Thanks and welcome to the channel! So happy to see the videos helping and getting people excited to learn MRI physics, the next video will be dropping in a few days so stay tuned!
As an MRI Field Service Engineer, it is my job to ensure that all the intricate MRI Physics are functioning properly every day. I'm grateful for the "MRI Physics EXPLAINED" channel on RU-vid, now I can direct people with questions to this resource. Your efforts are much appreciated, please continue to create valuable content.
Thank you for the comment and for keeping these amazing machines running! We've got a whole set of advanced lectures coming that will get into some engineering topics so stayed tuned!
Fantastic content. Thank you for including visuals aids and a dark backdrop that's easy on the eyes. I'm heading into school for MRI this fall and this is a valuable resource. 🍻
Okay...so I'm currently cross training in MR and my company is structuring a track based on my experience for future employees also wanting to cross train. I'm using the ASRT modules for my required structured education hours and I can not tell you how glad I am to have stumbled upon these videos. They're great. I'm going to recommend that we add them to the other supplemental materials. Thank you for doing this!
Doesn't the precession happen as soon as the protons enter the magnetic field? A combination of the field b0 and the spin angular momentum of the protons cause them to precess. The RF pulse just tips the alignment of that precession and causes phase coherence. In other words how would the lamor frequency work if the protons did not already precess at that frequency?
These are good questions, and as always with MRI physics there are layers of ever finer details you will find the more specific you try to understand it. When we talk about precession in MRI physics, what we're really referring to is the precession of the net magnetic vector. Yes, the individual protons precess about their axis when put into a magnetic field. You don't even need an MRI machine, we're in a magnetic field right now on Earth. But does this generate signal in our MRI machine? So we need to get these individual precessing protons aligned, and with enough energy from our magnetic field, we can cause more to align with the field than the random orientations caused by the background kinetic energy. This is what builds our net magnetic vector, and it doesn't necessarily mean all the individual protons are in phase with each other, but there is a net magnetic vector due to their alignment. The RF pulse then tips all of these aligned protons off the B0 axis, and they precess together at the larmor frequency, generating our signal. It is the dephasing of the orientation that causes our signal loss. Check out this article for more information: www.mriquestions.com/how-does-b1-tip-m.html
Thanks for this amazing set of lectures; Question... in the Noa image when the hand pokes the vectors I understand in whats its said that only after the poking of the protons start to precess, or that move already exist before the stimulation?
Hello, thanks for commenting and great question! While the individual protons will have some baseline spin like all atoms and particles, they are not precessing all together as one. We need to impart them with some angular energy with our RF pulse to get them precessing as one unit together. Hope this helps!
Bump! Ouch! I've just arrived from Reddit! I'm so delighted to have found you, I'm brushing up on the subject before I start my new job after many years away. Thanks for being here 😊
I always been weak in physics and after taking ur lecture.. involutarily i just said waaaooo! Bcz i m amazed that this complex topic can be so simple ...hats off for ur teaching!
Local AM radio stations operate between 540 and 1700 kHz, not 68 MHz. FM radio stations operate between 88 and 108 MHz which is slightly higher than your example of a 1.5T magnetic field.
Thanks for the comment. This (should have been) already corrected with a caption that pops up during this segment saying the band is analog TV and into the FM range.
Hello, I think the term "spin" is one that's commonly used in MRI physics but can have multiple meanings so can be quite confusing. Every particle (protons in our case) have a quantum spin at rest (spin up or spin down). But the spins are randomly aligned in space. When we stick them in a magnetic field, we get a few of these to align along the magnetic field, but they aren't precessing. It is the RF pulse that makes these protons ("spins") precess in concert together about the Z-axis (confusingly also sometimes referred to as "spinning" about the Z-axis). We go into a little more depth into the equation that governs this alignment in the following episode: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-wDimnC2EWa8.html. Hope this helps.
I appreciate this so so much! Thank you for breaking down this very complex topic and explaining it in a simple and easily understood manner. Please keep the videos coming!
Hi! I am interested in getting into the radiology field, most especially MRI. Do most of the physics that they teach you in school apply to what you actually do in the MRI field or you just have to know the basics and use common sense?
Hello and congratulations on your interest in radiology, it's a great field to be in! By radiology field do you mean as a technician acquiring the exams, or as a radiologist reading them? Either way, both will have standardized exams that include some base knowledge of MRI physics. Unfortunately, this is typically in the form of random facts you'll need to memorize and which aren't very useful in actually understanding the physics, one of the reasons I made these videos. But in reality, only the engineers designing the machines will need to fully understand the physics and work with them on a daily basis. The rest of us are more users of the machine. Think about your car, a team of people behind the scenes did all the math, designing and testing to produce the car you drive, and you as the driver are the one working the controls to move and navigate the car. You really don't need to understand how the machine was engineered, just how to operate it. Radiologists and especially MRI technologists are the drivers of the MRI machine, working the controls to make sure the images are useful by understanding how changing parameters within the machine affect it's performance. If this sounds fun to you then definitely try to shadow a technologist or radiologist. If you would like to be a designer of the machine and live with the physics everyday, I would suggest studying engineering and look at jobs for companies that produce the machines such as Siemens or General Electric!
@@MRIPhysicsEXPLAINED Wow, thank you so much for that thorough explanation. I am gearing towards being an MRI technologist, and just the thought of seeing how the results come out has always been fascinating. Thank you and more blessings to you!
ERROR at 10:08. It is not AM radio at this frequency. AM radio band stops at about 1.5 Mhz. 68Mhz is in the VHF range (30 to 300Mhz). The radio frequency spectrum was set by ITU at the dawn of (broadcasting) time.
