Lung Scan Procedure PDF

And before we get started here, I've got a couple of learning objectives to cover. 1:31 Differentiate between a Xenon 133 gas ventilation versus a technique ISM 99 m DTA aerosol. 1:35 Then describe the process for performing a perfusion lung scan for pulmonary embolism. 1:43 Describe the process for...

And before we get started here, I've got a couple of learning objectives to cover. 1:31 Differentiate between a Xenon 133 gas ventilation versus a technique ISM 99 m DTA aerosol. 1:35 Then describe the process for performing a perfusion lung scan for pulmonary embolism. 1:43 Describe the process for performing both ventilation and perfusion collectively for VQ scan 1:49 Differentiate between a low probability VQ and a high probability VQ for pulmonary embolism. 1:56 And describe the process for performing a quantitative lung scan. 2:02 So we are going to start off with what a VQ scan is and then we'll talk about the the two different components of the VQ scan. 2:10 So the VQ, at least in terms of I guess you could say general nuclear medicine lingo stands for a ventilation and a perfusion study. 2:23 Obviously you might be thinking, okay. Q Where exactly does that come into play? 2:39 You know, back in the day there were there was a quantitative component to the perfusion study and 2:46 the name just essentially or the abbreviation essentially kind of kind of stuck there. 2:55 We do also have what we call a quantitative lung scan, which I'm going to talk about at the end of this procedure. 3:02 But but basically today, in today's nuclear medicine world, 3:09 that is kind of a stand alone and not generally performed as part of the quote unquote, the queue to rule out pulmonary embolism. 3:13 Anyway, that being said, the primary purpose for doing these lung scans is to rule out pulmonary embolism. 3:24 That is the primary concern. And certainly there are other things that could be diagnosed as part of the lung scan. 3:31 But generally speaking, this is the most common concern and the most common reason for performing it. 3:41 Given that pulmonary embolism is an emergency type condition that needs to be diagnosed as quickly as possible, 3:48 these scans should be performed as step procedures. 3:58 That being said, there are some doctors who will order these, I guess, as part of a, you know, an outpatient procedure and schedule it in advance. 4:03 That being the case, they're probably less concerned about pulmonary embolism as the primary condition. 4:16 But far and away, the most common reason for doing it is PE, and that should be done step. 4:23 So patients typically are going to exhibit shortness of breath in chest pain. 4:32 The most common type of patient that that a nuclear medicine tech is going to get under these circumstances is somebody who comes into the E.R., 4:37 you know, with with chest pain or shortness of breath. 4:47 We might have somebody who recently had surgery and they're concerned, you know, that there could be a blood clot somewhere, 4:50 deep vein thrombosis that will eventually kind of break off and work its way into the lungs, forming a pulmonary embolism. 4:58 Occasionally, we're going to have patients from like the ICU that come down. 5:05 Again, those are going to be, you know, the stat variety. 5:11 This should be done in conjunction with a chest X-ray or a venous Doppler ultrasound for correlation purposes. 5:16 And, you know, as technology has advanced, CTE has really become the primary modality for diagnosing pulmonary embolism and nuclear medicine. 5:24 Lung scans are not done nearly as commonly as often as they have been in years past. 5:36 CT is a a better diagnostic tool for for determining pulmonary embolism. 5:44 The resolution is going to be much more clear. 5:51 It's faster, but there are occasions where we would still perform a lung scan and typically those are going to be. 5:54 On individuals who are highly claustrophobic, individuals who are allergic to the contrast that's given through the exam. 6:02 If a seat is simply not available, and on occasion, 6:11 if we're dealing with very obese patients who simply are too large to fit in the CT scan, then we can accommodate those patients. 6:16 Now there are two. Different methodologies, I guess you could say, for performing a the ventilation portion of the lung scan. 6:30 There is the xenon gas and there is also the DTA Tech Museum aerosol. 6:41 So we're going to talk about the Xenon gas first. This is going to be used when you have a negatively pressurized room with an exhaust. 6:49 This is very, very important because it is a gas. 6:58 And as a gas it can easily escape. 7:02 And if it does get into the environment of the room, you know, 7:05 it's it's basically going to have the potential to contaminate anything as the air flows, right. 7:12 So your walls can become contaminated. 7:21 You're sealing, you know, just anything that as as that xenon is is being picked up, you know, within the air and moved around there. 7:23 There's high levels of contamination. I'll talk about the half life as well. 7:34 The the natural half life of xenon is much longer than what technician is. 7:40 So if there is an area of contamination, then the risk of that area being contaminated is much greater because of the longer half life. 7:46 Approximately 10 to 20 militaries is going to be administered via this ventilation system. 7:57 And you can see that illustrated on the right if you open up. 8:04 This cabinet's down at the bottom. There's going to be essentially all of the. 8:10 All of the airflow mechanism down in through here, as well as what we call a xenon charcoal trap. 8:22 And it's there's a filter like mechanism. And basically, you know, as the patient breathes through this, through this mouthpiece here, 8:32 through this mask, you know, things are moving in and out through through this. 8:42 And most of it ideally provided that there's no break in the seal around the mask. 8:48 The xenon should flow directly into the patient. 8:55 They breathe it in, it gets it, and it gets taken up by the lungs. 8:59 And then as they breathe out, some of that excess will be sent back through the tubing and kind of trapped down in here. 9:05 And it keeps it contained. And prevents it from, you know, contaminating the the room. 9:16 That being said, you know, it's very important that there is a tight seal around the patient's face using this mask, 9:24 because if it does escape, as I said, that can be very problematic as far as contamination is concerned. 9:30 So the patients will breathe this in. 9:37 It is this contraption is going to be hooked up, obviously, to a gas tank. 9:42 And we're going to crank the the flow of the gas usually to about 12 liters a minute so that there's good airflow. 9:47 If you look right here. There is like a little access port. 9:55 And what we do is we take our vial of xenon and we put it in a LED shield. 10:03 And on the back end of that led shield, there's going to be almost like a little like a little hand pump, 10:10 almost like a little rubber ball that you squeeze. And what it does is that it pushes the xenon into the system. 10:19 And then with the oxygen that's going to be, you know, sent through here, 10:29 it will carry the xenon through the tubing and into the patient for the ventilation component. 10:36 There's a dial right over here where we start with the patient's, the patient's inspiration. 10:43 We call this oftentimes the wash in the patient should be instructed to take a deep 10:50 breath to try to get as much of this xenon in at the very beginning as possible. 10:55 They kind of hold that for, you know, as long as they can and it fills them with the lungs. 11:01 Once it's in the lungs, we switch this dial. From the wash in to the equilibrium phase. 11:09 And we take a series of of dynamic images of the lungs during that time. 11:15 And, you know, that's basically just, you know, equilibrium. 11:22 That's it's, you know, the maximum uptake to the lungs at that time for a very short period of time. 11:26 It'll stay in the lungs and then it will begin to wash out. 11:31 And then we switch the dial over here to the end with the wash out phase, and we'll start to see the xenon clearing out of the lungs. 11:35 The whole process is going to take approximately 60 seconds to do this event. 11:43 So that's one of the things that is kind of, I guess you could say, a disadvantage to performing the xenon gas. 11:49 One. You know, again, you have to have the properly then it room, you know to you know the physical half life is, 11:57 you know five, you know five plus days, 5.3 days as it shows here on this slide. 12:06 But the biological half life is very short. It's only, you know, approximately 30 seconds. 12:12 And that's why we're saying, you know, 12:18 this entire lung event is only going to take approximately 60 seconds in that, you know, you take the deep breath, 12:20 you get the initial flow, you get the equilibrium, and then, you know, 12:27 30 seconds to 60 seconds, it's beginning to kind of wash out and clear out of the lungs. 12:32 So if you miss it and you don't have your set up done properly, 12:38 you you're not going to get a good that you're not going to get any really good diagnostic information. 12:42 So it's very important that you have everything ready to go set up properly and and that no 12:49 mistakes are made here because you're not going to get a you're not going to get a second chance. 12:54 You do need to make sure that the patient is positioned properly to ensure that the lungs are within the field of view prior to administration, 12:59 because, again, nuclear medicine technologists know this. 13:07 But, you know, for those of you that aren't nuke med techs listening, you know, our cameras don't produce any radiation. 13:10 So, you know, we're not going to be able to see the lungs until after the patient begins to actually 13:17 breathe this in once it's in their body for the duration that it's in their body. 13:25 Our cameras will be able to pick up the information and see it. 13:32 But, of course, if we don't have them properly positioned within the detector field of view before we begin. 13:36 The ventilation. Obviously, you know, we're going to miss what we need to see. 13:44 So what we do is we can mark the patient ahead of time. 13:51 We take the isotope and we position it briefly over the super sternal notch or on top of the shoulders to represent the upper field of view. 13:54 And then we put it along both sides of the patient left to right. 14:05 And as long as as long as we can see, you know, this this dots essentially from our isotope showing up at the top, the left and the right. 14:09 And then, you know, at the area of the safe, we process just below where the base of the lungs are going to be. 14:18 And all of that is within the field of view. Then we know that the patient's properly positioned and we can begin the ventilation process. 14:24 So we're going to administer the xenon and then the lungs will begin to visualize, 14:34 as I described before, patient is going to receive approximately 10 to 20 militaries of xenon. 14:39 As I said, it's got a 32nd biological half life, but a 5.3 physical day, half life. 14:46 And again, that in that 5.3 physical half life is is certainly a concern when it comes to contamination. 14:52 So, as I said, very important to make sure that the patient understands how to use the mask properly. 14:59 And you as the technologist explain that clearly so that so that there's no gas that escapes out. 15:07 The energy's very low. 81 KTV is is a very low gamma energy for our purposes. 15:14 Anything below 150. Kev is considered low energy. 15:21 Basically between 150 to 300 is considered medium and anything above 300 is considered high. 15:28 So most of what we use is TEC Museum Base and that has 140 Kev energy. 15:34 This being 81 is significantly less than that. So the exposure rate to the patient is, is very, very minimal. 15:40 So we position the mask and again explain the need to maintain a tight seal and then we 15:50 inject or we pump the gas into the machine and instruct the patient to take a deep breath. 15:57 So the images that are going to be acquired are going to be the dynamic flow for the inspiration of the wash washing. 16:03 And then we get our equilibrium images. And then lastly, our wash out. 16:10 The mask remains on for approximately 60 seconds, and then once we have our images collected at that point, 16:14 we can move on into the second phase of the VQ scan, which is the perfusion portion of the study. 16:22 But more on that in just a little bit. 16:32 Normal results for the Xenon events are a uniform and symmetric wash in equilibrium and wash out in both ones. 16:37 The left lung should have what appears to be a light cardiac notch. 16:48 Basically, you know, you kind of see a rounded I guess it looks like a shadow in the left lung because, 16:55 you know, of the of the heart kind of overlapping. 17:04 You know, the photons are, you know, in the lungs and they're working their way out of the body, traveling towards the direction of the camera. 17:08 And as they are passing through the body, of course, they're passing through other tissue, the heart included. 17:16 And as it does that, it creates a little bit of a shadow like effect. 17:24 So that's not a concern. That is completely expected. 17:29 And the wash out should be fairly complete with no retention of the gas. 17:34 So we should see the ones empty out clearly at the end. 17:38 Excuse me. Abnormal results are going to be areas of decreased activity where the lungs were not vented. 17:41 That can happen for a number of reasons, many of which are listed here below. 17:50 The ventilation study should present itself as normal in cases of pulmonary embolism, with a mismatch in areas for the perfusion. 17:56 So it's, you know, one, when we diagnose pulmonary embolism and again, 18:08 PE is the most common reason for having a lung scan or typically going to see a normal ventilation good airflow throughout the lungs. 18:14 And we're going to see abnormal areas in the perfusion only. 18:25 And I'll give you some examples of what that looks like as we go through this. 18:30 COPD and emphysema will be will present as inhomogeneous Washington with a patchy equilibrium and 18:37 areas of trapping during the delay during or I'm sorry delaying the wash out in the lower lobes. 18:46 Matching defects may be presence in the perfusion portion of the study. 18:55 Bacterial pneumonia may present as a significantly decrease ventilation and slightly decreased perfusion. 19:01 Localization and retention in the liver with with the vents will indicate a fatty 19:08 liver that is often prevalent in individuals who are alcoholics or morbidly obese. 19:14 You know, this these drugs that we use, you know, really are very, very good at. 19:23 Ads targeting the lungs, specifically many of the isotopes that we work with. 19:33 You know, obviously are designed to target different organs. 19:39 And there's there's oftentimes, you know, a much higher percentage, you know, let's say, of this particular isotope in the heart, not xenon. 19:43 But, you know, I'm just speaking general, You know, the technique is the ancestor maybe or my of you or something like that. 19:55 You know, the highest concentration is going to be in the heart, but there's also going to be subsequent uptake in surrounding organs. 20:03 You know, it's not uncommon to see high liver uptake or gallbladder or bowel uptake with these lung studies, 20:12 though the vast majority of this goes to the lungs and we do not typically see a lot of additional tissue uptake. 20:19 Now, this point. Here. The second to the last point showing liver uptake is one of the exceptions and not that that's very common, 20:31 but that would be indicative of, you know, somebody with a failing liver due to typically alcoholism. 20:43 If one leg is not presenting or presenting very poorly, it indicates it had a left, 20:52 which is a collapsed lung or complete or partial bronchial obstruction. 20:57 So that is the xenon ventilation option. 21:07 As I said, we have a secondary type option and that's the aerosol. 21:14 This is technically a based tech museum, as I said before, has a 140 KV energy associated with it. 21:21 So it is a little bit higher energy, but it is still considered low energy. 21:33 So it's very good for diagnostic purposes, not much exposure to the patients. 21:37 And you know, this has a six hour, six hour half life. 21:43 So now this will actually stay in the patient's lungs a little bit longer. 21:48 Right. With the with the xenon, it had a 32nd biological half life, so it cleared out rather quickly. 21:53 But that's actually kind of a. You know, kind of an added benefit, I think, when it comes to the actual imaging here, 22:00 because let's say you vent the patients with the DTA aerosol and, you know, maybe you didn't really get that great of event. 22:07 You know, you take a look at the lungs and, you know, they're not showing up all that clear. 22:19 You could always resent the patients. There's going to be some of that DTA still left in the in this in this aerosol nebulizer. 22:24 And, you know, maybe you just need to turn up the oxygen a little bit more or you didn't venom quite long enough initially, you know, 22:37 and it'll stay in the lungs and for a little bit longer period of time and you'll be able to work with it just a little bit more effectively. 22:46 The dose is going to be about 25 to 40 militaries. 22:54 That will vary based on departmental protocol. 22:58 And it does use this nebulizer or nebulizer that's very similar to it. 23:03 Get my pointer here. You know, your your aerosol is going to your aerosol. 23:09 I guess you can say trap is going to look something similar to this. 23:16 There's there's a filter in here. And basically what there's going to be a small little, I guess you could say rubber injection port. 23:20 So you're going to take your syringe that has your DTP aerosol and you're going to inject it through this little rubber stopper right here. 23:31 And the that liquid is going to be right here in in this little compartment. 23:38 And then at the base of this, there's an access port for oxygen tubing. 23:46 So you're going to hook up your tube right here, turn your oxygen tank on, 23:51 and then the oxygen is going to flow into this compartment where that liquid air is or where that liquid is. 23:57 And when the air when the oxygen rather, mixes with the DTA, it creates an aerosol mist so that oxygen is going to push that. 24:05 Up here into this tubing, and then you instruct the patient to breathe. 24:18 They do need to make a tight seal with their lips around this. 24:23 I like to describe it kind of as a as a snorkel like mouthpiece. 24:27 Tight seal, again, is very important because you don't want that to escape. 24:31 And then you're going to place this little nose clamp over top of their nostrils and you're 24:36 going to instruct them to breathe in and out through the mouthpiece using their mouth only. 24:40 And they should take a nice, slow, kind of exaggerated, deep breaths. 24:47 Generally speaking, the vents will last up to approximately 5 minutes. 24:53 The oxygen flow is going to be around ten liters a minute, perhaps 12 liters a minute. 25:01 You know, you definitely want to have a nice, forceful flow of oxygen, you know, to really to really mix and create that aerosol. 25:10 Now the patient can breathe in an upright position or in the supine position, whichever they're most comfortable. 25:20 A lot of times, you know, because we are scanning the lungs, Right. 25:26 Patients have different lung conditions. They do complain about not being able to lay flat on their back for lengthy periods of time. 25:31 So you could do your patient a little bit of a favor by venting them upright. 25:39 And then, you know, if you had to scan them upright for the ventilation scan. 25:44 Certainly the camera and detector heads can be manipulated in a way that, you know, 25:49 they can be seated in a stool with their back, you know, flat up against the detector head, kind of in a 90 degree type position. 25:53 Ideally, though, it's just a little easier if the patient is capable of laying in the supine position. 26:04 At any rate, getting back to. 26:12 Getting back to your setup, you know this because it is radioactive needs to be positioned in a led shielded container such as this. 26:15 And, you know, this will fit in will fit inside here or in a in a lead container of a similar design. 26:27 You know, they are different shapes and sizes depending upon what manufacturer you're buying these from. 26:38 But at any rate, you put it inside of this container, it's shielded with lead. 26:45 And then the photons that are coming off of here naturally are not going to, you know, work their way into the room environment and expose you, 26:52 the technologist or your coworkers who happened to be in here or happen to be working with the patient. 27:03 Once the once the scan is done, what we typically do is we take this out, 27:12 we put it in a plastic bag because there typically is a little bit of liquid still here and it is radioactive. 27:18 And then we have to store this in a lung. 27:27 Well, in a in a storage area. Typically, about ten a half lives is what the regulations usually require for storage and decay. 27:32 So we decay this for approximately ten half lives and we put the date on it so we know when it was placed in storage. 27:41 And then we use our GM survey meter to survey it several weeks later. 27:50 And then once it's once it's background, then we can dispose of it in the in the normal trash. 27:59 This is what our ventilation images are going to look like. 28:09 And this is a good vent right here. We are going to take images anteriorly posteriorly left anterior oblique, right, anterior oblique, 28:12 left posterior oblique, right, posterior oblique, as well as our right lateral and left lateral. 28:23 So typically what we're going to do is we are going to get these images. 28:31 For the ventilation. And then we're going to get matching images for the perfusion. 28:38 It's most common. To do the ventilation before the perfusion. 28:44 That seems to be kind of the standard protocol. That being said, there are some occasions where the perfusion study might be done first. 28:51 But, you know, it's it's usually a little bit. 29:01 Easier, I guess, to to diagnose the patient's condition if you do the ventilation initially. 29:06 The reason being is because the counts in the lungs are going to be much lower for the vents. 29:12 And if the isotope for the perfusion portion of the study is already present, 29:19 it's it's really going to be difficult to see any mismatch areas where the vent might have filled in following the perfusion. 29:24 That'll make a little bit more sense once I show you the perfusion study. 29:34 But for what it's worth, usually the vent has done a first. 29:37 Normal DTP aerosol results may show the fair mix. 29:43 It is not because the patient is breathing this in and it's not uncommon because there is a liquid component to this. 29:50 The a little bit, you know, kind of catches the fair next and that shows up a little bit bright. 29:59 The stomach in the gut may show if the patient's. 30:07 If the patient is swallowing a lot of contaminated saliva in their mouth, 30:12 you might again see a little bit of stomach uptake during the processing phases of this study. 30:18 We do have the ability to kind of mask out some additional areas of uptake outside of the lungs that we don't typically want to see. 30:25 And I know that that's probably not common protocol for other. 30:37 Imaging modalities. I know there's been a lot of controversy when it comes to presenting the images as they are. 30:45 With nuclear medicine, it's it's a little bit different when it comes to that. 30:54 Because, you know, the the the patients, you know, is receiving maximum exposure at the point of the injection. 31:00 And know any rate that's it's a it's a it's just different Let's just go that direction for now. 31:09 So it's not uncommon for us and it is acceptable within our modality to to typically 31:17 mask in order to bring out the areas that are most needed to see clearly now, 31:22 because you might see some of this stomach uptake, 31:31 you might ask the patient to expect a rate basically spit out their saliva into a tissue once the mouth piece is removed, 31:34 once the ventilation portion is over, if they have a lot of the saliva buildup in their mouth, they really should try to get rid of it. 31:43 And that should minimize the likelihood of of stomach uptake. 31:50 The trachea and the bronchi may also be visualized. 31:56 So if I jump back to this slide here, you're really not seeing a lot of that. 31:59 Like I said, this is this is actually a really good event. You know, areas that the you know, the trachea, for example, that might begin to show. 32:05 You may see just, you know, just a touch of it right here. 32:15 It's not uncommon to see, you know, some some considerable uptake, you know, basically coming in between the two lungs, 32:19 kind of a straight vertical line representing, you know, that that trachea take. 32:28 Okay. Abnormal results. Areas of decreased activity may occur when the lung is is not properly vented. 32:44 Again, that's it's up to you as the technologist to ensure that the patient is getting an adequate vent. 32:53 And again, usually the biggest problem is one of two things. 33:00 Either the oxygen flow is not strong enough or the patient is not making a tight 33:06 enough feel and the majority of the isotope is escaping during the vent process. 33:12 So those things are easily prevented by, one the technologist taking the time to explain to the patient and setting everything up properly. 33:16 So. Ventilation studies will usually present as normal in cases of pulmonary embolism with mismatching areas of activity in perfusion. 33:28 So much like I said, with the xenon vents, this is the same, right? 33:39 It doesn't matter whether you're doing a xenon vent or a technique fiom DPA aerosol. 33:46 The concept remains the same that you will likely see a normal vent with an abnormal perfusion. 33:52 Obstruction presents with bronchial branching missing or noticeably less ventilated distal to the obstruction. 34:01 One lung, not presenting or presenting poorly will indicate a collapsed lung or complete or partial bronchial obstruction. 34:12 Particle. The deposition presents in large central airways with obstructive lung disease with. 34:21 What what what we can commonly see here is particularly patients who say have COPD, emphysema. 34:32 You know, different types of obstructive lung disorders is that you will see almost what appear to be clumping like areas throughout the lungs. 34:42 Now you will still see. Oftentimes areas of uptake throughout the rest of the lung. 34:58 But those kind of clumpy areas or this you know, these these particle high particle content areas are where those breathing disorders typically are. 35:05 Now, of course, there is going to be a chest x ray to correlate with this. 35:20 So you wouldn't want the aerosol only to diagnose COPD, emphysema and whatnot. 35:25 But if you know that the patient does have that condition, this is very, very common. 35:31 That is not at all indicative of a pulmonary embolism because the pulmonary embolism is is 35:37 really going to be diagnosed with the perfusion or the blood flow portion of the study. 35:45 So the patient can have really, really terrible looking lungs on the vent, 35:50 but still be low probability for pulmonary embolism, provided that the perfusion portion of the study is. 35:59 You know, is is showing blood flow throughout. 36:11 Accelerated clearance of aerosols may be present in patients with chronic interstitial lung disease, 36:16 inflammation of the lung, such as acute respiratory distress syndrome and numerous cystic pneumonia. 36:23 So that represents the ventilation portion of this discussion. 36:33 Next, we are going to discuss the lung perfusion. 36:40 This is the most important part of the lung scan, because this is where we're going to really be able to see if there are blood clots. 36:44 Now, what the. What? 36:55 Blood clots in the lungs are going to present, as during a perfusion study, are usually going to look as triangular wedges around. 36:58 Typically the perimeter of the lung. So you'll see what appears to be kind of a well, perfused lung in the center. 37:10 And then all of a sudden you see kind of a wedge that's taken out of the side or the base of the lung. 37:18 Looks like a triangular wedge or an area of significantly lower uptake in the shape of of this triangle wedge. 37:29 So I'll show you what that looks like here in just a few minutes. Indications, though, again, are primarily for pulmonary embolism. 37:36 That really should be the primary reason for doing this. 37:45 You know, as I said, the resolution with these studies are not nearly as good as CT. 37:49 So, you know, if if if the doctor is concerned about other breathing disorders, there's there's a variety of other studies that can be done. 37:53 But historically, you know, it's to rule out pulmonary embolism. 38:02 And that's really what this is most commonly for. But, you know, it has been used for evaluation of of pulmonary perfusion to evaluate chest pain, 38:07 shortness of breath, evaluation of low blood, oxygen saturation. 38:19 Evaluation and management of carcinoma of the bronchus evaluation of perfusion affected by emphysema, 38:24 chronic chronic bronchitis, asthma, inflammatory disease and cardiac disease. 38:32 Detection of left or right. Shunt evaluation of lungs for pre and post lung surgery and evaluation for lungs. 38:37 Lung transplantation. Contraindications are going to be individuals who have pulmonary hypertension, you know, and areas of pulmonary hypertension. 38:45 You know, the patient is, you know, in a in a fairly critical state to begin with. 39:03 And they know they're going to be having some breathing, breathing trouble now. 39:07 One of the concerns with the perfusion study is that the isotope that we use a technique. 39:13 ZM 99 M MRI, which is macro aggregate aggregated albumin that's going to be listed here on an upcoming slide here in just a minute. 39:21 But it is made up of many, many small particles that essentially get get trapped in the lungs. 39:32 And depending upon the patient's condition and depending upon how many particles happen to be present, 39:44 those particles can essentially obstruct portions of the one that can impact the patient's ability to breathe if they're already compromised. 39:53 So I'll explain that a little bit more detail here in a couple of minutes. 40:08 But you know that that is a concern, particularly for those of pulmonary hypertension. 40:11 So what we would do in these cases is instead of giving, say, 40:17 four or five militaries of our MRA, we would reduce that down to maybe one military of a. 40:22 So, you know, the patient's getting far less particles. There's less protons present, obviously. 40:32 So you're not it's going to take longer to get the necessary counts that you need. 40:38 But, you know, we can still get the counts we need simply by extending our imaging. 40:43 So with our perfusion study, what might take. 40:48 Typically 30 seconds to a minute for each of our views that we're acquiring. 40:52 Um, you know, that might be extended, you know, up to 5 minutes per acquisition. 40:58 Um, you know, it's all based off of our accounts within, within a period of time. 41:04 So if we're using less activity, we'll just acquire, say, for a longer period of time to get what we need. 41:11 But, and it benefits the patient by giving them less. 41:15 Less particles. Another country indication would be acts of pneumonia or chronic COPD. 41:20 Right to left front. And hypersensitivity to human serum albumin. 41:26 Now the patient is first preparation should have a chest x ray within 24 hours if they are not currently symptomatic. 41:34 For correlation, however, if the patient is symptomatic, then that chest x ray should be within one hour of having the VQ study. 41:44 To assist in distribution to the lungs. The patient should be asked to cough and then take several deep breaths prior to injection. 41:55 So just again for clarification, the ventilation portion is again showing the airflow to the lungs was given via. 42:03 Either the the xenon or the DTP aerosol. 42:14 Right. They breathe that in with the perfusion. 42:21 They're not breathing anything. This is an injection into a vein and it will travel through the blood. 42:25 And end up in the heart. Therefore, showing us blood flow to the lungs. 42:33 The dose, the patient, then they should be placed in the supine position. 42:43 We're going to inject them with the radiopharmaceutical. Straight stick is preferred. 42:47 We want to try to avoid injecting through tubing because the MRA at macro 42:52 aggregated albumin being in albumin is sticky and if we inject through tubing, 43:01 a great deal of this isotope can be trapped in the tube and never actually make it into the patient's system. 43:08 So they're not getting their full dose. So we do want to try to avoid that at all costs. 43:16 That's not to say we would never inject through tubing. If you have patients who just simply have horrible veins and there's only one 43:22 access point and that is only accessible through an I.V. that's been placed, 43:30 you don't really have much choice under those circumstances. 43:37 And if you did inject through any kind of tubing, 43:40 you would flush it very thoroughly with failing to follow so that they can get as much of that dose as possible. 43:43 That being said, we want to try to give them a straight stick injection and then we're going to acquire the same use as we did for the ventilation, 43:52 which would be the interior, the posterior right, lateral, left lateral, right, 44:00 anterior oblique left anterior oblique right, posterior oblique, left posterior oblique. 44:04 And basically what we do is we kind of we take each of those acquisitions the anterior for the lung, 44:09 and then we view it right and right next to the end. I'm sorry, the anterior for the vents. 44:17 We view that right next to the anterior for the perfusion. 44:22 Posterior for the event. We view it right next to the posterior for the perfusion and so on and so forth. 44:27 The dose is, as I said, TEC Museum 99 M macro aggregated albumin or MRA for short patients typically are 44:35 going to get anywhere from 2 to 6 military's IV injection protocols very of course, 44:43 but that seems to be pretty standard. Their energy is 140 KV with a six hour half life and the patient should get, 44:51 you know within that dose range of 2 to 6 militaries, anywhere from 75000 to 700000 particles. 45:00 Localization is going to be blood flow to the pulmonary capillary or arterial or embolism. 45:09 Method of administration is supine. We want the patient in the supine position. 45:20 We don't want them sitting up for the perfusion portion of the study, 45:27 because what can happen is a high concentration of the MRA can end up being in the lower lobes of the lungs, 45:30 and we're not going to get good perfusion throughout. 45:40 So the best way of of minimizing that and ensuring that you're getting good blood flow throughout 45:43 the entire lung in both lungs ideally is to inject them in the supine position as a straight stick. 45:52 We want to, as I said, avoid I.V. administration when we do our straight stick injection. 45:59 We do not want to draw blood into the syringe. 46:07 We just want to, you know, get our little flash of blood in the hub of the needle and simply push the isotope through. 46:12 If you pull back on the plunger and draw blood into the syringe, mixing it with the MRA, that's already present. 46:21 What happens is because of that albumin, it will start to form these small little blood clots within the syringe, 46:30 and then you are injecting tiny little blood clots into the patient. 46:39 Now, if they already have a pulmonary embolism, obviously that can be a concern. 46:44 But in terms of imaging diagnostics, what that will show as we refer to as hot clots in the patient's lungs, 46:48 and you'll see these kind of blotchy like areas of increased activity in different areas of the lungs. 46:58 Again, that could be a health concern if they have to begin with. 47:08 But secondarily, it makes it very, very difficult to diagnose properly because of those those really highly concentrated areas. 47:11 Patient could be instructed to lift their arm following the injection with pressure on the site holding a piece of gauze or cotton ball, 47:23 and then you simply tape it on their end and that'll get the they will get the blood flowing, so to speak. 47:30 Normal results are going to be homogeneous uptake except for normal attenuation of skeletal structures, breasts or the heart. 47:37 These things are not overly common. 47:47 As I said, it's these drugs are usually very, very good at kind of just localizing within the lungs and minimizing. 47:48 Other organ uptake. Scanning in the upright upright position allows for better lung based visualization. 48:00 This is an option, particularly for patients who are very large. 48:08 Most commonly, our tables have a weight limit of 350, maybe up to £400. 48:12 When patients are having lung scans, it's not uncommon for our patients to be quite large, 48:23 which would would make sense in a lot of cases of patients with breathing problems. 48:27 But, you know, you might have a patient who is just simply too large for for the camera, 48:35 or you might have a patient or a table, rather, you might have a patient who is highly claustrophobic. 48:41 So what we can do is position those detector heads to scan them in an upright position. 48:49 It's going to take a little bit more time because in this case, 48:53 you're only going to have one detector head scanning the patient as opposed to two at a time. 48:55 But you can you can still get really good images this way. 49:02 The April activity is going to be less than the base, and subsegment defects affect about 7% of the normal population. 49:07 No abnormal results. 49:17 As I said before, we're typically looking for these kind of wedge shaped areas within kind of the periphery, oftentimes of the lungs. 49:19 It may involve portions or much of the lung, which shows a high probability of PE, especially with a mismatched ventilation correlation. 49:29 A striped sign in the images might indicate COPD matching defects with ventilation. 49:38 Scan in conjunction with the perfusion scan will indicate COPD, emphysema, lung dysfunction or tumors. 49:45 And if there's a reverse mismatch. 49:54 In other words, they have a a normal perfusion but an abnormal ventilation, then oftentimes that indicates pneumonia or adeleke ptosis. 49:56 So this is what the perfusion lungs will look like. 50:11 And this is this is indicative of a possible pulmonary embolism. 50:16 And I wanted to show you specifically what we're referring to by these wedges. 50:22 Under normal circumstances, you would see nice uniform blood flow throughout the lungs here, extending all the way to the periphery. 50:27 But you can see here there's this kind of triangular chunk that's just been taken out of the lungs. 50:34 Right. So this is the kind of stuff that we're looking for. We see it here, you know, to us to a little bit lesser degree here. 50:42 And the posterior let's see again, you can kind of see it here. 50:50 Here it actually looks like there's two segments and the right anterior oblique, 50:57 you got one here on this end and then you got another one here on this end. 51:03 So, you know, this is something that would certainly raise some red flags. 51:08 However, you would want to you would definitely want to correlate that with both the ventilation 51:11 portion of the study as well as the chest x ray in order to make a firm diagnosis. 51:16 Now in terms of how to diagnose, again, this is up to the physician. 51:25 But this is good information for the technologists to be aware of. 51:31 We have a prospective investigation of pulmonary embolism, diagnosis commonly referred to referred to as the the pipe head protocol, 51:35 where it gives indications for, you know, if you see no perfusion defects in the ventilation as well as the chest x ray is normal. 51:46 We say it's normal. There is there is no no likelihood of pulmonary embolism. 51:55 The the next level up where there's moderate risk or low risk, 52:04 I think you should say low probability 0 to 10% would be non segmental perfusion defects with no with a indicating hearty MAGLI 52:10 or an enlarged aorta with no additional perfusion defects or the perfusion defect with a larger chest x ray of normality. 52:27 Or perfusion defects that are matched with ventilation defects and a negative chest x ray with some normal lung perfusion. 52:41 Again, low likelihood, very low probability. 52:49 Next is low probability between 10 to 19%, 52:53 where there's one moderate or large match defect or greater than three small perfusion defects with a negative chest x ray, 52:55 one lung not showing perfusion. 53:04 A singular single lobular mismatch, a moderate pleural effusion with no other perfusion defects in the lung or heterogeneous perfusion. 53:06 This is not just to be clear. 53:16 You do not need to meet all of these criteria, right? This is this is an either or in many cases. 53:21 When it comes to this. 53:28 Next then is our intermediate probability between 20 and 79%, where there's one moderate up to less than two large mismatch perfusion defects, 53:30 one mismatched ventilation perfusion defect with negative chest x ray, 53:41 one matched ventilation perfusion defects with negative chest x ray may also be classified as low, depending on the size. 53:46 Any defects that are not difficult to place. In a lower high probability. 53:54 And then we have our high probability, which is 80% or higher, 54:00 indicating two or more large mismatch segmental perfusion defects or equivalent in moderate or large and moderate defects with a negative chest, 54:04 right chest x ray or two large mismatch segmental perfusion defects or equivalent borderline high. 54:13 That's a lot of information and that's a lot of scenarios. 54:21 And in many cases, again, probably one of the. 54:25 Really kind of difficult things, I think for the physician, for the radiologist to diagnose is, you know, 54:31 the level of probability with respect to a lung perfusion or with respect to the pulmonary embolism, 54:37 because there are so many variables, as we quick very quickly went through here with very low probability, low, intermediate, high. 54:46 My experience, and this is not carved in stone by any stretch, but my experience is that physicians oftentimes tend to be, I would say, a little. 54:57 Cautious in their approach with diagnosing these and probably tend to side a little bit more as, 55:12 you know, a moderate probability to a high probability. 55:19 If they see something, if they see a mismatch defect, 55:24 they're probably going to be a little more cautious and not take a chance as misdiagnosing something that might be there, 55:29 because the treatment, the reality is the treatment is usually just going to be some blood thinners to keep them off their feet for a couple of days. 55:37 You admit them into the hospital and, you know, they're on some high, 55:44 highly effective blood thinners on an inpatient basis and then they might be discharged 55:49 and continue to take blood thinners for a period of time outside the hospital. 55:54 You know, and it's again, it's relatively low risk, all things considered. 55:59 But the treatment is usually very simple and highly effective. 56:05 The last thing that a physician wants is the liability associated with. 56:10 Not catching a pulmonary embolism that's actually there. 56:16 And then, you know, the patient ends up dying because, you know, they diagnosed it is very low probability when it was more likely intermediate. 56:19 So, again, 56:28 physicians do tend to be somewhat cautious in their approach and maybe lean towards the side of moderate to high if there's something there, 56:30 if there's something there. So this is, I think, a really good illustration of what a normal lung scan on the ventilation would look like. 56:40 And that's what we have on the left. Normal lung vents. 56:50 And here we see an abnormal perfusion, right? 56:54 Um, you know, nothing out of the ordinary here. 56:59 You get good lung, good airflow throughout the lungs here. 57:04 You know, you're really seeing those triangular wedges here. 57:08 You know, you see one down here, you know, So there's there's there might even be something going on right here to a, you know, to a smaller degree. 57:12 But it becomes it becomes usually pretty clear that there's definitely. 57:23 That there's definitely something going on and, you know, should be concerned about. 57:33 Again, you need the chest x ray. You're not going to diagnose this without it. 57:37 So that is very important. But at least in terms of what we see as new Pentax, that would be a pretty good indication of of a pulmonary embolism. 57:43 This is what all of the. Of the images would look like. 57:53 Now, this doesn't appear to have the laterals, but we have our interior event, our interior perfusion, 57:59 our posterior event, posterior perfusion, left anterior oblique vent, left anterior oblique perfusion. 58:09 LPO via LPO profusion RPO event, RPO profusion, RPO, then RPO profusion. 58:18 And again, as I said, in most cases you would also have the right lateral and left lateral event and perfusion to kind of finish it all out. 58:26 So again, not being a radiologist, 58:36 we see what appears to be a normal ventilation throughout with some some wedges areas of concern 58:41 in the in the perfusion that would be indicative likely of a pulmonary embolism to some degree. 58:50 And then lastly, we have another study that is our quantitative lung. 59:00 Now, the quantitative lung is used is performed to evaluate high risk patients pre operatively for surgical candidacy. 59:06 And basically what we're looking for is just to see, you know, how strong are their lungs. 59:17 Essentially, we do a perfusion of the lungs. 59:22 We're not going to do event in this case. We simply do a perfusion of the lungs. 59:25 We inject the MRA and we get typically at a at a bare minimum, our are posterior perfusion. 59:30 Some protocols might call for the anterior and the laterals and some of the obliques. 59:42 But the most important view in this case is the posterior perfusion. 59:48 All right. And we're looking at both lungs. 59:53 And it is a quantitative study in that we have to draw a region of interest around various segments of the lungs to 59:55 show that this segment of the lung had this much blood flow by percentage of the total compared to this segment. 1:00:02 Compared to this segment compared to this segment. So generally speaking, what we do is we get we draw regions of interest in the upper left lung, 1:00:11 the lower left lung, the upper right lung and the lower right lung. 1:00:23 And then the computer system will calculate the percentage of the uptake in each of the four lobes of a lung. 1:00:29 So, you know, there's going to be certain counts based off of the region of interest that we draw around the lungs. 1:00:36 And you'll see that here in the next slide. And then the computer simply quantifies all that. 1:00:43 It says there's this many counts in this region and that compares that to this many counts within the total lung or within the two lungs combined. 1:00:49 Results are going to be indeterminate. 1:01:05 If greater than 75% of the lung zone has obstructive lung disease patients in the supine position for injection to avoid gravity, 1:01:07 fill in the lower lobes. Very similar to what I discussed during the perfusion portion of the VQ scan. 1:01:17 We inject the patient straight stick if possible, and we don't flush the syringe with the patient's blood to avoid the clots. 1:01:24 Again, same concept as what I described before, because we are still using the tech museum Mra. 1:01:31 The patient should remove jewelry, medallions, buttons, 1:01:38 etc. as they could cause artifacts within our images and it becomes even that becomes very, very important when we're trying to quantify. 1:01:40 And then we these are performed on patients with with known compromised pulmonary function, but not with pulmonary hypertension. 1:01:50 And again, this is this is kind of talking about the particles, a minimum of 75,000 particles per dose to prevent quantum modeling. 1:02:04 But ideally, anywhere between 200000 to 700000 particles are needed for viewing. 1:02:16 And the particles of the air can cause micro emboli and 100,000 of the capillaries out of 350 million arterials and 280 billion small. 1:02:22 There are 280 billion small capillaries in the lungs. So again, this is it's these little micro emboli that are that are a concern. 1:02:36 And again, it's, you know, 100,000 per 350 million. 1:02:45 You know, by comparison, it's relatively low. But we do have to be very careful, excuse me, of the total particles, because if, you know, 1:02:53 if we're injecting these micro emboli, you know, that can certainly complicate, complicate problems. 1:03:00 Okay, So here's ultimately what I wanted you to see when it comes to this are our computer system. 1:03:07 Our software applications that we work with essentially are going to look something similar to this. 1:03:13 And this is something that I just kind of hand drew as a demonstration, not using the software application that you might have within your hospital. 1:03:19 But at any rate, you're going to draw your four regions like this. 1:03:30 And some hospitals might do kind of the right the right up here and then maybe another region within the center and then the right lower. 1:03:34 So it might be three segments per lungs, but commonly two. 1:03:43 And you're going to compare the total counts in each segment of the lungs, usually by the total counts between both lungs combined. 1:03:48 In order to get a left upper quadrant percentage, a left lower quadrant percentage. 1:03:58 Right upper quadrant percentage, Right lower quadrant percentage. 1:04:05 You can see those down here. And then you can also get a left lung total and a right one total. 1:04:08 Okay. So as I said before, we're typically going to shoot for a right lung of 55% to a left lung, 45% ratio. 1:04:18 And again, the main difference between there is because of the overlay of the heart within the left leg, 1:04:33 it is going to commonly show a little bit less uptake in the left than what it would what it would the right. 1:04:38 But as long as you're within that ballpark, that's usually what you're shooting for. 1:04:46 And that is all I have. My references are listed here and I hope this was beneficial to everybody. 1:04:52 Again, you know, our VQ consists of ventilation and a perfusion. 1:05:00 We've got the two different types of ventilation, the aerosol as well as the the aerosol, 1:05:07 as well as the xenon, followed by the perfusion study collectively. 1:05:14 And then we have our lung quantification, which is typically a standalone study. 1:05:21 That being said, we can also some protocols might want to try to get the quantification as part of the VQ, 1:05:27 but that's usually not what they're shooting for in that case. 1:05:33 So but at any rate, thank you for your time and I wish you all well. 1:05:36 All right. Thank you, Dr. Smith, for your presentation on behalf of SRT. 1:05:44 Thank you for completing this SRT live recorded program. 1:05:48 Have a great day.