalities (devices and/or visualizations) have been used in the literature, but few studies investigated the adequacy/superiority of one modality over the other. For instance, the use of optical see-through (OST) HMDs has not always been scientifically justified. Our goal is to compare various visualization modalities for catheter insertion in external ventricular drain and ventricular shunt procedures. We investigate two AR approaches: (1) 2D approaches consisting of a smartphone and a 2D window visualized through an OST (Microsoft HoloLens 2), and (2) 3D approaches consisting of a fully aligned patient model and a model that is adjacent to the patient and is rotationally aligned using an OST. 32 participants joined this study. For each visualization approach, participants were asked to perform five insertions after which they filled NASA-TLX and SUS forms. Moreover, the position and orientation of the needle with respect to the planning during the insertion task were collected. The results show that participants achieved a better insertion performance significantly under 3D visualizations, and the NASA-TLX and SUS forms reflected the preference of participants for these approaches compared to 2D approaches.

Expanding Educational Frontiers in Neurosurgery: Current and Future Uses of Augmented Reality

BACKGROUND

Augmented reality (AR) technology is a new and promising option to advance and expand neurosurgical training because of recent advances in computer vision technology, improved AR software and hardware, and growing acceptance of this technology in clinical practice.

OBJECTIVE

To analyze the current status of AR use cases with the goal of envisioning future uses of AR in neurosurgical education.

METHODS

Articles applying to AR technology use in neurosurgical education were identified using PubMed, Google Scholar, and Web of Science databases following the Preferred Reporting Items of Systematic Reviews and Meta-Analyses guidelines. Articles were included for review based on applicable content related to neurosurgical or neuroanatomy training. Assessment of literature quality was completed using standardized MERSQI scoring.

RESULTS

The systematic search identified 2648 unique articles. Of these, 12 studies met inclusion criteria after extensive review. The average MERSQI score was 10.2 (SD: 1.7). The most common AR platform identified in this study was the Microsoft Hololens. The primary goals of the studies were to improve technical skills and approaches to surgical planning or improve understanding of neuroanatomy.

CONCLUSION

Augmented reality has emerged as a promising training tool in neurosurgery. This is demonstrated in the wide range of cases in technical training and anatomic education. It remains unclear how AR-based training compares directly with traditional training methods; however, AR shows great promise in the ability to further enhance and innovate neurosurgical education and training.

Use of Mixed Reality in Neuro-Oncology: A Single Centre Experience

(1) Background: Intra-operative neuronavigation is currently an essential component to most neurosurgical operations. Recent progress in mixed reality (MR) technology has attempted to overcome the disadvantages of the neuronavigation systems. We present our experience using the HoloLens 2 in neuro-oncology for both intra- and extra-axial tumours. (2) Results: We describe our experience with three patients who underwent tumour resection. We evaluated surgeon experience, accuracy of superimposed 3D image in tumour localisation with standard neuronavigation both pre- and intra-operatively. Surgeon training and usage for HoloLens 2 was short and easy. The process of image overlay was relatively straightforward for the three cases. Registration in prone position with a conventional neuronavigation system is often difficult, which was easily overcome during use of HoloLens 2. (3) Conclusion: Although certain limitations were identified, the authors feel that this system is a feasible alternative device for intra-operative visualization of neurosurgical pathology. Further studies are being planned to assess its accuracy and suitability across various surgical disciplines.

Mixed Reality in Modern Surgical and Interventional Practice: Narrative Review of the Literature

BACKGROUND

Mixed reality (MR) and its potential applications have gained increasing interest within the medical community over the recent years. The ability to integrate virtual objects into a real-world environment within a single video-see-through display is a topic that sparks imagination. Given these characteristics, MR could facilitate preoperative and preinterventional planning, provide intraoperative and intrainterventional guidance, and aid in education and training, thereby improving the skills and merits of surgeons and residents alike.

OBJECTIVE

In this narrative review, we provide a broad overview of the different applications of MR within the entire spectrum of surgical and interventional practice and elucidate on potential future directions.

METHODS

A targeted literature search within the PubMed, Embase, and Cochrane databases was performed regarding the application of MR within surgical and interventional practice. Studies were included if they met the criteria for technological readiness level 5, and as such, had to be validated in a relevant environment.

RESULTS

A total of 57 studies were included and divided into studies regarding preoperative and interventional planning, intraoperative and interventional guidance, as well as training and education.

CONCLUSIONS

The overall experience with MR is positive. The main benefits of MR seem to be related to improved efficiency. Limitations primarily seem to be related to constraints associated with head-mounted display. Future directions should be aimed at improving head-mounted display technology as well as incorporation of MR within surgical microscopes, robots, and design of trials to prove superiority.

Attitudes Toward Neurosurgery Education for the Nonneurosurgeon: A Survey Study and Critical Analysis of U.S. Military Training Techniques and Future Prospects

BACKGROUND

The U.S. military requires medical readiness to support forward-deployed combat operations. Because time and distance to neurosurgical capabilities vary within the deployed trauma system, nonneurosurgeons are required to perform emergent cranial procedures in select cases. It is unclear whether these surgeons have sufficient training in these procedures.

METHODS

This quality-improvement study involved a voluntary, anonymized specialty-specific survey of active-duty surgeons about their experience and attitudes toward U.S. military emergency neurosurgical training.

RESULTS

Survey responses were received from 104 general surgeons and 26 neurosurgeons. Among general surgeons, 81% have deployed and 53% received training in emergency neurosurgical procedures before deployment. Only 16% of general surgeons reported participating in craniotomy/craniectomy procedures in the last year. Nine general surgeons reported performing an emergency neurosurgical procedure while on deployment/humanitarian mission, and 87% of respondents expressed interest in further predeployment emergency neurosurgery training. Among neurosurgeons, 81% had participated in training nonneurosurgeons and 73% believe that more comprehensive training for nonneurosurgeons before deployment is needed. General surgeons proposed lower procedure minimums for competency for external ventricular drain placement and craniotomy/craniectomy than did neurosurgeons. Only 37% of general surgeons had used mixed/augmented reality in any capacity previously; for combat procedures, most (90%) would prefer using synchronous supervision via high-fidelity video teleconferencing over mixed reality.

CONCLUSIONS

These survey results show a gap in readiness for neurosurgical procedures for forward-deployed general surgeons. Capitalizing on capabilities such as mixed/augmented reality would be a force multiplier and a potential means of improving neurosurgical capabilities in the forward-deployed environments.

Mixed reality surgical mentoring of combat casualty care related procedures in a perfused cadaver model: Initial results of a randomized feasibility study

BACKGROUND

Most telemedicine modalities have limited ability to enhance procedural and operative care. We developed a novel system to provide synchronous bidirectional expert mixed reality-enabled virtual procedural mentoring. In this feasibility study, we evaluated mixed reality mentoring of combat casualty care related procedures in a re-perfused cadaver model.

METHODS

Novices received real-time holographic mentoring from experts using augmented reality via Hololens (Microsoft Inc, Redmond, WA). The experts maintained real-time awareness of the novice's operative environment using virtual reality via HTC-Vive (HTC Corp, Xindian District, Taiwan). Additional cameras (both environments) and novel software created the immersive, shared, 3-dimensional mixed reality environment in which the novice and expert collaborated. The novices were prospectively randomized to either mixed reality or audio-only mentoring. Blinded experts independently evaluated novice procedural videos using a 5-point Likert scale-based questionnaire. Nonparametric variables were evaluated using the Wilcoxon rank-sum test and comparisons using the χ² analysis; significance was defined at P < .05.

RESULTS

Surgeon and nonsurgeon novices (14) performed 69 combat casualty care-related procedures (38 mixed reality, 31 audio), including various vascular exposures, 4-compartment lower leg fasciotomy, and emergency neurosurgical procedures; 85% were performed correctly with no difference in either group. Upon video review, mixed reality-mentored novices showed no difference in procedural flow and forward planning (3.67 vs 3.28, P = .21) or the likelihood of performing individual procedural steps correctly (4.12 vs 3.59, P = .06).

CONCLUSION

In this initial feasibility study, our novel mixed reality-based mentoring system successfully facilitated the performance of a wide variety of combat casualty care relevant procedures using a high fidelity re-perfused cadaver model. The small sample size and limited variety of novice types likely impacted the ability of holographically mentored novices to demonstrate improvement over the audio-only control group. Despite this, using virtual, augmented, and mixed reality technologies for procedural mentoring demonstrated promise, and further study is needed.

Pre-Interventional 3D-Printing-Assisted Planning of Flow Disrupter Implantation for the Treatment of an Intracranial Aneurysm

Intrasaccular flow disrupter devices (ISFD) have opened up new ways to treat intracranial aneurysms but choosing the correct size of ISFD can be challenging. We describe the first use of 3D printing to assist in the choice of ISFD, and we report an illustrative case. We developed a technique that uses preoperative angiography to make a plastic model of the aneurysm. We tested the deployment of different sizes of intrasaccular flow disruptor on the 3D model under fluoroscopy. The best devices were then used as the first-line strategy to treat the patient. The preoperative 3D printing helped in the successful selection of a first-line ISFD, which was not the one recommended by the manufacturer. Three-dimensional printing can provide interesting information regarding the treatment of intracranial aneurysms using ISFD. Further studies are needed to fully assess its benefits.