Avoiding 3D Obstacles in Mixed Reality: Does It Differ from Negotiating Real Obstacles?

Application of Augmented Reality for Accurate Punctures During Stage 1 Sacral Neuromodulation

PURPOSE

Precise electrode placement is crucial for the success of sacral neuromodulation (SNM). The aim of this study was to explore a more accurate and convenient method for positioning punctures during the first stage of SNM.

METHODS

This retrospective study compared preoperative baseline values, intraoperative indicators, postoperative scores, and other clinical data from 130 patients who underwent SNM electrode implantation at our department between 2018 and 2023. The patients were divided into an experimental group and a control group to assess the advantages and feasibility of augmented reality (AR)-guided sacral nerve electrode implantation.

RESULTS

The experimental group experienced fewer intraoperative puncture attempts and achieved more accurate AR-guided localization punctures. Additionally, there were more responsive electrode contact points (2.74±0.51 vs. 2.46±0.74) and a lower initial voltage postimplantation (1.09±0.39 V vs. 1.69±0.43 V). The number of intraoperative x-ray fluoroscopies was significantly lower in the experimental group than in the control group (5.94±1.46 vs. 9.22±1.93), leading to a shorter overall operation time (61.32±11.27 minutes vs. 83.49±15.84 minutes). Furthermore, there was no need for additional local anesthetic drugs during the surgery in the experimental group. Comparative observations revealed no significant differences in intraoperative blood loss or the sacral hole location for electrode implantation between the 2 groups. Although the incidence of wound infection and the rate of permanent implantation in stage 2 were similar in both groups, the pain score on the first day postoperation was significantly lower in the experimental group than in the control group (2.62±0.697 vs. 2.83±0.816).

CONCLUSION

AR-guided sacral nerve modulation implantation can reduce both the number of punctures and the duration of the operation while ensuring safety and effectiveness. This technique can enhance the contact points of the response electrode, effectively lower the initial response voltage, and stabilize the electrode.

A larger augmented-reality field of view improves interaction with nearby holographic objects

Augmented-reality (AR) applications have shown potential for assisting and modulating gait in health-related fields, like AR cueing of foot-placement locations in people with Parkinson's disease. However, the size of the AR field of view (AR-FOV), which is smaller than one's own FOV, might affect interaction with nearby floor-based holographic objects. The study's primary objective was to evaluate the effect of AR-FOV size on the required head orientations for viewing and interacting with real-world and holographic floor-based objects during standstill and walking conditions. Secondary, we evaluated the effect of AR-FOV size on gait speed when interacting with real-world and holographic objects. Sixteen healthy middle-aged adults participated in two experiments wearing HoloLens 1 and 2 AR headsets that differ in AR-FOV size. To confirm participants' perceived differences in AR-FOV size, we examined the head orientations required for viewing nearby and far objects from a standstill position (Experiment 1). In Experiment 2, we examined the effect of AR-FOV size on head orientations and gait speeds for negotiating 2D and 3D objects during walking. Less downward head orientation was required for looking at nearby holographic objects with HoloLens 2 than with HoloLens 1, as expected given differences in perceived AR-FOV size (Experiment 1). In Experiment 2, a greater downward head orientation was observed for interacting with holographic objects compared to real-world objects, but again less so for HoloLens 2 than HoloLens 1 along the line of progression. Participants walked slightly but significantly slower when interacting with holographic objects compared to real-world objects, without any differences between the HoloLenses. To conclude, the increased size of the AR-FOV did not affect gait speed, but resulted in more real-world-like head orientations for seeing and picking up task-relevant information when interacting with floor-based holographic objects, improving the potential efficacy of AR cueing applications.

Validation of a Persian version of an English language ecologically-valid assessment of executive functions through childhood and adolescence

Childhood and adolescence are pivotal periods for cognitive development. Executive functions are crucial for efficient cognitive functioning, so accurate assessment is important. One ecologically-valid virtual reality test is the Jansari assessment of Executive Functions for Children (JEF-C©). In a cross-sectional study, we aimed at translating, adapting and validating JEF-C into Persian, and at investigating whether this Persian version (JEF-C (P)) can identify stages of development of executive functions in children aged from 8 to 16. Children and adolescents (N = 146) falling into three age groups participated: 8-10, 11-13 and 14-16 years old. They completed JEF-C (P) and the Wisconsin Card Sorting Test (WCST). There were acceptable Cronbach's alpha coefficients for JEF-C(P) total score (α = .72) and all constructs, except action-based prospective memory, had a positive impact on total internal consistency. There was an effect of age group on overall JEF-C (P) performance and of age on four constructs. There was also a correlation between the number of categories on WCST and the prioritization construct of JEF-C (P). It seems that JEF-C (P) is an ecologically valid executive function assessment sensitive to age and could be useful for both researchers and clinicians working with children.

Gait-modifying effects of augmented-reality cueing in people with Parkinson's disease

Introduction

External cueing can improve gait in people with Parkinson's disease (PD), but there is a need for wearable, personalized and flexible cueing techniques that can exploit the power of action-relevant visual cues. Augmented Reality (AR) involving headsets or glasses represents a promising technology in those regards. This study examines the gait-modifying effects of real-world and AR cueing in people with PD.

Methods

21 people with PD performed walking tasks augmented with either real-world or AR cues, imposing changes in gait speed, step length, crossing step length, and step height. Two different AR headsets, differing in AR field of view (AR-FOV) size, were used to evaluate potential AR-FOV-size effects on the gait-modifying effects of AR cues as well as on the head orientation required for interacting with them.

Results

Participants modified their gait speed, step length, and crossing step length significantly to changes in both real-world and AR cues, with step lengths also being statistically equivalent to those imposed. Due to technical issues, step-height modulation could not be analyzed. AR-FOV size had no significant effect on gait modifications, although small differences in head orientation were observed when interacting with nearby objects between AR headsets.

Conclusion

People with PD can modify their gait to AR cues as effectively as to real-world cues with state-of-the-art AR headsets, for which AR-FOV size is no longer a limiting factor. Future studies are warranted to explore the merit of a library of cue modalities and individually-tailored AR cueing for facilitating gait in real-world environments.

When running is easier than walking: effects of experience and gait on human obstacle traversal in virtual reality

Humans readily traverse obstacles irrespective of whether they walk or run, despite strong differences between these gaits. Assuming that the control of human obstacle traversal may be either gait-specific or gait-independent, the present study investigates whether previous experience in an obstacle traversal task transfers between the two gaits, and, if this was the case, whether transfer worked both ways. To this end, we conducted a within-group comparison of kinematic adjustments during human obstacle traversal in both walking and running, with distinct participant groups for the two gait sequences. Participants (n = 12/12 (f/m), avg. 25 yo) were motion captured as they traversed obstacles at walking and running speeds on a treadmill, surrounded by an immersive virtual reality (VR) environment. We find that kinematics recorded in our VR setup are consistent with that obtained in real-world experiments. Comparison of learning curves reveals that participants are able to utilize previous experience and transfer learned adjustments from one gait to another. However, this transfer is not symmetrical, with previous experience during running leading to increased success rate in walking, but not the other way round. From a range of step parameters we identified lacking toe height of the trailing leg as the main cause for this asymmetry.

Visual Feedback in Augmented Reality to Walk at Predefined Speed Cross-Sectional Study Including Children With Cerebral Palsy

In an augmented reality environment, the range of possible real-time visual feedback is extensive. This study aimed to compare the impact of six scenarios in augmented reality combining four visual feedback characteristics on achieving a target walking speed. The six scenarios have been developed for Microsoft Hololens augmented reality headset. The four feedback characteristics that we have varied were: Color; Spatial anchoring; Speed of the feedback, and Persistence. Each characteristic could have different values (for example, the color could be unicolor, bicolor, or gradient). Participants had to walk for two consecutive walking trials for each scenario: at their maximal speed and an intermediate speed. Mean speed, percentage of time spent above or around target speed, and time to reach target speed were compared between scenarios using mixed linear models. A total of 25 children with disabilities have been included. The feasibility and user experience were excellent. Mean speed during scenario 6, which displayed feedback with gradient color, attached to the world, with a speed relative to the player equal to his speed, and that disappeared over time, was significantly higher than other scenarios and control (p =0.003). Participants spent 80.98% of time above target speed during scenario 6. This scenario mixed the best combination of feedback characteristics to exceed the target walking speed (p=0.0058). Scenarios 5 and 6, which shared the same feedback characteristics for spatial anchoring (world-locked) and feedback speed (equal to the player speed), decreased the time to reach the target speed (p=0.019). Delivering multi-modal feedback has been recognized as more effective for improving motor performance. Therefore, our results showed that not all visual feedback had the same impact on performance. Further studies are required to test the weight of each feedback characteristic and their possible interactions inside each scenario. This study was registered in the ClinicalTrials.gov database (NCT04460833).

A Wearable Mixed Reality Platform to Augment Overground Walking: A Feasibility Study

Humans routinely modify their walking speed to adapt to functional goals and physical demands. However, damage to the central nervous system (CNS) often results in abnormal modulation of walking speed and increased risk of falls. There is considerable interest in treatment modalities that can provide safe and salient training opportunities, feedback about walking performance, and that may augment less reliable sensory feedback within the CNS after injury or disease. Fully immersive virtual reality technologies show benefits in boosting training-related gains in walking performance; however, they lack views of the real world that may limit functional carryover. Augmented reality and mixed reality head-mount displays (MR-HMD) provide partially immersive environments to extend the virtual reality benefits of interacting with virtual objects but within an unobstructed view of the real world. Despite this potential advantage, the feasibility of using MR-HMD visual feedback to promote goal-directed changes in overground walking speed remains unclear. Thus, we developed and evaluated a novel mixed reality application using the Microsoft HoloLens MR-HMD that provided real-time walking speed targets and augmented visual feedback during overground walking. We tested the application in a group of adults not living with disability and examined if they could use the targets and visual feedback to walk at 85%, 100%, and 115% of each individual’s self-selected speed. We examined whether individuals were able to meet each target gait speed and explored differences in accuracy across repeated trials and at the different speeds. Additionally, given the importance of task-specificity to therapeutic interventions, we examined if walking speed adjustment strategies were consistent with those observed during usual overground walking, and if walking with the MR-HMD resulted in increased variability in gait parameters. Overall, participants matched their overground walking speed to the target speed of the MR-HMD visual feedback conditions (all p-values > 0.05). The percent inaccuracy was approximately 5% across all speed matching conditions and remained consistent across walking trials after the first overall walking trial. Walking with the MR-HMD did not result in more variability in walking speed, however, we observed more variability in stride length and time when walking with feedback from the MR-HMD compared to walking without feedback. The findings offer support for mixed reality-based visual feedback as a method to provoke goal-specific changes in overground walking behavior. Further studies are necessary to determine the clinical safety and efficacy of this MR-HMD technology to provide extrinsic sensory feedback in combination with traditional treatments in rehabilitation.

A Review of the Potential of Virtual Walking Techniques for Gait Rehabilitation

Virtual reality (VR) technology has emerged as a promising tool for studying and rehabilitating gait disturbances in different cohorts of patients (such as Parkinson's disease, post-stroke, or other neurological disorders) as it allows patients to be engaged in an immersive and artificial environment, which can be designed to address the particular needs of each individual. This review demonstrates the state of the art in applications of virtual walking techniques and related technologies for gait therapy and rehabilitation of people with movement disorders makes recommendations for future research and discusses the use of VR in the clinic. However, the potential for using these techniques in gait rehabilitation is to provide a more personalized approach by simulate the experience of natural walking, while patients with neurological disorders are maintained localized in the real world. The goal of our work is to investigate how the human nervous system controls movement in health and neurodegenerative disease.

Review of Microsoft HoloLens Applications over the Past Five Years

Since Microsoft HoloLens first appeared in 2016, HoloLens has been used in various industries, over the past five years. This study aims to review academic papers on the applications of HoloLens in several industries. A review was performed to summarize the results of 44 papers (dated between January 2016 and December 2020) and to outline the research trends of applying HoloLens to different industries. This study determined that HoloLens is employed in medical and surgical aids and systems, medical education and simulation, industrial engineering, architecture, civil engineering and other engineering fields. The findings of this study contribute towards classifying the current uses of HoloLens in various industries and identifying the types of visualization techniques and functions.

Auto-Refining Reconstruction Algorithm for Recreation of Limited Angle Humanoid Depth Data

With the majority of research, in relation to 3D object reconstruction, focusing on single static synthetic object reconstruction, there is a need for a method capable of reconstructing morphing objects in dynamic scenes without external influence. However, such research requires a time-consuming creation of real world object ground truths. To solve this, we propose a novel three-staged deep adversarial neural network architecture capable of denoising and refining real-world depth sensor input for full human body posture reconstruction. The proposed network has achieved Earth Mover and Chamfer distances of 0.059 and 0.079 on synthetic datasets, respectively, which indicates on-par experimental results with other approaches, in addition to the ability of reconstructing from maskless real world depth frames. Additional visual inspection to the reconstructed pointclouds has shown that the suggested approach manages to deal with the majority of the real world depth sensor noise, with the exception of large deformities to the depth field.

Applications of Head-Mounted Displays and Smart Glasses in Vascular Surgery

OBJECTIVES

Advances in virtual, augmented and mixed reality have led to the development of wearable technologies including head mounted displays (HMD) and smart glasses. While there is a growing interest on their potential applications in health, only a few studies have addressed so far their use in vascular surgery. The aim of this review was to summarize the fundamental notions associated with these technologies and to discuss potential applications and current limits for their use in vascular surgery.

METHODS

A comprehensive literature review was performed to introduce the fundamental concepts and provide an overview of applications of HMD and smart glasses in surgery.

RESULTS

HMD and smart glasses demonstrated a potential interest for the education of surgeons including anatomical teaching, surgical training, teaching and telementoring. Applications for pre-surgical planning have been developed in general and cardiac surgery and could be transposed for a use in vascular surgery. The use of wearable technologies in the operating room has also been investigated in both general and cardiovascular surgery and demonstrated its potential interest for image-guided surgery and data collection.

CONCLUSION

Studies performed so far represent a proof of concept of the interest of HMD and smart glasses in vascular surgery for education of surgeons and for surgical practice. Although these technologies exhibited encouraging results for applications in vascular surgery, technical improvements and further clinical research in large series are required before hoping using them in daily clinical practice.

C-Gait for Detecting Freezing of Gait in the Early to Middle Stages of Parkinson's Disease: A Model Prediction Study

Objective

Efficient methods for assessing walking adaptability in individuals with Parkinson's disease (PD) are urgently needed. Therefore, this study aimed to assess C-Gait for detecting freezing of gait (FOG) in patients with early- to middle-stage PD.

Method

People with PD (PWP) diagnosis (Hoehn and Yahr stages 1-3) were recruited from April 2019 to November 2019 in Beijing Rehabilitation Hospital. The participants performed six items of walking adaptability on an instrumented treadmill augmented with visual targets and obstacles (C-Mill). The patient's walking adaptability was evaluated by C-Gait assessment and traditional walking tests, and FOG-related indexes were collected as outcome measures. Two discriminant models were established by stepwise discriminant analysis; area under the receiver operating characteristic (ROC) curve (AUC) was used to validate the models.

Result

In total, 53 patients were included in this study. Most C-Gait assessment items had no or low correlations with traditional walking tests. The obstacle avoidance (r = -0.639, P = 0.003) and speed of adaptation (r = -0.486, P = 0.035) items could lead to FOG with high sensitivity. In addition, the C-Gait assessment model (AUC = 0.755) had slightly better discrimination of freezers from non-freezers compared with traditional walking test models (AUC = 0.672); specifically, obstacle avoidance and speed of adaptation have uniquely discriminant potential.

Conclusion

C-gait assessment could provide additional value to the traditional walking tests for PD. Gait adaptability assessment, as measured by C-Gait, may be able to help identify freezers in a PD population.

Hebrew version of the Jansari assessment of Executive Functions for Children (JEF-C©): Translation, adaptation and validation

The Jansari assessment of Executive Functions for Children (JEF-C^©) is a non-immersive computerized assessment of executive functions (EFs). This study aimed to create a cross-culturally adapted Hebrew version, JEF-C(H)^© and to assess reliability and validity in the Israeli context. Forty typically developing Israeli children and adolescents, aged 11-18 years, were assessed with JEF-C(H)^©. In addition, participants and their parents filled in the Behaviour Rating Inventory of Executive Function (BRIEF). JEF-C(H)^© was found to be feasible in Israeli children and adolescents. The internal consistency was acceptable (Cronbach's alpha = 0.79). Most of the JEF-C(H)^© subtests and the Average score showed significant positive moderate to high correlations with age, ranging from 0.40 to 0.78 demonstrating construct validity. Multiple significant correlations were also found between the JEF-C(H)^© Average score and the BRIEF indices as well as total score in the Parent and Self-report questionnaires. These preliminary findings support the reliability and validity of this version. Current findings demonstrate the potential clinical utility of JEF-C(H)^© as an ecologically valid tool for Israeli children and adolescents in the assessment of EFs.

Quantifying Spatiotemporal Gait Parameters with HoloLens in Healthy Adults and People with Parkinson's Disease: Test-Retest Reliability, Concurrent Validity, and Face Validity

Microsoft’s HoloLens, a mixed-reality headset, provides, besides holograms, rich position data of the head, which can be used to quantify what the wearer is doing (e.g., walking) and to parameterize such acts (e.g., speed). The aim of the current study is to determine test-retest reliability, concurrent validity, and face validity of HoloLens 1 for quantifying spatiotemporal gait parameters. This was done in a group of 23 healthy young adults (mean age 21 years) walking at slow, comfortable, and fast speeds, as well as in a group of 24 people with Parkinson’s disease (mean age 67 years) walking at comfortable speed. Walking was concurrently measured with HoloLens 1 and a previously validated markerless reference motion-registration system. We comprehensively evaluated HoloLens 1 for parameterizing walking (i.e., walking speed, step length and cadence) in terms of test-retest reliability (i.e., consistency over repetitions) and concurrent validity (i.e., between-systems agreement), using the intraclass correlation coefficient (ICC) and Bland–Altman’s bias and limits of agreement. Test-retest reliability and between-systems agreement were excellent for walking speed (ICC ≥ 0.861), step length (ICC ≥ 0.884), and cadence (ICC ≥ 0.765), with narrower between-systems than over-repetitions limits of agreement. Face validity was demonstrated with significantly different walking speeds, step lengths and cadences over walking-speed conditions. To conclude, walking speed, step length, and cadence can be reliably and validly quantified from the position data of the wearable HoloLens 1 measurement system, not only for a broad range of speeds in healthy young adults, but also for self-selected comfortable speed in people with Parkinson’s disease.