T2 Relaxation, Spin-spin Relaxation, Free Induction Decay, Transverse Decay

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T2 Relaxation, Spin-spin Relaxation, Free Induction Decay, Transverse Decay | MRI Physics Course #4

Рет қаралды 46,675

Radiology Tutorials

Күн бұрын

Пікірлер: 73

@davidbeacham4865 11 ай бұрын

Nobel prize award winner. You have my vote!!

@radiologytutorials 11 ай бұрын

Haha 🤣 Appreciate it!

@mullvinayak 6 ай бұрын

binge watching these like a netflix series lol. Really great work, Dr. Nel. Thanks a lot for making these videos.

@eucalyptuszigzag484 2 ай бұрын

Started MRI program and have been struggling to understand the textbook physics until came upon your videos. Now I get it! Thank you so much for your teaching method, it works!

@thetitansfan02 9 ай бұрын

This whole playlist has been AMAZING!!! Each one covers the given topic better than any other videos I've seen AND does it in half the time. You are the best :)

@radiologytutorials 9 ай бұрын

Wow, thank you! That means a lot 😊

@hadiakhan51 11 ай бұрын

Amazing work , you have made MRI physics possible to me . Thank you

@radiologytutorials 10 ай бұрын

I'm so glad 🙌. Thanks for your support!

@yasmintan5522 11 ай бұрын

you saved my life! now i understand it all so much better :) keep on enlightening us with your wonderful videos! THANK U !!!!!!!!!

@radiologytutorials 11 ай бұрын

I'm so glad! Thank you 🙂

@Papasmurf2k7 Жыл бұрын

I've seen so many videos and this is the only one that has ever made sense! Thansk

@radiologytutorials Жыл бұрын

That’s so good to hear!

@MuhammadAbdullah-el5wz Жыл бұрын

😂in between the video, i get out off face, but after apply 180 degree magnetic field, finally catch up a little! Thank you for your efforts! Highly appreciated sir!

@radiologytutorials Жыл бұрын

Haha, imagine we had a 180 degree pulse at our disposal 😯

@nunya3399 Ай бұрын

As a nuc med tech training into mri I really appreciate these videos. I realize the reason mri physics have eluded me is because no one really ever explained it very well. Thanks for these.

@petevhn 7 ай бұрын

Your knowledge and the ability to explain it are truly unparalleled. Thank you.

@radiologytutorials 7 ай бұрын

Wow, thank you! Glad you're enjoying the videos!

@fazaltahir4216 Жыл бұрын

Much awaited lecture, thanks a lot sir Michael 🎉

@radiologytutorials Жыл бұрын

Hope it made sense 🤞🏼 T1 relaxation will be uploaded tomorrow 🎉

@bedilumelesse3948 Жыл бұрын

Interesting like always,cant wait next part T1 relaxation keep safe doc!

@radiologytutorials Жыл бұрын

Thank you Bedilu ☺️ T1 relaxation will be out tomorrow. Glad they’ve been interesting

@GhazalMehri-Kakavand-sr9ce 2 ай бұрын

Your abiluty in explanation of such complex content is amazing 👏

@zdiegi5493 Жыл бұрын

Thanks a lot for this explanation: it really helped me to better understand the concept!

@radiologytutorials Жыл бұрын

That’s excellence to hear 🎉

@husseinsa5050 Ай бұрын

born to be a great teacher!

@Bananakid11 Жыл бұрын

I'm studying chemistry in my masters now and your video was really helpfull, thanks a lot!

@radiologytutorials Жыл бұрын

Great to hear!

@shahadab6294 11 ай бұрын

Thank you for being amazing as always, this was well explained ! I had a little bit of confusion when you said that because of magnetic field inhomogeneity the spins are going to precess with different frequencies and thats why T2* are generated. but since we have different frequencies how do we send an RF pulse that will match these changing frequencies due to inhomogeneity and knock them out of the Z-axis to the x,y axis in the first place???

@nialladams4009 7 ай бұрын

i think it is local inhomogeneity rather than a field effect and this would explain why there is local signal void associated with metal, etc.

@M_mbn92 Жыл бұрын

Superb lecture like always! Thanks 🙏🏻

@radiologytutorials Жыл бұрын

Appreciate it Nick 👌🏼

@Hana-ken 10 ай бұрын

Thank you for all the great videos! Is there a book that you follow for creating your lectures videos?

@abdallahdia4657 13 күн бұрын

Thanks for this great information

@ZahraHassani-ld7rm 9 ай бұрын

Perfect as always. well explained. thank you so much.

@chrisdao 10 ай бұрын

Another question for you! At 15:00-15:50... you said this basically that we flip to 90 degrees and turn off the RF pulse and immediately sample. this is where I'm confused.... I thought the TE was when we... flip to 90 ... (wait) ... flip to 180 ... (wait) = TE. and sample here! so am I understanding this right? basically this explains the contrast differences between different tissues.... flip to 90 ... (wait 1 second) ... flip to 180 ... (wait 1 second) TE. and sample here! = small differences / all white flip to 90 ... (wait 2 seconds) ... flip to 180 ... (wait 2 seconds) TE. and sample here! = appropriate differences lets say at 37% transverse mag left. flip to 90 ... (wait 5 seconds ) ... flip to 180 ... (wait 5 seconds) TE. and sample here! = small differences / all black, no signal. in all of these examples we found the T2 values of the tissues souly based on the spin-spin interactions because we applied an RF pulse, waited some time (A), applied a second 180 RF pulse and waited that exact same time(A) and sampled the data. am i understanding this correctly?

@divyanshjha9369 2 күн бұрын

yes, the time difference between 90-180 RF pulse, is the same time after we measure the signal, TE. This is what I understaood from the lecture.

@Interesting_cases 6 ай бұрын

Thanks so much for your great exaplanation and videos. When 180 pulse applied , the slower spin will be trailing behind the faster spin right. How they catch up ? Couldnot understand that concept

@minakshi2412 7 ай бұрын

Great explanation..thank you for these lessons.

@hajerboudriga7659 3 ай бұрын

Can I use your animations and slides for teaching purposes? Best MRI course I came across❤

@Km1tidjeik 8 ай бұрын

님은 천재입니다...

@stellamakrigianni608 Жыл бұрын

Wonderful analysis, thank you!

@radiologytutorials Жыл бұрын

Thank you. That's very kind of you 😊

@Nittaku2000 Жыл бұрын

Why is it that a 180 degree RF pulse rephrases all the moments, but the transverse magnetization hits a ceiling at the T2 decay curve? If it is only an issue of how long the RF pulse is on for, then why would having it on for the duration of a 90 degree pulse restore full transverse magnetization and break the ceiling of the T2 decay curve. Something quantum? As always, thank you!

@radiologytutorials Жыл бұрын

Hi 👋 Not quite sure what you're asking exactly. The 180 degree pulse will only cause rephasing of spins if a previous 90 degree pulse has been applied prior. The first 90 pulse flips the spins in to the transverse plane. The spins will then decay at T2* - some will dephase faster than others depending on tissue type. If we then apply a 180 degree pulse the spins that dephased faster will now be lagging behind the spins that had slower T2* decay. This allows the faster spins to catch up with the slower spins at the TE when the spins will be in 90 transverse plane. If we were to only apply a 180 degree pulse as our first RF pulse the spins would flip a full 180 degrees and have no transverse magnetisation. They will decay at a rate of T1 (ie. regain longitudinal magnetisation) but have to T2 decay because there is no transverse magnetisation in the sample. This is actually a key feature of inversion recovery sequences which we will cover in two weeks time. I may be completely off what you were asking! Feel free to rephrase your question if I haven't answered it! Hope you're doing well!

@radiologytutorials Жыл бұрын

If you're asking why can spins with a 180 RF pulse 'break through' the 90 degree angle (because surely once they resonate at 90 degrees and we continued to apply an RF pulse they wouldn't continue to flip to angles above 90) then yes you are right, this is due to a quantum property. It has to do with energy states of the spins (at resting state with just the main magnetic field spins are in two energy states - lying parallel [low energy] and antiparallel [high energy]). In the quantum world the spins can exist in both states until measured. Continuing the RF pulse for a longer period of time adds energy into this system and allows the a slight majority of spins to now exist in the antiparallel state (higher energy), therefore they are flipping past the 90 degrees. I hope I'm making some sense, very difficult to explain in text 😅

@Nittaku2000 Жыл бұрын

This was exactly what I was trying to understand, watching again with your explanation really helped! Thank you for the detailed response!

@tanchienhao 9 ай бұрын

Thanks for this awesome video! Helped me understand

@radiologytutorials 9 ай бұрын

So glad it helped 🙌 thanks for your support

@chrisdao 10 ай бұрын

I had a question! At the diagram at 15:50, looking at TE2 --> is this approximately when we have lost 63% of the signal and basically why we need to time our echo appropriately to get a good image? Also!! Thank you so much for these videos! I'm an MRT(R) from canada, a new graduate looking to take MRI in 2024, so these videos are a big help!! If you need any help vetting questions or writing new ones for your x-ray bank, let me know and I'd love to give back!

@divyanshjha9369 2 күн бұрын

If we only care about the contrast, why does it matter to get the actual T2 instead of T2*, can't we just measure T2* and have similar signals?

@bmilano1580 8 ай бұрын

Practically when do you apply the 180° flip for a T2 weighted image? T2 relaxation is 63% of transverse signal loss. Do we then flip it when the T2* relaxation signal is at 37%? Is there an automated mechanism that does that because the fewest radiology technicians can react within milliseconds. Also the time T2 is different for different tissues. If the flip was done as I figured which of the 37% signal times(T2 of muscle, fat, CSF) would we take for the T2* flip?

@denizsiste9393 3 ай бұрын

thnx

@shahnavajtamboli9166 8 ай бұрын

Sir I want to buy a complete MRI course if you have

@christainbilna4619 11 ай бұрын

Sir , can you explain bulk magnetization of mri

@LivLyfofficial Жыл бұрын

Superb lecture

@radiologytutorials 11 ай бұрын

Thank you!

@mahdighanbari8331 7 ай бұрын

At 12:36, your explanation does not make sense. I mean both fast and slow spins are experiencing the same changes in their phase, so nothing changes and the leading one will remain the leading again. Could you please explain a bit ?

@wojciechpaweska7116 7 күн бұрын

upp

@wojciechpaweska7116 7 күн бұрын

I mean i think i figured that out. I had the same issue in understanding this. The answer is - you are applying the 180* flip in Z axis (in ZY plane) not in XY plane. If the 180* RF pulse acted in XY plane - then it would happen as you say - nothing would change - the leading one would still be leading. But when it acts in ZY plane - then they flip making like a mirror reflection along the X axis - so they switch and the leading one is now lagging and can catch up

@divyanshjha9369 2 күн бұрын

@@wojciechpaweska7116 Its genious.

@ELDHO360 14 күн бұрын

👍👍👍

@stavroslv9184 4 ай бұрын

I think that the video shows something that doesn’t really makes sense. In the longitudinal plane the net magnetisation vector is not processing because the individual atoms’ spins are out of phase. If somehow they were IN phase the Net magnetisation vector would have been processing in the exact way you show at the Course 3 11:15 minute. So, I m thinking that when the B1 magnetic field is applied, it turns the net magnetisation vector at the transverse plane, But now, we have every atom processing IN phase and this leads to the movement of the now vertical Net magnetisation vector. This movement I think should be the same with the one you show at the course 3 11:15 as a mentioned before and not as the rotational movement you show at the video. Showing the NET vector changing direction (becoming continuously parallel and anti parallel with the B1) doesn’t make any sense to me. I’m a medical student and I’m trying to figure it out so please, answer if you can. Thank you, your videos help too much!

@suhanakohri8928 Жыл бұрын

❤️❤️

@ariwasonemeka9142 11 ай бұрын

Do video on CT scan physics 🙏

@radiologytutorials 11 ай бұрын

Once I've finished the MRI series, I will move on to CT

@ariwasonemeka9142 11 ай бұрын

@@radiologytutorials ok. Sir

@DaibooDimension 4 күн бұрын

for those visual learners, here is a simulation for 180 degree flip kzfaq.info/get/bejne/fap1n7dnueCbj4U.html notice that the fastest becomes the latest after the flip