IMG Radiology Series: CT (Head, Thorax, Abdomen, Pelvis)



Join medical student Randa and Dr. Hamza Khan in this fifth installment of the radiology series, focusing on CT scans and how to interpret them effectively, hosted in collaboration with LF One and the Medical University of Ple Emergency Medicine Society. This teaching session covers the fundamentals of CT imaging, touching upon crucial elements like the application of basic principles, understanding Hounsfield Units, Windowing, and the use of contrast. The lecture emphasizes how these principles can be applied when viewing CT scans, alongside providing practical advice on how to differentiate various types of tissues. It is beneficial for professionals who regularly engage with these types of scans and desire to refine their skills and understanding further. We look forward to having you participate in this informative and in-depth discussion.
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This seminar of the series will focus on key sections of CT interpretation. Application of basic principles for pathologies relevant to head, thorax, abdomen and pelvis on a CT.

Learning objectives

1. Understand the basic principles of CT imaging and the role of voxels and Harfield units in image creation. 2. Utilize the concept of windowing in CT imaging to differentiate between similar shades of gray and identify specific tissues. 3. Identify and apply the specific parameters of width and level in the windowing of CT scans. 4. Understand the different stages of contrast in CT imaging and how they assist in the visualization of structures. 5. Recognize the clinical indications for CT Abdo Pelvis and interpret the related scans in clinical scenario discussions.
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Computer generated transcript

The following transcript was generated automatically from the content and has not been checked or corrected manually.

Hello, everyone. Good evening and welcome to our fifth lecture for uh radiology series. My name is Randa and I'm 1/4 year medical student at LF One and also an education officer at U MSI. Welcome to all of you to our fifth lecture in collaboration with the Medical University of Ple Emergency Medicine Society. Today, our speaker is Doctor Hamza Khan. I warmly welcome him and all of you to our lecture. If you guys have any questions, please post in the chat and over to doctor Hamza. Thank you very much. All right, the presentation. OK. Uh Good afternoon everyone. Uh Hi, my name is uh Hamza. Uh And I'm going to be presenting uh a presentation on uh CT scans today. So thank you for those of you who are joining us. Um And uh thank you very much for that warm introduction. That's fantastic. Just uh for those of you who are here. Can you see the screen? Uh just one today? Thumbs up uh maybe in the comments section just to see if you guys can see the screen. Perfect. Excellent, great. OK, cool. So we can see the screen. Excellent. So um we can start right. So uh firstly, a special thanks to UI MS uh in Czech Public. Thank you very much for hosting us. Uh me and my colleagues from uh the UK. Uh I actually graduated from the Czech Republic in 2020. I studied at uh Paz University in Omo. Uh So check is very familiar to me. I'd also like to thank er Cleverer University's Medic Emergency Medicine Society and uh my colleagues from Croydon Hospital, which is where I work and where they work as well as Doctor Ti Zakaria and Doctor Karger go and finally, er doctor Parames per, who's a consultant radiologist at Croydon University Hospital. So today's main uh objective essentially is to learn how to apply the basic principles of CT imaging. Um Little disclaimer, we're not clinical radiologists, uh we're not uh diagnostic radiologists. So uh we're gonna teach you well, I'm gonna teach you as best as I can and we'll teach you as best as we can throughout this series. Um Any issues with audio, by the way, please let me know I can try and sort out as soon as possible. And uh what I would also like to say is the whole point of this lecture is to give you some basic principles and teaching so that you can, when you look at CT scans, you can try and apply them, you're not going to be experts by the end of this lecture. But at least you'll know something. So as the introduction, there are three things that we're gonna be focusing on. The first is recapping the basic principles of uh interpreting CT scans. And I think the basic principle is the main thing that we want you to take away from this series. When it comes to CT S. Um CT scans are very complex uh depending on the patient, their uh complex medical history and comorbidity as well. And uh essentially uh because of that, um interpreting them can be quite difficult. So that's exactly why as long as you know, the basic principles, you can try and figure out to piece together a couple of uh pieces of part of the puzzle. Uh We were going to focus on the ct thorax as well as the CT Abdo Pelvis in today's lecture. But I don't want to overwhelm you guys. So I think we'll just focus on the CT Abdo Pelvis today. Uh with the aim of discussing CD to in the next upcoming lecture, we're gonna be talking about the clinical indications for uh the CT Abdo Pelvis. And there will be some clinical cases as well as we go through, they're not too hard clinical cases. Um But once again, uh we, they will be used to practice what we plan to. So let's recap the basic principles. Um There are essentially uh three basic principles that we're going to be focusing on. Um And there will be a couple of other ones that uh we can uh we can talk about afterwards. But the main three principles that I want to focus on are field units and using Handfield Handfield units. Uh the concept of windowing and finally contrast and what contrast is and how contrast works. Uh So before we move on, does anybody know uh what Handfield units are for those of you people who are here? Any, any particular idea of what they are and what they, what they have a look at. OK. So we can move on to the next bit where we talk about the hands for units. So uh essentially, when a person goes through a CT scan, the CT scanner directs a number of x rays to um to the patient. Uh And it, it happens in a 360 degree uh motion. Essentially. Uh what happens is when the x-rays uh essentially uh when the patient exposed to those x rays, they calculate what the patient would look like uh using something called Voxel. Now, Voxel is basically a small unit as such. Um And they're a bit like pixels. So if you put those pixels together, you then form the whole image. Um how do you differentiate between the different voxel? How do you differentiate between different types of tissue? Uh You've got water, you've got soft tissue, muscle mass, uh you've got arteries, you've got veins, you've got bone. And how do you differentiate between all those two? All those different things because all of them will be represented by these voxel. And essentially what we use on CT scans anyway, is something called Harfield units. There are everything is presented in different shades of gray. All right. Um And here we can see a small diagram which is just to represent, don't worry about the numbers at the moment. The numbers are not so important at the moment. It's just the concept of what they represent. Um And essentially, we can see in this particular diagram that um uh there are certain types of tissue which are very hard. And so we will be higher on the scale of the field units. In, in other words, bone, it's plus 1000. And then there are literally nonexistent areas where there's air essentially and that's minus 1000 and somewhere in the middle, we've got soft tissue. So you've got fat, water and muscle. Now, some people think that fat is actually more dense than water. Water is meant to be zero. But actually, if you think about your science lessons back in school, if you mix water and fat, you'll find that they're actually invisible, which means that the water actually sinks beneath the fat. So the fat is actually lighter than water. So in that particular case, the fat and water will present differently on a CT scan and water will probably represent like something a bit lighter on a CT scan. And more importantly, not just water. But when we're looking at something a bit thicker, like blood, blood will present a little bit more lighter in comparison to fat or, uh for example, air, uh it's good to get used to the terminology. So we in CT scans, we look at uh densities or essentially attenuation and they're both the same thing really. Uh So the higher the density, the whiter it appears on a CT scan and the lower the density, the darker it appears on a CT scan. So we refer to that as hyperdense and hypodense. All right. Uh Later on, we'll talk about playing around with these Harfield units in order to differentiate between very, very, very similar shades of gray that we see in a CT scan. So I'm talking about, for example, uh if you're looking at a tissue and you're not too sure if there is some water edema or swelling, you can change the settings of the CT scan in a particular way or the actual scan itself, not the scanner, but the actual scan in order to create some contrast between those layers of gray. So that you can see the difference between those layers of gray more easily. In other words, you're creating a greater difference that you wouldn't be able to see with the naked eye. We talk about that. So the concept of windowing uh is basically uh well, we're coming on to what we just discussed about three seconds ago. Now, the concept of uh windowing. I essentially is focusing on a particular set of tissues. Um in order to differentiate between the different types of tissues. Windowing also allows something called the region of interest, which again is what we discussed uh differentiated between different shades of gray. So you're focusing on a particular area and you can see there are different types of windowing in each particular case or each particular type of tissue. The key point here essentially is two terms width and level and what do they mean? So I'm gonna go back to the image that we just showed and take, for example, uh bring as an example. So the width is 70 the level is 30. If we go back to this, the the width is uh 17, the level is 30. So the the level is the specific point in uh the range that essentially we're looking at. OK. So plus 30 is around here somewhere. So we're looking at some soft tissue but the, the 70 which is the width is how far apart we are looking in terms of tissues that might represent um what we're looking at. So in this particular case, it it will be uh 45 either way and that will give you a width of uh sorry, 35 by the way, that would give you a width of 70. OK? Um And that's important because what happens is that in brain tissue, say, for example, you're looking at a patient who may have had a stroke. OK. Uh you can differentiate between what might be edema and what might be brain parenchyma. Uh And so you, you know, differentiating between subtle uh differences, there can help you achieve an accurate diagnosis. But as I said, the, the numbers aren't so important at this stage. I think the key understanding or key concept is um understanding that you can essentially play around with a CT in order to look or differentiate between different shapes of break. Let's uh move on to the idea of contrast. So contrast in in a CT is usually ID based in an MRI MRI, it's usually gadolinium based and the contrast essentially enhances particular structures. All right. Um Any questions, by the way, please feel free to pop it into the uh comment section and we'll, we will answer them as we go along. So the uh in terms of contrast, what happens is is the contrast will go through different stages and those different stages will allow us to visualize er different structures. So the first stage is the arterial stage and this is usually the 1st 20 to 40 seconds of the contrast being uh administered. And so it goes through the arteries. Essentially. The second is the venous or the fourth venous stage. This is about 60 to 80 seconds into administering the contrast. And finally, the third is what we refer to as the delayed phase, which is about 5 to 10 minutes after administering the contrast, why are these three things important and how they're used? So, if you want to look at arteries, the best phase to look at it is the arterial phase. Um And you can see an example of the pulmonary arteries which will be discussing more in the next lecture in our CT chest and CTPA. Uh but uh and also systemic arteries as well, which come a little bit later. And that makes sense. Ok? Because it's gonna go through your pulmonary vessels first and then your heart and then it's pumped out, out of your heart or the left ventricle to the rest of your organs. So it goes into your systemic circulation. And then if you want to have a look at things like the liver, for example, uh then the best uh thing to look at or the best point to look at a after administering contrast would be the portal venous base that will enhance things like the portal vein, hepatic vein, for example. Um and uh any pathologies specific to the liver. Um and finally, the delayed phase. Uh So, an example of the use of delayed phase is in the kidneys. If you're looking at, for example, the collecting system, and more specifically, you're looking at the ureters and the urinary pelvis or the pelvis of the kidney. Um we're gonna talk a little bit about kidneys later on. So not gonna go into too much detail just yet, but that's essentially the idea of contrast. Uh So the key thing is there are three different phases and also um it's usually iodine based great. Um Another concept to understand is planes. So again, you know, there's your sagittal, your coronal um and uh your transverse as well or axial plane. Uh Once again, this isn't so important just yet because you'll be seeing most of the time your CT scans are done in, uh you know, you'll, you'll see the men in axial plane. So if the body has been cut into half, but you could also see it in coronal uh planes as well, for example. So um the ct that when you, when you get a scan, it will allow you to flip between different uh planes in order to understand uh what you're looking at. Really. Um And when you, it's important to know that when you're looking at a CT scan, it's as if the, the patient's feet are facing towards you and their head is facing away. So that's a concept that sometimes throws people off. Um You have to imagine that the feet are facing towards you and the head is facing away from the patient. So you are standing at one end of the CT scanner or one end of their bed uh with their feet facing towards you. OK? And that's how the CT scan is basically looked at when you scroll up and down a CT scan. That's how we, how we imagine things or that's how we essentially look at things. And that also means that your left is their right and their left is your right. You know. So it's, it, it, it becomes the opposite essentially. And that's important when you're looking at it because otherwise you'll end up making mistakes and saying, oh, well, that's left to right. And actually, yeah, so, um, we're gonna talk about uh the indications or a little bit about indications. Do you really need? Act? Uh because a lot of research shows that actually maybe we are over scanning. Ok, maybe we are um uh doing too many X CT S um and, and X rays and other scans as well. Why is that a problem? The problem is that we expose uh patients to a lot of radiation when we do uh CT scans. And there are some patients who have certain diseases or disorders comorbidities which require interval CT scans. For example, patients who have ITP um or uh bleeding disorders may need to have interval CT scans if for example, they, you know, and more importantly, they present certain symptoms like for example, headaches, you know, you're thinking to yourself, is there a potential bleed or for example, patients who are on blood thinning medications? Um and have had a particular fall, you know, they would need most likely a CT scan of the head. Um if they're having any kind of, if you're considering any kind of internal bleeding, they would need a CT scan. So the indications for a CT scan really depend on a couple of things. It depends on your clinical judgment and it also depends on clinical guidelines um towards the um the, the right. Uh I included uh are nice guidelines for our CT head. OK. So essentially we have a look at this when uh we are considering doing a CT head scan on adults. And you can see there are a couple of things that we look at, we look at the gcs, we look at the number of times they vomited any acute neurology. Um, so, but it varies from physician to physician. Some people are a little bit more lenient on ordering the scans. Others are very strict in following the guidelines and technically you should be following the guidelines. Ok? Uh I work in the emergency department and so does doctor T and doctor, um, uh, uh doctor kick. And, uh, we, uh, we, we have this debate every now and then as to whether the patient really needs a scan or not. But, uh, sometimes it's safer to do it if for example, the elderly and as I said, on blood thinning medication, you don't want to miss a potential bleed in the head. Ok. So, uh, this is just to practice, uh, what we basically learned so far. I know you guys probably know what it's showing, which is great Uh but I'm gonna point to a couple of structures and if you guys can, that'd be great. If not, I'll talk through it. Um II want to try and practice the terms that we've just used. So, um this is obviously, what is this? Uh what are we looking at here? Would that be soft tissue? What, what, what would that be? So, this is essentially bone. This is your lumbar sacral spine, this is your pelvis. Um And the reason why it's completely white is because this is a high attenuation or hypertense essentially, but high attenuation. Um And in terms of how this feels, we said bone was right at the end, which is about uh plus 1000. Um then we've got some soft tissue here. Most soft tissue will lie anywhere between minus 100 to plus 100. You have air here in the colon that's going to be at the other end of the spectrum. And finally, we look at the kidneys, for example. So this in particular, um you know, if we're looking at a contrast scan, it, this is probably towards the late arterial phase of some kind. I think um we'll talk about the kidneys a bit later on and how the different phases affect what you see in the kidney. And again, in terms of detecting abnormalities. So you can see here, for example, this is the brain tissue or brain pyma and surrounding this is basically the skull and there's obviously an abnormal mass there and this is how the abnormal mass presents. So sometimes abnormalities can be more subtle than this. But this is just an example and it's a very easy example. But something to illustrate the point that you have a slightly lighter shade of gray in the middle and surrounding it, you've got a darker shade of gray and then everything else looks pretty normal around here. So this slightly, this circumcised, slightly lighter shade of gray is most likely a mass of some sort. Um And it looks, you know, it's called for an irregular border. Uh and around it is some hypoattenuation in comparison to the mass that hypoattenuation represents a bit of swelling or edema. Essentially. Um If it grows even darker, it could, it might even represent some blood. But re really, I think at this point, it just represents some edema. So you know that there's something wrong here and this is essentially a brain tumor. All right. So we're gonna move on to uh the C tablet health and we talk about that. Any questions so far. Anyone have any questions so far? No. Great. Fantastic. So, um let's move on. So, key indications for acute abdominal pain, we've got a couple of key uh reasons why we do a CT of the pelvis. The first are gastrointestinal causes. So, uh you've got your cholecystitis, your obstruction, appendicitis, perforation types of infection, like for example, intraabdominal sepsis, abscesses. Um you want to know, for example, how big the abscess is so that you can eventually drain it. Uh, other causes include vascular causes. So, uh AAA, for example, and in AAA, we know that it's usually, um, aneurysms and ruptures more commonly in males, particularly middle aged males. Um, and there's a particular pattern of surveillance for it as well. So if it's less than five centimeters, then it's usually a, um, a, uh, six month due to yearly surveillance. If it's more than five centimeters, then it's a little bit more common. It's about three months. And if it's more than 5.5 centimeters in particular, uh then you should scan them really, they're presenting with symptoms. Um Other indications include trauma. So, uh if for example, you're considering a potential bleed in the abdomen. So someone's come in a little bit hypertensive, he's had, you know, an RTC or a road traffic accident of some sort. And he's having acute abdominal pain, you should really scan them to understand what's going on in the abdomen. Do they have a liver laceration? Uh have, is, has there been a perforation of some kind? Has there been some blunt trauma that you're not, you know, uh that you can't really see. Um And finally, we've got gynecological causes of acute abdominal pain, uh ovarian torsion, um pain from cysts, for example, or midcycle pain. Uh These are particular causes of acute abdominal pain. So, I actually once had a patient myself who I thought had an appendicitis female patient. Um, she was in her forties, uh late forties actually. Um And I think she was basically perimenopausal at the time. Of course, uh she presented with right lower quadrant pain guarding abdomen. And I thought, you know, the first, what, what, what would kill her quickly. Uh Would it be an appendix or would it be um, a very important, to be honest, both of them are very, are very dangerous things. So, II, uh, of course, before you scan, you should do a pregnancy test to make sure that they're not pregnant. But to be honest, you have to weigh up what you're looking at in a clinical scenario and a lot of, uh, you know, radio, they ask for pregnancy tests and things like that, which is great. So, um, but you gotta think about, you know, what's gonna happen to the patient is and what's the best for the patient? We should probably scan her. So I sent her for a scan, obviously she was not pregnant at the time. Um, and uh, when the scan came out the, the appendix was completely fine but it was actually mid cycle pain that she was having. Um, and the radiologist could see, er, from the stage of, uh, of, of a cycle that she was in. So, um, e essentially, uh, there's lots of different causes of acute abdominal pain and it's never a wrong decision. To scan someone if you think that they have a life threatening condition. Ok. Going back to what we were talking about in terms of indications. Cool. So we're gonna go for some basic anatomy. Um Now this is a lot of, a lot of information here. So if you need to but me in at some point, please do. I'm more than happy. Let's talk about some basic anatomy. So there are two major areas of the abdomen, the peritoneal area or um the peritoneal space and you have a space behind it named L Retro B. So essentially the uh in the peritoneum, we've got the stomach, the spleen, uh the 1st and 4th parts of the duodenum, the J midi. So the rest of the small and you've got the transverse and sigmoid in the retro peritoneum. So, behind the peritoneum, uh you've got the kidneys, the adrenal. Uh you've got the pancreas, uh ascending b, ascending colon and also the 2nd and 3rd parts of the duodenum. Now, what is the peritoneum? It's essentially a sheet of connective tissue and there's two parts to it. You've got your parietal and your visceral. Ok. So the visceral basically line the internal organs. Um In this particular case, you can see that this is all the visceral uh peritoneum lining particular organs. That's the liver, stomach. Um So, uh this is the uh uh parietal uh peritoneum and the parietal peritoneum lines, the um lining of the abdominal wall and the space between it is what we call the peritoneal cavity. So, uh there's particular areas uh of this that we can essentially scan if we are thinking of things like free fluid or blood and come to her in just a minute. We also have uh peritoneal, excuse me, peritoneal ligaments, which are essentially extensions of the peritoneum. Uh and they connect to different organs. So you've got the omentum and the mesentery, OK. Uh And clinically, it's important because when you're looking at a scan, uh you, there may be things that you want to comment on with those particular ligaments, right? So, um in terms of the basic vasculature, I think the key things to understand is uh basically the, if I take a couple of things away, your main bifurcation happens at L5, your mesenteric arteries which supply the intestines come off by L1 and L3. So, superior mesenteric and inferior mesenteric. Um and uh the uh uh renal arteries come off the superior mesenteric arteries. So talk about when we talk about kidneys, we'll learn more about in a minute. And uh that's that. So just a couple of bits of information about important spaces as we talked about. So, uh we have a space by the name of Morrison's pouch. It's also called the hepato renal space. And that's important. You can actually see this on what's called a fast scan, um which is an, an ultrasound scan, essentially um and it's a focus assessment on that particular area. And what you're looking for is free fluid in that particular area. And if there is free fluid, um then that's dangerous for the patient. That could mean uh blood essentially in, in that particular cavity. Ok. Uh And as I said, it's between the liver, hepato renal. So, liver and the kidney, uh there's also in the pelvis. Uh there's also the retrouterine pouch in females, uh or it's called the pouch of Douglas. And in, in males, it's of course, in the uterus. So it'll be the recto vesical pouch between the rectum and the bladder. Ok. So you've got your bladder. Uh and then in between the bladder and the rectum, you usually have the vagina in females and superiorly, you've got the uh the uterus and in males, of course, it's just the bladder and the rectum. Ok. So those are those that's the basic anatomy of the pelvis. Uh And in, in the pelvis, the, the terms are opposite. So you usually go from anterior to posterior, but in the pelvis, you go the opposite way, it's posterior to anterior other spaces. Um So, I mean, this is uh a little bit less um how do we say it uh important as such, but it's good to know. So, um uh less important at your stage. I mean, if you want to become a radiologist, it's all important stuff. So, uh but yeah, um essentially you've got the subphrenic spaces which is under the diaphragm. You've got the right and the left. Uh, so, uh, in the right subphrenic space, um, you know, you've got the liver and you've got the, um, the gallbladder and the left subphrenic space. You've got the spleen and the para hispanic space. Um, and at the bottom, you've got the paracolic gutters and they are essentially the left and right, uh, lower quadrants. Now, the paracolic gutters uh include different things. So your right paracolic gutter will include your right colon or your ascending colon. So, remember the, the intestines we can see in this particular image it'll go from caecum appendix, ascending colon, transverse colon, descending colon, sigmoid rectum and then into the anus essentially. So you've got the right paracolic left paracolic gutter. Um And as I said, these are important spaces and then around the kidney, you've got the perirenal uh space. Um So that's important. Uh You've got the anterior pararenal space and posterior pararenal space. The pararenal is basically essentially close to the kidneys per, surrounding the kidneys. Ok. Um Now, the perirenal space is covered by the perirenal fascia, which can be split up into the anterior and posterior. Ok. Um So, in the anterior, uh you, it's close to the pancreas as we can see here essentially. And uh the posterior perirenal space mainly contains fat. So, now we're gonna look at um uh the cta pelvis or by open, I'm gonna start off with the liver. So, this is the liver essentially right here. Ok. In both these particular cases, all right. Now, the liver can be split up into eight segments, uh, radiologically or radiographically if you want to call it that, uh, and it's split up by an important structure. Does anybody know what might be used to split up the liver into its different segments? So, uh, the structure that we use is the hepatic vein. Ok. So the hepatic vein essentially drains into the vena vena cava and it drains the liver. Um, the, don't confuse it for the portal vein which drains the superior mesenteric vein and the splenic vein. So, the hepatic vein is what we use to uh drain the, um the uh the, the actual liver itself and splits the liver into eight different segments. Um These are some of the branches. So we've got the uh uh the, the middle, um, the left and then the right. Ok. So that's the hepatic vein. That's what the liver looks like on. Uh the CT. And you can see that obviously, blood flowing will be a bit more high attenuation than the soft tissue. This is the stomach as well. With contrast, this is the spleen here. That's the spleen there. These are your kidneys and here you can see a little bit of the pancreas actually, which hugs the splenic vein. So, as I said, liver split into eight different segments. Um, now in terms of the segments, uh the functional left lobe is segments 1 to 4 and then segments 6 to 8 are the functional uh right lobe. Six is a little bit more posterior uh compared to the other lobes essentially. But this, these are the branches of the hepatic vein that spits it up and underneath you have the gallbladder. Um the portal vein which comes off at about the second number vertebrae roughly around that level, uh splits into the right and left and this is the hepatic portal vein here. So when you give a patient contrast, remember that the stage of contrast reading is important. So if you want to look at the portal vein, you waiting for the port penis, which is about 60 to 80 seconds into administering the contrast. So, just a recap of the blood supply of the arterial blood supply, which is the right and left hepatic arteries. Uh You've got the portal vein that drains the superior mesenteric and splenic vein, which is roughly here. That's the splenic vein, that's the pancreas, that's the body and the tail of the pancreas. Um And then you have the hepatic veins. So we've got a small case here. Um I know it's, it, it looks a bit uh it's pretty obvious, but we can, we can go through uh what we see essentially is the main thing. So you've got an 80 year old man. Uh He's an Asian man. He has a history of alcoholism. Um, and you know, he's had occasional pain abdominal distension for about a year or so. He doesn't understand why he keeps getting, uh, his body is becoming bigger. Basically, he's having some weight loss as well around the body. Um, and the last two weeks, he's developed jaundice uh on a blood test. Uh, you get a little bit suspicious and you order some specific blood tests and you order a protein. Um and you do the serum, the, the regular blood test that you do and you realize his liver function tests are significantly raised. What are you thinking? This patient might have, you have a cirrhosis? Ok. So that's a good shout because he has a history of carcinoma. All right. Very good. Any other cases? So we're on, we're along the right lines already, which is great. Hepatomegaly can be seen. Great. These are all fantastic answers. Yeah. So history of alcoholism, of course, you'll have some degree of cirrhosis and cirrhosis presents with in, in, in different ways, basically, but mainly you see a lot of scarring and cirrhosis. In this particular case, you can see that the tissue here is quite different to the tissue around here. It's a different attenuation. It's actually a low attenuation. It's more hypotense or hypoattenuated compared to the tissues surrounding it. So, you know, there's something different and the liver looks a bit enlarged as well. Correct. So, um the correct answer is actually hepatocellular carcinoma. Absolutely. Uh So I think it's ly said carcinoma. That's, that, that's correct. Uh You can see the hepatic veins here, by the way. Um So, yeah, that's, that's, that's the correct answer. Now, hepatocellular carcinoma. There are lots of causes for it. It could be virally induced through uh hepatitis, for example, alcoholism. Uh most commonly it's found in developing countries. Ok. And a specific tumor marker is what we discussed with protein. Usually, in most cases, more than about 400. And the second case here, you've got a 50 year old man involved in road traffic accident. He's a bit more drowsy, lower G CS, he's slightly hypertensive and he looks pale when you examine his tummy, uh he's very tender um and uh you know, screaming and a bit of pain as well. Uh So he is stable enough for you to send him to a CT scanner. Um And he just come back and this is what the scan shows again. What do we think might be going on? So, this particular region here and here and here, how would you compare it to this region here? Do you think it's, it's different? And what is the term that we would use to describe these tissues? So, again, the this is more hypo attenuated or hyperdense compared to the surrounding tissues. Um hyperdense. Yep good. So, uh this is actually blood and um essentially a little bit of edema as well. But the the patients had a liver laceration, that's what happened and they are essentially bleeding. So, there's a bit of edema and swelling and some blood there as well. So we'll move on to the next G, which is the gallbladder. Um, now, the anatomy is important. Uh, this is the gallbladder here, by the way, uh, you've got the fundus, the body and the neck of the gallbladder, which feeds into the cystic duct, which eventually feeds into the CBD or actually joins the hepatic uh, duct form the CBD. Um, the CBD, uh, you can't sometimes see it very clearly on a CT scan. Uh But uh if it's dilated, for example, or if there's signs of infection, which we'll look at soon, uh, then you will be able to see it a little bit better. That's the liver. So the gallbladder sits beneath the liver and the gallbladder fossa. These are your kidneys. This is your pancreas coming through. Uh It's a bowel and this is the spleen essentially. Ok. So that's where we are at the moment. So it should be less than six millimeters at around the age of 60 or less than 60. And then after that, for every decade, you can add on another one millimeter essentially. So, here's a particular case that, um, we can discuss, uh, this is what a normal gallbladder looks like. This is when it's dilated or essentially, it's infected. Uh And what we refer a infected gallbladder as what's the term that we use to describe it? So, for example, if you have a, a female seven months of vomiting, right quadrant pain, um, infection markers erased. What do you think she has in this particular case? Citti? Yeah. So, um what kind of changes would you expect to see around the gallbladder? So it's dilated, the CBD might be dilated but around the actual organ itself. What would, what do you think we might, we might see um would be swelling tissues? Yeah, at, at G and eventually thank you. And um yeah, uh that's correct called styes. Uh What do you think we might be able to see? Uh will there be some bleeding, will there be edema? Will there be uh what do you think that you, that you might be able to see so surrounding any organ where there is some kind of infection or most organs when there's some kind of infection? Um uh mucosal enhancement? Right. Thank you. Um That's good. Uh So surrounding uh the gallbladder, there's going to be signs of uh edema. Exactly impossible. Ru and cystic duct. Yep, correct. Um that edema and signs of inflammation or infection essentially present as what we refer to as stranding and stranding is a concept where you see different shades of gray, essentially that show edema. So you see some darker, more hypo intense shades compared to some lighter shades. And you'll see that with some other organs in a CT scan as well like kidney, we'll come on to that in a minute. Um, so essentially you'll see a thickened gallbladder wall. Ok. And you'll see some peri, uh, cholecystic, uh, fat stranding or, uh, signs of infection, right? So, the next, uh, organs are spleen, which is here. Ok. Uh, so that's the left side of the abdomen and it varies with age and sex, but it shouldn't be more than 13 centimeters in the largest diameter, which is going to be basically the diameter where you can measure the largest uh size. Ok. And the one of the best ways to find the spleen is basically to follow the splenic vein and it comes off the infer vena cava. Uh So here it's basically the splenic vein, uh the pancreas. So um uh the best way to uh find uh the pancreas is it's going to hug the tail of the uh splenic vein. So it goes around here, this is actually the head of the pancreas, this is the neck and the tail of the pancreas essentially right here. Um So, uh in terms of the uh parts of the pancreas, you've got the dorsal and the ventral part of the, of the pancreas. Now, in this particular case, uh dorsal, usually most of the time means uh more of a posterior. Um whereas the ventral um really refers to anterior, but in this particular case, it's going to be somewhat of the opposite because embryologically, when the, when the pancreas is formed, um the dorsal bud actually forms most of the head and the neck and the tail and the anterior of the ventral part forms one of the inferior parts of the head and the uh unicate swab. Uh So that's the pancreas here and that's the head here, essentially. And these are your kidneys, that's your spleen, that's your liver. This is your gallbladder. We went into the CBD right there. Uh, so in this particular case, you've got a 40 year old male. He's an alcoholic. Four days history. They're all alcoholic, sorry. Um, four days history of epigastric pain radiating to the back. He's vomiting. He's ignored his symptoms for a couple of days. Come in a bit late. His lipase is significantly increased with infection markers. You're worried for this patient. He doesn't, he doesn't look well. Uh, is this, I mean, it looks abnormal. Um, and what do you think is going on here? Pancreatic cancer? Ok. Good guess. Um, pancreatitis. Ok. Cool. So, what are the most common causes of pancreatitis? One of the two most common causes alcohol and gallstones. Fantastic. Great. So, um, alcohol, uh, history of alcohol, think pancreas, if they got complaining of epigastric pain, vomiting and, uh, gallstones because gallstones, as we said before, we talked about before, you've got the pancreatic duct which joins the, um, the common, uh, bile duct and that basically comes off. So you've got the hepatic duct which comes with the liver, you've got the cystic duct, uh they both join together and then later on, you got the pancreatic duct that joins in essentially. Um So, uh if there's any blockage or stone stuck in the CBD, it can cause the, the pancreatic enzymes to flow backwards. And that can cause infection and inflammation causing pancreatitis or acute pancreatitis. Essentially. Uh alcoholism can also cause it as well as we discussed. So, in this particular case, once again, you can see some hypo dense and massive irregularity compared to the structure that we saw before, which looks normal here. Um And this is actually forming uh or in the process of forming what's called necrosis. So this is basically necrotizing pancreatitis. Um and it's, it's forming a wall, it's essentially. So it's walled off necrosis. But uh this is all massively inflamed and dying tissue of pancreas, right. So, moving on further down, uh we're gonna talk about the adrenal glands. So, uh these are them here essentially in the retroperitoneum just above or superior to the kidneys. And they're usually less than about a centimeter thick or so. And they're usually concave if they're, if they don't have the same concaveness to them, uh then sometimes you think there may be cysts or masses of some kind that they're sitting there, um or abnormal masses, not cysts, sorry, but abnormal masses that might be causing a change in shape, but usually that's one centimeter once again, here's the spleen, here are the kidneys. This is the liver, there's the pancreas here. Now, we're gonna talk a little bit about the kidneys. So, uh the kidneys has uh we need to understand the system um of uh the f how, how the kidney functions. Essentially you have your renal artery renal vein which supply uh the kidney. Um Now, in terms of the uh in terms of how the, the renal system works, um essentially uh you've got the cortex and then you've got the medulla and this is all your filtering system. So, from the cortex, blood travels to the medulla and then uh from the medulla to the calles. And that's, that's essentially your filtration happening here and from metallic into the hilum and from the hilum into the test and that's your urine and uh re products. So, um once again, cortex to the medulla medulla, to uh your calluses and then to your hilum and then to your ureter. So we talked about different stages of contrast. Before in the arterial phase, you'd usually see the cord commu phase. So it would be around here, basically the cord cedary phase. And uh this phase happens first. So you see that in the 1st 20 to 40 seconds, followed by that you've got the nephrographic phase. Um So it's just before the delayed phase, essentially where you can see most of the tissue, uh the uh uh kidney tissue, the prime chal tissue essentially and that's good to highlight any particular prime chy of pathologies followed by the delayed phase, which is basically where you see the contrast of the ureter and the collecting system. So in cases of, for example, um a dilated ureter possibly secondary to a stone or infection of some kind um or dilated renal pelvis, uh you'd be able to see that best in the delayed face. So here, for example, you can see that this isn't, it doesn't look like it's a delayed phase. It's probably most likely in the corticomedullary arterial phase. Uh Here, it's pretty much progressing towards delayed because you can see the pelvis is starting to get whiter here or high, higher attenuation and then once the ureters have a bit of higher attenuation, then it's definitely into the delayed phase. So, um right. So we've got a, a case here which we probably, you guys probably know uh a 60 year old um who presents with urinary symptoms for five days, didn't take any medication, ignored symptoms, developed fever, vomiting and some flank pain and now in the urine, uh there's some blood and leucocytes. What do we think is going on any guesses, nephritis? Ok. Um Yeah. So, uh we refer to this as pyonephritis. This is a kidney infection essentially. All right. So you can see here, there's a bit of what I call before is fat stranding. So the tissue around, it looks a bit in inflamed and infected. Ok. And the kidney looks slightly larger than normal as well. And this is what I mean, by the different types of tissue you can see. Yeah, pds, Etgar. Yeah, you're correct. Um, so you've got a bit of higher attenuation and a bit of high, uh, hypoattenuation here. And that tells you that there's a bit of edema and swelling around that particular area. So, we refer to this as perinephric back stranding and that's a sign of an infected kidney or pyonephritis. Great. So we're gonna talk about the uh the bowel now. So a bit of a recap. Um So you've got your esophagus, gastroesophageal junction to the stomach, um which then goes into the small intestine, the duodenum jun ilium, uh which then goes into the caecum through the ileocecal valve. So the ilium goes into the caecum, uh caecum and appendix are in the same region which is the right, lower quadrant, ascending colon, transverse, descending colon, sigmoid rectum and then anus. Ok. So that's a basic overview of the uh different parts of it. If you don't know, the basic anatomy can be difficult to orientate where you are. So it's always good to know and also bear in mind, of course, that your left is there right and vice versa. Ok. The blood supply we've got uh slightly higher up at L1. So, superior mesenteric, which uh supplies uh most of the large intestine essentially. So, two thirds of the transverse colon, the splenic flexure which is close to the uh the spleen on the left side as we go down, uh the descending colon, the sigmoid and the rectum. Ok. So it's basically the latter half or the later half of the uh large intestine. And then you have the inferior mesenteric at L3. And that supplies the small bowel mainly as well as the transverse colon and the ascending colon which goes to the hepatic flexure. Ok. So ascending colon, hepatic flexure, transverse colon and then the splint flexure and descending colon. All right. So this is your stomach full of contrast essentially. And this is where we can see the gastroesophageal junction around this area region here. Uh Yes. As I said, this is full of contrast. Here's your spleen and your liver. Um 01 thing I forgot to point out the stomach. Uh This is referred to as the greater curvature and this is the lesser curvature essentially. So, just a bit of anatomy to go through. So we're gonna look at the uh small bowel. Uh So remember that the, the, the bowel can be divided into peri with peritoneal and they have different blood supply as well. Um So when we look at the duodenum, which is here, basically, um the essentially what happens is is that it, it, it effectively moves across to the right and then back to the left. Ok. Um So, uh you've got your kidneys here and this is the duodenum and from the duodenum, you've got your jun and then ilium and these are some ileal loops that you can see here. Essentially, they're sort of contrast in this particular picture. OK. Um And they go towards the right hand side and when they go towards the right hand side, the ilium then joins in with the large bowel through the ileocecal valve. And we're gonna talk about that in just a minute. So here's the ileocecal valve. Um and one of the signs of the ileocecal valve, sorry. Uh It's meant to be around here. This is the IDOC valve there is that there's a bit of fat around it. So we call that uh fat attenuation and that's how you can find the ileocecal valve. All right. So with the small bowel, remember that it kind of transverses across again, it goes back into the right, lower quadrant, not the left, I think, accident to the left before, but it's the right, lower quadrant and joins, joins into the uh cecum in the right, lower quadrant from the appendix, but into the sequence with the ial valve and then the ascending colon. And uh yeah, so that there's ileocecal vs right there. Uh We're gonna talk about trying to find the appendix in just a minute. Uh Because when, when you look for the appendix, uh there's different ways people use, but um a good way is using the Ileocecal valve as a checkpoint and progressing from there essentially. So here we've got uh the colon. So you've got the ascending colon and then moving forward, you've got the transverse colon. So, just going across here and the descending colon around here. And if we scroll a bit further down, the descending colon will go into sigmoid in the rectum and the anal canal, which will come down further just around this area. Essentially, if you scroll down, you'll be able to see it a little bit more. Um So I've saved this bit purposely for this particular case. Um What do we think we're looking at in this particular region? What do you think this is? I kind of mentioned it about three seconds ago, but it's a common case that you'll probably see if you work in A&E or in hospital departments. Yeah, appendicitis. So the normal appendix or finding the normal appendix, um, appendicitis, inflammation and obstruction. Great. So, yeah, so, absolutely, one of the causes of a, of an appendicitis could be that they're obstructed. Um uh So, uh and that's using matter, for example, like, you know, uh uh fecaliths, um which can cause obstruction surrounding inflammation around the appendix. So, here's a dilated appendix essentially. And similarly to other organs, we see some infective changes around the appendix, uh which suggests that it's inflamed and the treatment is basically, it has to be surgically removed. Uh So they go for uh laparoscopic surgery to remove the appendix, but to find the appendix, uh essentially, if you go back to the Ileocecal valve, usually, if you scroll a little bit more uh approximately to it, uh you'll find that the appendix is basically on the same side of the Ileocecal valve. Uh So whenever you're looking for the appendix, it, it will be in the same region or the same side as the Ileocecal valve. So it won't be anywhere up here, but rather down here. Um And that's important because there's lots of causes for right lower quadrant pain. So when you're looking for the cause for extreme, right, lower quadrant pain, if you follow that through, you'll be able to see the appendix. OK. And uh just recommended resources. We approach the end of the lecture. Uh If you guys want to learn more, I used a uh youtube website uh to help my supplement my knowledge as well as well as my experience. And that's the navigating radiology um which has some great lectures by Dr Rajesh, by uh baa uh who's an American doctor. Uh radio PD is a great website as well as radiology cafe and some basic literature, which is useful. Uh So, uh who can we see infection after the uh ruptured appendix, uh Edgar. Uh I'm assuming you are asking where we can see the infection. So it was, it was a ruptured appendix. It would uh usually present as massively dilated and also uh with infective changes uh around it in this particular region. So, yes, you're right. Uh There will be a lot of infective changes around this particular region and it will be enlarged as well. The usual appendix, uh it depends on the age of course and the body type, but essentially, it ranges from about 2 to 8 centimeters. Um And so we referred to the inflammation around it as periappendiceal uh inflammation. Um So, uh if we see some of that, then we think, yeah, it's, it's an infective appendix. But if it's, if it's ruptured, it's usually quite, quite large and also clinical presentation of the uh patient would give it away as well. Uh They'd be quite sick uh and a lot of pain as well with very infective uh high, highly infective changes in their bloods to uh reflect that. Ok. Um Yeah, any other questions you guys have, I'm happy to go back over any of the slides. If you guys want to for appendicitis, would you prefer? Uh would you prefer ultrasound or CT really depends on the uh presentation if it's acute. Um in, in, in terms of, you know, uh if the pa if patients in extreme pain, um and also uh their observations that may be slightly abnormal or their new score, which is a scoring system that we give patients to the United Kingdom is high and you're clinically worried about the patient that I think consider a CT quite strongly unless there are reasons not to um an ultrasound is more an ultrasound is great as well to have a look at the appendix. But it's usually usually better to use an ultrasound if the patient has presented uh quite stable. Um So, uh yeah, that would be the difference between the two and when to use them. What is the percentage that the appendix would be of the left lower quadrant? Oh, ok. Yeah, good. I'm glad you asked this question actually. So, uh that's a variant or abnormal variant as most people consider it. Um I'm not sure the exact percentage a but what I would say is it would be in the minority of patients. But you're right. Uh Some patients do present with the left side one, I've read about it in textbooks in medical school as well. Um There are a couple of tests that you can do on a patient to uh examine an appendicitis essentially. Um And uh you've got the Robson's uh for uh test, for example. Um but having uh having a feel of the tummy sometimes if they, I've never actually come across a patient who's come across as an appendicitis with a left, lower quadrant pain. Uh they, all of them are pretty much right, lower quadrant. So I'd say I'd say it's a minority of patients that present with the left, lower quadrant pain or left quadrant appendicitis. Yeah. And the other test I think it was a so, so I sign, but yeah, any other questions? Great. Perfect. I think that's pretty much done. Um If you guys do come across any, well, have any other questions or any other thoughts, please feel free to let me know. I'm more than happy to answer your questions. Um You can either contact UI MS or even your emergency medicine site at pre and um or even me personally, I or whatever. Um And I'm happy to, to answer your questions to the best of my knowledge. All right. Thank you very much. Thank you so much everyone for attending and thank you, Doctor Hansen for hosting such an interesting seminar for all of us. It was really great and uh for everyone who attended you all will receive an email in an hour with the feedback forms if you could fill that and once you fill it, you will be able to get your certificates. Thank you so much. Thank you very much.