When MRI was first invented, it was initially called "Nuclear Resonance Imaging." However, no one wanted to use it because everyone was afraid of the word "Nuclear" in the title. Therefore, it was renamed "Magnetic Resonance Imaging", and even though the nothing about the underlying technology had changed, everyone now felt that it was safe to use.
+IamGrimalkin, some people call it Nuclear Magnetic Resonance Imaging (and I have called it that too in the past), but the word "nuclear" is usually left out, because this word makes people think that there is nuclear radiation involved, even though there is not.
+Physics Videos by Eugene Khutoryansky Of course MRI is a further development of NMR, but used for imaging, so calling it NMRI isn't much of a stretch, though it should really have a much more creative acronym.
I worked in a medical center and during construction and installation, an MRI was turned on before anyone checked for nearby metal. A minute later an acetylene tank in the next room came crashing through the wall and hit the MRI so hard it left a dent.
Every MRI centre I've used has a collection of nasty things that happen if you aren't careful. My main place has a picture of a bicycle stuck on the machine. They swear it didn't happen in their machine....
Hi ! I'm a 9 year-old girl. I love watching your videos to learn physics! You talked about possible dangers of bringing metal objects in the MRI room but didn't really talk about how MRI scans may impact your brain functions. Is it really safe to have brain MRI?
Hi Maya, this comment is 5 years old so likely you will not read this, but for those who are, brain MRIs are completely safe. MRI does not use any ionizing radiation (like x-rays or CT scans) therefore there is no risk of cancer from repeated scans. All an MRI does is apply several magnetic fields to generate a series of responses that formulate an image. The only risk from the magnetic fields is something called peripheral nerve stimulation, which is a tingling sensation felt when the imaging magnetic field switches on and off very fast (unlikely to happen in a clinical setting). MRI scans are not recommended for those with pacemakers as the electromagnetic signals may interfere with its functions. You can even get an MRI if you have a titanium or non-magnetic implant! Source: I am a physicist that researches MRI methodologies :)
@@layalebazzi1244 Thank You ma'am.. I was correct when I was against about the risk of getting cancer through MRI my teacher said MRI causes cancer you shouldn't do a MRI. I researched and finally I found myself correct. Everybody in my class judged me for knowing nothing and spitting shits of zero knowledge that appears to be true. Aaha... Finally I cam prove that teacher now wrong! Thank you!
MRI machines do transfer energy to the tissues of your body, which results in a very mild heating effect. During the only MRI I have had, I found myself getting warm, which was easily remedied by the operator increasing the speed of the fan blowing on me.
Dear PhysicsGirl, What effect do MRI's have on naturally occurring ferrous metals in the body? In particular, I'm thinking of the iron our body uses in red blood cells. Thanks for yet another awesome video!
To flip the question around: what effect does hemoglobin or hemosiderin have on MR images? It can actually cause measurable susceptibility distortions! Lookup SWI, which can be used to detect microbleeds
I've had 3 MRI techs refuse to run me through their machines when they find out I have titanium aneurysm clips around my cortex. I've heard my doctor practically yelling at them that titanium isn't ferrous, but the techs all said that doesn't mean they might not heat up or shift in such a strong magnetic field. After talking to the last tech, I've opted out of having further MRI's after having the clips because the risk isn't really worth it. Anyway, thanks for the video! That chair pulling at over 2,000lbs of force was amazing.
The danger of titanium clips is from them heating up from the RF fields produced by transmit coils (not from the magnetic field as titanium is not magnetic like iron, cobolt, or nickel for example). The brain can actually withstand more RF heating in general than other parts of the body because it has so much blood flow (liquid cooling), but something metal could still result in excess localized heat and the consequences in the brain are much higher.
You could look into: blast welding which is pretty cool, you basicly weld 2 pieces of metal together with an explosion. Fusion reactors. Thorium / molten salt reactors. The natural nuclear reactor that was running a few thousand years ago, aka a fission reactor that arose naturally. (Oklo / Gabon) Burning coal mines. The ongoing fission in the earths core. How the different types of nuclear weapons work. A few tips for your channel if you are interested, might take some travelling to get to make a video of, but most can be done through animations, this is at least some things i am interested in and if something peaks your interest look it up.
I'm a brain cancer patient, and I get regular MRIs, to check on my head, and see for potential recurrence. Knowing more about MRI helps me understand more about the scans that I have done that are so important to my survival now. Thanks for making this video, Dianna, and PBS for supporting it.
I imagine they keep the field always active because the cool-down cycle prior to startup for the superconductors would be pretty long. To be superconducting, they need to be kept at liquid helium temperatures, which just is a few degrees above absolute zero.
+BlackEpyon It's super expensive to quench the magnet, then cool it back down. That's the real reason. Hence why you can do it in emergencies, but it's never done otherwise.
tobywilson Not really. Just cut the power to the cooling pump, and it will eventually return to room temperature. It's the cool-down cycle that makes it impractical.
+BlackEpyon I think maybe you didn't understand what I wrote properly, or I didn't write it well... The magnet is a superconductor, it's super cold. Turning it off heats it back to room temperature. Getting all the supercooled helium you need to re-cool the magnet back down from room temperature is super expensive. You're right it also takes a lot of time too though.
tobywilson I understand what the superconducting part means. I don't have a schematic to see if they have a large drain tank or it the system maintains it's pressure like an AC unit. If it has a tank, then deactivating the pump will allow the system to equalize and heat up. Obviously you don't just let the helium vent into the air. If it doesn't have a tank, then obviously you would need to have the service technician come in to drain it. The electromagnet will retain it's saturation for a long time as long as it's kept cryogenic.
+BlackEpyon Some superconducters become superconducters at about -200°C (70°K). I've studied one a few weeks ago using a SQUID but can't remember its name. We used liquid nitrogen to get to this temperature.
Thanks for this video! I'm sure my students will love it! I plan on showing it in class tomorrow! You should do some of the others like EEG, CT, and PET scans!
I almost became an MRI repair tech after my service on a sub, but unfortunately I lost the job opportunity due to my not living in Hawaii (I had just moved from Hawaii to California). The technology is amazing and I enjoy studying it as a pastime interest.
+Physics Girl ...any chance of 3D printing an .stl from your fMRI scans---skull, brain stem, or something? Don't know why, but I think that would be really neat to do!
+Robert Durham Yeah, and the workflow is a little bit convoluted: the tutorials I've read use a program called 3DSlicer (others use FreeSurfer + MeshLab) to convert the fMRI files to a 3D model.
One thing you didn't discuss is that the energy from each radio pulse gets dumped as heat into the patient's body as the hydrogen nuclei relax. That's why you might feel warmth in your body as each slice is scanned. How much effect does this have on a living brain?
So I've had over a dozen MRI's now with mostly 1.5T machines, mostly of the brain, one previous of lumbar. I think I was in a 2 or 2.5T pancake once. I've never experienced or noticed a heating effect and never considered that it existed. I was in a 3T (Siemens) machine earlier this week for lumbar and HOLY COW did that surprise me very quickly once it got into the hard continuous sequences. I recognized the sudden growing heat in my pelvis and back immediately (raise hand, degree'd Engineer) and thoroughly enjoyed the pleasing deep tissue muscle relaxing warmth. The whole time I'm thinking "so this is what the burrito in the microwave feels like ". It's not the SAME effect, or the intended effect, but vibrating and rapidly re-orienting nuclei and molecules are going to dissipate some energy. I spoke of my surprise with the very cool and experienced tech and he chuckled about how alarming it is to folks sometimes, and that he was happy I ultimately found it pleasant.
@@DougKremer I find it gratifying that someone else can confirm the effect. Some while ago I was berated online by an MRI technician who more of less accused me of lying or stupidity as he claimed the heating effect just doesn't happen. Go figure.
The whole NMR field of research is an absolute blast for the mind. Medical imaging is just the tip of the iceberg, NMR can be used to acquire data on so many levels...
The relaxation of the hydrogen atom also releases a small amount of heat caused by Eddy currents, this heat can in theory build up to significant levels. As a student, I have been told by radiographers working in MRI that the weight of the patient is recorded as to prevent excessive heating.
IMO the animation at 2:28 is slightly misleading - the oscillation or precession would be centered around the mean position imposed by the primary magnet. Great video though!
Not using ionizing radiation makes rhem safer, but it also reduces rhe odds of a malfunction giving you super-powers. It's true. Cross-referencing MRI and super-powers in the medical literature came up blank.
I have had 10 MRI's in my life, and I'm only 16... I had one in like 3rd grade on my foot, then February 11, 2013, I had one on my brain. They found a tumor that was causing a ton of problems. Had surgery less than 12 hours later due to my condition. They said I was extremely lucky. Most people that were in the condition I was, usually start losing senses, having seizures, or going into a stroke. After that I have had 6 follow-up MRI's on the surgery, 1 on my wrist, and 1 I got 6 hours ago on my foot. MRI's are really cool. Scary at first but now I'm used to it and I don't worry about going in.
4:00 When I was working as a welder I had to have an MRI, but FIRST I had to have my eyes x-rayed. I was told that the MRI would cause metal particles to spin at tens of thousands of RPM. Scary.
in MRI there's a lot of teoretical math too, the inventors of MRI imaging are mathematicians, though. They got physical principles and based on that they created algorithms. And it's not true that 3T is most common MRI equipment (for FMRI yes, but for general scanning there are also 0.5T, 1T and, the most common, 1.5T systems). I'm service engineer of the MRI systems ;-)
My 5 month old daughter just had an FMRI, she has seizures and they were looking for anything not normal. Didn't find anything bad, but they said it is harder to scan young brains because they "are mostly water" as the doctor put it, I never heard that before. Anyway great video, keep them up!
2 hours just for the pictures? It's usually quicker. Did you do something more? When I spent 2 hours in an MRI we tried to measure glutamate in a region of the brain. I listened to music by Jean Michel Jarre, the machine became a sort of extra instrument in the music :-)
Glad to see years of schooling haven’t affected your posture negatively at all! Though I’m curious what’s going on with your medulla oblongata… did you move during the scan?
I get comments all the time from people who have physicsophobia about how thrilled they are with your videos. You do an excellent job of reducing their anxiety and sparking their excitement. Perhaps there should be an FMRI study of brain activity while watching your videos. :-) Seriously, that might actually teach us something about teaching physics.
+Amit H While I'm sure that PBS gets ad revenue, donations and grants keep the lights on. I doubt UA-cam ad revenue puts a dent into the production cost of any of their shows.
snika123 OK i do agree? But don't you get irritated if the title says something and you get is that video for ads??? Yes you can post ads in video but not show video in ads? Yes i love to make videos and surely will do in future. Just google ads is sufficeint for me not that video ads that appears in middle of kipkay videos .
So I've had over a dozen MRI's now with mostly 1.5T machines, mostly of the brain, one previous of lumbar. I think I was in a 2 or 2.5T pancake once. I've never experienced or noticed a heating effect and never considered that it existed. I was in a 3T (Siemens) machine earlier this week for lumbar and HOLY COW did that surprise me very quickly once it got into the hard continuous sequences. I recognized the sudden growing heat in my pelvis and back immediately (raise hand, degree'd Engineer) and thoroughly enjoyed the pleasing deep tissue muscle relaxing warmth. The whole time I'm thinking "so this is what the burrito in the microwave feels like ". It's not the SAME effect, or the intended effect, but vibrating and rapidly re-orienting nuclei and molecules are going to dissipate some energy. I spoke of my surprise with the very cool and experienced tech and he chuckled about how alarming it is to folks sometimes, and that he was happy I ultimately found it pleasant.
How not to get shocked ?... We feel shock because of high current that flows from our body to the "ground". Hence discharge yourself slowly through a 100 ohm resistor. Hold one end of resistor in your hand and touch other end to car/some large metallic object. IMO, this should work. I have not tried it though. You will have to hold the resistor for few seconds for all the charge in your body to drain.
Key word in your statement is “studies.” “No STUDIES have found any adverse effects from MRIs. But there actually have been adverse effects after patients had MRIs. There just hasn’t been any funding to make a study attractive to scientists.
I check everyday for your video.. And I love the way you explain things.. Its because of you, I got interest in physics so now I check with other physics related youtube channels also, but you are my no1 favorite...
MRI can cause tissue heating. There are limits of how many Watts/kg are allowed over a certain time period, based on the body being imaged. For the brain, the FDA sets the limit at 3.2 watts/kg per 10 minutes.
It works exactly off the same concept that Nuclear Magnetic Resonance Spectroscopy. (It was built from the same technology) that organic chemistry uses to determine what the structure of organic molecules are.
I've been in a 9T fMRI machine. It's a unique experience. Another thing to watch out for are body piercings, steel toed shoes, belts.... People forget how much metal they might have on or around them.
+wordsnwood Only loose magnetic items are dangerous. The danger comes from them flying around at high speeds. I've been in an MRI, and I have a ring that I can't remove, but for exactly that reason it was safe. Funny thing was I couple feel the ring moving with the pulses. Belts and such are usually safe. Like they don't tell you to remove the rivets from your jeans. But NOBODY want's their piercings ripped out!
People with tattoos are at risk when in a MRI machine. The worst case being a patient receiving second-degree burns on and around his or her tattoo(s).
+Joshua Guillemette That is from the radio frequency or gradients. The ink used in the tattoo was probably conductive and was heated up like an induction stove.
That relaxation time explanation is pretty wrong, and gives no help understanding how the machine picks up the signals from the hydrogen reacting to pulses in a magnetic field. Hint: It is all about precession (that wobble, when a coin spins down to lying flat on a table). This process emits radio waves that can be picked up by the antenna array, around the inside of the hole in the magnet. The chemical bonds, around the hydrogen atoms, vary the wobble down frequency. Hydrogen in water produces a different wobble down frequency than hydrogen in a protein.
The relaxation time explanation is correct (admittedly very abbreviated). Differences in relaxation times between tissues are the source of contrast for the most common types of images in MRI. The chemical shift effect you describe is separate, although precession is important for both. MRIs basically turn your hydrogens into wobbling tops
+Joshua Walters Not necessarily. It might but it really depends. The buttons and zippers on jeans are fine, I have a permanent retainer on my bottom front teeth and I don't feel a pull when I have MRI's. There's a chance but you have to fill out something before listing things to see if you're okay to have one.
I am a MRI technican for GE AND everything you stated is entirely true. I've had my credit card wiped before when I was performing tests on a ramped up (active) MRI.
Awesome timing, had one of these yesterday (precautionary). I rather enjoyed the process, though the various sounds and their levels caught me off guard! I expected it to have some form of 360 degrees of rotation behind the tube, making it more or less silent.
Yeah! They can definitely save lives, but they definitely take a long time, and can be quite noisy! I used to have MRI scans regularly to monitor my Chiari Malformation, and, up until the invention of non-metallic headphones, I had to be sedated because I couldn't stand the noise long enough to sit still for the duration of the scan, even with earplugs.
You know the real name for MRI is actually NMR. NMR stands for "nuclear magnetic resonance" or you may have also been told about H-NMR or Proton NMR which is a spectroscopic technique which takes advantage of a nucleus with an odd spin and determines it's spin in a magnetic field. The shielded or deshielded electrons will play a huge role in the identification of an unknown organic compound. The reason they called it MRI "magnetic resonance imaging" is because the public gets scared of the word "nuclear."
You are a legend! The way you explain stuff with your sweet voice is just awesome! Thank you for answering so many burning questions i always had in my mind.
It works the same way your eye sight works and that appears to be safe. There is a magnetic field of photons at equilibrium all around us and the sun stimulates the magnetic field around us with photons. Our eye sight seems to work well and safe. Same technology in an MRI we set up strong magnetic field and stimulate a cross section with photons and get a transverse wave from the field. Very nice image. Multiple cross-sections and get a 3D image.
hi, it's a really great video. But you could talk about dehydration and burning effect when using MRI too! These could happen on high tesla MRIs (1.5T and above) although it doesnt really matter on low Tesla ones (0.2 - 0.5 T)
There’s no such thing as fMRI machine. It is the same MR scanner. Functional MRI is using a different sequence design called echo planar imaging that allows faster acquisition so that we could see the brain’s reaction to functional tasks (BOLD signals)
Two questions: How does the hydrogen proton alignment work? Do hydrogen atoms in all molecules (polar and nonpolar) and compounds align with the field, or is it just mobile H+ ions? If it's in a molecule, does it break off in order to align, or does the whole molecule align? Also, are MRI and FMRI both the tube shaped apparatus? Can one machine have both features?
Thank you physics girl I was told to get an MRI but I was scared about it because I didn’t know what it was and whether it was safe or not I’m glad I won’t be harmed as long is there is no iron or some similar stuff on me
The thing about studies is they are only good until the next one comes out. I have had a few MRI's because they were needed and would not hesitate to get another one(barring copays).
So jealous! I've always wanted time on an clinical MRI to image fruit and also get a good dataset of my own head. I love NMR in general, I've been collecting the bits to build a basic non-imaging 300 mT one for a while. So far I've only got FID out of a test tube of water with a crappy lash-up. One day I will finish it, then maybe build an earth-field imaging one.
I really should get an FMRI some day. I have had an EEG, but never an FMRI. I suffered some minor brain damage when I was very young due to a lack of blood flow. It happened when I was so young though that my brain simply developed differently, bypassing if you will the damage. Though it gives me some minor quarks, for the most part I am nearly unaffected. I would find it interesting to see what parts of my brain do what as I know it will not be totally normal.
I think the MRI is strong enough to move around most common metals, not just ferrous ones. I know it would "grab" stainless steel shards, I can do that with a rare earth magnet. Not sure about aluminium...
When MRI was first invented, it was initially called "Nuclear Resonance Imaging." However, no one wanted to use it because everyone was afraid of the word "Nuclear" in the title. Therefore, it was renamed "Magnetic Resonance Imaging", and even though the nothing about the underlying technology had changed, everyone now felt that it was safe to use.
+Physics Videos by Eugene Khutoryansky Nice :) Waiting for your videos as well :)
It's called Nuclear Magnetic Resonance Imaging, actually.
+IamGrimalkin, some people call it Nuclear Magnetic Resonance Imaging (and I have called it that too in the past), but the word "nuclear" is usually left out, because this word makes people think that there is nuclear radiation involved, even though there is not.
+Physics Videos by Eugene Khutoryansky
Of course MRI is a further development of NMR, but used for imaging, so calling it NMRI isn't much of a stretch, though it should really have a much more creative acronym.
+Physics Videos by Eugene Khutoryansky Just tell them it might give them super powers and they will be lining up to get an MRI.
Great video Dianna. I learned a lot
Thanks for filming you helpful, talented man!
Here's the real hero
I worked in a medical center and during construction and installation, an MRI was turned on before anyone checked for nearby metal. A minute later an acetylene tank in the next room came crashing through the wall and hit the MRI so hard it left a dent.
omg, that mustve been scary
That’s awesome! Reminds me of x men
Every MRI centre I've used has a collection of nasty things that happen if you aren't careful. My main place has a picture of a bicycle stuck on the machine. They swear it didn't happen in their machine....
Hi ! I'm a 9 year-old girl. I love watching your videos to learn physics! You talked about possible dangers of bringing metal objects in the MRI room but didn't really talk about how MRI scans may impact your brain functions. Is it really safe to have brain MRI?
Hi Maya, this comment is 5 years old so likely you will not read this, but for those who are, brain MRIs are completely safe. MRI does not use any ionizing radiation (like x-rays or CT scans) therefore there is no risk of cancer from repeated scans. All an MRI does is apply several magnetic fields to generate a series of responses that formulate an image. The only risk from the magnetic fields is something called peripheral nerve stimulation, which is a tingling sensation felt when the imaging magnetic field switches on and off very fast (unlikely to happen in a clinical setting).
MRI scans are not recommended for those with pacemakers as the electromagnetic signals may interfere with its functions. You can even get an MRI if you have a titanium or non-magnetic implant!
Source: I am a physicist that researches MRI methodologies :)
@@layalebazzi1244 Thanks
@@layalebazzi1244 Thank You ma'am.. I was correct when I was against about the risk of getting cancer through MRI my teacher said MRI causes cancer you shouldn't do a MRI. I researched and finally I found myself correct. Everybody in my class judged me for knowing nothing and spitting shits of zero knowledge that appears to be true. Aaha... Finally I cam prove that teacher now wrong! Thank you!
@@layalebazzi1244 so can you describe the differences btw MRI scan & MRI SPECTROMETRY ??
@@layalebazzi1244 Im not sure what metal clips my dr used for gallbladder surgery and his notes do not state what kind were used years ago.
This is great... I spent 3500 for an MRI scan and you get to run a bunch of fruit through it for free. Wonderful.
andrew balliet 😔
Pierre-James Murphy dumbass no one cares about you being in Canada.
Yep had one this morning for free - In Canada.
I paid a whopping....... 4€
Did you have insurance?
MRI machines do transfer energy to the tissues of your body, which results in a very mild heating effect. During the only MRI I have had, I found myself getting warm, which was easily remedied by the operator increasing the speed of the fan blowing on me.
I thouht I was just imagining the heat
If you think about, you're sitting inside a microwave oven.
Nicole K
ya I guess you just might feel the heat after an hour of being in there
Nicole K me to my head got hot in the being of it
Nicole K yeah but the waves are weaker than microwaves. The waves in a mri have the same frequency as a radiowave
Dear PhysicsGirl,
What effect do MRI's have on naturally occurring ferrous metals in the body? In particular, I'm thinking of the iron our body uses in red blood cells.
Thanks for yet another awesome video!
Iron in our body is not present in free form... It's part of haemoglobin... Thus it doesn't get effected by magnets at all
To flip the question around: what effect does hemoglobin or hemosiderin have on MR images? It can actually cause measurable susceptibility distortions! Lookup SWI, which can be used to detect microbleeds
MRI are way too expensive, I now use the microwave.
Bahahaha! Nice one! 😂😂😂
Is it? I'm having one today and they're charging me $30. But then I live in Norway, so I guess that is a factor.
Just had one this morning in Canada - Free - I even got a lollypop.
Correct sir there's a lot of Riff Raff going on in the medical system that you end up finding out the hard way when you're sick
At $8500 for an MRI session, even after the insurance discount, you can buy a lot of microwaves. Remember, never get sick.
I've had 3 MRI techs refuse to run me through their machines when they find out I have titanium aneurysm clips around my cortex. I've heard my doctor practically yelling at them that titanium isn't ferrous, but the techs all said that doesn't mean they might not heat up or shift in such a strong magnetic field.
After talking to the last tech, I've opted out of having further MRI's after having the clips because the risk isn't really worth it.
Anyway, thanks for the video! That chair pulling at over 2,000lbs of force was amazing.
The danger of titanium clips is from them heating up from the RF fields produced by transmit coils (not from the magnetic field as titanium is not magnetic like iron, cobolt, or nickel for example). The brain can actually withstand more RF heating in general than other parts of the body because it has so much blood flow (liquid cooling), but something metal could still result in excess localized heat and the consequences in the brain are much higher.
You could look into:
blast welding which is pretty cool, you basicly weld 2 pieces of metal together with an explosion.
Fusion reactors.
Thorium / molten salt reactors.
The natural nuclear reactor that was running a few thousand years ago, aka a fission reactor that arose naturally. (Oklo / Gabon)
Burning coal mines.
The ongoing fission in the earths core.
How the different types of nuclear weapons work.
A few tips for your channel if you are interested, might take some travelling to get to make a video of, but most can be done through animations, this is at least some things i am interested in and if something peaks your interest look it up.
+Daniel Lassander you seem like a pyromaniac.
+Supreet Sahu Us pyromaniacs are many. :)
Supreet Sahu
I just want to see the world burn! :P
+Daniel Lassander Ooh. I'd watch those!
I'm a brain cancer patient, and I get regular MRIs, to check on my head, and see for potential recurrence. Knowing more about MRI helps me understand more about the scans that I have done that are so important to my survival now. Thanks for making this video, Dianna, and PBS for supporting it.
How are you now?
Stopping by to see your old videos at the time you are struggling with post covid syndrome. Thank you for the body of your work. Best wishes!
Seen MRI machines all the time but had no idea on how it works & precautions before entering it. Interesting stuff :)
It is strong enough to realign Hydrogen atoms but how come they do not affect Iron in our blood?
Monjur Hassan iron in blood is non magnetic, Branic 75 has shown it on his video.
Wan HL its magnetic if you get it from
Most any iron fortified breakfast cereal or similar processed fake food product
Coz ferrous oxide (feO²) is dimagnetic
I imagine they keep the field always active because the cool-down cycle prior to startup for the superconductors would be pretty long. To be superconducting, they need to be kept at liquid helium temperatures, which just is a few degrees above absolute zero.
+BlackEpyon It's super expensive to quench the magnet, then cool it back down. That's the real reason. Hence why you can do it in emergencies, but it's never done otherwise.
tobywilson
Not really. Just cut the power to the cooling pump, and it will eventually return to room temperature. It's the cool-down cycle that makes it impractical.
+BlackEpyon I think maybe you didn't understand what I wrote properly, or I didn't write it well...
The magnet is a superconductor, it's super cold. Turning it off heats it back to room temperature. Getting all the supercooled helium you need to re-cool the magnet back down from room temperature is super expensive. You're right it also takes a lot of time too though.
tobywilson
I understand what the superconducting part means. I don't have a schematic to see if they have a large drain tank or it the system maintains it's pressure like an AC unit. If it has a tank, then deactivating the pump will allow the system to equalize and heat up. Obviously you don't just let the helium vent into the air. If it doesn't have a tank, then obviously you would need to have the service technician come in to drain it. The electromagnet will retain it's saturation for a long time as long as it's kept cryogenic.
+BlackEpyon Some superconducters become superconducters at about -200°C (70°K). I've studied one a few weeks ago using a SQUID but can't remember its name. We used liquid nitrogen to get to this temperature.
Thanks for this video! I'm sure my students will love it! I plan on showing it in class tomorrow! You should do some of the others like EEG, CT, and PET scans!
Wasn’t there issues with the contrast dye being used with certain scans?
Yeah pretty odd for contrast not being brought up once in a video about the safety of MRIs
Can you do a video on ionising vs non-ionising radiation? :)
I almost became an MRI repair tech after my service on a sub, but unfortunately I lost the job opportunity due to my not living in Hawaii (I had just moved from Hawaii to California). The technology is amazing and I enjoy studying it as a pastime interest.
This is something that students find really hard to understand, very nicely explained
I have epipelsy and I have had so many MRIs I can not count them all. great video.
I really like to learn with you!
+mahina1963 I love sharing the science!
Nuclear energy video?
+Physics Girl ...any chance of 3D printing an .stl from your fMRI scans---skull, brain stem, or something? Don't know why, but I think that would be really neat to do!
+Tristan Morrow I'm no expert on mri but doesn't it just take a series of 2d images? To generate a .stl you would need a 3D model.
+Robert Durham Yeah, and the workflow is a little bit convoluted: the tutorials I've read use a program called 3DSlicer (others use FreeSurfer + MeshLab) to convert the fMRI files to a 3D model.
One thing you didn't discuss is that the energy from each radio pulse gets dumped as heat into the patient's body as the hydrogen nuclei relax. That's why you might feel warmth in your body as each slice is scanned. How much effect does this have on a living brain?
They likely either have no idea, and if they do, it’s probably better that we don’t know. Don’t take the red pill!
@@OfftoShambala good question and response..
Patty Goddard lol, thanks patty
So I've had over a dozen MRI's now with mostly 1.5T machines, mostly of the brain, one previous of lumbar. I think I was in a 2 or 2.5T pancake once. I've never experienced or noticed a heating effect and never considered that it existed. I was in a 3T (Siemens) machine earlier this week for lumbar and HOLY COW did that surprise me very quickly once it got into the hard continuous sequences. I recognized the sudden growing heat in my pelvis and back immediately (raise hand, degree'd Engineer) and thoroughly enjoyed the pleasing deep tissue muscle relaxing warmth. The whole time I'm thinking "so this is what the burrito in the microwave feels like ". It's not the SAME effect, or the intended effect, but vibrating and rapidly re-orienting nuclei and molecules are going to dissipate some energy. I spoke of my surprise with the very cool and experienced tech and he chuckled about how alarming it is to folks sometimes, and that he was happy I ultimately found it pleasant.
@@DougKremer I find it gratifying that someone else can confirm the effect. Some while ago I was berated online by an MRI technician who more of less accused me of lying or stupidity as he claimed the heating effect just doesn't happen. Go figure.
Thanks for the explanation. This was way more better than what I learned in school. Now I can easily explain to my patients
The whole NMR field of research is an absolute blast for the mind. Medical imaging is just the tip of the iceberg, NMR can be used to acquire data on so many levels...
I really like this... but I can't subscribe a second time
The relaxation of the hydrogen atom also releases a small amount of heat caused by Eddy currents, this heat can in theory build up to significant levels. As a student, I have been told by radiographers working in MRI that the weight of the patient is recorded as to prevent excessive heating.
Thanks Dianna.
IMO the animation at 2:28 is slightly misleading - the oscillation or precession would be centered around the mean position imposed by the primary magnet. Great video though!
Not using ionizing radiation makes rhem safer, but it also reduces rhe odds of a malfunction giving you super-powers.
It's true. Cross-referencing MRI and super-powers in the medical literature came up blank.
I have had 10 MRI's in my life, and I'm only 16... I had one in like 3rd grade on my foot, then February 11, 2013, I had one on my brain. They found a tumor that was causing a ton of problems. Had surgery less than 12 hours later due to my condition. They said I was extremely lucky. Most people that were in the condition I was, usually start losing senses, having seizures, or going into a stroke. After that I have had 6 follow-up MRI's on the surgery, 1 on my wrist, and 1 I got 6 hours ago on my foot. MRI's are really cool. Scary at first but now I'm used to it and I don't worry about going in.
4:00 When I was working as a welder I had to have an MRI, but FIRST I had to have my eyes x-rayed. I was told that the MRI would cause metal particles to spin at tens of thousands of RPM. Scary.
Wow... so all kinds of metals? Surely not the aluminum in the brain from all the vaccines, right?
Your channel has grown so much in the last few years! Holy moly! Congrats
Since the magnetic field of the earth is weakening shall we build two powerful mris on the north and south ball respectively?
no cause they dont have the range
ItsErikz r/woooosh
I was literally looking up how an MRI works last week. this video was much simpler :)
in MRI there's a lot of teoretical math too, the inventors of MRI imaging are mathematicians, though. They got physical principles and based on that they created algorithms. And it's not true that 3T is most common MRI equipment (for FMRI yes, but for general scanning there are also 0.5T, 1T and, the most common, 1.5T systems). I'm service engineer of the MRI systems ;-)
The ultimate insight into The Physics Girl!!
My 5 month old daughter just had an FMRI, she has seizures and they were looking for anything not normal. Didn't find anything bad, but they said it is harder to scan young brains because they "are mostly water" as the doctor put it, I never heard that before. Anyway great video, keep them up!
another amazing video, good going
See these pictures, they are all pictures of me, I was young and I needed the work. :P
Haha! You called it. I had to lie still for 2 hrs without moving my head in an incredibly loud machine!
2 hours just for the pictures? It's usually quicker. Did you do something more? When I spent 2 hours in an MRI we tried to measure glutamate in a region of the brain. I listened to music by Jean Michel Jarre, the machine became a sort of extra instrument in the music :-)
Your videos are getting better and better.
Keep up the good work!
Glad to see years of schooling haven’t affected your posture negatively at all! Though I’m curious what’s going on with your medulla oblongata… did you move during the scan?
I get comments all the time from people who have physicsophobia about how thrilled they are with your videos. You do an excellent job of reducing their anxiety and sparking their excitement. Perhaps there should be an FMRI study of brain activity while watching your videos. :-) Seriously, that might actually teach us something about teaching physics.
tomorrow is my first time fmri scan! i'm volunteering for a research at my faculty! i'm quick nervous and safety concern :D
No ads on this video?
+Amit H Everyone is not like kipkay , vertatism etc.
+Shirshak Bajgain Wow! I actually turn off adblock when i watch videos of my favorite channels. Thats how noticed :)
+Amit H While I'm sure that PBS gets ad revenue, donations and grants keep the lights on. I doubt UA-cam ad revenue puts a dent into the production cost of any of their shows.
+Shirshak Bajgain you try making videos out of ur time. they wouldnt be able to do it if it wasnt for the ads...
snika123 OK i do agree? But don't you get irritated if the title says something and you get is that video for ads??? Yes you can post ads in video but not show video in ads? Yes i love to make videos and surely will do in future. Just google ads is sufficeint for me not that video ads that appears in middle of kipkay videos .
So I've had over a dozen MRI's now with mostly 1.5T machines, mostly of the brain, one previous of lumbar. I think I was in a 2 or 2.5T pancake once. I've never experienced or noticed a heating effect and never considered that it existed. I was in a 3T (Siemens) machine earlier this week for lumbar and HOLY COW did that surprise me very quickly once it got into the hard continuous sequences. I recognized the sudden growing heat in my pelvis and back immediately (raise hand, degree'd Engineer) and thoroughly enjoyed the pleasing deep tissue muscle relaxing warmth. The whole time I'm thinking "so this is what the burrito in the microwave feels like ". It's not the SAME effect, or the intended effect, but vibrating and rapidly re-orienting nuclei and molecules are going to dissipate some energy. I spoke of my surprise with the very cool and experienced tech and he chuckled about how alarming it is to folks sometimes, and that he was happy I ultimately found it pleasant.
I would request you do an explanation of the invention of the different machines. It is really interesting how they all came to be.
How not to get shocked ?... We feel shock because of high current that flows from our body to the "ground". Hence discharge yourself slowly through a 100 ohm resistor. Hold one end of resistor in your hand and touch other end to car/some large metallic object. IMO, this should work. I have not tried it though. You will have to hold the resistor for few seconds for all the charge in your body to drain.
Glad you did this video! I just had my first MRI a week ago and was curious about how it worked and if there were any dangers.
4:10 That goes for tattoos as well if the inc contains metal. Something to be careful with when considering a tattoo.
House? :D
No, I have just been in and around MRI and NMR a bit.
www.ncbi.nlm.nih.gov/pmc/articles/PMC3445217/
1:05
Oooooooooh!!!!! Who lives in a pineapple in an mri machine?
Spongebob Medical Pants!
Key word in your statement is “studies.” “No STUDIES have found any adverse effects from MRIs. But there actually have been adverse effects after patients had MRIs. There just hasn’t been any funding to make a study attractive to scientists.
I am having a stomach MRI on Friday. A brain one in January. And a chest CT at 12th December.
Too much examinations.
Nice vid btw :) I just hate MRI.
+VickeyHungary get well soon
+Vishnu Ramachandran you are so sweet! Thank you :)
+VickeyHungary I wish you a fast recovery!
+Beskhuepnm Thank you so-so much. 💙
I check everyday for your video.. And I love the way you explain things.. Its because of you, I got interest in physics so now I check with other physics related youtube channels also, but you are my no1 favorite...
As always, thanks for your awesomeness :D
MRI can cause tissue heating. There are limits of how many Watts/kg are allowed over a certain time period, based on the body being imaged. For the brain, the FDA sets the limit at 3.2 watts/kg per 10 minutes.
It works exactly off the same concept that Nuclear Magnetic Resonance Spectroscopy. (It was built from the same technology) that organic chemistry uses to determine what the structure of organic molecules are.
I've been in a 9T fMRI machine. It's a unique experience.
Another thing to watch out for are body piercings, steel toed shoes, belts.... People forget how much metal they might have on or around them.
+wordsnwood Only loose magnetic items are dangerous. The danger comes from them flying around at high speeds.
I've been in an MRI, and I have a ring that I can't remove, but for exactly that reason it was safe. Funny thing was I couple feel the ring moving with the pulses.
Belts and such are usually safe. Like they don't tell you to remove the rivets from your jeans.
But NOBODY want's their piercings ripped out!
People with tattoos are at risk when in a MRI machine. The worst case being a patient receiving second-degree burns on and around his or her tattoo(s).
+Joshua Guillemette That is from the radio frequency or gradients. The ink used in the tattoo was probably conductive and was heated up like an induction stove.
That relaxation time explanation is pretty wrong, and gives no help understanding how the machine picks up the signals from the hydrogen reacting to pulses in a magnetic field. Hint: It is all about precession (that wobble, when a coin spins down to lying flat on a table). This process emits radio waves that can be picked up by the antenna array, around the inside of the hole in the magnet. The chemical bonds, around the hydrogen atoms, vary the wobble down frequency. Hydrogen in water produces a different wobble down frequency than hydrogen in a protein.
The relaxation time explanation is correct (admittedly very abbreviated). Differences in relaxation times between tissues are the source of contrast for the most common types of images in MRI. The chemical shift effect you describe is separate, although precession is important for both. MRIs basically turn your hydrogens into wobbling tops
I can imagine your channel in a year having at least 500k subscribers.. Fun and educational videos!
So what's the difference between an MRI and an NMR machine used in organic chemistry?
Cool video, but didn't see what type of dye you got and the pros/ cons
Awesome sounds good 😅 I’m in an neuro ward right now and wondering if I should Gould suggest having an MRI
You are doing great job. Appreciate it.
I have Titanium dental implants. Would those become affected if I stuck my head in one of those?
+Joshua Walters Not necessarily. It might but it really depends. The buttons and zippers on jeans are fine, I have a permanent retainer on my bottom front teeth and I don't feel a pull when I have MRI's. There's a chance but you have to fill out something before listing things to see if you're okay to have one.
titanium is a non ferrus material so you should be safe. If you happens to have screws holding it in place then those might be affected.
Good to know, I have some screws that go into the Titanium posts that hold my crowns but I think those are titanium as well.
I have titanium brackets in my jaws and get MRIs annually (of my head). I'm sure that position matters but in my case it's not a problem.
+Thomas Maufer I think the only issue there must be shadows cast by your titanium pieces. Which is pretty cool.
I am a MRI technican for GE AND everything you stated is entirely true. I've had my credit card wiped before when I was performing tests on a ramped up (active) MRI.
Awesome timing, had one of these yesterday (precautionary). I rather enjoyed the process, though the various sounds and their levels caught me off guard! I expected it to have some form of 360 degrees of rotation behind the tube, making it more or less silent.
I didn't realize it was just a magnet, good video!
Yeah! They can definitely save lives, but they definitely take a long time, and can be quite noisy! I used to have MRI scans regularly to monitor my Chiari Malformation, and, up until the invention of non-metallic headphones, I had to be sedated because I couldn't stand the noise long enough to sit still for the duration of the scan, even with earplugs.
@@cellogirl11rw55, I fall asleep in them.
Your beauty makes you pretty,
your intellect makes you stunning...
You da best. Bridging dis knowledge to my brain. Uhhh too tired to say something linking that to the videoooo..... Nice vid yo.
Your channel is awesome,you deserve much more attention.
Great video... Love the tan.. did you pick that up in Uruguay?
Rob
+Rob Tesar Quite possibly, though I do live in San Diego. It's hard to avoid the sun here.
+Physics Girl thanks for doing this episode. I've worked with MRIs for quite a while and think of them as a very underrated modern marvel.
You know the real name for MRI is actually NMR. NMR stands for "nuclear magnetic resonance" or you may have also been told about H-NMR or Proton NMR which is a spectroscopic technique which takes advantage of a nucleus with an odd spin and determines it's spin in a magnetic field. The shielded or deshielded electrons will play a huge role in the identification of an unknown organic compound. The reason they called it MRI "magnetic resonance imaging" is because the public gets scared of the word "nuclear."
I had a MRI scan in 2010 when i was beaten up,BUT i enjoyed it because of my love for physics. it went like tak tak tak tak
Very understandable and informative. You have a new sub. Thank you!
Another great vid, keep it up!
You are a legend! The way you explain stuff with your sweet voice is just awesome! Thank you for answering so many burning questions i always had in my mind.
Thanks Physics Girl, very interesting video
you can make a video of "string theory vs loop quantum gravity", it will be fun
This earned my subscription
It works the same way your eye sight works and that appears to be safe. There is a magnetic field of photons at equilibrium all around us and the sun stimulates the magnetic field around us with photons. Our eye sight seems to work well and safe. Same technology in an MRI we set up strong magnetic field and stimulate a cross section with photons and get a transverse wave from the field. Very nice image. Multiple cross-sections and get a 3D image.
Thanks for the effort
hi, it's a really great video. But you could talk about dehydration and burning effect when using MRI too! These could happen on high tesla MRIs (1.5T and above) although it doesnt really matter on low Tesla ones (0.2 - 0.5 T)
Thanks For Sharing
There’s no such thing as fMRI machine. It is the same MR scanner. Functional MRI is using a different sequence design called echo planar imaging that allows faster acquisition so that we could see the brain’s reaction to functional tasks (BOLD signals)
I like this informative channel
Two questions: How does the hydrogen proton alignment work? Do hydrogen atoms in all molecules (polar and nonpolar) and compounds align with the field, or is it just mobile H+ ions? If it's in a molecule, does it break off in order to align, or does the whole molecule align? Also, are MRI and FMRI both the tube shaped apparatus? Can one machine have both features?
Thank you physics girl
I was told to get an MRI but I was scared about it because I didn’t know what it was and whether it was safe or not
I’m glad I won’t be harmed as long is there is no iron or some similar stuff on me
The thing about studies is they are only good until the next one comes out. I have had a few MRI's because they were needed and would not hesitate to get another one(barring copays).
the mri is safe but the gadolinium in the contrast can be dangerous
I remember learning about NMR when I was taking organic chemistry as a sophomore in college.
If the magnetic field is that strong can it influence the blood flow as blood contains iron molecules in haemoglobin? can it cause hemorrhage?
Really cool video!
liked the doc's T-shirt.... she sure is a metalhead... 🤘
So jealous! I've always wanted time on an clinical MRI to image fruit and also get a good dataset of my own head.
I love NMR in general, I've been collecting the bits to build a basic non-imaging 300 mT one for a while. So far I've only got FID out of a test tube of water with a crappy lash-up. One day I will finish it, then maybe build an earth-field imaging one.
Thanks, this helped me a lot!
Watching you smiling, enjoying and getting excited about physics at 6 am, what a great way to start my day. Thank You :)
Wow! I love the work you do!! I really like this channel and the content you provide :)
I really should get an FMRI some day. I have had an EEG, but never an FMRI. I suffered some minor brain damage when I was very young due to a lack of blood flow. It happened when I was so young though that my brain simply developed differently, bypassing if you will the damage. Though it gives me some minor quarks, for the most part I am nearly unaffected. I would find it interesting to see what parts of my brain do what as I know it will not be totally normal.
I think the MRI is strong enough to move around most common metals, not just ferrous ones.
I know it would "grab" stainless steel shards, I can do that with a rare earth magnet. Not sure about aluminium...