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Hi, my name is William. Can you all hear me? I just want to check the audio's working. So I don't go through the session and then realize you guys can't hear me because I wanna make sure it, we have the audio working. Ok. I'm just gonna create a pole. Can you hear me? Yes or no? So later. Ok. I'll just give it a second to accumulate. Ok. All right. Someone says they can hear me. I'm gonna take that as a good sign and I'm going to begin. So we're going to present our now share entire screen. There you go. Ok, bring this up here. Can you see that good? OK. I'm gonna put it on to presenter mode so you can see what I see cos I've got some notes in the section and then it'll be recorded and put up on the website. I should warn you guys that med all as a website is going to be folding unfortunately soon. And that means we're probably going to move into a different website called Career Books. So make sure to look at the 6 p.m. series Instagram page for updates on that. Ok. Ok. So my name is Willie. This is the presentation we have here. Now, a short disclaimer, this is teaching, this isn't for a doctor to take and use as medical material for practice because of course, there are differences between exams and real life, but it is a good foundation point for medical students and for people who want to know just that little bit more. Ok. So let's just compare CT compared to MRI. So MRI uses magnets, it doesn't use ionizing radiation. So the risk of cancer is pretty much zilch. It however does take longer and it's availability because it's so expensive and such a large piece of apparatus actually quite difficult to use. Most hospitals will only have one maybe two at a push. Whereas CT scanners are much easier to store multiple of it's excellent for soft tissue. So for the brain, it's fantastic. Let's say you're looking for a stroke. It's perfect for that though. Quite often you'll do act first to see if you can find any damage of the brain. It uses gadolinium as, as opposed to iodine and there are contraindications. Of course. So ferrous metal in the body because of the magnets, you don't want to move something about that's metallic embedded inside the body. And of course, people can have allergies to iodine if there's act. So there's reasons you might choose one as opposed to the other. I'm going to cover the basics of how an MRI works I've got one side that is a bit more complicated, but basically think of it like this. Imagine the hydrogen ions in Co2. Sorry h2o. And imagine that's a can of coke. The magnetic feels like a hand that grabs the cook and shakes it. And then once the magnetic field stop, once the shaking stops and you release the top, you get a fizz that fizz is metaphorically like the release of energy from the hydrodine, which is used to generate the signal. That's a gross location. That's basically we provoke the hydrine to get it moved in a certain alignment. And then we release the magnetic field in a sense and that releases energy, which is used to paint a picture. This is more complicated. So of course, we're talking about protons in CO2. So where there's more CO2. So sorry, I don't know why I keep saying that h2o water and we use that to align them. So they slowly return to Z alignments. This is called T one relaxation and protons slowly return to spinning at different speeds. T two degradation. Protons give off a signal when realigning and T two signal their grades when protons no longer spin altogether. That's the more complicated way of putting it. And you don't need to know that for your exam. So that's just there for those who want to know that little bit more now to put it very crudely. T one and T two are sort of like opposites. It's a bit like when you flip the polarity of an image. So they're used for different tissues and they degrade at different rates. Now, I have a youtube video here which I hope is going to work. This explains it's better. I'm gonna put the subtitles on just in case cos I'm not convinced it's gonna work. Come on. OK. OK. I don't know about you. I'm not getting sound of this so I'm going to assume you guys aren't getting sound either. I'm gonna try opening as a youtube page and then we can just watch it there. I'll put it on 1.5 speed because it's not too complicated. But I think watching it as a cartoon will probably make it even easier to understand and it helps things click in the ass, just give it a second to load. Yeah. OK. And now it wants to work. OK. So looking here, we have two different types. T one, T two, what you can see is T one is basically what you'd expect. So you have white matter is white. CSF is dog, T two is the opposite of this. I think T two H two because it focuses on H 2 L makes it bright. So it sort of does the opposite. So the CSF in the ventricles here is dark, but in T two, the H two, which makes it a huge part of CSF, it will appear brighter and that's an important thing to remember. So we have fluid attenuated inversion recovery, which is useful. It's a version of T two. It's basically where you account for the CSF and fluid. It's where it's nullified or removed. And this is useful for spotting cysts. And I'll show you an example of that in a moment. So this is basically a version of T two. So here we have the cyst risk score, which is basically used to see what is the risk of a cyst in the brain. And effectively, you can get them around about here and they block off the drainage of the CSF which can lead to enlargement of the ventricles. So, ventriculomegaly and it can cause hydrocephalus which can cause headache and damage to the brain because if you have blockage and pressure in the system, it won't work well. But knowing when to remove these and when not to is tricky because you can often find them incidentally and you don't know which ones are going to get worse or not get worse. And there's actually some debate about whether or not they're just purely incidental findings. And if you leave them alone, will they just not grow or do they grow? Col are technically speaking tumors, but generally speaking, they're believed not to grow. But there have been cases where they have been believed to. So it's one of those areas of research where we're not entirely certain