MR001 Week 3

Good morning. Good morning. Good morning. Good morning. Good morning. Wow. Let me just say that you guys blew me away. You blew me away. Quiz one and quiz two, how'd you guys feel? Because I know how you scored. So how did you feel? I felt like I overprepared.

No, no. Okay. That was the mama bear. Just a lot of stuff. Yes. That was the mama bear that came out a little bit. Some questions were easy and some were more difficult. Did you guys pick up on that? Most of them were a little bit on your side, right? Yeah.

I wanted to introduce you. I wanted to introduce you to the different styles of questions. Okay. There's a, an array of ways to ask one thing. Okay. So, um,

You still had difficult questions, but as we progress through the quarter, they're going to get a little bit harder. OK, so those of you that felt you overprepared, keep doing what you were doing. OK, because that's going to allow you to score and perform the same way. You guys between quiz one and quiz two, the class average was 90, 98 percent.

98% you guys almost all about every question, right? I'm going to get to another, I'm going to get to something real quick though, but I wanted to say, keep doing what you're doing. Keep studying the way you are studying because I did throw some difficult questions in there and you guys aced it. You guys passed for flying colors. So good job guys. Keep, keep it up, keep it up.

I had to have you a little nervous. I feel like that's only fair, but, uh, I did reassure you guys on, um,

What was it on that app? Did everyone, uh, those of you that are on the, what is it called? Oh, discord. Those are those of you that are on the discord. If you've got my messages, a lot of you guys reached out on how to study, how to study, what to do. I gave some tips and tricks on, uh, what to do. I hope that helped. Um,

I think I'm going to put it in the general forum too. For those of you that are not on discord, I want to make sure that everybody has that. I did get emails. Um, you guys know that I did respond to you over the weekend, right? Uh,

I do my best. I won't always, always respond on the weekend, but I usually do. I'm supposed to step away from my work, but I don't, guys. I don't. I don't like to make you guys wait. I feel like it's important, especially to calm your nerves with your emails. So I will respond to you guys. With regards to the questions, let me...

There was one question that was just my feet, my freebie. It had something to do. Do you guys remember where it said? I'm still happy that I chose MRI, even though Ms. Gray went into how difficult the physics is going to be. The answer bank recorded that incorrectly. So if you go into judge or if you go into Moodle, you will see that I gave that point back. Okay. So you're going to see a difference in your points. I gave that that point back this morning.

I'm going to double check. Sometimes things don't always cross over the way they're supposed to cross over. So I will be checking and going over each question one by one to make sure nothing is wonky. Okay, guys. There is one other question. In fact, let me open it up now. Okay. Can you guys see that? Let me zoom in. Can you guys see this question? Yeah. Okay. There was...

Half of you that got it right and half of you that didn't. So everyone's going to get this point back if you if you marked it wrong, because it is partly my fault. Let me explain why. I was typing so fast that I in the question, I did not write what is the first of the four steps to

Okay. Does that make sense? I just said, what are the four steps illustrating? Half of you got it right. Half of you went with your gut. And even though the question was wonky, you're thinking, okay, well, I know without a shadow of a doubt that the answer, the first step is having aligned hydrogen atoms by placing the patient inside the MRI machine. Okay. Don't worry if you did not mark this.

I wanted to bring this up because your ARRT board exam, which you will have about 230 questions, you will have three right answers. Let me say that again. You will have three right answers and you have to pick which one is more right. Which one is more right? They do this every,

to see your critical thinking. Do you truly understand the concept? Okay. Does that make sense? Throughout the program, you will encounter some instructors that will give you three right answers and you have to pick the most right. So if you marked none of the above,

Don't be upset. I will give that point back. But the correct answer was the first one. Looking at all these answers, you have to process of eliminate, right? What are we talking about? We're talking about the four steps illustrating how MRI works.

So when you go through the answers, you know it's not first placing the RF coil on the patient because we identified that that was later. You know it's not first giving the patient a radio frequency pulse because we have to put the patient and the hydrogen atoms have to be aligned with the magnetic field first, right? So your only logical answer would have been first having aligned hydrogen atoms by placing the patient inside the MRI machine, okay?

It comes, it comes with time to trust your gut and to trust your intuition comes with time and comes with studying. Okay. How many, be honest, how many of you wanted to put a, but because of the way the question was worded, you picked C. Yeah. Okay. And that's okay. That's okay. But, and you knew that a was right. Right. Cause you wanted to pick a.

You got to go with your gut. You got to go with your gut. Always. You knew without a shadow of a doubt that that was the right question or that was the right answer. Right. So we're going to keep going through this. I'm going to keep giving you examples. We if anything, you know, comes up like this again, I will absolutely go over it. The idea, guys, is I want you to learn. You guys know that I want you to be successful.

I don't really fuss over a point and give any question back. You guys are going to get this question back. But more importantly, I want you to learn from this. I want to be able to teach you and learn and you guys learn from this experience. Does that make sense? A.R.T. will give you three right answers. And I'll show you guys that by the end of the quarter. OK, no tricky questions in my class. There are some fair tricky with maybe.

Maybe there's a step missing or a word missing, but you guys are going to intuitively be able to pick up on that. OK, you guys are all doing fantastic. So I will finish editing the quizzes by today. Definitely by today. You guys will see all your grades in Jeji today. OK, Diana, go ahead.

Does that mean that once you're done grading them, we'll be able to like look at which ones we got wrong? Because like right now it's completely closed. Yes. Okay. Because as I'm saying, if that's not the case, that'd be awesome. Like obviously once it's due and it's closed, like if we could look at it just to get feedback. Okay. I said yes to, I want to answer your question. Not yes to, they're going to be available. Thank you for bringing this up.

you guys will not be able to see your questions after but if but after you complete the quiz you can see the questions and the answers with meeting with me one-on-one why we can't have them open um to maintain integrity right we don't want answers and questions being shared um but you absolutely can see what you got wrong

what you what you answered right I'll pull it right up and I'll share my screen with you guys I just ask that we do it one-on-one privately okay so that I have the opportunity again to kind of course correct a little bit and that we don't kind of share the answers for any new students coming in not saying you guys would do it but you know accidents can happen things can kind of be exposed so yeah you will absolutely see them

If you want to schedule office hours with me. Okay. Got it. Thank you. You're welcome. Any questions guys on that? Okay. Week three. Now technically we're only in week two, but we are going to go into week three course material. We explained guys, remember first class, we're kind of jumping ahead a little bit so that we have our midterm week open to studying. I want to go over the weekly instructional breakdown. Okay.

Before I do that, actually, you're going to begin with chapter two and Mariah at a glance, and we're still in chapter one. Okay. You'll see that I repeat a chapter. What that means is we're still covering some of the concepts and the points in that chapter, which is why you'll see a repeat of the chapter. So every week, guys, I want you to open this up and take a look. You'll see that it was available yesterday. This week opened up yesterday. Okay. Okay.

Um, that will always happen. So you'll come in, you'll look at week three and you'll say, okay, what are we doing for the week? You've got a little excerpt here of what we're going to be going into. We're going to zoom in on the hydrogen atomic structure and connect weeks one and two material further building on our understanding. Okay. To give you a little glimpse of what we're going to be doing for the week or for the lecture. Um,

I've got Clover Learning here for you. Watch the Clover Learning videos. It will be under the image production, physical principles of image formation. What I did here is

You'll see that it says listed below. I have them here and you see my little hand changing. They're clickable links. Okay. So all you have to do is just click on the link. It'll take you right to the video. You may have to log into Clover and then come back into Moodle. Just click on these. Okay, guys.

Not too much of your time. I've got the minutes here. I don't know what happened to this atomic structure. It's about four minutes. So not too much of your time. That's going to be part of your study for this week. Of course, complete your assignment. Only one assignment. Right. Because now we're just.

In that week, in this week. So only one assignment week three is going to be due. That's going to be due next Monday. So everything we covered today, you're going to have an assignment. It's already available and uploaded. Some of you guys have already turned that in. I ask you, I'm okay with you guys working ahead in that fashion, but we haven't had lecture. So if you want to turn it in early, maybe type it up on Monday when the week opens and turn it in after class. See if you want to change your answer a little bit, right? Right.

Your class discussion forum is due no later than next Monday. And of course, you're going to submit your quiz for week three, what we're covering today in lecture by next week, Monday. Any questions on the due date or what to expect? Every week, guys, we have an assignment, we have a discussion, and then we have a quiz. That's every, every week. Let me move this thing all the way. Okay.

Every week we have that. Every week we have our lecture. Every Tuesday, 9 a.m. Pacific Center time, which you guys are all here. I do want to make a side note. If you are logged in, not using your Gurnick email, please, please try to use your Gurnick email. If you had if you typed in your name, can you please include your first and last name? It's a little time consuming, guys, to take attendance.

I will take it a little bit later here. Just do a quick roll call. But it was hard when I don't have your full name and I'm kind of going through my list. So if you don't mind doing that, that would be helpful. Any questions on our week? What we're doing? Before we dive into the material. I have a question about discussions. Absolutely. So is that going to be the...

Is the normal format going to be you're going to give us a prompt and then we'll respond to that? And then you also want us to respond to the classmate? Is that going to be kind of the thing we do every week? Thank you for bringing that up. Yes, that is going to be the format. I want to, I mean, the idea behind discussion forums is in the title, right? Discussing. And it's a forum where we're all coming in and we're all discussing what it is that we

that I'm bringing up, right? So I want to keep it that format. So I will start the conversation, right? I will, I will make my initial post, which is what you guys saw. Then you guys will go in and you'll keep the conversation going. You'll respond to me. You'll respond to a classmate. You'll make your initial post. Okay. So you only need two posts. You need to have your initial post and

And then you reply to a classmate. The reason I've been trying guys to override those settings in Moodle. The reason why there's a delay is so that you make your initial post and you can't see anybody's answers yet. Cause I want your, your answer, your post to be original. I want it to be,

from you and without without sneaking without getting a sneak peek at what others have said and then you'll be able to reply to your uh classmates if i see guys that it's too cumbersome it's bogging things down you guys are having to wait too long um

And it's more disruptive than it is good. I'll change the format. Okay. But I'd like to keep it this way because it really facilitates a true, true discussion where I start it and you keep it going. Does that make sense? Yeah. Okay. All right, guys. Let's dive in. Hydrogen atoms. As I mentioned, we're going to be diving deep into hydrogen atoms today. We're going to discover that it is the...

simplest atom in our body that gives us the ability and creates detailed images of your brain, muscles and your organs. Okay. How does, how does the small atom help us see inside the body? We've already got an idea, right? With last week's lecture, the patient has to be placed in the scanner. We have to have those hydrogen atoms aligned with the main magnetic field. So let's go into a little bit more detail.

We're going to go over the chemical structure of hydrogen. Okay. As I mentioned, it is the simplest atom. Hydrogen is a simplest atom with just one proton in its nucleus and one electron in its orbital shell. Are you going to have to know for your ART board exam that hydrogen has one proton and one electron? Probably not. I'm going to safely say probably not. However, it may ask you questions.

or give you a case scenario of why you would want to use hydrogen versus another atom in the body. And what I'm going to, uh, um, show you guys in demonstrate is that there's a reason why we pick hydrogen and why we use hydrogen. Okay. So you may have to, uh, know that I encourage you to know and memorize that it is one proton and one electron, but, um, you'll be more, uh,

The questions will be more of case-based. Why? Okay. Why we're using hydrogen. It is because of the nuclear structure that gives us the ability to use hydrogen and the benefit of using hydrogen. It has a spin property. Okay. The single proton has a quantum spin of one half or of half. Sorry, not one half of half.

making it behave like a tiny bar magnet with a strong magnetic moment. These are new terms, guys, new terms. Go ahead. If you make a site, make a note, write these terms down because I'm going to expound on them later as we progress through the lecture so that you'll be able to understand, well, what exactly is a magnetic moment? Why do we have them and how what's the connection? Why are we using the term magnetic moment to talk about hydrogen atoms? Okay.

The most obvious, the most obvious reason of why we're going to use hydrogen is because it is highly abundant. Are we or are we not water, right? We are mostly water composition of the human body. And so hydrogen is extremely abundant in the human body found in every water molecule and in fat tissue throughout. Okay.

Why we want to use hydrogen just mentioned it's abundance. So that's our first reason it's highly abundant in the body. Reason number two is that because of the single proton nucleus, having that, that half spin is,

It gives a large magnetic moment and produces the strongest MRI signal of any element. What do I mean by large magnetic moment? We're going to get into that in just a minute. But a hint is I just explained that it is the most abundant in the body, meaning we have lots of hydrogen atoms within the body.

within the water molecules, the H2O. So if I have a lot of something, I'm going to have the ability to obtain a very strong signal. It is favorable relaxation. That's something new. We're going to dive into that as well. Hydrogen nuclei have optimal relaxation times, T1 and T2. That's a new term, guys. Make a note of that.

The favorable relaxation gives excellent contrast between different tissues in the body. Excellent contrast. Other elements. Why are we not using other elements in the body? Why have we chosen hydrogen? Lower abundance, weaker signals, and making body imaging impractical. Okay. For your ART board exam, like I mentioned, you'll definitely have to know why we're using hydrogen. Okay.

When I gave you guys study tips and those of you that want to do the flashcards, I said flashcards are still useful. However, you've got to word and phrase your questions a little bit differently. Instead of saying what element, let's give an example, hypothetical. On the front card of your flashcard, if you say, what element do we use in MRI? And on the back, you're going to write hydrogen. That's true.

But what I want you to get in the habit of if you want to continue to use flashcards is I want you to test why. I want you to test why you're using hydrogen. Does that make sense, guys? You've got to ask yourself these questions. Why? If you can do that, I promise, I promise it will make sense and it will give your brain the ability to compartmentalize that information for faster recall as we build. And the other buzzword, how?

How is hydrogen used? How are we using hydrogen? You guys already, you already picked up on that last week and week one. We have to have alignment. We absolutely have to have alignment. We cannot image without alignment.

When placed in the MRI scanner, the strong magnetic field, hydrogen nuclei in the body are going to align parallel or anti-parallel to the field direction. This is something new, guys. We're building. Remember last week, we only talked about alignment. Now I'm giving you something new. Now I'm telling you that that alignment is even deeper, more another layer of the onion peeled back. That alignment is either going to be

parallel or anti-parallel to the field direction. That's important because it gives us an indication of how we're using the hydrogen and why we're using the hydrogen. We have our excitation, okay? The radio frequency pulse, we give the patient another layer of the onion at the resonant frequency, at the resonant frequency is going to tip the hydrogen nuclei

What it's going to tip them out of alignment. Last week, we explored the steps of the patient going into the magnet. Then we give them the hydrogen or then we give them, give the patient the RF pulse. The next layer to that, please make a note is that we're tipping where the RF pulse is being used to tip the hydrogen out of alignment. And when we do so, we are able to,

We are able to record a signal. Let's dive into that. How are we doing that? As we tip those hydrogen out of alignment, the hydrogen get excited. They absorb some energy from the RF pulse. I'm jumping ahead a little bit, but let's not go too far. But they absorb that energy, they get excited, and they're going to release that energy as they relax back to equilibrium.

What is equilibrium? We're going to get into that. We're going to get into that. What does that mean? If they're relaxing back to equilibrium, make a note in your guys's notes. What does equilibrium mean? Where is equilibrium? When the hydrogen atoms relax back to equilibrium, they emit an RF signal that is detected by the receiver coil of the scanner. And then the

Then we get to the image formation where those signals are processed by computer algorithms to create detailed cross-sectional images rich in hydrogen. Do you guys see now how we just very rapidly reached two different layers? We just dove deep into the steps that we introduced last week. There's a lot of keywords that we just went over.

Those keywords give us an indication that the process, there is a more specific, deeper process happening here when we give that RF pulse, when we have that excitation. You guys with me? Does that make sense? Okay. Okay. Let's go into alignment a little bit more. When the patient enters the MRI scanner, they are placed inside an extremely powerful magnet. It's either going to be 1.5 or 3.0 Tesla.

The hydrogen nuclei in the body, which normally spin randomly, we identified that last week, they're going to be spinning randomly, but they're going to respond to the magnetic field by aligning either parallel or anti-parallel. Here's another layer to the onion. If they align in a parallel fashion, they are defined as low energy. This is very important.

If they are aligned anti-parallel, they are defined a little bit further as being high energy. Let me know if I'm going too fast, guys. I can slow down. The slight excess of protons aligned parallel creates a net magnetization vector. A net magnetization vector. And it is here, here, here,

is the start where the signal, the MRI signal is exploited, meaning we can, we're using it to our advantage. Okay. The stronger the magnetic field, the greater the net magnetization, which is why higher field scanners produce better images. What do I mean by better images? Higher resolution. It's going to be higher resolution. So the key points that I want you to take away from the alignment

is that the protons are going to behave like tiny magnets due to their spin. The main magnetic field, remember, is going to be labeled as B sub zero, B sub zero. That's important to note. The net magnetization points along B sub zero. These are key keywords, guys. Just make note of them. We're going to expound on them later.

and that higher field strengths means an equals more signal, which means an equals better image quality. So when I asked you why hydrogen atoms, they're highly abundant and we've just, we've just got an idea of their behavior in the, in the presence of a strong magnetic field, which is going to be the low energy and the high energy. Vincent. Quick question. Um,

I'm not sure if you mentioned the thermal equilibrium. I didn't mention it because it's not as important. Oh, got it. Okay. I listed it because it's, it's, it is a point, but that's why I highlighted the key points. Okay. I just want to make sure I didn't miss. Yes. Thank you. It just gives you some context that the, that there is a thermal equilibrium that determines the population difference, the population difference of those parallel and anti-parallel.

but I've already given you the main point of the, of what it is, low energy and high energy with being parallel and type, but great question. Let's explore. Let's explore what these tiny bar magnets are. Why Diana, go ahead. Sorry. I wrote a question in the chat, but I guess I could just answer it. Yeah. It's best guys. If you, let me change my mouse. If you guys pull it up.

So under the under that logic, a 3T would create better image. Yes. Okay. Yes, absolutely. Yep. And when you get to me in safety, which you will guys, you will all see me in later courses, I'm going to explain to you why we've got great high resolution images. But when we go on to a three Tesla magnet, why that could be problematic for patients with implanted devices.

And why could be problematic for some patients? Okay, but we get fantastic resolution images. Fantastic. These tiny bar magnets from the protons in the one proton in the hydrogen atom is a property that gives us the ability to image. We have to have the tiny magnet. So let's let's explore that some dense terminology here a little bit heavy.

This lecture is being recorded, so do your best to take notes and then I'll have this recording up today so that you guys can refine your notes, okay? Each hydrogen proton possesses a quantum property called a spin. That was that half spin I just explained to you. That half spin gives us a tiny magnetic moment.

The tiny magnetic moment essentially has a north and a south pole, just like any magnet, just like any handheld magnet. You're going to have a north and a south pole. It is this intrinsic magnetism that is the foundation of MRI.

Because protons act as bar magnets, they're going to respond to the external magnetic field by aligning along the field direction. How many of you try? How many of you guys kids have when you were kids or ever experienced putting two magnets together and having them repel or having the magnets attract, right? Yes. Because of these little tiny magnets, right?

that the protons are in the hydrogen, we are going to have favorable alignment. The magnets are going to be attracted and aligned in a certain fashion, just like you had two magnets that stuck together when you put them together, or two magnets that fought against each other. The connection to that would be parallel and anti-parallel, essentially.

on a microscopic level. I don't want to go too deep. I don't want to go too deep guys, but just know that the tiny bar magnets, the protons behavior giving us the tiny bar magnet is what gives the ability to align along the field direction. Millions of protons in the body tissue align together and that is what gives us the measurable net magnetization vector.

The collective alignment is what MRI scanners detect. It's not just one hydrogen atom, it's the collective. And it's not just one hydrogen atom, but the collective that gives us the net magnetization vector. That's important to note. Also favorably why we use hydrogen because of its abundance in the human body. So now you can kind of put those pieces together

We're using hydrogen because it's highly abundant. We know that the one proton of the hydrogen behaves as a tiny magnet. And we know that there's going to be a collective alignment. Once the patient is inside the scanner, aligning with the magnetic field, that's a lot of tiny bar magnets, right? When you think about it, if we're mostly made up of water and we have an abundance of hydrogen atoms, that's a lot of atoms that,

that are aligning with the magnetic field, which gives us the ability to image. Does that make sense, guys? Gives us the ability to image because we have a net. We have a collection, a group that we can tap into. It gets a little bit deeper. Stay with me. Different tissues contain different concentrations of hydrogen. That's important. When you get to physical principles with Kevin, um,

Believe it's next quarter. No, not next quarter, the quarter after you're going to build. Sorry, I'm covering the words here. You're going to build on that more. You're going to build that different tissues contain different concentrations of hydrogen. So the strength of the net magnetization is going to vary across the body.

By measuring how these tiny magnets behave, how they align and how quickly they return to equilibrium. This is important. The scanner can distinguish between fat, water, muscle and pathology. Say that again, because that is crucial to our understanding of how we create MRI images, how they align.

and how quickly they return to equilibrium. The scanner can distinguish what's fat in the body, what's water, what's muscle, and what's pathology. We're going to build on this more with our discussion on pulse sequences. There are certain

rhythms, I'm going to say there are certain rhythms of the RF pulse that we deposit into the patient that we give the that we give the patient that is going to manipulate and dictate, I want to see more fat, I want to see more water, I want to see pathology. And so you are going to pick and you're going to be introduced later to different pulse sequences if you want to make a side note.

Those pulse sequences are designed to tap in and highlight and just show us only fat, only water, only muscle. Are we still going to see everything else? Yes, we are still going to see everything else. However, the contrast, not to be confused with injectable contrast in the vein, the contrast, black, white, and shades of gray are going to vary.

Does that have anything to do with like mass of like the fat, water or like muscles for, you know, how quickly they get back to equilibrium? Mass has a little bit to do with to do with it. Yes, I'm glad you bring that up. This is going to be more advanced, more advanced in your physics. But I will give you a little hint and a little sneak peek. If I have somebody that is.

a bodybuilder, or I have somebody that is morbidly obese, I'm going to be able to essentially pick up if I'm, if I am tapping into the fat, if my rhythm of the pulse sequence, the RF pulse that I'm giving is designed to pick up on fat more, and I have a morbidly obese patient, I've got more mass, got more to work with, right? So in theory, it's going to be brighter, because I've got more to work with.

Right. It's not going to, for sale, it's not going to, it's not going to dictate whether it's still a good quality image or a bad quality image. I'm still going to be able to see everything I need to see, but mass does have something to do with it. Similar to the fashion of abundance. If I have more fat or if I have more muscle, there's, there's going to be a little bit more water molecules. There's more hydrogen in that, right? You guys will see an experience in the clinic where,

what we call artifact. If a patient has too much mass, and if a cell, if you want to make a side note of this in the abdomen, and this is later, later, later, later for clinic guys in the abdomen, there is a pathology called ascites too much water, too much water in the abdomen. The machine freaks out.

The machine will freak out because there is an overabundance. And that's what gives us the ability to tap into pathology. Does that make sense? We're able to see what looks normal. And when there's an excess of quote unquote mass, quote unquote water, we're able to see that that isn't quite necessarily normal, which gives us a good clue and indication into pathology. Does that make sense? Yeah. Yeah, it does. Yeah.

Yeah, it does. I have some more questions I'll ask later on, but yeah, that's good. Thank you. Yeah, you're welcome. It's exciting, guys. It is super exciting. I have to go slow. I have to go slow. You can see why. There are a hundred different layers to this. Yes. I've just introduced new terms, net magnetization vector. What does the net magnetization vector have to do with imaging, right? The alignment, all of that. Okay.

Key points that I want you to take away from protons as tiny bar magnets, that the proton spin creates an intrinsic magnetic dipole moment. I haven't defined what dipole moment is, but I will. We're not there yet. Each proton is going to act like a bar magnet with a north and a south pole.

The alignment with B sub zero, remember B sub zero is the static field, meaning your machine. That is the 1.5 Tesla machine or 3.0. The alignment in B sub zero, when we put our patient in and the hydrogen are going to align, produces a net magnetization vector. Tissue contrast arises from differences in proton density.

indirectly connected to mass, a cell indirectly connected to mass, and that it's non-ionizing radiation. Only magnetic interactions are used. No radiation. We're playing with magnets and we're playing with magnetic properties in the patient's bodies and our bodies because hydrogen has little bar magnets with the proton. Before we move to step two, excitation.

Let's take a five. It's 944. I like to take a break 45 minutes in. It's 944. Come back in five. So come back at 950.

9.50 Pacific soundtrack, Pacific Standard Time. Take a breather, run to the bathroom, grab a drink, stand up and stretch. It's a lot of material. It's very dense, very heavy. It's a lot. So stand up and stretch. I'll be here if you have any questions. Thank you. You're welcome. Let me turn off my mic here. Isabella, did you have a question? I see your hand is up.

Yeah, I have a quick question. Yesterday when I posted my discussion, it was like, I think around seven o'clock in the evening. Okay. I didn't until I read my email just now, but at 1am I was sent an email with all the discussion replies and,

um i know it's like a delay like you said earlier is there any way i can still reply back to one person to get partial credit i'll make sure i post earlier so i don't have to deal with this again yeah it usually it's only a 30 minute only a 30 minute delay oh okay i probably got the notification later but oh okay then then that's probably okay yeah i didn't refresh it and then check it on my end yes

Okay, guys, let's jump back in. Turn your cameras back on. Let's jump back into the material. See some cameras are still off. You guys can come back, turn on your cameras so I can see all your faces. Okay. I do want to remind you guys that we are introductory. Some of these key terms I'm just sharing with you so you can get an idea of

Of which puzzle piece goes with what? What I mean by that is you're going to take this information and continue to build on it. Okay. We're not going to go very, very deep because we want to stay introductory to make sure that we have a good, strong foundation so that when you get to your physics classes, you're

Kevin will be going into this in a much greater detail. You can still come to me with questions when you're in those courses and feel free to say, hey, remember when we were in class and you introduced me to this concept, this topic, these are the terms you used. Kevin is using these same terms and he went another three layers deep in the onion. Can you help me put it all together? Absolutely. Absolutely.

Okay. After you leave here, it doesn't mean you leave me forever. Okay. I will still be here, guys. Okay. Excitation. We connect the term excitation to the concept of using the RF pulse to tip the protons out of alignment. Does that make sense? When we use that RF pulse,

and we put it in the patient's body to disturb that alignment. We use the term excitation. When the hydrogen are aligned, a radio frequency pulse is transmitted at the precise Larmor frequency. That's a new term. Make a note, Larmor frequency. The Larmor frequency is the resonant frequency of hydrogen in that magnetic field.

The RF energy is absorbed by the protons, causing them to flip away from their equilibrium alignment. I'm going to go into the Lombard frequency more in just a moment. The RF pulse tips the net magnetization vector into the transverse perpendicular to B sub zero. Stay with me. I'm going to build on this. This is called excitation.

The flip angle depends on the strength and duration of the RF pulse. A 90 degree pulse tips the magnetization fully, fully into the transverse plane while smaller angles are used for faster imaging sequences. And there's that word. I gave you guys a hint that we use sequences. What are sequences? Sequences are special rhythms, rhythms of that RF pulse.

And different rhythms are going to give us a different outcome. So let's go over this. Let's go over this paragraph a little bit more detail together. When the patient is inside the magnet, we identified that the abundant hydrogen atoms are going to align parallel or anti-parallel.

They're going to align more or more hydrogen are going to align parallel because we identified that as low energy. It doesn't require the hydrogen atoms to put a lot, exert a lot of energy to align. It's natural. It's a natural movement. It's a natural response being introduced into the magnetic field. We don't talk too much about the anti-parallel, the higher energy energy.

Because we don't focus and predominantly use that. Does it have purpose? We're going to dive deeper into that in physics later in the program. We are going to focus on the abundance of the parallel low energy hydrogen atoms. When they are aligned with that magnetic field, envision that they're all standing up.

They're all standing up and they are matching the direction of the magnetic field. When we give the RF pulse, that alignment of all these millions of hydrogen atoms are going to be tipped into what we call the transverse plane. You guys with me? Does that make sense? We're tipping them. They're no longer aligned with the magnetic field. We're tipping them into what we call the transverse plane.

which is going to be perpendicular to B sub zero. What do I mean by perpendicular? If the magnetic field theoretically is going in this direction, up and down, and the hydrogen atoms are mirroring that, they're aligning up and down, right? The only thing that's going to change is the hydrogen atoms. The magnetic field doesn't, the main magnetic field doesn't change.

Only the hydrogen atoms position changes. You guys with me? Does that make sense? So when I give the RF pulse to the hydrogen atoms, they're going to tip into the transverse plane and my shoulder won't do it, but it will be like this. The hydrogen atoms will be perpendicular to the magnetic field. Bardo, go ahead. Oh, um,

So when we were doing the Clover learning, I was reading about the B sub one. So is that what you're talking about currently right now? Oh, it's perpendicular or is that more so for the magnetic field and the actual hydrogen? So, yes, we are. But we're more talking about the behavior of the hydrogen. But you're absolutely right. Bardo, the let me put this in a different color. See if this works.

When I say that the RF pulse tips the protons out of alignment, Bardo, the RF pulse is B sub one. That was in the video, right? Correct. Yes. So B sub one is the RF pulse. They're synonymous. They mean the same thing.

An RF pulse is either going to be referred to as an RF pulse, could be referred to as B sub one. Excellent point, Bardo. Thank you for bringing that up. And as you can see, when you watch the Clover Learning videos before coming to class and you read a little bit of your textbook, now it's starting to come together, right? You read those terms, you're like, wait, what the heck is this book talking about?

What the heck are those these videos talking about? But now, yes, Bardo, thank you. Now you see where I come in. Right. And why it all comes together, guys. You need all those puzzle pieces to see the bigger picture. Right. You've got to do the reading. You've got to watch the Clover Learning. And then when you come to lecture, I put the picture together.

Okay, so yes, it is B sub one, the RF pulse. Now what we're talking about is the excitation. And what we had defined is, is excitation means when we give the RF pulse B sub one to the hydrogen atoms, what are they going to do? What are they going to do? We already identified last week, and we refresh this week that they're going to align parallel.

They're going to align with the main magnetic field. This hand is the direction of the main magnetic field. Don't focus too much, guys, on the direction. Just know, envision this is the magnetic field. Then I want you to envision that it's a mirror. This is hydrogen atoms. It's mirroring, meaning it's aligned. It's doing the same thing. The hydrogen atoms are matching the direction parallel to B sub zero, which is your main magnetic field.

And when we deliver B sub one, the RF pulse, it is going to tip the protons, hydrogen atoms out of alignment. And when that tipping happens, if I were to give you a picture and your textbook is going to have a picture, it's going to look like this. The hydrogen atoms are

are perpendicular. They're aligned perpendicular to B sub zero. This is B sub zero. What does perpendicular mean? If I wanted to show you a picture of perpendicular, what is it? This. They're intersecting. They're no longer parallel. They are perpendicular. Does that make sense? They're perpendicular. If I wanted to use

terminology, if I wanted to use math, if I wanted to use words to tell you, instead of using the picture of perpendicular, I would then use math and new words to say, I am now forming a 90 degree angle. I have tipped those hydrogen into 90 degrees into the transverse perpendicular plane. Okay. Just make a note of it, guys.

Go over, study, study, study, write these things, these key terms down, watch the Clover learning videos, keep chipping it away. It'll all make sense and come together. When I tip those hydrogen atoms out of alignment into the perpendicular position of B sub zero into the transverse plane, what's going to happen? The hydrogen are still in the presence of the magnetic field and they're going to what?

They're going to relax back to equilibrium. They're going to relax back to equilibrium. Do you remember what I said that we remember? I said we're going to talk about equilibrium. That's it. Transverse plane. When they're here, they've been tipped over. They naturally want to realign with the magnetic field. It's a natural phenomenon. Always going to happen in the presence of a large magnetic field.

So we say a 90 degree pulse tips the magnetization into the transverse plane fully. All of those hydrogen atoms are tipped over, tipped. It takes time. It takes time to tip those. It is a millisecond. It is a fraction of a second, but it still takes time.

So the point of this statement with while smaller angles are used for faster imaging sequences gives you a clue and an indication that we're going to use some angles that are less than 90 degrees where we may not tip all of those hydrogen atoms 90 degrees. We may tip them 30. We may tip them 40. Are you guys with me? Okay.

It's a lot, I know guys, it's a lot. Stick with me. We identified that in the beginning of class that the protons have a spin to them. Right now, as you and I stand and sit and we face each other, our hydrogen atoms are randomly moving and they're randomly spinning in random motion. But when we align with the magnetic field,

They are going to align parallel, but they're still going to have a spin to them. They are still moving and have a spin to them. We use the term Larmor frequency to match this spin. The Larmor frequency is the rhythm of the RF pulse.

the strength of the RF pulse that is matching this spin. And we quantify and define that as 42.58 megahertz. This comes together later more. This is just an introductory to terminology and to concepts. You'll hear me say that a lot, guys, because some of you are like, oh my gosh, what are we getting into? What are we saying here?

Write it down, take notes, and we're going to keep building. The reason why we use Larmor frequency, I'll get to that in just one second, is because only protons at the resonant frequency are going to absorb energy. Remember we said in the beginning, they're just going to absorb that energy and then they're going to release the energy. We can't have that absorbing of energy unless we match.

And that matching is termed Larmor frequency. And that matching number, how do we know that we're matching? Physicists and scientists figured it out. But the matching number for the protons to absorb the energy is 42.58 megahertz. Diana, go ahead. I see that it says per Tesla. So again, being that there are different...

like quantities of the Tesla? Does that mean that it gets multiplied by those? Okay. Beautiful. Yes. Yes. I'm glad that your brain went there. As you guessed it, if I'm going to have a 1.5 Tesla versus a 3.0 Tesla, I'm going to have a different megahertz of what we call procession, spinning movement. We're going to build on this guys. When we get into the RF lecture, okay.

after our midterm. We're going to build more on what this Larmor frequency is, why we have to have this matching number. Right now, just introductory, write down the key terms. Larmor frequency is equal to 42.58 megahertz per Tesla for hydrogen.

Very important to note that only protons at the resonant frequency absorb the energy. What does resonant frequency mean? Simply that we're using this number. The RF pulse is delivered by transmitter coils. Flip angle controls how much magnetization is tipped. Why would we want to know that? I'll give you a hint. We're not there yet, but I'll give you a hint. Remember how I said we can just, we can zoom in on just fat and zoom in on just water?

We do that with this key point here, flip angle. Slice selection gradients excite only one slice at a time. We're going to build on this, but just please note that one slice or slice selection gradients excite one slice at a time. This is why MRI takes so long. How many of us have had MRIs and we hear the noise on and off, on and off, on and off, on and off? How many of us have heard that?

We're exciting one slice at a time. We're exciting one slice at a time. Let's go a little bit more in our discussion of long more frequency, but we'll again hit this a little bit harder on the RF when we go into RF.

The Larmor frequency describes the rate at which the nuclear spin processes around an external magnetic field. And like your classmate Diana just said, well, if I'm on a stronger Tesla magnet, does that mean it's going to change? Yeah, it does. Absolutely.

It was named after Sir Joseph Larmore, an Irish physicist who first described this procession mathematically in 1897. You do not need to know that specific detail for your ART board exam. You do not need to know that for this class, for quizzes and midterms and your final. Just give you some context of where it came from. He discovered this while studying the motion of charged particles in electromagnetic fields. Isn't that amazing? If you think about it, in 1897, they were studying

charged particles, charged particle would be our proton, inside electromagnetic fields. We have an equation, and this is going to be the equation for the Larmor frequency. You will have to know this for your board exam, because later on you're going to have to calculate. Diana gave us a hint. You're going to have to calculate between the difference of a 1.5 versus a 3.0 Tesla. This little squiggle W here,

with the sub-zero is the precessional frequency, the spin of those protons, where y is the gyromagnetic ratio that is constant for the field, for the magnetic field. Just write these numbers down. I will not test you on these right now. I will not test you in this class. You will be tested on it later in your physics classes.

In MRI, the alarm frequency is critical because the RF pulse must what? It must match this exact frequency to transfer the energy to the protons. And it is that that we term resonant condition. Also underpins spatial encoding. Now we introduce spatial encoding a little bit. That's how we form the image.

Spatial encoding, we're going to talk much, much later in the program, but spatial encoding, spatial meaning in space and encoding. How do we know the nose is here and the chin is here and the ear is here and the eye is here when we're scanning? The whole patient is in the magnet.

When we're constructing that image and we're constructing all the energy from the excitation of those hydrogen atoms, how are we differentiating what from what? That's going to be later in spatial encoding. That's what that term means. Spatial encoding, what I just mentioned, how do we know our ears from our nose, from our chin? It's a process where we use imaging gradients to vary our

B sub zero across the body, making each location process at slightly different frequencies, which allows the scanner to map signals back to their origin and construct an image. Takeaway points for the Larmor frequency.

is that the Larmor frequency gives us a quantifiable number to explain and give us an understanding of the natural spin, natural precession rate of nuclear spins in the magnetic field. Are other atoms spinning and moving too? And do they have their own frequency? Absolutely. We're only concerned with hydrogen. The frequency is explained using

and expressed using this mathematical formula, it is unique to each nucleus type. And for hydrogen, it's going to be 42.58 megahertz per Tesla. Step three, signal emission. Signal emission. I have a quick question. Yes. Sorry for interrupting. But for the...

uh larmor frequency equation it i noticed it said twice for hydrogen specifically and i know we'll be looking at hydrogen but are there any other times we'll be using that equation for like other

Okay. Great question. Yep. Great question. The only variation that you're going to see will be, of course, later in your physics classes, you're going to have to calculate the processional frequency of the hydrogen. When is it, when it is introduced to a 1.5 Tesla versus a 3.0 Tesla. Okay. Okay. Thank you. Yeah, you're welcome. And as we mentioned, guys, signal emission is,

comes from relaxing protons that emit the detectable RF signal. We've given the RF signal. We've tipped the hydrogen into the transverse plane. They've absorbed that energy. And when they relax back to equilibrium, what is equilibrium? Where is equilibrium, guys? Back to alignment. Yes. Thank you, Vincent. Back to alignment with...

the main magnetic field which we define as or term label b sub zero yes sir thank you after excitation the hydrogen nuclei begin to relax back to their equilibrium state

And it is during this relaxation process that the processing, the spinning of the transverse magnetization induces a small but measurable electrical signal in the receiver coils. And it is this that is the MR signal. And to make it more complex and more difficult, you guys are studying MRI. This isn't easy. It's not easy to make it more complex.

We have two types of relaxation that occur simultaneously. We have two relaxations that occur simultaneously. One is T1 relaxation. In parentheses, I have spin lattice. That is another layer to the onion to define and label and quantify T1 relaxation. We'll get into that later.

T1 relaxation is where the longitudinal magnetization recovers. And then our second simultaneous happening at the same time, our second type of relaxation is T2 relaxation. We define that as spin-spin. And this is where the transverse magnetization decays. Decays is loses signal.

Different tissues have different T1 and T2 times, which is what creates the contrast between the tissues in the final image. I don't want to get too heavy here yet. Okay, we're not there yet. I just want you to know that there are two types of relaxation, T1 and T2. If we want to write on our flashcard what T1 relaxation is, you're going to write that it is recovery of the longitudinal magnetization.

And if we write T2 relaxation is going to be the decay, not the recovery, the decay of the transverse magnetization. Same thing as the transverse magnetization vector that we just defined. Fat has a short T1, recovers quickly and appears bright. Water has a long T1 and T2 value.

Signal decay is a free induction decay curve. Okay. I only gave you these points to give you a hint as to what comes next in the layer of the onion. You're going to have some layers with Kevin in physics, not here. You will not get this information guys, just from lecture today. It will not make sense. And if you're feeling confused, lost or frustrated, it is normal. This is very heavy information.

Complex physics. Please know that this is introductory. It does get deeper. Vincent, go ahead. Does decay in this context mean like the magnetization slowly goes away? Yes. Kind of thing. Okay. Yes. Yes. It fades, essentially. Yes. It actually loses its phase coherence is the term that we use. You may hear that phrase.

in one of the videos and you may see that in your textbook, but that's later, that's later, later, later. So now we've gotten the signal. Now we understand what B sub one, which is synonymous with the RF pulse. We've excited the hydrogen atoms. We know it can predict their behavior because we've tapped into their spin and their procession using the Larmor frequency. Now we generate our image.

Signals are processed into detailed images. The raw RF signal collected by the receiver coil is encoded with spatial information using magnetic field gradients. Imaging gradients. These gradients slightly alter the magnetic field strength at different positions, giving each location a unique frequency and phase signature. The collected data fills a mathematical space called K-space.

And the four-year transformer converts the frequency domain data into spatial domain images we see. Don't be intimidated by this terminology. We're going to study what these terms mean next quarter and the quarter after. I just remember, you're going to hear me say it and I've said it again and again and again and again and again and I will continue to say it. We are building our foundation. We're building our base. We're building an understanding of how

we generate and how we obtain our images, different pulse sequences, different rhythms of the RF pulse are either going to be T1 weighted, T2 weighted, flare, et cetera. Get into that later. Remember how I said certain rhythms are going to

tap into the contrast, how black, how white, and how gray, and how many shades of gray in between those two points are all dictated by different pulse, oops, different pulse sequences. So for image formation, I just want us to have the basics, the key points that we use gradient coils to encode spatial positioning X, Y, and Z.

What is X, Y, and Z? We are 3D beings and the X, Y, and Z is tapping into each one of those three dimensions. What are the three dimensions? One dimension, head to foot, top to bottom. The other dimension, front to back, back to front. And the other last dimension is left to right.

The machine has to pick up the 3D signal. We're not just one dimension. We've got some contours and volume to us, right? We have the machine, it has to pick up on all those. So we use gradient coils to encode spatial position. Where's the nose? Where's the eyes? Where's the chin? How far forward are the eyes? How far back are the eyes? How high are the ear lobes?

Hello. All of that is used with gradient coils. We have frequency encoding identifies the position along one axis. We have phase encoding that identifies the position along another axis. This is the key points for image formation and that case space stores the raw data before image reconstruction. And that we use a Fourier transform to convert case space to viewable images.

I don't want to scare you, but there are about a hundred different layers to the onion for just case space. There are, there are. I have to share it with you guys. I have to, which is why you can see the importance of why we have to build such a strong base, strong foundation here. Almost done guys. Almost done. Summary, summary and what's next from alignment to image and the physics beyond. We identify the process and the four steps.

We identified step one was alignment. Hydrogen protons align with a strong B sub zero magnetic field, creating a net magnetization. Step two, we have to excite them. We're not going to generate a signal just because they're aligning, which a lot of you guys, I read your discussion forum posts and you guys already gave me the right answers. No, we cannot produce an MRI image without the RF pulse.

The RF pulse at the Larmor frequency tips the protons out of alignment into the transverse plane. And step three is the signal emission. Protons are going to relax back and when they do they're going to emit RF signals and these signals are defined as having two different relaxations T1 and T2 and that the T1 and T2 times to relax back are going to differ

based on the tissue type. And when that happens, we are going to see different contrast. How many of us have seen MRI images? Yes. Have you seen the differences that there is really, really bright sections and really, really dark sections? And then there's a bunch of different shades of gray. That's what this is, guys. This is a microscopic zoomed in view of what how we're able to see those different shades.

And even though it's still black and white and shades of gray, it's still in our eyes, you'll see it's color. So the MRI technologist is different colors. It is. Now that we have the four steps, the next layer is to explore the physics that make these steps possible. We already gave you a hint to the quantum spin mechanics. Those are protons behaving like tiny magnets. The Larmor frequency, the math behind the resonant frequency.

You don't need to know block equations. I put it in. That'll be later. You don't need to know that for this class. Gradient field mathematics, how spatial encoding works will be later. These three will be later in case space and for your theory will be later. How we're taking that raw signal to an image. These concepts build directly on steps one through four in an unlock advanced pull sequence design. I call it rhythm. Means the same thing.

I feel like rhythm kind of helps make it make a little bit more sense. But the pulse sequence is a rhythm. I want to give a little more context to the spin because the spin is so important. The spin is so important. That's why we're able to determine higher resolution images on a 3.0 Tesla versus a 1.5 Tesla because the spin is going to change. A little bit more context here for you guys and we'll finish it.

The hydrogen single proton has a quantum spin of half. Okay. What this means is that it only has two energy states. It's either going to align parallel and have low energy, or it's going to align anti-parallel and have high energy to the magnetic field. This creates a clean two-state system that produces a strong, well-defined signal.

Remember, I used a very superficial example of why we use hydrogen atoms versus other atomic particles, other atoms. And I said, what? It's abundant. Now I'm zooming in and going 50 layers deeper. And I'm letting you know that we choose hydrogen. And it's ideal for MRI because it is clean energy.

And we define clean as only having two-state system. Two-state. Parallel and anti-parallel. And why? Why we use hydrogen? Staying superficial, it's abundant. But going deeper is that it is a tiny bar magnet. And spinning positive charge of the proton generates a magnetic dipole moment.

It behaves exactly like a miniature bar magnet. And when we have billions of these mini magnets in your body, we can create a measurable net magnetization. Why does this matter? If I have a clean two-state system that the hydrogen atom gives me, what did we define as two-state? Parallel, anti-parallel.

gives me the ability to have a strong net magnetization. I want a strong net magnetization because I'm gaining a lot of hydrogen being aligned either parallel, anti-parallel, for our purposes, parallel, and I can generate a very strong signal that the receiver coil that we put on top of the patient is going to pick up that signal. A large magnetic moment is detectable by the RF signal.

Simple energy, precise resonant frequency combined with abundance on match signal strength. You'll see that everything in MRI has to do with signal strength because signal strength is going to determine resolution. And resolution is how clearly we see the signal.

inter, inter canal, inter auditory, the seminal vesicles inside the ear, how teeny, teeny, tiny, we can see the pituitary gland sitting in the middle of the brain that requires resolution, that requires an abundance of a substance to give us the signal. And that abundance is hydrogen. You guys with me on that? I know it's a lot. It's a lot.

There are nuclear spins of other atoms that have 3, 2, 5, 2 split into more energy levels, meaning that there's more than anti-parallel and parallel. And that's going to dilute a signal across multiple transitions, making imaging far less efficient. This is another deeper level of why we chose and pick hydrogen versus any other of these elements. Hydrogen is going to give us the strongest signal.

As I already hinted, so we'll move through this slide faster. What does, what does the spin, half spin mean? It simply means that the hydrogen only has two orientations. That's it. Two. Spin up, spin down. Low energy, high energy.

and more protons prefer spin up creating that net magnetization and higher nuclei split across more levels diluting the signal. This is why I gave you guys the hint that we're not going to focus on the high energy. We're only going to focus on the low energy. If I'm using hydrogen instead of sodium here,

Because I'm using that two state, I'm going to have 100% sensitivity, meaning I'm going to really be able to tap into that energy much more easily and generate a very strong signal that the receiver coil is going to pick up on. Sodium has four states and is going to give us 9.3% signal return. Do I want you to memorize these? No memorization. You do not need to know these.

I'm simply giving you context again and driving point or driving home the point. Why hydrogen? Because if I ask you on the quiz or your board exam asks you or Kevin and later physics asks you why hydrogen? And you say, well, because it's abundant. Are you right? Yes, you're right. But are you giving me what I want? No, you're not telling me why hydrogen? Why? Because hydrogen.

of the half spin because it only has two orientations because we can create a strong net magnetization. Does that make sense guys? Okay. So having that strong signal and tapping into our understanding is that we have billions of hydrogen again, abundance, abundance, abundance. Those protons do spin randomly in all directions without the magnetic field. Okay.

their tiny magnetic moments cancel out and there is no net magnetization when they're random, which gives us the understanding that we have to have that external magnetic field so that we can have that net magnetization. So when we place the patient in the MRI scanner, strong magnetic field B sub zero, those protons align either with or against the field. They align with or against the field.

Slightly more aligned, spin up, lower energy. Slightly fewer. We are here. We focus on these guys. We tap into those guys to get our signal. Now, your classmate, Diane. Oh, Ty, go ahead. So as you're explaining this, I'm starting to picture it as, like if you're looking at an MRI image, that the bright parts of that image would represent areas of high density of spin up, and then the dark areas would represent

Less spin up or more spin down. Am I oversimplifying that? You're not oversimplifying it because I want your brain to stay there. But I want you to also bring in and not forget the fact that when we said we have two different relaxation types based on the tipping angle.

and how much time certain tissues have time to relax, that's also going to give us that brightness or that dull black. Does that make sense, Ty? So not oversimplifying it, stay where you are with that. And just know that there are more components that are going to give us the understanding of those differences. Okay, got it. Thanks.

You're welcome. Now, as your classmate mentioned, 1.5 versus 3.0 net magnetization and signal how field strengths affect MO. Uh-oh, what's MO? We haven't gone over that yet. MO is net magnetization. Net magnetization. At 1.5, the magnetic field creates a moderate population between the spin up and the spin down.

We define the net magnetization as large amount of those hydrogen being aligning parallel low energy. And there's a lot of them. So we quantify and we image all of those and define them as having the net magnetization. That net magnetization is,

which is labeled as M sub zero is proportional to the field strength. Diana, this one's for you, which is what you had asked earlier. I couldn't get there yet. We have to build, we have to build their low signal to noise ratio adequate for most routine clinical, less susceptibility artifacts means why put these in is that they're

On a 1.5 Tesla, let's go to the picture here. Go away. Let me just come up here. On a 1.5 versus a 3.0, I've gotten more hydrogen aligning parallel spin up low energy. That's all I want you to take away. And if I have more hydrogen being aligned, I can measure more signal.

And if I have more signal, I'm going to have signal intensity that's going to give me better image resolution. Okay, that's where I want to leave us. I apologize. We're going in, guys. You picked MRI. Bardo, go ahead.

So each one of those arrows represent a single hydrogen? Yes. Okay. Yes. I see there's more with the three point. Yes. Okay. Yes. And if I've got more, I'm going to be able to capture more signal, which is going to signals directly connected to image resolution. And that's the idea here, that net magnetization difference between a 1.5 Tesla versus a 3.0 Tesla.

So I noticed that there's some that are, they're not all facing upwards. So it doesn't matter which direction as long as they're just aligned. Well, the ones that are facing down are the high energy, which we're not tapping into for MRI. They're still there, which is why I have them because I can't ignore them. They are still there. But if you notice here, I have more spinning up than I do spinning down.

And that signifies the hydrogen atoms that are aligning parallel with the field, low energy. I have more of them, which is why we tap into their resonant frequency versus these guys. Does that make sense? Yes. Okay.

And then if I go over to a 1.5 Tesla, I have two rows of hydrogen atoms that are aligning parallel with that 3.0 Tesla magnet field. And I have even more hydrogen atoms in that lower energy parallel state. And if I've got more, I'm going to have a brighter, I could say brighter, I'm going to have a better signal, which is going to give me better resolution.

it's exciting stuff i love it i love it i totally geek out over the physics guys it's exciting okay that's it i don't want to go anymore i don't want to go anymore that's it please please please please watch the clover learning videos that i gave you and assigned read your textbook look over your notes

Rewatch this lecture if you have to. You can fast forward me, you can pause me, right? To kind of fill in the blanks on your notes and ask yourself, I gave you guys a hint with the slides. Why? Where's my other one? That's how you study and prepare for this class and any physics class. Why and how? And when you progress, it's going to eventually turn into when.

Not only how and why, but when. Timing is everything. Okay, guys, that's it. That is it. No more. I know you guys want to keep going, but no more. No more. Thank you guys for a great class. Please, please email me. I will have grades up today. All your coursework that was due last night, I'll have them in today. I will also have this. Let me stop recording. I will have this.

up as soon as it's done post-processing.