A guide to stereoscopic 3D displays in medicine

Autostereoscopic 3D viewing can change the dimensions of the crystalline lens in myopes

PURPOSE

Autostereoscopic displays have become increasingly common, but their impact on ocular dimensions remains unknown. We sought to identify changes in the crystalline lens dimensions induced by autostereoscopic three-dimensional (3D) viewing.

METHODS

Forty young adults (age: 22.6 ± 2.0 years, male/female: 15/25) were consecutively enrolled and randomly divided into two groups (3D and two-dimensional [2D] viewing groups) to watch a 30-min movie clip displayed in 3D or 2D mode on a tablet computer. The lens thickness (LT), diameter, curvature, decentration and tilt were measured with anterior segment optical coherence tomography under both non-accommodating (static) and accommodating conditions.

RESULTS

In the static condition, the LT decreased by 0.03 ± 0.03 mm (p < 0.001) and the anterior radius of curvature (ARC) increased by 0.49 ± 0.59 mm (p = 0.001) post-3D viewing. In contrast, following 2D viewing, the ARC decreased by 0.23 ± 0.25 mm (p = 0.001). Additionally, the increase in the steep ARC post-3D viewing was greater in high-myopic eyes than low to moderate myopic eyes (p = 0.04). When comparing the accommodative with the static (non-accommodative) condition, for 3D viewing the lens decentration decreased (-0.03 ± 0.05 mm, p = 0.02); while for 2D viewing, the posterior curvature radius (-0.14 ± 0.20 mm, p = 0.006) and diameter (-0.13 ± 0.20 mm, p = 0.01) decreased.

CONCLUSIONS

Viewing with the autostereoscopic 3D tablet could temporally decrease the thickness and curvature of the lens under non-accommodating conditions. However, its long-term effect requires further exploration.

The value of stereoscopic three-dimensional vision on dental students' performance in a virtual reality simulator

PURPOSE/OBJECTIVES

The aim of this study was to quantitatively investigate the impact of stereoscopic three-dimensional (3D) vision on students' performance when compared with that of two-dimensional (2D) vision in a 3D virtual reality (VR) simulator.

METHODS

Twenty-four dental students (second- and fourth-year BDS) were assigned to perform three operative tasks under 3D and 2D viewing conditions on a Virteasy (HRV) simulator. Groups were crossed over and all students performed the same tasks under the alternate viewing conditions. The performance was evaluated by (1) accuracy, (2) outside target area removal, and (3) tooth cutting time, automatically using the generated feedback.

RESULTS

Twenty-one participants completed all sessions. The results revealed a statistically significant effect of 3D vision over 2D vision on students' performance in terms of accuracy (p = 0.035). Stereoscopic 3D vision showed significant effect on outside target area removal in the first task (p = 0.035). Tooth cutting time was the same under both conditions (p = 0.766). The findings revealed improvement in accuracy score and reduction in outside target area removal over the course of the experiment under both conditions. Comparing the difference in 3D effect in the early and advanced learning groups revealed no significant difference among the groups (p > 0.05).

CONCLUSION

Utilizing stereoscopic 3D vision in the training session improved students' perception of depth which led to more accurate tooth cutting within the target area, and less outside target area removal. However, 3D shows a limited impact on task completion time.

3D vs. 2D simulated fetoscopy for spina bifida repair: a quantitative motion analysis

3D imaging technology is becoming more prominent every day. However, more validation is needed to understand the actual benefit of 3D versus conventional 2D vision. This work quantitatively investigates whether experts benefit from 3D vision during minimally invasive fetoscopic spina bifida (fSB) repair. A superiority study was designed involving one expert team ([Formula: see text] procedures prior) who performed six 2D and six 3D fSB repair simulations in a high-fidelity animal training model, using 3-port access. The 6D motion of the instruments was recorded. Among the motion metrics are total path length, smoothness, maximum speed, the modified Spectral Arc Length (SPARC), and Log Dimensionless Jerk (LDLJ). The primary clinical outcome is operation time (power 90%, 5% significance) using Sealed Envelope Ltd. 2012. Secondary clinical outcomes are water tightness of the repair, CO[Formula: see text] insufflation volume, and OSATS score. Findings show that total path length and LDLJ are considerably different. Operation time during 3D vision was found to be significantly shorter compared to 2D vision ([Formula: see text] vs. [Formula: see text] min; p [Formula: see text] 0.026). These results suggest enhanced performance with 3D vision during interrupted suturing in fetoscopic SBA repair. To confirm these results, a larger-scale follow-up study involving multiple experts and novice surgeons is recommended.

Technology enhanced neuroanatomy teaching techniques: A focused BEME systematic review of current evidence: BEME Guide No. 75

BACKGROUND

In response to growing curriculum pressures and reduced time dedicated to teaching anatomy, research has been conducted into developing innovative teaching techniques. This raises important questions for neuroanatomy education regarding which teaching techniques are most beneficial for knowledge acquisition and long-term retention, and how they are best implemented. This focused systematic review aims to provide a review of technology-enhanced teaching methods available to neuroanatomy educators, particularly in knowledge acquisition and long-term retention, compared to traditional didactic techniques, and proposes reasons for why they work in some contexts.

METHODS

Electronic databases were searched from January 2015 to June 2020 with keywords that included combinations of 'neuroanatomy,' 'technology,' 'teaching,' and 'effectiveness' combined with Boolean phrases 'AND' and 'OR.' The contexts and outcomes for all studies were summarised while coding, and theories for why particular interventions worked were discussed.

RESULTS

There were 4287 articles identified for screening, with 13 studies included for final analysis. There were four technologies of interest: stereoscopic views of videos, stereoscopic views of images, augmented reality (AR), and virtual reality (VR). No recommendation for a particular teaching method was made in six studies (46%) while recommendations (from weak to moderate) were made in seven studies (54%). There was weak to moderate evidence for the efficacy of stereoscopic images and AR, and no difference in the use of stereoscopic videos or VR compared to controls.

CONCLUSIONS

To date, technology-enhanced teaching is not inferior to teaching by conventional didactic methods. There are promising results for these methods in complex spatial anatomy and reducing cognitive load. Possible reasons for why interventions worked were described including students' engagement with the object, cognitive load theory, complex spatial relationships, and the technology learning curve. Future research may build on the theorised explanations proposed here and develop and test innovative technologies that build on prior research.

360° 3D virtual reality operative video for the training of residents in neurosurgery

OBJECTIVE

Training of residents is an essential but time-consuming and costly task in the surgical disciplines. During the coronavirus disease 2019 pandemic, surgical education became even more challenging because of the reduced caseload due to the increased shift to corona care. In this context, augmented 360° 3D virtual reality (VR) videos of surgical procedures enable effective off-site training through virtual participation in the surgery. The goal of this study was to establish and evaluate 360° 3D VR operative videos for neurosurgical training.

METHODS

Using a 360° camera, the authors recorded three standard neurosurgical procedures: a lumbar discectomy, brain metastasis resection, and clipping of an aneurysm. Combined with the stereoscopic view of the surgical microscope, 7- to 10-minute 360° 3D VR videos augmented with annotations, overlays, and commentary were created. These videos were then presented to the neurosurgical residents at the authors’ institution using a head-mounted display. Before viewing the videos, the residents were asked to fill out a questionnaire indicating their VR experience and self-assessment of surgical skills regarding the specific procedure. After watching the videos, the residents completed another questionnaire to evaluate their quality and usefulness. The parameters were scaled with a 5-point Likert scale.

RESULTS

Twenty-two residents participated in this study. The mean years of experience of the participants in neurosurgery was 3.2 years, ranging from the 1st through the 7th year of training. Most participants (86.4%) had no or less than 15 minutes of VR experience. The overall quality of the videos was rated good to very good. Immersion, the feeling of being in the operating room, was high, and almost all participants (91%) stated that 360° VR videos provide a useful addition to the neurosurgical training. VR sickness was negligible in the cohort.

CONCLUSIONS

In this study, the authors demonstrated the feasibility and high acceptance of augmented 360° 3D VR videos in neurosurgical training. Augmentation of 360° videos with complementary and interactive content has the potential to effectively support trainees in acquiring conceptual knowledge. Further studies are necessary to investigate the effectiveness of their use in improving surgical skills.

MRI Stereoscope: A Miniature Stereoscope for Human Neuroimaging

Stereoscopic vision enables the perception of depth. To study the brain mechanisms behind stereoscopic vision using noninvasive brain imaging (magnetic resonance brain imaging; MRI), scientists need to reproduce the independent views of the left and right eyes in the brain scanner using "dichoptic" displays. However, high-quality dichoptic displays are technically challenging and costly to implement in the MRI scanner. The novel miniature stereoscope system ("MRI stereoscope") is an affordable and open-source tool that displays high-quality dichoptic images inside the MRI scanner. The MRI stereoscope takes advantage of commonly used display equipment, the MRI head coil, and a display screen. To validate the MRI stereoscope, binocular disparity stimuli were presented in a 3T MRI scanner while neural activation was recorded using functional MRI in six human participants. The comparison of large binocular disparities compared with disparities close to zero evoked strong responses across dorsal and ventral extra-striate visual cortex. In contrast, binocularly anti-correlated stimuli, which are not perceived in depth, did not evoke comparable activation. These results are the proof-of-concept that the MRI stereoscope can deliver dichoptic images that produce the perception of stereoscopic depth during acquisition of MR responses. Application of the MRI stereoscope to neuroscience can help to address important questions in perception and consciousness.

Study of the Immediate Effects of Autostereoscopic 3D Visual Training on the Accommodative Functions of Myopes

Purpose

Stereoscopic viewing has an impact on ocular dynamics, but its effects on accommodative functions are not fully understood, especially for autostereoscopic viewing. This study aimed to investigate the changes in dynamic accommodative response, accommodative amplitude, and accommodative facility of myopes after autostereoscopic visual training.

Methods

We enrolled 46 adults (men = 22 and women = 24; age = 21.5 ± 2.5 [range = 18–25] years, spherical equivalent: −4.52 ± 1.89 [−8.88 to −1.75] diopters [D]) who visited the Eye & ENT Hospital of Fudan University. The study population was randomly divided into three-dimensional (3D) and two-dimensional (2D) viewing groups to watch an 11-minute training video displayed in 3D or 2D mode. Dynamic accommodative response, accommodative facility, and accommodative amplitude were measured before, during, and immediately after the training. Accommodative lag and the variability of accommodation were also analyzed. Visual fatigue was evaluated subjectively using a questionnaire.

Results

Accommodative lag decreased from 0.54 ± 0.29 D to 0.42 ± 0.32 D (P = 0.004), whereas accommodative facility increased from 10.83 ± 4.55 cycles per minute (cpm) to 13.15 ± 5.25 cpm (P < 0.001) in the 3D group. In the 2D group, there was no significant change in the accommodative lag (P = 0.163) or facility (P = 0.975), but a decrease in accommodative amplitude was observed (from 13.88 ± 3.17 D to 12.71 ± 2.23 D, P = 0.013). In the 3D group, the accommodative response changed with the simulated target distance. Visual fatigue was relatively mild in both groups.

Conclusions

The immediate impact of autostereoscopic training included a decrease in the accommodative lag and an increase in the accommodative facility. However, the long-term effects of autostereoscopic training require further exploration.

Burnout and Cognitive Functioning: Are We Underestimating the Role of Visuospatial Functions?

Job burnout is a psychological syndrome which results from chronic occupational stress and cognitive impairments are among its negative consequences. The demands of the COVID-19 pandemic have challenged the healthcare system increasing the risk of job burnout among healthcare professionals. The studies conducted so far have mainly focused on the effects of job burnout on executive functions. Visuospatial functions are a cognitive domain which plays an important role in healthcare workers' optimal performance. Healthcare workers are constantly relying on their visuospatial abilities in order to care for their patients as they are required to use techniques that involve manipulation of medical instruments, they need to have excellent hand-eye coordination and great perception of spatial anatomy, factors that can affect healthcare workers' performance is of significance and can put patient safety at risk. However, our understanding of how visuospatial functions are being affected in job burnout is limited. The scope of this mini-review is to examine the evidence concerning the relationship of job burnout with visuospatial functions. The sparsity of the relevant empirical evidence does not allow for definite conclusions. However, given the implications of diminished visuospatial abilities in patient safety we highlight the need for studies exploring the effects of job burnout on visuospatial functions. Limitations of studies are discussed.

Augmented reality, virtual reality and new age technologies demand escalates amid COVID-19

The coronavirus disease (COVID-19) pandemic is having a significant impact on healthcare, education, economics and general human well-being. Augmented reality (AR) and virtual reality (VR) have experienced a tremendous increase in demand as they play an important role in avoiding travel, social contacts and providing adequate audiovisual communication and virtual presence. AR/VR is helping in the fight of this pandemic through their deployment in various crucial areas such as telemedicine, online education and training, marketing and healthcare monitoring. AR/VR provides resolutions for the distribution of antibiotics to control the spread of the COVID-19 virus. This paper discusses the demand for AR and VR as well as other notable new technologies explored recently to support the fight against COVID-19. The same technologies are in high demand, in the form of 2D-3D visualization and tracking software, flow and dynamic wearable headsets, potentially responsible for displaying the geographic location mostly affected with COVID-19.

Comprehensive review of surgical microscopes: technology development and medical applications

SIGNIFICANCE

Surgical microscopes provide adjustable magnification, bright illumination, and clear visualization of the surgical field and have been increasingly used in operating rooms. State-of-the-art surgical microscopes are integrated with various imaging modalities, such as optical coherence tomography (OCT), fluorescence imaging, and augmented reality (AR) for image-guided surgery.

AIM

This comprehensive review is based on the literature of over 500 papers that cover the technology development and applications of surgical microscopy over the past century. The aim of this review is threefold: (i) providing a comprehensive technical overview of surgical microscopes, (ii) providing critical references for microscope selection and system development, and (iii) providing an overview of various medical applications.

APPROACH

More than 500 references were collected and reviewed. A timeline of important milestones during the evolution of surgical microscope is provided in this study. An in-depth technical overview of the optical system, mechanical system, illumination, visualization, and integration with advanced imaging modalities is provided. Various medical applications of surgical microscopes in neurosurgery and spine surgery, ophthalmic surgery, ear-nose-throat (ENT) surgery, endodontics, and plastic and reconstructive surgery are described.

RESULTS

Surgical microscopy has been significantly advanced in the technical aspects of high-end optics, bright and shadow-free illumination, stable and flexible mechanical design, and versatile visualization. New imaging modalities, such as hyperspectral imaging, OCT, fluorescence imaging, photoacoustic microscopy, and laser speckle contrast imaging, are being integrated with surgical microscopes. Advanced visualization and AR are being added to surgical microscopes as new features that are changing clinical practices in the operating room.

CONCLUSIONS

The combination of new imaging technologies and surgical microscopy will enable surgeons to perform challenging procedures and improve surgical outcomes. With advanced visualization and improved ergonomics, the surgical microscope has become a powerful tool in neurosurgery, spinal, ENT, ophthalmic, plastic and reconstructive surgeries.

Recent evidence on visual-spatial ability in surgical education: A scoping review

BACKGROUND

Understanding the relationships between structures is critical for surgical trainees. However, the heterogeneity of the literature on visual-spatial ability (VSA) in surgery makes it challenging for educators to make informed decisions on incorporating VSA into their programs. We conducted a scoping review of the literature on VSA in surgery to provide a map of the literature and identify where gaps still exist for future research.

METHODS

We searched databases until December 2019 using keywords related to VSA and surgery. The resulting articles were independently screened by two researchers for inclusion in our review.

RESULTS

We included 117 articles in the final review. Fifty-nine articles reported significant correlations between VSA tests and surgical performance, and this association is supported by neuroimaging studies. However, it remains unclear whether VSA should be incorporated into trainee selection and whether there is a benefit of three-dimensional (3D) over two-dimensional (2D) training.

CONCLUSIONS

It appears that VSA correlates with surgical performance in the simulated environment, particularly for novice learners. Based on our findings, we make suggestions for how surgical educators may use VSA to support novice learners. Further research should determine whether VSA remains correlated to surgical performance when trainees move into the operative environment.

Mixed reality holograms for heart surgery planning: first user experience in congenital heart disease

AIMS

Proof of concept and feasibility study for preoperative diagnostic use of mixed reality (MR) holograms of individual 3D heart models from standard cardiac computed tomography angiograms (CTA) images. Optimal repair for complex congenital heart disease poses high demands on 3D anatomical imagination. Three-dimensional printed heart models are increasingly used for improved morphological understanding during surgical and interventional planning. Holograms are a dynamic and interactive alternative, probably with wider applications.

METHODS AND RESULTS

A 3D heart model was segmented from CTA images in a patient with double outlet right ventricle and transposition of the great arteries (DORV-TGA). The hologram was visualized in the wearable MR platform HoloLens® for 36 paediatric heart team members who filled out a diagnostic and quality rating questionnaire. Morphological and diagnostic output from the hologram was assessed and the 3D experience was evaluated. Locally developed app tools such as hologram rotation, scaling, and cutting were rated. Anatomy identification and diagnostic output was high as well as rating of 3D experience. Younger and female users rated the app tools higher.

CONCLUSION

This preliminary study demonstrates that MR holograms as surgical planning tool for congenital heart disease may have a high diagnostic value and contribute to understanding complex morphology. The first users experience of the hologram presentation was found to be very positive, with a preference among the female and the younger users. There is potential for improvement of the hologram manipulation tools.

Smartphone- versus smartglasses-based augmented reality (AR) for percutaneous needle interventions: system accuracy and feasibility study

PURPOSE

To compare the system accuracy and needle placement performance of smartphone- and smartglasses-based augmented reality (AR) for percutaneous needle interventions.

METHODS

An AR platform was developed to enable the superimposition of annotated anatomy and a planned needle trajectory onto a patient in real time. The system accuracy of the AR display on smartphone (iPhone7) and smartglasses (HoloLens1) devices was evaluated on a 3D-printed phantom. The target overlay error was measured as the distance between actual and virtual targets (n = 336) on the AR display, derived from preprocedural CT. The needle overlay angle was measured as the angular difference between actual and virtual needles (n = 12) on the AR display. Three operators each used the iPhone (n = 8), HoloLens (n = 8) and CT-guided freehand (n = 8) to guide needles into targets in a phantom. Needle placement error was measured with post-placement CT. Needle placement time was recorded from needle puncture to navigation completion.

RESULTS

The target overlay error of the iPhone was comparable to the HoloLens (1.75 ± 0.59 mm, 1.74 ± 0.86 mm, respectively, p = 0.9). The needle overlay angle of the iPhone and HoloLens was similar (0.28 ± 0.32°, 0.41 ± 0.23°, respectively, p = 0.26). The iPhone-guided needle placements showed reduced error compared to the HoloLens (2.58 ± 1.04 mm, 3.61 ± 2.25 mm, respectively, p = 0.05) and increased time (87 ± 17 s, 71 ± 27 s, respectively, p = 0.02). Both AR devices reduced placement error compared to CT-guided freehand (15.92 ± 8.06 mm, both p < 0.001).

CONCLUSION

An augmented reality platform employed on smartphone and smartglasses devices may provide accurate display and navigation guidance for percutaneous needle-based interventions.

Situating space: using a discipline-focused lens to examine spatial thinking skills

Spatial skills are an important component of success in science, technology, engineering, and math (STEM) fields. A majority of what we know about spatial skills today is a result of more than 100 years of research focused on understanding and identifying the kinds of skills that make up this skill set. Over the last two decades, the field has recognized that, unlike the spatial skills measured by psychometric tests developed by psychology researchers, the spatial problems faced by STEM experts vary widely and are multifaceted. Thus, many psychological researchers have embraced an interdisciplinary approach to studying spatial thinking with the aim of understanding the nature of this skill set as it occurs within STEM disciplines. In a parallel effort, discipline-based education researchers specializing in STEM domains have focused much of their research on understanding how to bolster students' skills in completing domain-specific spatial tasks. In this paper, we discuss four lessons learned from these two programs of research to enhance the field's understanding of spatial thinking in STEM domains. We demonstrate each contribution by aligning findings from research on three distinct STEM disciplines: structural geology, surgery, and organic chemistry. Lastly, we discuss the potential implications of these contributions to STEM education.

Augmented and Mixed Reality: Technologies for Enhancing the Future of IR

Augmented and mixed reality are emerging interactive and display technologies. These technologies are able to merge virtual objects, in either 2 or 3 dimensions, with the real world. Image guidance is the cornerstone of interventional radiology. With augmented or mixed reality, medical imaging can be more readily accessible or displayed in actual 3-dimensional space during procedures to enhance guidance, at times when this information is most needed. In this review, the current state of these technologies is addressed followed by a fundamental overview of their inner workings and challenges with 3-dimensional visualization. Finally, current and potential future applications in interventional radiology are highlighted.

Comparison of Magnetic Resonance Angiography and Computed Tomography Angiography Stereoscopic Cerebral Vascular Models

In this paper, we will discuss and compare the stereoscopic models developed from two types of radiographic data, Magnetic Resonance Angiography (MRA) images and Computed Tomography Angiography (CTA) images. Stereoscopic models were created using surface or volume segmentation and semi-auto combined segmentation techniques. Although, the CTA data were found to improve the speed and quality of constructing virtual vascular models compared to conventional CT data, small blood vessels were difficult to capture during the imaging and reconstruction process thereby limiting the fidelity of the stereoscopic models. Thus, high contrast Magnetic Resonance Angiography (MRA) images offer better resolution to visualize and capture the smaller branches of the cerebral vasculature than CTA images.

The effect of autostereoscopic holograms on anatomical knowledge: a randomised trial

CONTEXT

Three-dimensional (3-D) visualisation in anatomical education has been shown to be broadly beneficial for students. However, there is limited research on the relative efficacy of 3-D modalities. This study compares knowledge performance, mental effort and instructional efficiency between autostereoscopic 3-D visualisation (holograms), monoscopic 3-D visualisation (3-DPDFs) and a control (2-D printed images).

METHODS

A cardiac anatomy model was used to generate holograms, 3-DPDFs and 2-D printed images. Nursing student participants (n = 179) were randomised into three groups: holograms (n = 60), 3-DPDFs (n = 60) and printed images (n = 59). Participants completed a pre-test followed by a self-study period using the anatomical visualisation. Afterwards, participants completed the NASA-Task Load Index (NASA-TLX) cognitive load instrument and a knowledge post-test.

RESULTS

Post-test results showed participants studying with holograms (median = 80.0, interquartile range [IQR] = 66.7-86.7) performed significantly better regarding cardiac anatomy knowledge than participants using 3-DPDF (median = 66.7, IQR = 53.3-80.0, p = 0.008) or printed images (median = 66.7, IQR = 53.3-80.0, p = 0.007). Mental effort scores, on a scale from 1 to 20, showed hologram (mean = 4.9, standard deviation [SD] = 3.56) and 3-DPDF participants (mean = 4.9, SD = 3.79) reported significantly lower cognitive load than printed images (mean = 7.5, SD = 4.9, p < 0.005). Instructional efficiency (E) of holograms (E = 0.35) was significantly higher than printed images (E = -0.36, p < 0.001), although not significantly higher than 3-DPDF (E = 0.03, p = 0.097).

CONCLUSIONS

Participants using holograms demonstrated significant knowledge improvement over printed images and monoscopic 3-DPDF models, suggesting additional depth cues from holographic visualisation provide benefit in understanding spatial anatomy. Mental effort scores and instructional efficiency of holograms indicate holograms are a cognitively efficient instructional medium. These findings highlight the need for further study of novel 3-D technologies and learning performance.

A Role for Virtual Reality in Planning Endovascular Procedures

Current imaging technologies are capable of acquiring volumetric data, but they are limited by the flat 2-dimensional representation of complex 3-dimensional data. This pictorial report illustrates the potential role of interactive virtual reality (VR) that enables physicians to visualize and interact with image data as if they were real physical objects. Increasing availability of tools that make the VR environment a possibility could potentially be valuable in the interventional radiology suite.

Three-dimensional holographic visualization of high-resolution myocardial scar on HoloLens

Visualization of the complex 3D architecture of myocardial scar could improve guidance of radio-frequency ablation in the treatment of ventricular tachycardia (VT). In this study, we sought to develop a framework for 3D holographic visualization of myocardial scar, imaged using late gadolinium enhancement (LGE), on the augmented reality HoloLens. 3D holographic LGE model was built using the high-resolution 3D LGE image. Smooth endo/epicardial surface meshes were generated using Poisson surface reconstruction. For voxel-wise 3D scar model, every scarred voxel was rendered into a cube which carries the actual resolution of the LGE sequence. For surface scar model, scar information was projected on the endocardial surface mesh. Rendered layers were blended with different transparency and color, and visualized on HoloLens. A pilot animal study was performed where 3D holographic visualization of the scar was performed in 5 swines who underwent controlled infarction and electroanatomic mapping to identify VT substrate. 3D holographic visualization enabled assessment of the complex 3D scar architecture with touchless interaction in a sterile environment. Endoscopic view allowed visualization of scar from the ventricular chambers. Upon completion of the animal study, operator and mapping specialist independently completed the perceived usefulness questionnaire in the six-item usefulness scale. Operator and mapping specialist found it useful (usefulness rating: operator, 5.8; mapping specialist, 5.5; 1–7 scale) to have scar information during the intervention. HoloLens 3D LGE provides a true 3D perception of the complex scar architecture with immersive experience to visualize scar in an interactive and interpretable 3D approach, which may facilitate MR-guided VT ablation.

Stereoscopic Versus Monoscopic Viewing of Aneurysms: Experience of a Single Institution with a Novel Stereoscopic Viewing System

OBJECTIVE

Stereoscopic viewing of computed tomographic angiography (CT-A) or magnetic resonance angiograms might increase the diagnostic potential of these imaging techniques. Our aim was to evaluate the benefits of a novel stereoscopic viewing system for aneurysm detection compared with standard monoscopic viewing.

METHODS

Retrospective patient data were used for 2 different evaluations. First, monoscopic and stereoscopic CT-A viewing was compared by 14 clinicians in 10 patients with challenging (i.e., small and initially CT-A negative) aneurysms. Second, stereoscopic CT-As and the reference standard, digital subtraction angiography (DSA), were compared in 15 patients with randomly selected aneurysms by 12 clinicians. The study participants rated the presence and location of any aneurysm and its morphological characteristics. The detection rates and interrater reliability were calculated.

RESULTS

The first evaluation showed superior aneurysm detection in challenging cases using stereoscopic versus monoscopic CT-A viewing (median: monoscopic, 20%; interquartile range [IQR], 10%-32.5%; stereoscopic, 40%; IQR, 27.5%-42.5%). The interrater reliability analysis revealed good to excellent agreement among raters for aneurysm detection in both viewing modalities (monoscopic, intraclass correlation coefficient [ICC(2,1)], 0.798; 95% confidence interval [CI], 0.549-0.941; stereoscopic viewing, ICC(2,1), 0.895; 95% CI, 0.770-0.968). The second part demonstrated that stereoscopic CT-A viewing is comparable to DSA viewing for aneurysm detection (median: DSA, 80%; IQR, 73%-100%; stereoscopic CT-A, 87%; IQR, 87%-93%). The interrater reliability analysis revealed excellent absolute agreement in aneurysm detection between DSA and stereoscopic CT-A viewing (DSA: ICC(2,1), 0.971; 95% CI, 0.944-0.989; stereoscopic CT-A: ICC(2,1), 0.972; 95% CI, 0.945-0.989). The aneurysm detection rates correlated significantly with the participants' years of experience.

CONCLUSIONS

Stereoscopic viewing of CT-As increases the diagnostic accuracy and represents a promising technique to reduce the need for invasive DSA.

Acquiring basic and advanced laparoscopic skills in novices using two-dimensional (2D), three-dimensional (3D) and ultra-high definition (4K) vision systems: A randomized control study

AIMS

To compare the performance of novices in laparoscopic peg transfer and intra-corporeal suturing tasks in two-dimensional (2D), three-dimensional (3D) and ultra-high definition (4K) vision systems.

METHODS

Twenty-four novices were randomly assigned to 2D, 3D and 4K groups, eight in each group. All participants performed the two tasks on a box trainer until reaching proficiency. Their performance was assessed based on completion time, number of errors and number of repetitions using the validated FLS proficiency criteria.

RESULTS

Eight candidates in each group completed the training curriculum. The mean performance time (in minutes) for the 2D group was 558.3, which was more than that of the 3D and 4K groups of 316.7 and 310.4 min respectively (P < 0.0001). The mean number of repetitions was lower for the 3D and 4K groups versus the 2D group: 125.9 and 127.4 respectively versus 152.1 (P < 0.0001). The mean number of errors was lower for the 4K group versus the 3D and 2D groups: 1.2 versus 26.1 and 50.2 respectively (P < 0.0001).

CONCLUSION

The 4K vision system improved accuracy in acquiring laparoscopic skills for novices in complex tasks, which was shown in significant reduction in number of errors compared to the 3D and the 2D vision systems. The 3D and the 4K vision systems significantly improved speed and accuracy when compared to the 2D vision system based on shorter performance time, fewer errors and lesser number of repetitions.

Utilizing Light-field Imaging Technology in Neurosurgery

Traditional still cameras can only focus on a single plane for each image while rendering everything outside of that plane out of focus. However, new light-field imaging technology makes it possible to adjust the focus plane after an image has already been captured. This technology allows the viewer to interactively explore an image with objects and anatomy at varying depths and clearly focus on any feature of interest by selecting that location during post-capture viewing. These images with adjustable focus can serve as valuable educational tools for neurosurgical residents. We explore the utility of light-field cameras and review their strengths and limitations compared to other conventional types of imaging. The strength of light-field images is the adjustable focus, as opposed to the fixed-focus of traditional photography and video. A light-field image also is interactive by nature, as it requires the viewer to select the plane of focus and helps with visualizing the three-dimensional anatomy of an image. Limitations include the relatively low resolution of light-field images compared to traditional photography and video. Although light-field imaging is still in its infancy, there are several potential uses for the technology to complement traditional still photography and videography in neurosurgical education.

Magnitude, precision, and realism of depth perception in stereoscopic vision

Our perception of depth is substantially enhanced by the fact that we have binocular vision. This provides us with more precise and accurate estimates of depth and an improved qualitative appreciation of the three-dimensional (3D) shapes and positions of objects. We assessed the link between these quantitative and qualitative aspects of 3D vision. Specifically, we wished to determine whether the realism of apparent depth from binocular cues is associated with the magnitude or precision of perceived depth and the degree of binocular fusion. We presented participants with stereograms containing randomly positioned circles and measured how the magnitude, realism, and precision of depth perception varied with the size of the disparities presented. We found that as the size of the disparity increased, the magnitude of perceived depth increased, while the precision with which observers could make depth discrimination judgments decreased. Beyond an initial increase, depth realism decreased with increasing disparity magnitude. This decrease occurred well below the disparity limit required to ensure comfortable viewing.

Evaluation of the effectiveness of 3D vascular stereoscopic models in anatomy instruction for first year medical students

The head and neck region is one of the most complex areas featured in the medical gross anatomy curriculum. The effectiveness of using three-dimensional (3D) models to teach anatomy is a topic of much discussion in medical education research. However, the use of 3D stereoscopic models of the head and neck circulation in anatomy education has not been previously studied in detail. This study investigated whether 3D stereoscopic models created from computed tomographic angiography (CTA) data were efficacious teaching tools for the head and neck vascular anatomy. The test subjects were first year medical students at the University of Mississippi Medical Center. The assessment tools included: anatomy knowledge tests (prelearning session knowledge test and postlearning session knowledge test), mental rotation tests (spatial ability; presession MRT and postsession MRT), and a satisfaction survey. Results were analyzed using a Wilcoxon rank-sum test and linear regression analysis. A total of 39 first year medical students participated in the study. The results indicated that all students who were exposed to the stereoscopic 3D vascular models in 3D learning sessions increased their ability to correctly identify the head and neck vascular anatomy. Most importantly, for students with low-spatial ability, 3D learning sessions improved postsession knowledge scores to a level comparable to that demonstrated by students with high-spatial ability indicating that the use of 3D stereoscopic models may be particularly valuable to these students with low-spatial ability. Anat Sci Educ 10: 34-45. © 2016 American Association of Anatomists.

3D Displays

Creating realistic three-dimensional (3D) experiences has been a very active area of research and development, and this article describes progress and what remains to be solved. A very active area of technical development has been to build displays that create the correct relationship between viewing parameters and triangulation depth cues: stereo, motion, and focus. Several disciplines are involved in the design, construction, evaluation, and use of 3D displays, but an understanding of human vision is crucial to this enterprise because in the end, the goal is to provide the desired perceptual experience for the viewer. In this article, we review research and development concerning displays that create 3D experiences. And we highlight areas in which further research and development is needed.

Stereoscopic Integrated Imaging Goggles for Multimodal Intraoperative Image Guidance

We have developed novel stereoscopic wearable multimodal intraoperative imaging and display systems entitled Integrated Imaging Goggles for guiding surgeries. The prototype systems offer real time stereoscopic fluorescence imaging and color reflectance imaging capacity, along with in vivo handheld microscopy and ultrasound imaging. With the Integrated Imaging Goggle, both wide-field fluorescence imaging and in vivo microscopy are provided. The real time ultrasound images can also be presented in the goggle display. Furthermore, real time goggle-to-goggle stereoscopic video sharing is demonstrated, which can greatly facilitate telemedicine. In this paper, the prototype systems are described, characterized and tested in surgeries in biological tissues ex vivo. We have found that the system can detect fluorescent targets with as low as 60 nM indocyanine green and can resolve structures down to 0.25 mm with large FOV stereoscopic imaging. The system has successfully guided simulated cancer surgeries in chicken. The Integrated Imaging Goggle is novel in 4 aspects: it is (a) the first wearable stereoscopic wide-field intraoperative fluorescence imaging and display system, (b) the first wearable system offering both large FOV and microscopic imaging simultaneously,

Augmented microscopy: real-time overlay of bright-field and near-infrared fluorescence images

Intraoperative applications of near-infrared (NIR) fluorescent contrast agents can be aided by instrumentation capable of merging the view of surgical field with that of NIR fluorescence. We demonstrate augmented microscopy, an intraoperative imaging technique in which bright-field (real) and electronically processed NIR fluorescence (synthetic) images are merged within the optical path of a stereomicroscope. Under luminance of 100,000 lx, representing typical illumination of the surgical field, the augmented microscope detects 189 nM concentration of indocyanine green and produces a composite of the real and synthetic images within the eyepiece of the microscope at 20 fps. Augmentation described here can be implemented as an add-on module to visualize NIR contrast agents, laser beams, or various types of electronic data within the surgical microscopes commonly used in neurosurgical, cerebrovascular, otolaryngological, and ophthalmic procedures.

[Skills comparison using a 2D vs. 3D laparoscopic simulator]

BACKGROUND

The development and application of 3D images in laparoscopic surgery has brought the benefit of in-depth perception that traditional laparoscopic surgery lacked. Previous studies in surgical populations have demonstrated the advantages of 3D technology. To limit bias of the previous experiences of participants, this study was performed in a population without any experience in this area.

MATERIAL AND METHODS

An experimental, open, cross-sectional, comparative study between surgical skills achievements using 2D and a 3D laparoscopy equipment, using each subject as their own control. Six skills were evaluated in 2D and 3D modalities.

RESULTS

Of the 40 participants included, 20 began the skills in the 2D modality and then performed them in 3D, and the other 20 began in 3D. Of the 118 skills evaluated there was a time improvement in 72% in the 3D group compared to 37% in the 2D modality (P=.000). The accomplishment percentage using the 3D laparoscopy was greater for both groups. There was a statistically significant difference in the better time for the 3D performed tasks. Just over half (52.5%) of participants preferred 3D laparoscopy, 15% preferred 2D, and 32.5% had no preferences.

DISCUSSION

As other studies have demonstrated, there was improvement in the overall performance using the 3D laparoscope. Bias was limited by using a population without surgical experience.

CONCLUSIONS

3D laparoscopic surgical skills showed superior to 2D, with higher percentages of tasks completion, less time in performing them, and a shorter learning curve.

Evaluation of monoscopic and stereoscopic displays for visual-spatial tasks in medical contexts

In the medical field, digital images are present in diagnosis, pre-operative planning, minimally invasive surgery, instruction, and training. The use of medical digital imaging has afforded new ways to interact with a patient, such as seeing fine details inside a body. This increased usage also raises many basic research questions on human perception and performance when utilizing these images. The work presented here attempts to answer the question: How would adding the stereopsis depth cue affect relative position tasks in a medical context compared to a monoscopic view? By designing and conducting a study to isolate the benefits between monoscopic 3D and stereoscopic 3D displays in a relative position task, the following hypothesis was tested: stereoscopic 3D displays are beneficial over monoscopic 3D displays for relative position judgment tasks in a medical visualization setting. 44 medical students completed a series of relative position judgments tasks. The results show that stereoscopic condition yielded a higher score than the monoscopic condition with regard to the hypothesis.

Dichoptic Viewing Methods for Binocular Rivalry Research: Prospects for Large-Scale Clinical and Genetic Studies

Binocular rivalry (BR) is an intriguing phenomenon that occurs when two different images are presented, one to each eye, resulting in alternation orrivalrybetween the percepts. The phenomenon has been studied for nearly 200 years, with renewed and intensive investigation over recent decades. Therateof perceptual switching has long been known to vary widely between individuals but to be relatively stable within individuals. A recent twin study demonstrated that individual variation in BR rate is under substantial genetic control, a finding that also represented the first report, using a large study, of genetic contribution for any post-retinal visual processing phenomenon. The twin study had been prompted by earlier work showing BR rate was slow in the heritable psychiatric condition, bipolar disorder (BD). Together, these studies suggested that slow BR may represent an endophenotype for BD, and heralded the advent of modern clinical and genetic studies of rivalry. This new focus has coincided with rapid advances in 3D display technology, but despite such progress, specific development of technology for rivalry research has been lacking. This review therefore compares different display methods for BR research across several factors, including viewing parameters, image quality, equipment cost, compatibility with other investigative methods, subject group, and sample size, with a focus on requirements specific to large-scale clinical and genetic studies. It is intended to be a resource for investigators new to BR research, such as clinicians and geneticists, and to stimulate the development of 3D display technology for advancing interdisciplinary studies of rivalry.

Application of stereoscopic visualization on surgical skill acquisition in novices

OBJECTIVE

The use of stereoscopic imaging can provide additional depth cues that may increase trainee performance on surgical tasks, but it has yet to be evaluated using a validated surgical skill system. This study examines the influence of monoscopic vs stereoscopic visualization in novice trainees performing the McGill Inanimate System for Training and Evaluation of Laparoscopic Skill (MISTELS) tasks, a validated laparoscopic skill-evaluation system, predicting a difference in performance based on visualization modality.

DESIGN

A total of 31 first- and second-year medical students at the University of Western Ontario were selected, each performed the MISTELS battery of tasks (circle cutting, peg transfer, ligated loop Placement, intracorporeal knot tying, and extracorporeal knot tying) using either monoscopic or stereoscopic visualization displays. Performance was evaluated in accordance with the MISTELS protocol. Participant visual spatial ability and manual dexterity skills were also analyzed and compared with performance. p values less than 0.05 were considered significant.

RESULTS

For ligated loop placement, extracorporeal knot tying, and intracorporeal knot tying, no significant difference was found between monoscopic and stereoscopic visualization on task performance (p > 0.05). Monoscopic visualization was shown to produce significantly better performance in the peg transfer task alone (p = 0.001). Qualitatively, 57.1% of participants believed their performance was aided by stereoscopic visualization and 68.8% believed that future learners would benefit from its implementation into surgical education. Most participants rated the peg transfer task to be the least difficult task (60%) and rated the intracorporeal knot-tying task to be the most difficult (65.9%).

CONCLUSIONS

These results suggest that the intrinsic difficulty of the MISTELS tasks may exceed a novice user's skill. No benefit with additional 3-dimensional cues in naïve surgical trainees was found. Additional visual cues in stereoscopic visualization may only serve to increase cognitive load and potentially decrease skill acquisition and learning.

Brain tumor surgery with 3-dimensional surface navigation

BACKGROUND

Precise lesion localization is necessary for neurosurgical procedures not only during the operative approach, but also during the preoperative planning phase.

OBJECTIVE

To evaluate the advantages of 3-dimensional (3-D) brain surface visualization over conventional 2-dimensional (2-D) magnetic resonance images for surgical planning and intraoperative guidance in brain tumor surgery.

METHODS

Preoperative 3-D brain surface visualization was performed with neurosurgical planning software in 77 cases (58 gliomas, 7 cavernomas, 6 meningiomas, and 6 metastasis). Direct intraoperative navigation on the 3-D brain surface was additionally performed in the last 20 cases with a neurosurgical navigation system. For brain surface reconstruction, patient-specific anatomy was obtained from MR imaging and brain volume was extracted with skull stripping or watershed algorithms, respectively. Three-dimensional visualization was performed by direct volume rendering in both systems. To assess the value of 3-D brain surface visualization for topographic lesion localization, a multiple-choice test was developed. To assess accuracy and reliability of 3-D brain surface visualization for intraoperative orientation, we topographically correlated superficial vessels and gyral anatomy on 3-D brain models with intraoperative images.

RESULTS

The rate of correct lesion localization with 3-D was significantly higher (P = .001, χ), while being significantly less time consuming (P < .001, χ) compared with 2-D images. Intraoperatively, visual correlation was found between the 3-D images, superficial vessels, and gyral anatomy.

CONCLUSION

The proposed method of 3-D brain surface visualization is fast, clinically reliable for preoperative anatomic lesion localization and patient-specific planning, and, together with navigation, improves intraoperative orientation in brain tumor surgery and is relatively independent of brain shift.