Virtual reality approaches for immersive design

The current application of virtual reality (VR) systems in the design process is limited mostly to design review. The reason for this limitation is the different data formats used for CAD and VR visualization. To use the benefits of VR during the design process, solutions for immersive design, the model manipulation inside the VE based on CAD data, are required. There are different approaches allowing VR systems to work as an active development platform. Three examples introduce the realization of the integration of CAD and VR software at different levels by the online coupling of complete applications or by integration of CAD core functionalities in VR systems.     

Improved virtual reality perception with calibrated stereo and variable focus for industrial use

3D image rendering for virtual reality HMDs is typically generated based on a set of parameters taken from the manufacturer-supplied specifications and an idealised perspective model. But actual displays may vary in build features that alter spatial perception. Moreover, the eye focusing effort is often ignored. The resulting visual discomfort and incorrect geometry perception has discouraged use of immersive virtual reality in industrial applications. This work addresses these issues and describes a system with per-device calibration and control of stereo perspective projections and focus. The ideas presented may improve the usefulness of VR in industrial training and visualization.     

A bi-directional interface for improved interaction with engineering models in virtual reality design reviews

Leveraging virtual reality (VR) technology to enhance engineering design reviews has been an area of significant interest for researchers since the advent of modern VR. The ability to interact meaningfully with 3D computer-aided engineering models in these VR design reviews is an important, though often neglected, capability due to the difficulty of performing data translation between native computer-aided design (CAD) data and VR compatible file formats. A bi-directional interface was developed between a VR design review environment and a commercial CAD package that streamlines the data translation process. Transmitting both geometric data and selected metadata from the CAD system enabled the development of enhanced model interaction tools in a VR design review application. User experiments were performed that compared the enhanced tools developed to a baseline toolset. Participants success using these toolsets was measured as they performed tasks related to design understanding and decision making, such as counting the number of gears in a gearbox or evaluating the feasibility of a proposed design change in a four-cylinder engine. The analysis of the data from these experiments showed a statistically significant improvement in participants ability to understand the geometry of the model correctly, confidently, and quickly, as well as in participants ability to correctly and confidently understand the implications of a proposed design change when using the Enhanced Toolset. We conclude that the bi-directional interface concept developed in this work can be extended to enable advanced interaction with a diversity of engineering data in VR.     

What virtual reality research in addictions can tell us about the future of obesity assessment and treatment

Virtual reality (VR), a system of human-computer interaction that allows researchers and clinicians to immerse people in virtual worlds, is gaining considerable traction as a research, education, and treatment tool. Virtual reality has been used successfully to treat anxiety disorders such as fear of flying and post-traumatic stress disorder, as an aid in stroke rehabilitation, and as a behavior modification aid in the treatment of attention deficit disorder. Virtual reality has also been employed in research on addictive disorders. Given the strong evidence that drug-dependent people are highly prone to use and relapse in the presence of environmental stimuli associated with drug use, VR is an ideal platform from which to study this relationship. Research using VR has shown that drug-dependent people react with strong craving to specific cues (e.g., cigarette packs, liquor bottles) as well as environments or settings (e.g., bar, party) associated with drug use. Virtual reality has also been used to enhance learning and generalization of relapse prevention skills in smokers by reinforcing these skills in lifelike environments. Obesity researchers and treatment professionals, building on the lessons learned from VR research in substance abuse, have the opportunity to adapt these methods for investigating their own research and treatment questions. Virtual reality is ideally suited to investigate the link between food cues and environmental settings with eating behaviors and self-report of hunger. In addition, VR can be used as a treatment tool for enhancing behavior modification goals to support healthy eating habits by reinforcing these goals in life-like situations.     

Incremental value of color coding in 3D volume rendered CT images for interpretation of complex cardiothoracic vascular malformations

Objectives

To evaluate the benefit of color coding of CT angiography images for the assessment of complex cardiovascular malformations by comparing the quality of 3D (dimensional) volume rendered (VR) images before and after vessel color coding.

Methods

Cardiothoracic CT images of 34 patients with complex vascular malformations were retrospectively selected for post processing. 3D VR images were created without and after color coding of the target vessels. Source images as well as selected 3D VR images without and with color coding were reviewed independently by 4 observers and scores were recorded on a 4-point scale for overall image quality, visualization conspicuity of target vessels, and final interpretation of target structures.

Results

Overall diagnostic advantages of color coded VR images compared with non-color coded VR images included; improved visualization of the anatomical course of vessels, improved visualization of the extent of abnormality, better understanding of the spatial relationship of structures (i.e. to right ventricle outflow tract), and improved overall quality of the images. For all comparisons the color coded score was statistically significantly better than the non-color coded score (p < 0.0001). A trend showed that review speed was faster for color coded images (p = 0.06). Good inter-observer agreement was achieved for the target conspicuity and final interpretation scores with weighted Kappa score of 0.66 (95% CI: 0.54, 0.79) and 0.71 (95% CI: 0.60, 0.81) respectively.

Conclusion

Color coded 3D VR images can optimize visualization of vascular structures and improve interpretation of complex vascular malformation in cardiothoracic CT studies.     

Virtual reality aided design of parts and assemblies

Current virtual reality (VR) systems provide an enormous potential for enhancing the visualization of 3D-design drafts. Based on new navigation techniques the designer is able to interact, model in a more intuitive and efficient way. In our contribution we present a novel interaction metaphor that facilitates the synthesis of efficient virtual reality interaction and visualization techniques with modern feature based CAD systems. We present “NAVIMODE”, an alternative approach for navigation, manipulation and selection, to combine the advantages of VR and CAD systems. The design engineer has the chance to design in his/her habitual environment using the advantage of virtual reality concurrently.     

Technology insight: assessment of myocardial viability by delayed-enhancement magnetic resonance imaging

Myocardial viability is of established importance to the management of cardiac patients being considered for revascularization. Existing noninvasive imaging tests to examine myocardial viability, such as stress echocardiography and nuclear scintigraphy, are of recognized utility but are subject to intrinsic limitations. Over the past few years delayed-enhancement MRI (DE-MRI) has emerged as an alternative to traditional tests and for the first time allows direct visualization of the transmural extent of myocardial viability. In this paper we review the scientific data that underlie the use of DE-MRI in patients with ischemic heart disease. Progress in this area is largely the result of the development of a new MRI pulse sequence in the late 1990s, which improved the detection of necrotic and scarred myocardial tissue. Following this technical development, a series of detailed histologic comparisons in large animal models revealed that both acute and healed myocardial infarcts appeared as brighter (hyperenhanced) areas than viable regions, and that the effect is independent of contractile function. The resulting 'bright is dead' hypothesis has thus far proven of significant use in patients with ischemic heart disease. Data are now emerging which suggest that the DE-MRI technique also has important implications for patients with nonischemic forms of cardiomyopathy.     

Vaginal Ring Adherence in Sub-Saharan Africa: Expulsion, Removal, and Perfect Use

In sub-Saharan Africa, HIV incidence and prevalence remain disproportionately high among women. Vaginal rings (VRs) have been formulated for the delivery of antiretroviral-based microbicides, and their favorable safety and tolerability profiles reported in clinical studies. Although the concept of drug release through a VR has existed since 1970, and VRs have been marketed since 1992 for contraceptive or hormone replacement purposes, VR use as a microbicide delivery system is a novel application. This is the first study to evaluate VR adherence among African women in the context of its potential use as an HIV prevention method, to examine predictors of adherence, and to describe clinical or contextual reasons for VR removals or nonadherence. This was a randomized trial of the safety and acceptability of a placebo VR worn for 12?weeks in 170 HIV-negative, African women aged 18–35 in four clinic sites in South Africa and Tanzania. The findings suggest that adherence to VR use in the context of HIV prevention trials in these communities should be high, thereby enabling more accurate assessment of an active microbicide safety and efficacy.     

Effectiveness of an immersive virtual reality environment on curricular training for complex cognitive skills in liver surgery: a multicentric crossover randomized trial

BackgroundVirtual reality (VR) is increasingly used in surgical education, but evidence of its benefits in complex cognitive training compared to conventional 3-dimensional (3D) visualization methods is lacking. The objective of this study is to assess the impact of 3D liver models rendered visible by VR or desktop interfaces (DIs) on residents' performance in clinical decision-making.MethodFrom September 2020 to April 2021, a single-blinded, crossover randomized educational intervention trial was conducted at two university hospitals in Belgium and Italy. A proficiency-based stepwise curriculum for preoperative liver surgery planning was developed for general surgery residents. After completing the training, residents were randomized in one of two assessment sequences to evaluate ten real clinical scenarios.ResultsAmong the 50 participants, 46 (23 juniors/23 seniors) completed the training and were randomized. Forty residents (86.96%) achieved proficiency in decision-making. The accuracy of virtual surgical planning using VR was higher than that using DI in both groups A (8.43 ± 1.03 vs 6.86 ± 1.79, p < 0.001) and B (8.08 ± 0.9 vs 6.52 ± 1.37, p < 0.001).ConclusionProficiency-based curricular training for liver surgery planning successfully resulted in the acquisition of complex cognitive skills. VR was superior to DI visualization of 3D models in decision-making.Clinicaltrials.gov idNCT04959630.     

Effects of antiarrhythmic drugs on QT interval dispersion--relationship to antiarrhythmic action and proarrhythmia

Class IA, IC, and III antiarrhythmic drugs prolong ventricular repolarization (VR) which is manifest as QT interval prolongation on the surface electrocardiogram. These drugs may prolong VR in a spatially heterogeneous manner which results in increased dispersion of VR. This may be manifest as increased QT interval dispersion. Antiarrhythmic drug-induced decreases in QT interval dispersion are associated with antiarrhythmic efficacy in patients with the long QT syndrome and in patients with sustained ventricular tachycardia. Antiarrhythmic drug-induced increases in QT interval dispersion are associated with ventricular proarrhythmia secondary to torsades de points ventricular tachycardia. A number of factors may modulate the effects of antiarrhythmic drugs on dispersion of VR, including the disease state, transient ischemia, electrolyte abnormalities, changes in autonomic tone, and hemodynamic stress.     

Clinical Benefits of Using Second Generation Ultrasound Contrast Agents in Stress Echocardiography

Stress echocardiography is an established and widely used method for the noninvasive detection of myocardial ischemia. However, despite introduction of new echocardiographic technologies, such as harmonic imaging, unsatisfactory image quality limits an accurate interpretation of left ventricular (LV) wall thickening and motion in up to 30% of patients during stress echocardiography. Development and availability of second generation transpulmonary contrast agents, which opacify the LV chamber and have the capability of enhancing endocardial border definition, facilitate high-quality imaging of LV structures even in technically difficult patients. Application of a contrast agent is not associated with significant extra cost of time and manipulations because bolus injections are sufficient in most instances and harmonic imaging capabilities as well as contrast specific presets are implemented and, thus, readily available in most modern ultrasound systems. Numerous studies have demonstrated that contrast echocardiography substantially improves LV cavity visualization at rest as well as at peak stress and, therefore, increases reader confidence and decreases interobserver variability. Moreover, enhanced learning curves for interpreting stress echocardiograms have been reported in novice readers. It has been reported that compared with native stress echocardiography the use of contrast results in identification of more true positive as well as true negative results and helps to avoid unnecessary invasive procedures in a considerable number of patients. Contrast stress echocardiography may, therefore, also prove cost effective in the future. Further refinements of contrast agent properties and new developments in imaging technology will likely continue to extend the spectrum of diagnostic cardiac imaging techniques and further enhance noninvasive assessment of the complex pathophysiology of coronary artery disease. (ECHOCARDIOGRAPHY, Volume 20, Supplement 1, 2003)     

Image processing in esophageal scintigraphy: topography of transit times

In the investigation of esophageal transport, the knowledge provided by scintigraphy is mostly based upon the extraction as well as representation of the information obtained. Recently, new tools have been developed for use in computer-based image processing which have made visualization and quantitation of esophageal bolus transport possible through depiction of the 'topography of transit times'. Data extracted from the images obtained in multiple swallowing studies from a single healthy volunteer as well as in patients suffering from gastroesophageal reflux disease (GERD) and from Barrett's esophagus are compressed, filtered and depicted in quantifiable concise plots or multidimensional images. Profile plots demonstrated a considerable increase in local transit times along the esophagus superimposed, however, by a distinctive pattern of local delays. Above the level of the lower esophageal sphincter (LES), the bolus accumulates in a functional ampulla. Subprocesses of bolus transit through the LES, disclosed by spatiotemporal enhancement, allow for the differentiation between mass transit of the bolus and closure of the LES which was considerably retarded in the case of the patient with Barrett's esophagus. The image-processing tools developed for topographic visualization of transit times for esophageal bolus transport have greatly improved the extraction and quantifiable depiction of information obtained by scintigraphy. This can be used for definition of pathognomonic indices.     

Developing a virtual reality simulation system for preoperative planning of thoracoscopic thoracic surgery

BackgroundVideo-assisted thoracoscopic surgery (VATS) has become a standard approach for the treatment of lung cancer. However, its minimally invasive nature limits the field of view and reduces tactile feedback. These limitations make it vital that surgeons thoroughly familiarize themselves with the patient’s anatomy preoperatively. We have developed a virtual reality (VR) surgical navigation system using head-mounted displays (HMD). The aim of this study was to investigate the potential utility of this VR simulation system in both preoperative planning and intraoperative assistance, including support during thoracoscopic sublobar resection.MethodsThree-dimensional (3D) polygon data derived from preoperative computed tomography data was loaded into BananaVision software developed at Colorado State University and displayed on an HMD. An interactive 3D reconstruction image was created, in which all the pulmonary structures could be individually imaged. Preoperative resection simulations were performed with patient-individualized reconstructed 3D images.ResultsThe 3D anatomic structure of pulmonary vessels and a clear vision into the space between the lesion and adjacent tissues were successfully appreciated during preoperative simulation. Surgeons could easily evaluate the real patient’s anatomy in preoperative simulations to improve the accuracy and safety of actual surgery. The VR software and HMD allowed surgeons to visualize and interact with real patient data in true 3D providing a unique perspective.ConclusionsThis initial experience suggests that a VR simulation with HMD facilitated preoperative simulation. Routine imaging modalities combined with VR systems could substantially improve preoperative planning and contribute to the safety and accuracy of anatomic resection.     

Development of and Feedback on a Fully Automated Virtual Reality System for Online Training in Weight Management Skills

Virtual reality (VR) technology can provide a safe environment for observing, learning, and practicing use of behavioral weight management skills, which could be particularly useful in enhancing minimal contact online weight management programs. The Experience Success (ES) project developed a system for creating and deploying VR scenarios for online weight management skills training. Virtual environments populated with virtual actors allow users to experiment with implementing behavioral skills via a PC-based point and click interface. A culturally sensitive virtual coach guides the experience, including planning for real-world skill use. Thirty-seven overweight/obese women provided feedback on a test scenario focused on social eating situations. They reported that the scenario gave them greater skills, confidence, and commitment for controlling eating in social situations.     

Wall shear stress--an important determinant of endothelial cell function and structure--in the arterial system in vivo. Discrepancies with theory

It has been well established that wall shear stress is an important determinant of endothelial cell function and gene expression as well as of its structure. There is increasing evidence that low wall shear stress, as present in artery bifurcations opposite to the flow divider where atherosclerotic lesions preferentially originate, expresses an atherogenic endothelial gene profile. Besides, wall shear stress regulates arterial diameter by modifying the release of vasoactive mediators by endothelial cells. Most of the studies on the influence of wall shear stress on endothelial cell function and structure have been performed in vitro, generally exposing endothelial cells from different vascular regions to an average wall shear stress level calculated according to Poiseuille's law, which does not hold for the in vivo situation, assuming wall shear stress to be constant along the arterial tree. Also in vivo wall shear stress has been determined based upon theory, assuming the velocity profile in arteries to be parabolic, which is generally not the case. Wall shear stress has been calculated, because of the lack of techniques to assess wall shear stress in vivo. In recent years, techniques have been developed to accurately assess velocity profiles in arterioles, using fluorescently labeled particles as flow tracers, and non-invasively in large arteries by means of ultrasound or magnetic resonance imaging. Wall shear rate is derived from the in vivo recorded velocity profiles and wall shear stress is estimated as the product of wall shear rate and plasma viscosity in arterioles and whole blood viscosity in large arteries. In this review, we will discuss wall shear stress in vivo, paying attention to its assessment and especially to the results obtained in both arterioles and large arteries. The limitations of the methods currently in use are discussed as well. The data obtained in the arterial system in vivo are compared with the theoretically predicted ones, and the consequences of values deviating from theory for in vitro studies are considered. Applications of wall shear stress as in flow-mediated arterial dilation, clinically in use to assess endothelial cell (dys)function, are also addressed. This review starts with some background considerations and some theoretical aspects.     

Optical imaging of the chorioretinal vasculature in the living human eye

Detailed visualization of microvascular changes in the human retina is clinically limited by the capabilities of angiography imaging, a 2D fundus photograph that requires an intravenous injection of fluorescent dye. Whereas current angiography methods enable visualization of some retinal capillary detail, they do not adequately reveal the choriocapillaris or other microvascular features beneath the retina. We have developed a noninvasive microvascular imaging technique called phase-variance optical coherence tomography (pvOCT), which identifies vasculature three dimensionally through analysis of data acquired with OCT systems. The pvOCT imaging method is not only capable of generating capillary perfusion maps for the retina, but it can also use the 3D capabilities to segment the data in depth to isolate vasculature in different layers of the retina and choroid. This paper demonstrates some of the capabilities of pvOCT imaging of the anterior layers of choroidal vasculature of a healthy normal eye as well as of eyes with geographic atrophy (GA) secondary to age-related macular degeneration. The pvOCT data presented permit digital segmentation to produce 2D depth-resolved images of the retinal vasculature, the choriocapillaris, and the vessels in Sattler’s and Haller’s layers. Comparisons are presented between en face projections of pvOCT data within the superficial choroid and clinical angiography images for regions of GA. Abnormalities and vascular dropout observed within the choriocapillaris for pvOCT are compared with regional GA progression. The capability of pvOCT imaging of the microvasculature of the choriocapillaris and the anterior choroidal vasculature has the potential to become a unique tool to evaluate therapies and understand the underlying mechanisms of age-related macular degeneration progression.     

Effect of Heart Rate on Ventricular Repolarization in Healthy Individuals Applying Vectorcardiographic T Vector and T Vector Loop Analysis

Background: Ventricular repolarization (VR) is strongly influenced by heart rate (HR) and autonomic nervous activity, both of which also are important for arrhythmogenesis. Their relative influence on VR is difficult to separate, but might be crucial for understanding while some but not other individuals are at risk for life‐threatening arrhythmias at a certain HR. This study was therefore designed to assess the “pure” effect of HR increase by atrial pacing on the ventricular gradient (VG) and other vectorcardiographically (VCG) derived VR parameters during an otherwise unchanged condition. Methods: In 19 patients with structurally normal hearts, a protocol with stepwise increased atrial pacing was performed after successful arrhythmia ablation. Conduction intervals were measured on averaged three‐dimensional (3D) QRST complexes. In addition, various VCG parameters were measured from the QRS and T vectors as well as from the T loop. All measurements were performed after at least 3 minutes of rate adaptation of VR. Results: VR changes at HR from 80 to 120 bpm were assessed. The QRS and QT intervals, VG, QRSarea, Tarea, and Tamplitude were markedly rate dependent. In contrast, the Tp‐e/QT ratio was rate independent as well as the T‐loop morphology parameters Tavplan and Teigenvalue describing the bulginess and circularity of the loop. Conclusions: In healthy individuals, the response to increased HR within the specified range suggests a decreased heterogeneity of depolarization instants, action potential morphology, and consequently of the global VR. Ann Noninvasive Electrocardiol 2011;16(3):287–294     

Artificial Intelligence and Machine Learning in Cardiac Electrophysiology

Cardiac electrophysiology requires the processing of several patient-specific data points in real time to provide an accurate diagnosis and determine an optimal therapy. Expanding beyond the traditional tools that have been used to extract information from patient-specific data, machine learning offers a new set of advanced tools capable of revealing previously unknown data patterns and features. This new tool set can substantially improve the speed and level of confidence with which electrophysiologists can determine patient-specific diagnoses and therapies. The ability to process substantial amounts of data in real time also paves the way to novel techniques for data collection and visualization. Extended realities such as virtual and augmented reality can now enable the real-time visualization of 3-dimensional images in space. This enables improved preprocedural planning and intraprocedural interventions. Machine learning supplemented with novel visualization technologies could substantially improve patient care and outcomes by helping physicians to make more informed patient-specific decisions. This article presents current applications of machine learning and their use in cardiac electrophysiology.     

Attenuation of thermal nociception and hyperalgesia by VR1 blockers

Vanilloid receptor subunit 1 (VR1) appears to play a critical role in the transduction of noxious chemical and thermal stimuli by sensory nerve endings in peripheral tissues. Thus, VR1 antagonists are useful compounds to unravel the contribution of this receptor to pain perception, as well as to induce analgesia. We have used a combinatorial approach to identify new, nonpeptidic channel blockers of VR1. Screening of a library of trimers of N-alkylglycines resulted in the identification of two molecules referred to as DD161515 [N-[2-(2-(N-methylpyrrolidinyl)ethyl]glycyl]-[N-[2,4-dichlorophenethyl]glycyl]-N-(2,4-dichlorophenethyl)glycinamide] and DD191515 [[N-[3-(N,N-diethylamino)propyl]glycyl]-[N-[2,4-dichlorophenethyl]glycyl]-N-(2,4-dichlorophenethyl)glycinamide] that selectively block VR1 channel activity with micromolar efficacy, rivaling that characteristic of vanilloid-related inhibitors. These compounds appear to be noncompetitive VR1 antagonists that recognize a receptor site distinct from that of capsaicin. Intraperitoneal administration of both trialkylglycines into mice significantly attenuated thermal nociception as measured in the hot plate test. It is noteworthy that these compounds eliminated pain and neurogenic inflammation evoked by intradermal injection of capsaicin into the animal hindpaw, as well as the thermal hyperalgesia induced by tissue irritation with nitrogen mustard. In contrast, responses to mechanical stimuli were not modified by either compound. Modulation of sensory nerve fibers excitability appears to underlie the peptoid analgesic activity. Collectively, these results indicate that blockade of VR1 activity attenuates chemical and thermal nociception and hyperalgesia, supporting the tenet that this ionotropic receptor contributes to chemical and thermal sensitivity and pain perception in vivo. These trialkylglycine-based, noncompetitive VR1 antagonists may likely be developed into analgesics to treat inflammatory pain.     

A new product design method based on virtual reality, gaming and scenarios

Through the years, many methods and tools have been developed that support designers in creating good products. Current trends, for example, are to use virtual reality (VR) simulation, gaming principles, and scenario based techniques during product design processes. Each of these methods and tools contributes to the potential effectiveness and efficiency of product design processes. However, in current practice, they are often applied in an ad-hoc manner. This paper presents a new product design method that integrates elements of a number of important trends in contemporary product design processes. Using VR simulation, gaming principles and scenarios, the new product design method gives non-designers (e.g. users, production engineers, marketing managers, maintenance workers) a proactive role in the design process. Within a dedicated design environment, all stakeholders are allowed to create their own designs and immediately test these in a wide variety of use scenarios. By letting stakeholders realistically interact with their personal creations, designers can quickly and reliably pinpoint their needs and preferences. At the same time, good designs are generated. The new product design method was applied to the design of a lane change support system; a system that supports the driver of a vehicle in performing lane change maneuvers. Using the design environment that was established for this case, the designer was able to get a consistent image of everyone's preferences as well as to draw a reliable conclusion about what would be a good design.