Could the Cath Lab One Day Use Virtual Reality to Prepare for Complex Procedures?

Introduction: How Does It Work? Volume Interaction’s virtual reality system is comprised of a software and a hardware component. The software (RadioDexter 1.0), is a DICOM-compatible three-dimensional (3-D) image reconstruction software. It allows you to generate 3-D images from various tomographic imaging data sets CT scans, MRI, MRA, MRV, functional MRI, CTA anything tomographic, meaning cross-sectional slices. Our software reconstructs a three-dimensional image, and the hardware displays it as a stereoscopic, three-dimensional image in an interactive virtual environment. You can then isolate and examine a patient’s carotid arteries, an abdominal aortic aneurysm, or the coronary artery tree, for example, all in 3-D, and physically manipulate the image with your hands or system tools. It is much faster and easier to interact with the image in this 3-D way than with the typical 2-dimensional (2-D) method employed by other systems, which offer a point-and-click mouse and computer screen (essentially, a 2-D method of interacting with a 3-D image!). The hardware component of the system comes in two versions: The Dextroscope®, for 1-3 users, and the DextroBeam®, for a larger group to participate. The hardware system allows you to interact with the virtual image of the patient’s anatomy visually, or you can work with 3-D objects with your hands, literally reaching into them. The Dextroscope uses a mirror to simulate reaching into a reflection of three-dimensional computer graphics, and the DextroBeam is a stereoscopic projection to a large screen, where the user also works with three-dimensional hand movements, and you see a big stereoscope projection in front of you. The advantage of the DextroBeam setup is that a larger group of people, perhaps 10-20 people wearing passive glasses, can share the experience of the three-dimensional data. Once the data is loaded into the system, the software has image segmentation components which allows you to segment the anatomical images, either automatically or through user interaction, depending on the application. You can segment structures such as tumors, blood vessels, aneurysms, parts of the skull base, and organs, for example. There are three main parts to the software: general image reconstruction, segmentation, and image co-registration. We have different methods to co-register CT and MRI. The most elegant method we have is an automatic method, which, in a couple of minutes and based on the integration of mutual information, gives you CT-MRI image co-registration. If you feel there is a need, you would first co-register CT and MRI, and then employ the segmentation tools. When you have appropriate three-dimensional images within the software, you then load those 3-D data sets into the virtual reality working environment (the hardware component: the Dextroscope or DextroBeam). Within this virtual reality (VR) environment, where you see active three-dimensional stereoscopic data, you can start inspecting that 3-D data. You can analyze the image, conveniently rotating and manipulating it with your hands. There are tools that allow you to conveniently measure vessel diameters or tumor sizes, or even simulate surgical approaches. There is even a drilling tool which allows neurosurgeons to simulate drilling into a patient’s skull. We have focused our energies and applications on the field of neurosurgery for many years. However, as we felt that our products are able to be applied to many other areas with good success, we have been diversifying into general radiologic image processing for the past 2 to 3 years. We realize that our system is ideal for looking at vasculatures. We are now in the process of refining applications specific to abdominal aortic aneurysms, and will probably next focus our efforts in the area of interventional cardiology. Essentially, the system takes a CT or MRI scan one step further, in allowing physicians to actually interact with the image that they see and take it apart, if they wish. Yes. Basically, it is one step further than current systems, where you work with three-dimensional objects using a mouse and a keyboard. Our approach was to have a 3-D, virtual object which is able to be treated similar to a 3-D object in the real world. In other words, if I am inspecting a 3-D object in the physical real world a cup in my hand, for example I can get the maximum and the most efficient 3-D information from it by just conveniently and intuitively holding it in my hand, turning it, rotating it, and simultaneously inspecting it by looking at it in stereo with my right and my left eye. In all of the currently available software out there, you cannot simulate moving and inspecting the object with your hands. You don’t have an intuitive way of turning and rotating the 3-D object, because you are accomplishing that action by using a mouse and keyboard, which is a 2-D means of working with a three-dimensional object. Second, you are looking at the object in mono in monoscopic representation on a flat monitor. We went ahead and brought three-dimensional objects closer to reality by displaying them both in stereo and in a 3-D working environment. When the data is collected from a patient, in terms of getting a CT, MRA, etc., does the software do all the work in terms of making all the 3-D data that is needed? As long as the data is in DICOM format, the 3-D reconstruction is automatic. It takes only a couple of seconds. Now, if you want to reconstruct a certain structure, let’s say a coronary artery of the heart, based on CTA, I would need to show the software where the coronary artery is, which means I have to click on that artery. Then, within a couple of seconds to minutes, I can reconstruct just that target object, or in the case of this example, only that coronary artery tree. In this case, the process of obtaining that isolated image would be partly automated. In the brain, if you want to segment a cortex, we have a segmentation module which automatically gives you the cortex. You just employ our cortical segmentation module, and the system shows you just the cortex, based on MRI. It’s all automated and it takes only a couple of seconds. You indicated that most of the system’s work has been in neurosurgery, and you have now also moved into the radiology field. Could you describe the sorts of patients or cases that physicians utilizing this software have been involved in treating? The advantage of our system is that we are able to work with multi-modality data, be it CT, MRI, or MRA, alone or in any combination. The flagship of our applications is in neurosurgery planning, especially for deep-seated lesions, aneurysms, arterio-venous malformations, deep brain tumors, skull-based tumors, and ventricular tumors, where we simulate and plan the ideal surgical trajectory. Beyond that, we have had good experiences with cranio-facial surgeons and with liver surgeons, who can utilize the system to better understand the anatomy and plan their approach. Orthopedic surgeons and trauma surgeons will also be able to find our system particularly useful. Essentially, our system is able to make the difference for any patient where there is a surgical challenge, an anatomical or structural complexity which requires you to try to understand in order to plan your surgical (or interventional) approach. In the field of diagnostic radiology, we are in the process of developing radiology-specific modules. One module is a stent-planning module for abdominal aortic aneurysms (our AAA module). As you probably know, nowadays we have the ability to treat this condition by putting a stent through the femoral artery. The planning of that stent, the dimensions of the stent and the decision-making - whether the stenting is possible or not, or deciding if surgery is required versus some other treatment option, can be done with a dedicated module which we have developed. This module is currently undergoing testing at the University of Pennsylvania and some European sites. This module for AAA stent planning provides you with the usual dimensions which are required in the process of stent planning, automatically and stereoscopically. It further allows you to check and modify the suggestions the module makes, within a virtual environment. This module is especially useful for abdominal aortic aneurysms for which surgery would otherwise be a challenge those with more extreme angulations of the aneurysm, or more dramatic tortuosity of the aorta. Even for cases where the AAA is straightforward, but where you need a bit further exploration of the structural position, we feel we have an advantage with our system and this particular stent planning module. Another module we’ve developed is a virtual colonoscopy module, which is also in the stage of prototyping, and which we are currently testing. It is essentially a stereoscopic, virtual colonoscopy. We are currently evaluating our technology in the diagnosis of coronary artery stenosis and the evaluation of ischemic heart disease, based on CTA. We think we have an advantage, but it needs to be clinically evaluated in studies. The system is suitable for easily, quickly and clearly evaluating the coronary vascular tree, based on CTA, in order to establish the diagnosis of coronary artery stenosis. Whether a patient has a stenosis or not could potentially be very quickly diagnosed, and any stenosis could be measured, by segmenting the coronary vascular tree and displaying it as a virtual image. By looking at it in stereo, you would be able to specifically inspect the vascular tree and therefore be much faster in your diagnosis than with monoscopic technology, meaning any image on a flat computer screen. If there is a stenosis, you can zoom into the stenosis and then employ manual measurement tools to try to find out the degree. We have utilized our system for carotid artery stenosis as well, all based on CTA data. You can isolate the two common carotids, or the tibial arteries (if you want to look at them), just by clicking on them and adjusting the image color and intensity threshold. The two carotids are then floating in front of you, in stereo. You may now rotate them with your hands, and very quickly appreciate the vascular structure, and see if there is a stenosis or not. Could you describe in more detail the system tools that are available and what operators can do once they have that stereoscopic 3-D image in front of them? For easy segmentation, we have system tools which allow you to manually delete or color structures of interest. We are able to make linear and curvilinear measurements. With respect to vascular work, the most important tool to have is the measurement tool. You’ll need to measure the diameter of the blood vessel before, in and distal to the stenosis, and you can do all that within your 3-D workspace. The system automatically generates a center line inside the blood vessel, so you can measure the diameters perpendicular to that center line inside the vessel. (I should mention that these system modules are FDA-approved in our system software, RadioDexter 1.0. Some of the other modules which we have mentioned previously are not yet FDA-approved and are still being tested.) The system comes with a DICOM viewer, so you can load any DICOM data, and then as with any other DICOM viewer, you can load the data and look at it in 2-D as well. You actually have multiple window views, and can have a preview of the 3-D reconstruction before you go into the virtual reality environment (the hardware component of the system). In 2-D, you can do basic things, like contrast and brightness adjustment, and some basic threshold adjustments. There are some filters which you can activate, along with 3-D previews and cropping. Once you are happy with the basic appearance of your 2-dimensional data, then you go into the 3-D workspace (automatic, at the click of a button), and work with the 3-dimensional reconstructed data. Currently, the neuro-surgeons who utilize our system need it for more for planning their surgical approach. We have simulated bone-drilling tools, where you can simulate drilling the skull, and we are also able to simulate surgical corridors and approaches, and so on. Diagnostic imaging employs a different approach to surgical planning. Here, you are trying to find out whether there is a stenosis or an aneurysm. Our system is able to efficiently and effectively allow you to diagnose if there is a stenosis or aneurysm. After establishing the diagnosis, you can utilize the system to find out the degree of the disease, and make measurements, which will be useful to help you determine the best treatment modality . With the current advances in multi-detector CT (MDCT) technology, we now have sufficient tomographic data available for coronary artery 3-D/ virtual image processing, and it is my belief that the new technologies will soon replace conventional invasive angiographic procedures. We will be positioning ourselves accordingly. Dr. Kockro can be contacted at rkockro@volumeinteractions.com

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