We're going to start out this morning with a talk on neuronavigation. This is going to be given by Eric Butler, who is a physician assistant. He's the chief surgical PA at Duke in neurosurgery. He graduated in 2004 from Duquesne University in Pittsburgh and joined Duke in 2010. And so he's going to give us a very informative talk on neuronavigation, which, by the way, when I went into neurosurgery over 30 years ago, didn't even exist. So he knows way more than I do at this point. Well, good morning, everybody. I'm glad to see everybody survived Saturday night in New Orleans. That's fantastic. She was so nice to introduce. My name is Eric Butler. I am the chief surgical PA for Duke Neurosurgery. And, you know, when they asked me to give this talk about neurosurgical navigation in neurosurgery, I started to break down how complex it really is. And I thought, wow, this could be a very technical talk or this could be a simple overlying type of talk. And so I kind of fell somewhere in the middle with that because I don't want to bore everybody to death. But I think if there's a couple of important points that we can all take away of how to make this a better tool in our momentum of what we do. So disclosures, none. Big sad face there. Duke Neurosurgery is the only people that pay me. So this is a nice quote. So I thought that starting today we'd do a little quick review on some geometric calculus, as this is the basis for a lot of what we do. So that's a nice quote from somebody there. And then we can talk a little bit about spherical coordinates and how that plays into the importance of how we navigate the human body. I got no winks on that one. So we're not going to do that. Because I spent a lot of time looking at that and refreshing myself and decided that that wasn't something I wanted to stand in front of a bunch of people and talk about. So this is what we're going to do. We're going to kind of do a brief overview. We're going to talk a little bit about the history because I believe that the history of navigation is important to understand where we come from, which helps you understand where we've arrived at and where we might go in the future for that. And then we're going to talk a little bit about roles and responsibility, but really just going to be some pearls and some things that I've learned over 13 years of doing this. So what is navigation? So navigation today, for those of you who are new to this field or just in the field the last couple of years, is an extraordinarily broad concept. And it's really a generic term which encompasses several different distinct disciplines. And it has many names. So you know in any scientific endeavor, particularly in neurosurgery and some of our other specialties, we have a lot of acronyms for things and we like to call things and what one company calls something another company calls something else. But at the end of the day they're really the same thing. So kind of a simple idea for what navigation is, is computer assisted surgery or CAS. And so to some extent in any of our endeavors where we try to apply a coordinate system to the human body, we have to involve mathematics, which in today's world means we involve computers. Because not very many people are sitting down and doing longhand algorithms to figure these things out anymore. Although this is how we started. So we also call it stereotactic surgery, stereotaxy. There are complete foundations now. So what really started out is navigation, as today probably best known as functional surgery, which is the stereotaxy side. And also today image guided surgery. And the list could go on and on with the amount of names that people have coined for this technology that we use. Kind of its simplest terms. And this is about as complicated as we're going to really talk today. You know three points defines the orientation of a plane in three dimensional space. You could also put up there the four points defines the volume. If you match those three points of the patient's anatomy on a plane or image of that anatomy to the coordinate system, then you can navigate that space. That's really the simplest, most generic term that I could come up with to help you understand. If you can identify a single plane on a planar acquired image and match that to those three points in space, then you can navigate that space. And this is really was the basis. And I think what has to be appreciated here is as we talk a little bit about the history, is how long ago this concept was really teased out and put into writing for folks to start to learn from. So a brief history of navigation I think has to start. There were some folks as I was doing my research for this, there certainly were some people who were before Horsley and Clark. So even in the late 1800s there were some folks around the world in different labs who were experimenting with different ways to reach inside the human anatomy without opening it up. But really Horsley and Clark had the first seminal paper on stereotaxy. And one of the ideas that they brought out in that was the application of Cartesian coordinates to the body. So to give a reference frame, how do I get back this? Unfortunately, as we'll see in the next slide, they didn't have the benefit of modern medical imaging. And so their landmarks were based mostly on external landmarks. And this limited some of their application. But they set the stage, and so they got a lot of people thinking, and they brought this to the forefront. 1933, Kirshner actually did the first stereotactic human procedure that was credited for that. The next big names on that list, Spiegel and Wykus in 1946, really competed for, you know, the important spot here. They brought a lot of things to the table that were built upon the ideas that Horsley and Clark put forward. And Clark himself continued to innovate even after his time with Horsley ended. And you can see that picture is actually a picture of their very first stereotactic frame that they put together for using on procedures on humans. So while Horsley and Clark did a lot of animal model studies, Spiegel and Wykus were some of the first to do on humans. And they were extraordinarily productive over the next decade and a half of moving this forward. And so, you know, there were some world things going on around 1946 that kind of slowed the international community down. But in 1949, Lars Lexell came out with his idea of a frame, which used a little bit different system of polar coordinates. And he also modified the frame in some different ways that we'll look at. At the same time, in a separate area, there were some gentlemen working on different models of atlases. So, you know, what's not on the list, and you'll see the next, there were some advances in radiology that took place over this time frame, which allowed us to start using internal landmarks to navigate the human anatomy. And then, you know, we kind of fast forward. We struggled through that time period where there were different frames, different things. But we were all kind of chewing with the same ideas of how to do something. And in 1979, a young graduate student came up with a device called the N-Localizer, which I think if you look back through history, or if history looks back on itself, will be one of the more important things that allowed us to do our modern stereotaxi. And this was really just a localizer system, which took a lot of that fancy mathematics and put it into a system where we could utilize it with different imaging techniques. And I'm sure you're all familiar with it. Whether you realize it or not, it's built into all the localizers that you see today. And this allowed the advancement of things such as the Brown-Robert-Wells frame, the BRW, or the modern version of that that we see more often, the CRW. And it's also used in the LexL frame. And then somewhere around the 1980s, with the advent of better computing systems, better imaging systems, we started to have the frameless stereotaxi, where we got away from applying frames onto people to be able to navigate space. So, as I mentioned previously, you can't really talk about the advancement of navigation without the second component, and that is medical imaging. Medical imaging, some could argue, really allows us to do what we do in navigation. Without that, we would be stuck doing some very complex algorithms that may or may not come out to be very accurate. So, you know, I won't bore you with that entire list, but, you know, some big things on there, obviously, the invention of X-ray, which, interestingly enough, was used just literally maybe a week after its discovery to do some medical intervention. Particular interest to us in the 1920s, while not necessarily an imaging discovery, Walter Dandy started using X-rays to do ventriculography. And he discovered that if he put air into the ventricles, he could get a very nice three-dimensional shape, which allowed him to see other anatomical structures within the brain, which were consistent across the human anatomy, that he could then start to map. The other one, which I think people kind of overlook, and I didn't quote an individual with the discovery because there were several listed there, was that 1960s, the image-intensive iron TV monitors. Prior to that time, utilization of these techniques required significant exposure to radiation, and it also was cumbersome at best. With this advancement, it really brought us into the modern age of what we understand of looking at a monitor to see things. And it's little things like that throughout history that change how we utilize this technology in our daily lives. Then, of course, the 60s through the 70s, we see the invention of the CT scan, the first 2D and 3D images from magnetic resonance images. And then in 1979, obviously, we had the availability of the first commercial MRI scanner. And I think you could have a lively and full discussion just on this list about who was the most important of these and who contributed the most, but I think they all deserve recognition of advancements in their field. So we talked earlier about what our base idea is. So this is really, at the end of the day, in any type of navigation, and you'll forgive the fact that this is a picture of a head because it can apply to any anatomical part. If we're trying to get a coordinate system, which you see on your left, and apply it to the anatomical structure that you see on your right, because this is what allows us to navigate in space. So, you know, we're trying to take this image, and we're trying to make it look like that. So if we could all become just engineered from start with a nice set of coordinates inside of us, it would be easy, but we're not, and so we have to have a multi-step process with a lot of checks and balances to make this happen. So, and this is how that takes place. Lots of complex math and algorithms, of which I don't think are pertinent here today, but understand that this is not magic that happens in space. There is no magic pixie dust that gives us this set of ideals that we do this. This is based on rigorous scientific work, and as such, it is potentially susceptible to errors, which I think is an important understanding to go with. So we talked about some of the early things. The picture on your left there is a model of the N-localizer, and I get a little bit on here, and you can see, for those of you who may not be familiar, the N-localizer is basically this. It's two parallel poles with a diagonal reaching between, and what this allowed us to do and why this is so important is because this allowed us to take computer tomography images, which are acquired in a planar, or a flat scan, and assign a set of coordinates to it based upon the distances between these two poles and the diagonal of the pole in the middle. And Mr. Brown and his colleagues figured out that if we add several of these together, we can create a very reliable and very accurate coordinate system. So this was a very important technology. And then on the right, you see the ENAC, which was our very first supercomputer. Today, you wear something on your wrist, which is probably 100 to 1,000 times more powerful than that. So we really have benefited by the age of modern electronics and the advances we've made in computer science. So, for purpose of this talk, this list could be much larger, but I basically put this into two categories. Frame-based stereotaxi and frameless navigation. And we're going to talk a little bit about those two ideas. Certainly, there are others that could be included on this list, but I think this is most of what people are going to see in their day-to-day practice. So, frame-based stereotaxi. When we talk about frame-based, we're going to limit this to the idea of the application of a rigid frame that is used for guidance. This frame is usually applied preoperatively, and most often with the patient being awake. We acquire preoperative acquisition of images, so we get our scans, we put the localizer on the patient, we send them to the CT scanner or the MRI, they get the images, we put these images into our computer, which is where we get our computer-assisted surgery, we pick our coordinates, and we go arrive at the target. A relatively simple idea, which is fraught with many ways to have error induced into the system. And as APPs who may be tasked with applying these frames, this is the point where you have to start thinking about, what's my role in the outcome of this surgery? Application of the frame is, you know, one of the very first places where you can have an error. Putting it on upside down, backwards, not getting it in the correct plane. These are all things that have to be taken extremely seriously because they are the base or the foundation for everything that's going to be built from there up. And it is a simple idea to that. We place a lot of CRW frames for posterior fossil work. If the frame is not put down low enough, the end localizer is not over top of the intended target area and hence decreases your accuracy level. So if you apply the frame incorrectly, at best you have to do some extra work with your mathematics to get what you need. But at worst, you have to take the frame off and reapply it, which is another insult to the patient, right? So you have to start to think ahead of time, even at the earliest stages, about how do I make this the most accurate thing that I can possibly do? See here, this is a picture of the CRW. A little jargon for this. The top piece you see on the left side of your screen, this is actually the arc system that you see. And what you see it sitting on top of is the phantom base, which is, as the name might imply, a phantom base. It's used to replicate the patient's head in three-dimensional space. And it didn't show up so great in the picture, but that little point right there, the top of that vertical bar, is the intended target. So we set the arc base on top of that. We dial in the coordinates. And then we double-check ourselves, make sure we arrive where we think we're going to arrive. The item on your right is a modern version of the Radionics Luminant localizer, which can be used for both CT and MR. And you can see in here our end localizers on all three sides, four sides, actually, for this. This is what the frame looks like in its disassembled state, vertical posts in which the pins are placed into the skull, and then the base ring of which it's attached to. Some versions of the early Lex-L frames. All the frames, even the modern frames, have gone through a myriad of changes over the years, both to increase reliability as well as ease of application, because they've tried as best they can to limit the amount of moving parts that can be put together incorrectly, which will result in a poor performance in the operating room. One of the things that Lex-L did, which was brilliant, was introduce the arc radiant system. Previous ones had multiple moving arms, which you had to move in three directions in order to get over your intended target. With the arc quadrant system, anywhere you have on this patient and this arc, you're going to arrive at the exact same spot, which sounds like a small thing, but when you start to apply this to the human anatomy, it becomes very quickly evident that it's advantageous to be able to enter the skull through different directions without having to do a lot of different calculations in the operating room. So that's kind of the frame base that we use today. Frameless navigation, as you're going to see later this week, if you stop by the vendor hall, the amount of variations of this technique are growing daily and can be quite overwhelming. But we're going to break it down into two relatively straightforward categories. The caveat here being is that there are other systems out there, and some of you may even use some of those other systems. The first one we're going to talk about is line-of-sight systems. So this is what you're going to think of when you think of your stealth station, your brain lab, your striker models. These are things that include an optical eye or a camera in one position, which looks at a reference array, which is rigidly fixated to the patient's anatomy, and then an optical array on an instrument. So the camera looks at the patient, it sees the array, the computer algorithm has put that into a coordinate system in space, and then it sees the tool, and so it knows where it's at in space. We'll talk a little bit more about that. And then the electromagnetic navigational systems, the EM systems, similar concept, but they use a magnetic field generator, which is rigidly affixed to the patient, and they have specialized instruments, which are registered within this field. The important thing here is that bottom line is that this type of system avoids the line of sight issues which you've, if you work with navigation in the operating theater, you understand how cumbersome that can be at times. Uh, and it also allows us to track non-rigid instruments. Uh, a technology that's really just coming into its own, uh, and will continue to improve with time, I think. Uh, this is just kind of a busy slide to show you that there are no shortage of different systems out there, but understand, at the end of the day, they all work on the same basic premise. So it's understanding what your needs are is gonna help you come to a decision about what system you're gonna use and how you utilize it. Uh, line of sight navigation. So this is just kind of a diagram explaining what we talked about, the optical eye, uh, as you see here, has to be able to see both the fixation, the reference grid attached to the patient, uh, as well as the instrument. And it has to occur at all times. So if anesthesia steps in the way or you have a drape in the way, uh, you're gonna lose that line of sight vision and your navigation system's gonna cease to work. Uh, frameless navigation. So how do we, how do we do some of the stuff with frameless navigation? So we talked about the frame, the stereotactic frames, and we know that we place a rigid frame on the patient's head, we put a localizer and we send them on down to radiology, they take the images, they acquire them, we feed that data into our computer systems and it gives us our coordinate system. Uh, with frameless navigation, we're still stuck with the same idea, how do I get the patient's imaging to match up to a coordinate system? And so over the years there have been a multitude of techniques, uh, but most of them revolve around some variety of a fiducial system. So what most people are probably familiar with are the skin fiducials, uh, which are placed on the skin, the patient is scanned, uh, and then in the OR we do a paired point match, where we stick our little magic wand into the, uh, fiducial and we match it up to what's on the scan. Uh, modern day navigation has made this much simpler than it was even five years ago, uh, and the variety of fiducials has kind of waxed and waned over the years. Uh, you have bone fiducials, which are rigid fixation pins which you can screw right into the bone, um, and again this is a paired point system to which you place the bone screws in, you acquire the images, and you come back and you show the pointer where the pin is at and you match it up to what's on the imaging scan. Uh, surface matching, uh, this bottom right here is, uh, the Z-Touch by Brain Lab, uh, they're devices for every manufacturer, they're very similar to this. Uh, what this does is this uses a short wave technology to basically do a facial recognition scan. Uh, and so we match the surface of the tissue to the imaging and we go from there. This acquires many more points for that. And then the automatic image registration is a newer technology that's come out and, and I should say it's been perfected more in the last several years, and it's continuing to improve. Uh, and this is where we don't actually put any fiducials on the patient, but we actually acquire the images inside of a scanner which is built into the navigational system. Uh, and so what that allows us to do is place the patient in the scanner either in the OR, usually, uh, this is, the scanner is already calibrated and built right into the navigational system, so as soon as the image is acquired, we verify that it's correct and then we can start to navigate. So kind of one stop shopping. And this is gonna be things that you're gonna see on like the AeroSystem or on, uh, Brain Labs OR, uh, these kind of things. You'll see other items come out for that again. I think the important point here is to talk about accuracy. Uh, and here's another point, this is our second point. So we were applying a frame, we had to think about how we applied it. The big thing here is with fiducials, how you apply them and how you acquire them determine absolutely about their accuracy. So skin fiducials, if everybody sticks their finger on their skin on their head and goes like this, it moves, right? So you have to think about where you place your fiducials at when you're putting these fiducials on the skin. Um, because where it's acquired during the scan may not actually be where it's acquired once the patient is positioned in the OR. So you have three things you really have to think about. A, making sure that the fiducials are all included in the scan. And as we're gonna talk about a little bit later, uh, one of the important things is your relationship with radiology is gonna be rocky, rough and tough based upon how the quality of the images come out. Um, so if they don't acquire the image with all the fiducials, they're of absolutely no value to you in the operating suite. Uh, secondarily, if you patient, if your operation is a left temporal craniotomy and you place all of your fiducials on the right side of the head, which is now going to be down, uh, everybody in the operating suite is gonna be very disappointed in you because now they're not gonna be able to acquire those images, uh, very easily inside the operating room. And thirdly, um, everybody comes with different sized heads, different densities of tissue. Uh, we like to place fiducials where they're simple, where they're easy. You see them down here in front of the ear a lot. You see them in places that are easily deformed, both in the scanner. So we put a patient in the scanner, we stick the, the coil over top of them and sometimes I like to stick a pillow in there and you get the scan and the fiducial is pushed in. Well, how do I match that in the operating suite? I have to just guess, right? I kind of push it in a little bit to register it. But again, it's an, it's an inadequate fiducial. And then when you're actually localizing, this is a skill that's acquired. Looking at a screen and using your hands separately. Those of you who are good video gamers, this comes naturally to, for those of us who didn't grow up playing video games, this is, this is a more difficult skill to master. Um, but not deforming the fiducial while you're doing the registration process. I know these sound like very simple things, but they all play in to the algorithm which feeds our final product, which is our target registration error. Uh, and so every fiducial that we don't acquire accurately is one step into that. So skin based fiducials, while this is where the majority of the research has been done, I would, I would argue are probably one of our less accurate systems. Uh, the benefit to them are they're easy to apply. You can put a lot of them. So the more points you have for registration, the better chance the algorithm has of matching. Um, but they are wrought with potential pitfalls of acquisition and placement. Uh, bone fiducials. The downside of bone fiducials is that you have to make a hole in the skin. Okay? So depending on where you do these, uh, this can be a discomfort to the patient, can result in excess blood loss if you're not careful. Um, and they also require an understanding of making sure they're solidly attached to the skull. Just sitting in the skull doesn't work. They have to be rigidly affixed. But because they are rigidly affixed, um, once you acquire the scan, they can be very, very accurate. Um, surface matching. The problem with surface matching in my mind is the, is the quality of the scan. So today, uh, radiology, depending on where you work at and what's your relationship with them, getting the correct type of radiological scan can be very, very difficult. Uh, and so you send somebody down for a CT scan, they come back and they've cut off the nose. Yeah, they showed you the brain. Well, it's a brain tumor. So I showed you the brain. Well, yeah, but I know it was labeled as a, you know, a surface match scan. I needed the nose, I needed the orbits, I needed the skin. Um, so making sure that you have the appropriate imaging series for that is gonna allow you to get the best use of that. So, and also MR tends to be very difficult, uh, to do surface matching on because of the distortions natural in the MR acquisition. Uh, getting a nice smooth skin plane can be difficult. So keep that in mind if you're having problems getting quality scans, surface registration is not gonna be your friend. Um, there are other varieties out there, um, that can help you with that. There are some masks that you can apply from different, different vendors, uh, which take into account some of those problems. Um, so with all of these, uh, in our line of site imaging, we have to maintain a relationship between the array, uh, and the patient. So once the patient's registered, uh, if that array, if the, if the dynamics between that array and the patient change in any factor, your navigation is now no longer accurate. Uh, we talked about clear line of site between, uh, the eye and the surgical field. Um, and one of the downsides I feel to this system is that you're limited to straight rigid instruments or instruments with known shapes. Uh, today's technology's gotten better and we now have a, a larger, uh, selection of instruments which we can utilize inside the, the surgical navigation field. But you're still limited to these, uh, these ideas, um, and you have to take that into account. So, uh, a device we're probably all familiar with, uh, the skull clamp, whether you call it a Doro, a Mayfield, whatever variety of tissue Kleenex you happen to have. Um, people talk about frameless stereotax or frameless neurosurgery. Well, yes, we don't apply a rigid frame for navigation, but we still fixate the patient, um, in some varieties of this. Um, but, you know, this is so, understand you have to be good at applying, uh, skull clamp. You have to understand the limitations of skull clamp application because, again, if the skull clamp were to shift after you've done your registration, your registration is now invalid. Uh, and so, again, this is another one of those bedrock things that you have to understand. You have to understand the steps in the ladder that get you to that final destination. Uh, and this is another one of those first steps. So, some different line of sight systems, uh, just a little picture to show you here. The one on top left is, uh, a brain lab system, uh, and you can see that, uh, they've applied the Mayfield and this is the relationship, which I'm speaking of, uh, between the reference array and the patient set. If this distance changes in any fashion, your accuracy is no longer valid. Uh, and we have tools today. Uh, Medtronic has a very nice drill, which is navigable today. So, this is your, would be your instrument in the field, uh, which you can see. Uh, EM navigation. So, people think, oh, EM navigation. I, I've had people say, well, I'd love to use that. You don't have to fix, you don't have to pin the patient. Well, true, you don't have to pin the patient, but you still have to attach something to that patient to register them within that magnetic field. So, the relationship between the field generator and the patient still must be unchanged. Otherwise, the system has no idea where it is in space. Uh, big benefit, allows the use of flexible systems and instruments. Um, and it's also worth noting that you can do this with traditional as well. So, in the bottom right-hand corner, this is a, a skull-based array, uh, from Brain Lab, which allows you to attach the array directly to the patient's head. Um, somewhat limited use, I think, uh, in our institution, but for the guys, some of our skull-based folks who want to move the head around ENT, uh, they also have a band version of this, which I, is not quite as rigid. Um, but it is possible to do this without the, the EM. Uh, just some, uh, different things here. You can see, uh, on the top right-hand corner there, from the Medtronic system, this is their, uh, adhesive tracker that they place on the patient's head. Uh, pediatrics often like this option if it's available to them, uh, as this allows them to not pin the patient and not have to put anything through the skin, but it gives you a fairly, fairly reliable tracking field. On the left, you can see, uh, the stylet, which is flexible, which is very nice if you're doing, uh, complex, uh, ventricular shunts or placements, uh, for things like that. And people like OHN, ENT, anybody doing, uh, endoscopic endonasal work, uh, can appreciate the, uh, ability to have a navigable, uh, flexible stylet, such as a sucker, so that you can be working with a tool that's already in the field, but now it's navigated so you can be constantly checking your location. Uh, so I'm not gonna read all of this slide, the why's, the where's, we use it. I think the bottom of this is probably the most important here. Why do we use it? What's the purpose of this technology? Well, the purpose of this technology is to increase efficiency and proficiency. I would put that on both sides of that coin. Uh, decrease radiation exposure to the spine, to the staff in the spine, because we're not using live fluoroscopy. Uh, and this is probably a good time for a small caveat. There are some systems on the market today, uh, that are working on decreased radiation exposure levels, which are doing very good work, uh, and allowing people to use live fluoro in the OR with, uh, scant amount of radiation. Uh, and then the bottom one, stress reduction. So complex cases, whether people like to admit it or not, induce a tremendous amount of stress, right? We have a patient's life in our hands, they're on the table, you're from the APP side, you're trying to help out as best you can, but sometimes the anatomy is very complex and it, it, it just doesn't look normal. So, you know, you're trying to do the best you can. Your surgeon, uh, whether they want to admit it or not, is oftentimes feeling that same stress. You know, hey, this is just not normal. How do I know where I'm at? And so the idea is that the stereotaxis is, is supposed to give us that little bit of reassurance. But it is not a replacement for good surgical knowledge and anatomical knowledge. It is an adjunct therapy. It's, it's something you add to an already solid base. No neuro, no neuro navigation system is going to make you great at doing something in the operative theater. It will enhance a good skill, but it will not replace that base knowledge. So, you know, this is what we're striving for. And what we're going to talk about next, um, I think is probably the most important part of the talk, because, uh, if the equipment doesn't actually do any of these things, then why are you using it? Right? So if it's not increasing your efficiency, if it's not, uh, helping to reduce your stress, if it's not helping you to do a better job for your patient, then you need to take a break and stop and ask yourself, hmm, why am I doing this? So how do I make it do all those things? Uh, so I look for really nice motivational quote here and I couldn't find one that suited me, so I just made one up. Uh, so implementing any new idea takes a team and every team needs a captain. And so this is one of my takeaway messages from today, is APPs in the OR, you know, I think you need to find something to be the champion of. You need to find your role, your position, and I would tell you if you're in a system that uses navigation, this is often a scenario that is lacking a strong champion. But it is such a vital important, so I work at Duke and on any given day, um, you know, we might do 15 to 20 navigated cases, uh, in the OR. And that's not just within the department of neurosurgery, we have orthopedics, we have OHN, we have trauma, cranial maxillary facial, so we have a lot of people using these systems. And to have reliable individuals who know, understand how to implement this and how to utilize it, is a very, very important job. Um, we're gonna talk a little bit about this too. Uh, selection systems are systems, I don't know what to say about that, no one system is gonna be perfect for everybody. Some of it has to do how your brain processes logic flow, some of it has to do with somebody likes a certain way a screen looks and others. So there might not be a single system that works. Um, newly integrated OR suites are a phenomenal thing, but they are outrageously expensive if you're not starting from scratch. If you're starting from scratch, you might be able to adjust the cost offset, but in most cases they're gonna be very, very cost prohibitive. Uh, and then you have to weigh the needs against the wants. Because inside all of us lives a little kid. Uh, and that little kid loves new technology. And so sometimes you get people who are like, hey, I really want that, that'd be great. Well, do we need that? So you, you need to, you need to have that, uh, time to step back and look at the bigger picture for that. So let's say you've become, you've decided to be the champion of this idea and you're like, where do I start? Well, this is as good a place as I could think for anybody to look at to start. The four pillars. So what's involved in neuro-navigation today? So it's come a long way from, uh, Horsley and Clark's lab where it was just two guys and some lab techs, you know, kind of figuring out what things worked. Today, hospital administration, hospital implementation is an extraordinarily complex, uh, area. And so we have a lot of different areas working together to make a realization happen in the operating suite. Um, so, you know, start with the administrator and the purchasing side. So when you're looking at these systems in your hospitals, if you don't already have them, you have to make sure everybody understands what they're buying and why they're buying it. And so this is going to require some research. This is going to require talking to a lot of people to get that plan in place so that you can help others understand what this technology is actually going to do in the, in the terms of generating better outcomes for your patients, bettering, better generating patient revenue streams, and the whole works. And so this is going to, you're going to find this is going to stretch you outside of the necessary, the clinical bounds into some of the administrative work as well. That's also going to cause cost benefits, disposables, uh, are there any reps in the room? Yeah, sometimes reps don't always tell you about all the disposable costs that come along with systems, uh, right? And so this is something you have to be aware of because they can be considerable, uh, especially depending on what system you have and how many patients you're having. Um, if you haven't, don't already have these and you're looking to bring them in, demo as many systems as is physically possible in your physical space. One of the things you're going to notice when you go down to the great hall today and you look at some of the vendor stuff is that's a gigantic room and everything looks like it fits. Okay? Uh, famous story, my wife and I went and bought our first bedroom suit furniture and we were in this gigantic warehouse, oh, it was really pretty, it was great. Only to get home and realize that the headboard wouldn't fit up the stairs. Okay? Same kind of deal. People will sell you systems that once you get a, get an OR theater set up with a patient, anesthesia, draping, all the other stuff that goes in there, the ultrasound, it just doesn't fit. So you need to demonstrate as many of these systems as possible. Um, and then you also have to think about how it will tie into your existing systems. Uh, and that, this, this blends us over and I'm going to, I'm going to skip the two rows down to information technology or your IT department because this really ties directly into that. In today's healthcare society, where we're at in our, our ever-present goal of pushing, you know, to make sure that we're spending our healthcare dollars appropriately, buying redundant systems or systems that don't already fit into our infrastructure, uh, is not a good thing. Right? And it puts us at odds with a lot of other entities within the hospital. So you know, when we're talking about this, we have to involve our IT guys early on. Make sure the ability of the system to fully integrate into the hospital network. Can it talk to your PAC system? Can it get access to the, to your storage system? How much storage system are you going to have? These things generate a tremendous volume of data, uh, that has to be stored somewhere. Uh, so, network security. Uh, we recently had an episode in our institution where we bought a, a fine piece of equipment, only to find out after it was purchased and was in that we couldn't install our virus software on it and so it could no longer attach to our system. Um, it's a big, it's a big deal. Something you have to think about. Um, cloud or server based storage. Again, this is going to take up a tremendous amount of that. Uh, access to the planning system across the hospital network. One of the goals of efficiency or streamlining process is being able to move some of the planning, whether it be for patient informational purposes or actual surgical planning, outside of the operating suite. If we're occupying that operating suite in everybody's time, we're not really saving anybody money. So if we can move some of that outside of the OR, we can save everybody some time. And part of that is being able to make sure that you can sit in your office and you can pull up the software planning and do your planning there and have access to that. Simple things. Do you have enough ports in the OR? They all have to connect. Uh, and then system access security. How are you going to lock down that data so that it's HIPAA, uh, privileged. Radiology. So, radiology is going to be either your best friend or your worst enemy in this endeavor. Uh, and what this comes down to is education. Spending time with your radiology techs, with your radiology department, whoever is, uh, doing your scan data, putting it together, uh, and defining the scan parameters that are needed for your machine. I purposely didn't include, um, what's needed for each machine because every company has a little bit different ideas of what they want works best with their system. There are some general concepts that you have to adhere to, but, uh, once you decide on a system, you're going to need to make sure that that's shared with and involved with radiology. Uh, a current battle that I'm, I'm trying to fight, defining diagnostic scans versus navigational scans. And this relates directly to the issue of storage and, uh, data size. Uh, you know, if we're performing scans for navigational purposes, I don't need 13 different sequences or series. I need a, you know, a T1 SPGR with contrast. Stop. Make sure it's the right quality. Make sure it's the right scan thickness. Make sure you include the anatomical, anatomical parts that I need. Don't give me everything else. Uh, PACS access issues, ties directly into the information technology. Image storage, again, this is going to be something that radiology is going to yell at you about because you're acquiring too many images. Uh, and the availability of technicians in the operating room. So this is something you have to think about if your system possesses a intraoperative scanner like the arrow or the stealth, uh, O-arm. Do I have availability of technicians throughout the day and night? Or is my technology going to be limited to the hours of 8 and 5? Uh, this is an important concept to have a discussion with early on, uh, before you go down this road. And if you've already gone down that road, you're probably fighting some of these issues. Uh, and again, I say it comes back to education. Uh, the operating room staff. So where the rubber meets the road, right? You've got to involve these people, uh, and some of the things you need to think about is do I have sufficient storage space in my O-arm? Physical storage space. These are very, very expensive pieces of equipment. Uh, they're going to be handled by people who may or may not have the same appreciation for them as you do. Um, and so they require a lot of education. If they're dropping your frames down in SPD or whatever your cleaning division is called, right? Uh, this is going to have a direct impact on their accuracy. Um, if they're pushing your, you know, brand new mobile unit into the corner and smashing it behind the, uh, ultrasound and the microscope, this is going to have a direct impact on the quality of that piece of machinery. Uh, availability of ancillary equipment. Um, these things don't operate in a vacuum, right? And so we need to have, if you're using things where you need radiolucent frames, you have to make sure that your operating room is staffed so that you have sufficient amount of equipment that goes with these navigational systems that can be cleaned in a repetitious fashion and can be available for multiple cases during a day. Carry the equipment. I think that speaks for itself, but the, the big caveat there I think is education. Education, education, education. Taking the time out of your day to spend with your room attendants and your OR staff and the people who are physically moving this around to explain to them why it's important that they care about it as much as you do. Um, and then find your champions inside the OR, right? Uh, and this is going to be depending how many you need is going to depend on what your workflow is. Uh, so this, this shows a little bit on a variance for do I show up to the OR after the patient, you know, is already in there and the room is set up or do I come early and make sure the room is set up? These are things that are going to determine how many champions you need. Do the OR nurses who do your case, do they know how to turn the system on? Do they know how to pull images from PAX? Um, do you, are you lucky enough to have the availability of a rep who's on hand all the time to do that for you? These are all factors that only you can answer inside your individual situation, but be aware that you need to find your champions, you need to educate them, you need to support them and you need to be great, grateful to them for what they do for you. It goes a long ways having people help you with this technology. Uh, some of the must do's. Um, kind of a long list, we'll kind of cruise through this. Uh, make sure your studies are loaded and the plans are correct before you get to the OR. This goes to my previous statement of if you do all this inside the OR, you're really not being efficient. Uh, so you need to make sure that you build this into your daily plans if you're going to be doing navigational work in the operating suite or even if you're outside and it's just your job to make sure this stuff is done. Get that stuff done, get it done correctly. Uh, spend time with your representative from your system to learn the entire system. Uh, the hardware, the software, the troubleshooting. Uh, so many times in today's world we like to say, well, you know, that's clinical engineering's problem. Well, that's fine, but in the operating suite, when you have a patient on a table and something happens, I don't know how it is at your hospital, but if I call clinical engineering, they're probably going to laugh at me first and the second be like, yeah, we'll be up sometime tomorrow afternoon. Right? So if you don't understand how to troubleshoot your system, at least for the basic stuff, uh, you're going to be behind the curve ball. So I think it's really something to behoove you to, uh, spend a little bit of time, understand the system, understand its weak points, its strong points. Talk with your surgeons to anticipate what they're expecting from the system. Um, the worst time to learn that your surgeon thought that some system could do something it can't is when the patient's on the table. Now, I would say that shame on them, but in the real world, this kind of stuff can happen. We're all busy, and if they thought somebody else was going to take care of it, you know, the, or conversations just take place, but make sure you spend time so they understand the limitations of what you can and can't help them do with it. Uh, keep track of your cases. I'm sure we all do this to some extent anyhow, but, uh, keep track of them with your, in particular, with regards to your navigation, particularly if this is something that's new to you, uh, so that you can learn where you did good and where you did bad. Help the streamlines say, well, you know what, we haven't used that particular function ever. Don't, don't buy that next time, you know, or we don't, we don't need this. So keep track of that. You'd be amazed at the treasure trove of data that you can pull from that. Uh, spend time training and working with the OR staff. Spend time training and working with the OR staff. And if you don't have them done it, spend some time training and working with the OR staff. I think part of our role as APPs has got to be to bridge that gap, right? Uh, it, it's a unique position that we're in, uh, which allows us to have access and understanding of the clinical, clinical ramifications of what we do in the operating theater is not always shared by the OR staff. Sometimes they just, they're busy, there might be, you know, travelers, they might be folks who work in a different service line. Uh, God bless you if you work in an institution where you have the same people all the time, that's fantastic, but not every place has that. Uh, and so being an educator, I think, comes hand in hand with what we do as APPs. It's having that extra little bit of time to free up, uh, your surgeons and your docs to go do other business while you're doing some education, which makes everybody's life much more, uh, appreciable. Uh, some things that we do inside there, so at Duke what we've done, and I apologize, uh, these scans didn't come across quite great, but what we've actually done is we have set up room charts. Uh, and the room charts are listed by case, by anatomical location, and by room number. Uh, and so what they do for the room attendants and the staff who help to bring equipment into the room for that first case of the day is they give them little picture diagrams. It sounds simple, but it alleviated tremendous amount of stress, uh, and a tremendous amount of back work of having to tear the room apart when you come in and realize that it's not set up correctly. So, you know, sit down, work with your representative, work with your surgeons, decide who does what cases in what room, and get to work drawing some diagrams. People love pictures. It helps. Uh, lessons learned. Sometimes the hard way. Uh, so this is the philosophical side of the conversation, right? Um, navigational systems are just tools. And like all tools, they take time to master. Um, you've got to spend time with the system. If you, if you jump into your first case and you haven't spent the adequate time with the system, it's gonna reveal itself. And, and that's not gonna lead to, uh, an improvement of efficiency, proficiency, or in a reduction of stress. Uh, no tool makes a great carpenter, right? Same thing we talked about earlier. You have to have excellent anatomical knowledge. You have to understand the idea of the case that you're helping with. Uh, and then, and only then can the system help to improve that. Um, start with cases you're already comfortable doing without navigation. Uh, and, you know, this is probably more aimed at your docs since they're gonna be the ones who are gonna select this stuff. But, you know, don't decide to do your first, uh, T10 to the pelvis adult rotational scoli deformity, um, with a system you've never used, right? Start with something simple because if in the middle of the case you find it, A, it's not working, or B, you're just not understanding it, you can abandon the navigation and still complete the case safely for the patient. Uh, eventually every tool will fail. Be prepared. Uh, and this goes directly to understanding how to do the case without it. Uh, there are gonna be some limitations. Obviously with that, there are certain cases that we do that are not possible without navigation. And so if the tool fails, the case has to be canceled. Um, and then a good craftsman never blames his tool. Uh, there's nothing that irritates me more when I hear people have a bad time of the case, it was rough, and all they do is complain about the instruments. Um, that's all of our responsibility ahead of time to make sure we know how to do it. Uh, takeaways, uh, the history is there. Study it. There's tremendous volumes of work, uh, inside the functional, uh, community on the early, uh, revolution of frames, uh, how they were developed, why they were developed. Uh, you know, we really stand on the shoulders of giants, uh, that, that came up with these ideas and put them into practice. Take a little bit of your, uh, yearly time that you spend on CME and reading and just pick up a book and read some about some of these things. They're truly amazing, the, the work that they did. Uh, be involved. Decide to be a champion from selection all the way to implementation. Understand the process, how it impacts every part of your hospital, and how it impacts your patient care. Uh, be your champion. Educate the end-user, about end-user needs. Um, and this includes your administration. You've gotta educate them sometimes about why you need it, what this really matters to you in the OR, where, where the knife meets the skin, why is this important, right? Uh, same thing with your information technology, radiology, you know, our staff, uh, be a champion, educate. Uh, and I, I, this is the thought I, I really want people to, to take home, you know. Master your trade. Be great at what you do, because that's what you do, and you know how to do it. Uh, failure of equipment is not an excuse for poor performance, right? So keep that in mind. I think, I think that, that caveat, that thought alone should drive you to all the other points that you need to reach to make this a productive tool for you. Oops. I don't know how to get back to that. Alright. Can I go back to my last slide? Questions? Thoughts? Concerns? Issues? Chirp, chirp, chirp. Yes. Thank you, sir. So, good point. The question is, when do I decide between a frame and a frameless application? Uh, this, I think, comes in particular, uh, play for items such as stereotactic biopsies, right? Uh, I'm not sure how many everybody else in the audience does, but at Duke, we do a high volume of stereotactic biopsies. So we have some surgeons who very much swear by the rigid frame application of the CRW or the wax cell. We have others who have moved on to the, the frameless, and we could include PBS in this category as well. Um, I think the simple answer is baseline inaccuracies. So the limited amount of parts that can induce inaccuracies in a frame are fewer than they are in a frameless system. Um, a frameless system, if you've trained on frame, there's a different skill set to using a frameless system and a level of comfort. Remember, we talked about stress reduction. I thought to stick a needle in this human's head and take out some tissue in a very eloquent, perhaps, spot, I don't want to mess it up. Uh, and if I do, I don't have access to, you know, to get a bleed. So I want to use what I believe to be the most accurate. So because it's all skull-based fixation, so the frame is rigidly attached to the skull, and then the frame itself is very rigid. And this takes a, this takes into account drilling of the bone, how we access the bone, how we access the cortex. Um, it's a little bit more rigid inside that frame. So in theory and practice reality, um, I think the CRW frames, less cell frames are more repeatedly accurate. And we're talking about, you know, sub-millimetric accuracy here, which by the way, can only be achieved truly with a CT scan, right? Because, uh, if you would go and think about how navigation works, voxel size of your acquisition for scan really determines your accuracy level. A CT scan obtained at .65 millimeter slices can give you a sub-millimetric accuracy in theory, but an MRI, even on a T1, which is your most accurate, uh, imaging study for navigation, can only give you one millimeter accuracy at best, because of the size of the voxel. If you go into the tissues or flares, that circle keeps getting bigger, uh, where it's at. So, but then we tell ourselves, well, my, my biopsy needle is 1.7 millimeters in diameter. If I have, if I'm doing 1.5 millimeters, I'm pretty accurate there. And so this leads to a really good question of what is accurate enough, right? What, when is accuracy clinically irrelevant anymore, or when is it not relevant enough? Um, and this is going to depend on the part of the body you're working on. Uh, so I, I think the, the answer to your question is history, what they've used in the past, what makes them comfortable, uh, what they know works. I think for newer guys coming up who have been born into the frameless, uh, side of stuff, they have a higher comfort level with that, and they understand the limitations applied. Uh, but I will tell you that we do both equally well. Um, I'm not sure there's a concrete reason to not use one or the other. I think it goes back to surgeon preference and the availability of that technique. Um, but, you know, we place DDSs framelessly, uh, but we place them with a frame as well. Uh, same outcomes across that biopsy, I think we've shown to be the same way as well. So I, a little bit of that, I think in theory, you're right. It might be sensitive. Yes, sir? I don't know if your talk is limited to the brain, but one of the other things is, does it also respond to radiation? Uh, that's an absolutely good point. We're looking at meningiomas and thyroid disease, cancers, and insurgents. It's really an amazing thing that you don't have to worry about it. And you can get out of the room, uh, if she's not doing it. That's important to everybody. This is very correct in writing that, and one of the things that got kind of cut from my talk, uh, was this idea specifically. By no means is this limited to the cranial bone, which was the easiest to talk about, but spine is a big player in modern frame of navigation, right? Uh, and one of the reasons for that huge driver is there have been some studies that have come out over the last 15 to 20 years talking about the radiation exposure of spine surgeons, right? And the fact that somebody coming into spine surgery early in their career who's going to be doing some sort of fluoroscopy-driven navigation can exceed their lifetime dose, you know, within 10 years, right? And so we won't potentially know the ramifications of this. For another 20 to 30 years as these folks are reaching a point where this is becoming clinically relevant to them, but the amount of radiation that we absorb using fluoroscopy is, even wearing leather, is significant. Uh, and so the danger is there, and so, you know, there's some technology out there, I'll take a second to tout some of the stuff that Duke has developed there, the lessorate technology, uh, that's out there today, which can really, really diminish by like 85% the amount of radiation you're getting with fluoroscopy if you're using that in your systems. You have to think about this. You have to think about not only yourself, but the OR staff, circulating nurse, scrub nurse, anesthesiologist, all being exposed to that radiation. So the opportunity to move away from that I think is very appealing. It's not about its drawbacks, but it's something you have to work into your armamentum and understand how to apply to your scenario. Uh, but it's certainly worth investigating for that. Anything else? Alright. Well thank you very much. Thank you very much. Thank you. Excellent talk. Thank you.

neuronavigation

Eric Butler

Duke University

computer-assisted surgery

frameless navigation

accuracy in neuronavigation

training for OR staff

implementation of navigation systems

surgeons and healthcare professionals