Speaker 1: Brought to you by the reinvented two thousand twelve camera.
Speaker 1: It's ready. Are you get in touch with technology with
Speaker 1: tech Stuff from how stuff works dot com. Hello again, everyone,
Speaker 1: welcome to tech stuff. My name is Chris Poett and
Speaker 1: I am an editor at how stuff works dot com.
Speaker 1: Sitting across from me, as usual, is senior writer Jonathan Strickland.
Speaker 1: I've been ionized, but I'm okay. Now, okay, let's move
Speaker 1: on to a little listener mail. This listener mail comes
Speaker 1: from Brad, and Brad says, how about a series of
Speaker 1: podcasts that explain the technologies of medicine between the diagnostics
Speaker 1: like m R I X ray, CT scans and nuclear
Speaker 1: medicine to read habilitative therapies like ultrasound and electrical stimulations.
Speaker 1: There are a lot of different possibilities. Well, Brad, we
Speaker 1: agree with you. Now, granted those are that's a lot
Speaker 1: of topics, so we can't really, we definitely cannot tackle
Speaker 1: them all in one go because we would be here
Speaker 1: for five hours and I am exhausted, So we are
Speaker 1: going to just do one of those. However, it is
Speaker 1: one of the more technically difficult ones to talk about
Speaker 1: in a way it's magnetic resonance imaging or m r I.
Speaker 1: S Yeah, you know, it's funny that you just said
Speaker 1: five hours, because the very first m r I, which
Speaker 1: was conducted on July third, seven, took about five hours.
Speaker 1: That's right. It took almost five hours to get one image.
Speaker 1: And what was weird was the image was of a
Speaker 1: man waving. No, that's that parts a lie. Well, the
Speaker 1: that that image was from a graduate student because the
Speaker 1: original um, well one hesitates to use the word victim,
Speaker 1: but subject, The original subject of the first m r
Speaker 1: I was supposed to be the fellow who was kind
Speaker 1: of the driving force behind inventing the m r I machine,
Speaker 1: Raymond Domedian. Yes, now, Raymond was not able to be
Speaker 1: the first subject of the first m r I because
Speaker 1: he didn't fit. Yeah, he was. He had a little
Speaker 1: too much junk in the trunk. That's that's never mind.
Speaker 1: Get in there, dude, My my trunk has got so
Speaker 1: much junk in it. I'm just saying so, yeah, do
Speaker 1: Median was not able to He was disappointed when he
Speaker 1: first used his machine because it didn't work, and at
Speaker 1: first he thought that perhaps all this work he had
Speaker 1: been putting into developing this device was for not and
Speaker 1: then someone suggested that perhaps a slightly thinner subject might
Speaker 1: be better suited for the first test, and so one
Speaker 1: of the graduate students that was working with him stepped
Speaker 1: up to the plate and said that they would take
Speaker 1: the place. And indeed it worked. It did take about
Speaker 1: five hours. Um, that's it's a long time to be
Speaker 1: in an MRI machine. Yes, and another just another trivia
Speaker 1: act for those of you who like to play trivia games.
Speaker 1: The very first machine was called the Indomitable. Yes. And
Speaker 1: you can actually see the Indomitable Yes, it's at the Smithsonian. Yes.
Speaker 1: So I wonder if the Abominable Snowman could be have
Speaker 1: an m r I in the in the Abdomitable. I
Speaker 1: am almost certain that the Abominable Snowman has even more
Speaker 1: junk in the trunk than the median. Probably probably does.
Speaker 1: I'll ask my sister. She knows him. Okay, yeah, actually, no,
Speaker 1: you're right, that's true. I'm not making it up. So so, yeah,
Speaker 1: there there's a very small space in an m r
Speaker 1: I machine. Um. And do you think we should mention
Speaker 1: before we get into the technology behind it, what you
Speaker 1: would use an m r I for sure? Sure? Why
Speaker 1: don't you Why don't you illuminate? Okay, well, there there
Speaker 1: are lots of different things that you can use an
Speaker 1: m r I for. Now, what it does is it
Speaker 1: basically captures an image of your insides. Um. I was
Speaker 1: going to say sort of like an X ray, But
Speaker 1: I don't really like an X ray at all, because
Speaker 1: X rays are really good for things like bone structure
Speaker 1: and but damage to bones, whereas m r I s
Speaker 1: are really good for soft tissue like organs. Yes, and Uh,
Speaker 1: if you ever have the opportunity to see pictures that
Speaker 1: have come from an m I, U might be worth
Speaker 1: looking up online. But um, it's it's really fascinating. You
Speaker 1: could see a whole lot of detail. Um. And speaking
Speaker 1: of of detail, I mean I could tell you a
Speaker 1: little bit about that. I actually had an m r
Speaker 1: I this year. We'll get into that in a minute.
Speaker 1: But you can look for things like tumors for different
Speaker 1: signs of disease, torn ligaments or damaged tendons. Um, just
Speaker 1: irregularities and organs. Someone might have an enlarged heart or
Speaker 1: things of that nature. You have damage to blood vessels. Uh,
Speaker 1: you know, if you have anything wrong with your abdominal area. Um,
Speaker 1: you know, you could you could look to see if
Speaker 1: there's something that's uh that's available, and the technology is
Speaker 1: is amazing to me. The things the report that I
Speaker 1: got back from the doctor when it was all done,
Speaker 1: it's going, how did you see as they sent the
Speaker 1: entire thing? So I saw all the other stuff, the
Speaker 1: um the person who did it catalog pretty much everything
Speaker 1: was visible, even things that they weren't looking for. So
Speaker 1: it was going, that's a little creepy, yeah, but it's amazing.
Speaker 1: You think the back scatter X ray machines at the
Speaker 1: airport are are really detail oriented. Well. Also, I found
Speaker 1: the key to my back door. It was it was,
Speaker 1: it was inside there all the time, and I wondered
Speaker 1: what happened to it? Apparently it fell in my burrito. Okay,
Speaker 1: I was wondering if that was a euphemism. Now, actually,
Speaker 1: actually we'll get into this. If there had been a key,
Speaker 1: that would have been extremely bad. All right, Yeah, so
Speaker 1: let's let's talk a little bit about m ris of
Speaker 1: why they are important. Besides the fact that they look
Speaker 1: at your squishy bits as opposed to your skeletal system
Speaker 1: like all the uh, your lungs and liver and all
Speaker 1: that kind of stuff that they're really good for that. Um,
Speaker 1: it's a scientific term squishy bits. Yeah, well I'm not
Speaker 1: I'm no adicition. Um, I don't have my my discinal degree. Uh.
Speaker 1: The it's it's non invasive, so that means it doesn't
Speaker 1: there's no there's no incisions that have to be made.
Speaker 1: And also unlike X rays, it is uh, it's not
Speaker 1: an ionizing form of radiation. Right now, X rays are uh,
Speaker 1: that is a form of ionizing radiation, which means that
Speaker 1: when the X rays hits you, they can create ions,
Speaker 1: which you know, it's essentially it's stripping electrons away from
Speaker 1: from atoms and this can cause cells to be damaged.
Speaker 1: It can cause mutations, which is why you hear about
Speaker 1: you know, it's it's it's why anyone who works in
Speaker 1: an X ray laboratory laboratory, I could hear it. I
Speaker 1: don't know why that has every now and then I oratory.
Speaker 1: My schedule has me in the laboratory this afternoon. They
Speaker 1: but anyone who works in one of those they they
Speaker 1: usually have to be behind like a protective barrier for
Speaker 1: whenever they're running the machines. It's why when you get
Speaker 1: an X ray done of your teeth. You may have
Speaker 1: to wear out like the lead apron because too much
Speaker 1: exposure to too too many X rays can cause damage. Well,
Speaker 1: m r I s do not use that kind of radiation.
Speaker 1: There is radiation that's involved, but it's not that it's
Speaker 1: not that ionizing radiation. So it's there's no real damage, um,
Speaker 1: that that could happen on that on that in that way.
Speaker 1: There are ways to get damaged getting an m r I,
Speaker 1: and you alluded to one of them earlier. So, um,
Speaker 1: what exactly is going on here? The m r I.
Speaker 1: We said that that stands for magnetic resonance imaging. That magnetic,
Speaker 1: of course, is the really big part of this. There's
Speaker 1: a an enormous magnet that is um uh generating a
Speaker 1: very powerful magnetic field. Yes, extremely powerful. In fact, um uh.
Speaker 1: They measure the field in in tesla, not in gaus,
Speaker 1: which is typical of measuring magnetic fields, right right, gals
Speaker 1: is a is a unit that's much smaller than a tesla. Yeah.
Speaker 1: As a matter of fact, a tesla is equal to
Speaker 1: ten thousand cows and uh typical m r I machine. Um.
Speaker 1: By the way, it's a very excellent article on this website.
Speaker 1: That you mentioned earlier, right, how stuff works dot com. Yeah, yeah,
Speaker 1: there is a great article on our m R I
Speaker 1: machines on there. But according to that article, um, we
Speaker 1: do uh there there is an field of about to
Speaker 1: tesla going on. So that's twenty thousand gaus if you
Speaker 1: are inside the machine and um, and it is a
Speaker 1: long machine. It's long enough to uh you know, stick
Speaker 1: a whole human in there. Um. But yeah, so it's
Speaker 1: it's got very very powerful magnets in their most frequently
Speaker 1: their permanent magnets. Yeah, superconduction magnets. There are some that
Speaker 1: do use permanent magnets, you're right, but the majority superconduct Now,
Speaker 1: a superconductor is an interesting thing. They in order to
Speaker 1: get a it's essentially a electro magnet. But to really
Speaker 1: reach superconductivity, they have to lower the resistance within the
Speaker 1: wires that create the magnetic field. Now if you I'm
Speaker 1: sure you all remember, but an electro magnet is essentially
Speaker 1: a coil of wire. You run an electric current through
Speaker 1: this coil of wire and that generates a magnetic field. Well,
Speaker 1: all wires have a certain amount of resistance. It's dependent
Speaker 1: upon the material of the wire and the gauge of
Speaker 1: the wire and resistance just that that that's going to
Speaker 1: inhibit the strength of the magnetic field. So to lower
Speaker 1: the resistance, you actually lower the temperature. And with superconductive
Speaker 1: magnets you do this using liquid helium, which is incredibly cold.
Speaker 1: This is the same stuff they used to cool the
Speaker 1: Large Hadron Collider at CERN. That's point four degrees below
Speaker 1: zero if you're talking fahrenheit, or about to sixty nine
Speaker 1: point one below zero celsius, or as I call it
Speaker 1: on my scale, really really really really cold. Yeah, you're
Speaker 1: approaching absolute zero zero kelvin and um and of course
Speaker 1: zero kelvin absolute zero. What that means is you've reached
Speaker 1: a point where there is no molecular movement. So really,
Speaker 1: when you think about temperature in a way, you're talking
Speaker 1: about how fast molecules move. That's that's kind of a
Speaker 1: way of thinking about it, right. Well, so this this way,
Speaker 1: you're reducing the movement of those molecules as much as possible.
Speaker 1: You run the electric current through it generates a very
Speaker 1: powerful magnetic field. Now why do you create this magnetic field? Well,
Speaker 1: to do to really understand that, you have to understand
Speaker 1: that the the whole basis of m R I is
Speaker 1: uh is on the principles of nuclear magnetic resonance. Now,
Speaker 1: first of all, when you hear the word nuclear, you
Speaker 1: start to freak out right because you know, yeah, well
Speaker 1: it's nuclear power plants, nuclear bombs. You think about these
Speaker 1: things that are potentially really powerful and devastatingly dangerous. But
Speaker 1: really it just means that it we're dealing with nuclei here, yes,
Speaker 1: the nucleus of an atom, and we're talking specifically about hydrogen.
Speaker 1: Hydrogen nucleus is a proton. You've got a proton an
Speaker 1: electron that's hydrogen, so you're nucleus is just proton. Now.
Speaker 1: Nuclear magnetic resonance is a spectroscopic technique that gets information
Speaker 1: about chemical and physical properties of a material at the
Speaker 1: microscopic level. And it was developed it was actually discovered
Speaker 1: by Felix Block and Edward Purcell at the same time, independently.
Speaker 1: In why is it always? It seems like big advances
Speaker 1: in science are always there are always two people that
Speaker 1: figured out about the same time. I don't know. It
Speaker 1: is pretty interesting when you sit there and you think, well,
Speaker 1: you know what driving forces inspired two people in different
Speaker 1: parts of the world to study the same thing and
Speaker 1: come to the same conclusion. Now, what I would argue
Speaker 1: is that that shows that science is good, because it
Speaker 1: means that if you follow the scientific method, you will
Speaker 1: reach the proper conclusion in time. Alright, then, so I
Speaker 1: figured there was some kind of bond between them. Science
Speaker 1: as good as the alternative title of this episode of
Speaker 1: tech stuff. Um. So, at any rate, they both actually
Speaker 1: were awarded the Nobel Prize in ninety two. Domedian did
Speaker 1: who invented the m R A machine, did not win
Speaker 1: the Nobel Prize. But at any rate, you've got this
Speaker 1: this principle, and the principle essentially essentially states that there's
Speaker 1: this feature of of atoms called spines nuclear spin. Um.
Speaker 1: It's a little interesting and a little difficult to explain,
Speaker 1: but but atoms are spinning in a particular direction all right,
Speaker 1: independently of other materials. But if you introduce a magnetic
Speaker 1: field that's strong enough to the to the atoms, their
Speaker 1: spin will align with that magnetic field. So it's kind
Speaker 1: of like when you think of iron filings and a magnet.
Speaker 1: If you have the magnet in a certain way, the
Speaker 1: iron filings will actually start to align themselves in the
Speaker 1: in the same direction as the magnetic field around that magnet.
Speaker 1: So first you create this magnetic field, a powerful magnetic
Speaker 1: field that's using the superconductor magnet, and you start to
Speaker 1: align these proton uh well, I'm starty, not just protons,
Speaker 1: but these hydrogen nuclei in the proper alignment. Then you
Speaker 1: use a radio frequency that's a tune specifically to those nuclei,
Speaker 1: and you hit the nuclei with a frequency. When you
Speaker 1: do that, you excite some of the nuclei to a
Speaker 1: higher state uh of energy. And then when you stop,
Speaker 1: when you remove that radio frequency, the nuclear returned to
Speaker 1: their relaxed state. They go back to what they were
Speaker 1: doing before, right. And by measuring this different difference, you
Speaker 1: can you can sort of see you know where the
Speaker 1: protons are, where the nuclear are, But you have to
Speaker 1: you have to get a little more specific than that.
Speaker 1: If you were just using the superconductor magnet and just
Speaker 1: using radio frequency, you would know that there were protons there,
Speaker 1: but you wouldn't really have a map, you wouldn't have
Speaker 1: an image that you could look at. It would just
Speaker 1: tell you that there were nuclei there. So what you
Speaker 1: have to do is you have to actually add more
Speaker 1: magnets to the mix and create a gradiated magnetic field.
Speaker 1: So this this gradation, this variable magnetic field, gives you
Speaker 1: more information and you can actually map out what the
Speaker 1: the inside of something looks like based upon the position
Speaker 1: of hydrogen uh atoms just through blasting it with radio
Speaker 1: frequencies and putting this magnetic field around them. It's it's
Speaker 1: pretty interesting stuff. And it's a little complicated. Um, actually
Speaker 1: it's a lot complicated. But because we're talking about really
Speaker 1: we're talking about nuclear physics when we get down to it,
Speaker 1: and um, of course, when you ever you talk about magnetism,
Speaker 1: eventually you get to a point where I'm just like, Okay,
Speaker 1: we're well beyond what I can easily explain. Nonetheless, they
Speaker 1: really like magnets, and you know what a super cool
Speaker 1: but um, and they're actually uh, I believe there are
Speaker 1: actually three gradient magnets in an MR machine. Um, and
Speaker 1: they're not as powerful as the superconductor magnet, but they
Speaker 1: don't need to be right. Um, But let's see the
Speaker 1: U the tunnel. There's basically it's if you think about
Speaker 1: it, it it kind of looks like a donut on a stand,
Speaker 1: a very long donut, and you the the hole. In
Speaker 1: this case, it is called the bore b o r E. Yes,
Speaker 1: I also get that term when I go to parties,
Speaker 1: but we won't go there now, or sometimes when our
Speaker 1: podcast goes long. But what happens when you go to
Speaker 1: UH to sit in for an m R I uh
Speaker 1: you are asked to basically leave everything behind. You don't
Speaker 1: wear your clothes. You have to you know, strip down
Speaker 1: and wear a hospital gown. They ask you things like,
Speaker 1: you know, do you have any metal in your body right?
Speaker 1: Any screws or metal plates or if you have like
Speaker 1: a pacemaker, anything like that could be um, well, that
Speaker 1: would definitely be a problem, yes, because what what can
Speaker 1: happen during the m R I process is depending on
Speaker 1: the kind of metal that maybe inside, say it's a screw, um, uh,
Speaker 1: steel screw it would it could heat up and because
Speaker 1: internal burns, which are bad. Yeah, and you can't have
Speaker 1: any metal in the room because it's gonna fly right
Speaker 1: at that MR machine once you turn it on. That
Speaker 1: would be fun. No, it's not fun. No, I mean
Speaker 1: that was sarcasm um and it's sadly it is. It
Speaker 1: has actually contributed well, it's contributed to a few pretty
Speaker 1: well publicized accidents in in m R I labs um,
Speaker 1: including I almost did again, Yeah, and you almost spit
Speaker 1: coffee all over me. Um. So I don't know what
Speaker 1: do with laboratory aluminium. Yes, aluminium, I think is you're
Speaker 1: you're pretty safe. It's not magnetics. And I have I
Speaker 1: have actually some some titanium inside and I was kind
Speaker 1: of wondering about that. What's your key was made out of? Yeah,
Speaker 1: yes it is. No, I had, uh yeah, some clips
Speaker 1: from a previous surgery. You know. It's kind of concerned
Speaker 1: because I knew they were made of metal and they said, no, no,
Speaker 1: that's titanium. You're fine. No, I honestly did not know this.
Speaker 1: But apparently Mr Palette is the bionic man. Well you
Speaker 1: know that sixty million dollars doesn't buy what it used to.
Speaker 1: This is this is becoming all that more more and
Speaker 1: more apparent. Actually was six million, it wasn't sixty adjusting
Speaker 1: for inflation. That's fair enough. But yeah, so they what
Speaker 1: they do is they have you lie down on this um.
Speaker 1: It's sort of like a long like you might see
Speaker 1: a gurney, except it's attached to the machine. You lie
Speaker 1: down and they there are motors attached to the underside
Speaker 1: of that and they when you are comfortably lying back
Speaker 1: on this device, they uh, the motors wheel you in
Speaker 1: and they don't necessarily have to put your entire body
Speaker 1: in the machine, which is good for people who are claustrophobic. Right,
Speaker 1: they don't have to look at your head. It's probably
Speaker 1: better not to just you can actually go in feat
Speaker 1: first if if that's the case, I mean, um, and
Speaker 1: there are there are times where people have been sedated
Speaker 1: to uh in order to calm down enough to be
Speaker 1: able to go through an m r I. But that's
Speaker 1: tricky too because one of the other parts about getting
Speaker 1: an m r I done is you have to stay
Speaker 1: very very still. That is the truth, because if you
Speaker 1: move at all, then you're going to distort the image
Speaker 1: because you're going to change the position of those those
Speaker 1: nuclei everything that happens to be inside you. By the way,
Speaker 1: in case you're wondering, we happen to have a lot
Speaker 1: of hydrogen in our bodies. Um, it's stored mostly in
Speaker 1: water and fat. But uh, one figure I read said
Speaker 1: that about oh of us is hydrogen, so uh, you
Speaker 1: know it's it's measuring where that is that we can
Speaker 1: make the the images to to show what's happening. So yeah,
Speaker 1: when you go in and uh the magnet kicks on
Speaker 1: and the radio frequency starts to blast you, what's that like? Um? Well,
Speaker 1: one of the things that I have to say that
Speaker 1: the technician who administered the m R I that that
Speaker 1: I had earlier this year was very very patient. Um,
Speaker 1: and although I'm not claustrophobic, I was a little concerned
Speaker 1: that I might uh feel a little uncomfortable being in
Speaker 1: such a tight space. Uh. They did put me all
Speaker 1: the way inside the bore of the m R I machine. Um.
Speaker 1: But one nice thing that they did, Uh they gave
Speaker 1: me a set of headphones and uh they had you know,
Speaker 1: gave me a variety of music to choose from, and
Speaker 1: I picked a station that I thought would be calming.
Speaker 1: Did you choose the Magnetic Fields Book of Love? No?
Speaker 1: I did not, but that is an excellent a series
Speaker 1: of records. Um. But uh no, that's funny. I'm sorry,
Speaker 1: I'm just kind of funny. Um. But that and they
Speaker 1: put a towel over my eyes, you know, and had
Speaker 1: me lay back, and uh, they can actually talk to
Speaker 1: you from the booth so that you know, what are
Speaker 1: you doing now? You are you feeling okay? Um? You know,
Speaker 1: are you concerned? Um? What they didn't tell me was
Speaker 1: it makes a whole lot of noise. And I didn't
Speaker 1: read this article, uh, nor do any other research before
Speaker 1: I went in. Uh so when this sounds, and I
Speaker 1: didn't hear a loud knocking, so this isn't uh you know,
Speaker 1: I've heard that some machines there is a loud knocking noise.
Speaker 1: Now I did not hear that. I heard sounded like
Speaker 1: a warning class in from a nineteen seventy two science
Speaker 1: fiction movie. And I'm going, well, either the bombing has
Speaker 1: started and they're leaving me here to die, or this
Speaker 1: is normal. Yeah, either the m I R I is
Speaker 1: going as planned, or the Klingons have have materialized off
Speaker 1: the starboard bell exactly. I'm not kidding. It was me,
Speaker 1: and I'm going interesting, I assume that this is part
Speaker 1: of the normal functioning of the machine. And as it
Speaker 1: turned out, the Klingons left the hospital pretty much, uh
Speaker 1: you know, untouched. So that's good, that's good. But yeah,
Speaker 1: it's it's a little it's a little disconcerting. But I
Speaker 1: didn't really I didn't really feel a lot, now, you
Speaker 1: know they that was up until that was probably the
Speaker 1: two thirds of the way through the m r I.
Speaker 1: And then they stopped and came in the room and
Speaker 1: had to move my body back out of the bore
Speaker 1: of the m r I. And I'm sure you probably
Speaker 1: know why that is. We got to the next phase
Speaker 1: of the m r I process because the m or
Speaker 1: I can only do so much by itself. At one
Speaker 1: point they ask you if you're willing to be injected
Speaker 1: with a die, yes, a contrast die. Yes. The thing
Speaker 1: is it's it's from what I understand, it's radioactive and
Speaker 1: can cause some problems. Some people can have an allergic
Speaker 1: reaction to it. That is one of the dangers of
Speaker 1: the m r I is that you can you can
Speaker 1: actually suffer an allergic reaction to the contrast material. Yea,
Speaker 1: they gave me a nice long form to sign saying
Speaker 1: you really won't be angry at us if we kill you, right,
Speaker 1: I'm kidding. It was yes, and they were They explained
Speaker 1: it in great details. So they were very many nice people.
Speaker 1: But um, but it's funnier to see it the other way.
Speaker 1: But yeah, and so they injected me with a die,
Speaker 1: which felt very weird and uh kind of kind of
Speaker 1: a cold feeling. Actually, yeah, I've I've had I've had
Speaker 1: various dyes injected into me, both on purpose and on accident. Hey,
Speaker 1: let's see if we can turn the more in. She's
Speaker 1: a weird your college experience. Anyway, Then they put me
Speaker 1: back inside the machine and ran the machine for another
Speaker 1: fifteen minutes. The whole thing for me only took probably
Speaker 1: about an hour. Yeah, the they tend to be between
Speaker 1: fifteen and forty five minutes, but some can be a
Speaker 1: little longer. It all depends on the equipment, the technician,
Speaker 1: and exactly why you need to have the the m
Speaker 1: r I done because you know, if it's just one
Speaker 1: where you have to scan one little part of your body,
Speaker 1: then obviously that's not gonna take as long as if
Speaker 1: you need, you know, like a full body scan. Um
Speaker 1: when when you're being put through the boar, or when
Speaker 1: anyone really is being put through the boar, the part
Speaker 1: of the body that needs to be scanned has to
Speaker 1: be in the center of it, which is called the
Speaker 1: ISO center of the boar um. And like I said
Speaker 1: that those radio frequencies start to excite the hydrogen atoms
Speaker 1: in your body flipping them making them go to a
Speaker 1: higher energy state. And then when what happens is when
Speaker 1: they go to that lower energy state, they actually give
Speaker 1: off radio frequencies the atoms do. The nuclei give off
Speaker 1: these radio frequencies, which you use. The m r I
Speaker 1: machine picks up those radio frequencies and that's what provides
Speaker 1: the information to UH to locate where the nuclei are
Speaker 1: and thus build the picture of what's inside you. It's
Speaker 1: actually pretty cool now, UM. Now, a lot of people
Speaker 1: kind of freak out because they or some people I'm
Speaker 1: sure do, because they hear the words radiation and they
Speaker 1: immediately think of ionizing radiation. But we're talking about radio
Speaker 1: frequencies here, not X rays or gamma raise or anything
Speaker 1: that would give you the power of super stretching abilities.
Speaker 1: So it was really disappointed. Yeah, I gotta admit I
Speaker 1: was a little disappointed to UM. But there are other
Speaker 1: things that can happen through an m r I that
Speaker 1: can some interesting side effects that are possible. Well, first
Speaker 1: of all, not everyone can have an m r I
Speaker 1: because if you have any materials in you that would
Speaker 1: caught would interfere, obviously, that would be a bad idea. Um.
Speaker 1: But also beyond that, there's the you know, if you're
Speaker 1: too large, you couldn't have an m r I UM.
Speaker 1: And the boar is very very narrow. Yeah, it's like
Speaker 1: two ft in diameter. So uh but yeah. One of
Speaker 1: the other possible side effects I've heard about are called
Speaker 1: magneto phosphenes. I'm impressed but that I was able to
Speaker 1: say magneto phosphines. Practiced that for about a minute before you. Yeah,
Speaker 1: I just I got to magneto and then I would
Speaker 1: say I'll crush you x men. But magneto phosphenes. The
Speaker 1: phosphene kind of gives it away. It's it's it's a
Speaker 1: visual phenomena. You get these visual sensations. It's like, um,
Speaker 1: it's like flashes of light, like you're like someone's taking
Speaker 1: photographs of you, which kind of they are, except it's
Speaker 1: not really photograph um. But you're getting these flashes of light.
Speaker 1: And what's happening is it's it's not entirely understood, but
Speaker 1: it's it's these induced electrical currents that are occurring inside
Speaker 1: your retina when you move through the magnetic field. UM
Speaker 1: or that the or a magnetic field is changing around you. UM.
Speaker 1: It's it doesn't happen with everyone, and it's not gonna
Speaker 1: happen on It's not gonna happen every time you get
Speaker 1: an m r I or even if you have experienced
Speaker 1: them before, there's no guarantee that you're going to experience
Speaker 1: them again if you have another m r I and Uh,
Speaker 1: they're harmless, but I'm sure that's very disorienting. Apart from these,
Speaker 1: there really aren't that many hazards to having an m
Speaker 1: r I done. Uh. And there are other potential uses
Speaker 1: of m r I s that we're just starting to
Speaker 1: kind of develop now, like the the functional m r
Speaker 1: I s, which are really interesting. It's kind of making
Speaker 1: a map of the human brain, and it can be
Speaker 1: a real time map. You're actually looking at the images
Speaker 1: as someone is being subjected to various stimuli, and then
Speaker 1: you look at the patterns that are occurring in the
Speaker 1: brain and you start to map functions that way. And
Speaker 1: the way this works is when you get someone to
Speaker 1: think about something like think about moving your hand, or
Speaker 1: think about the color blue or whatever, you know, whatever
Speaker 1: the criteria are. Um oxygen goes to the brain and
Speaker 1: the level of oxy as the level of oxygen increases
Speaker 1: in the regions where there's brain activity that actually affects
Speaker 1: that magnetic field because oxygen is paramagnetic, and by measuring
Speaker 1: the differing levels of oxygen in the brain, you can
Speaker 1: kind of see brain activity. Interesting. Yeah, there's it's I mean,
Speaker 1: just the idea that you could you could do that,
Speaker 1: I wonder how long. It seems like that would be
Speaker 1: sort of impractical though, well, because you'd have to I mean,
Speaker 1: you can't use you wouldn't. You would be limited in
Speaker 1: what you could offer the subject in stimuli because it
Speaker 1: had to it would have to fit in the more
Speaker 1: and not interfere with the machines. Involve a lot of
Speaker 1: thinking and what you can do. But there's one one potential,
Speaker 1: uh use I've heard that's kind of scary and interesting
Speaker 1: at the same time, which is to use an f
Speaker 1: m R I as a new and improved lie detector.
Speaker 1: That's true, where you ask the subject questions and you
Speaker 1: observe the brain activity and look for attempts to be
Speaker 1: subversive or to elude the the question asker, person, interrogator.
Speaker 1: That's a good word. We'll use that one. Hey, whatever, man,
Speaker 1: I've been up for a really long time, so um, yeah,
Speaker 1: that's that's kind of the the overall statement about m
Speaker 1: R eyes and how they work. It's it's really a
Speaker 1: very fascinating subject and if you really want to delve
Speaker 1: into the science. Um Dr Joseph P. Hornack h O
Speaker 1: r in A k of Rochester Institute of Technology, has
Speaker 1: a hypertext textbook on m R eyes onlines free. You
Speaker 1: can read all about everything the science behind MR eyes,
Speaker 1: the math behind it, the math behind electron spins and
Speaker 1: and nuclei spins. It's really fast, sinating reading and it
Speaker 1: goes into way more detail and um you may need
Speaker 1: most of the most of the text is pretty understandable
Speaker 1: to someone who's got, you know, a good grounding in
Speaker 1: math and science, but some of it's going to go
Speaker 1: beyond that. So you know, if you are interested in
Speaker 1: this sort of thing, I do recommend it, and also
Speaker 1: our article if you want to have kind of the
Speaker 1: general overview, and you know, we dive into the science,
Speaker 1: but we don't get so far down that you need
Speaker 1: a degree in science or mathematics in order to understand it.
Speaker 1: Our article at how stuff words dot com is also great,
Speaker 1: So I do recommend that. So that wraps up this
Speaker 1: discussion on m r I s if you have any
Speaker 1: questions or suggestions for topics. We do plan on hitting
Speaker 1: some of these other medical topics in the future, so
Speaker 1: keep an ear out for those. Maybe we'll even have
Speaker 1: another like we've got our movie making series or medical
Speaker 1: series focus on series denystifying series. We could be called
Speaker 1: this demystifying the m R. I. I guess, but if
Speaker 1: you have any suggestions for similar topics, let us know.
Speaker 1: You can let's know on Twitter and Facebook are handled.
Speaker 1: There is text stuff h s W or you can
Speaker 1: email us and that address is tech stuff At how
Speaker 1: stuff works dot com, Chris and I will talk to
Speaker 1: you again really soon for moral this and thousands of
Speaker 1: other topics. Is it how stuff works dot com. To
Speaker 1: learn more about the podcast, click on the podcast icon
Speaker 1: in the upper right corner of our homepage. The how
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