How Bandwidth Affects Signal to Noise Ratio (SNR) in MRI | MRI Physics Course #12
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- Опубликовано: 29 сен 2024
- High yield radiology physics past paper questions with video answers
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How does changing receiver bandwidth affect signal to noise ratio? Here we review narrow bandwidth and wide bandwidth sequences and look at how this changes both signal and acquisition time. We will calculate sample interval/dwell time, sample rate and total acquisition time. Lastly. we review the pros and cons of a narrow bandwidth.
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Not sure if the question banks are for you?
If you're here, you're likely studying for a radiology physics exam. I've spent the last few months collating past papers from multiple different countries selecting the most commonly asked questions. You'll be surprised how often questions repeat themselves!
The types of questions asked in FRCR, RANZCR AIT, ARRT, FC Rad Diag (SA), ABR qualifying Core Physics and MICR part 1 are surprisingly similar and the key concepts remain the same throughout. I've taken the most high-yield questions and answered them in video format so that I can take you through why certain answers are correct and others are not.
Happy studying,
Michael
#radiology #radres #FOAMrad #FOAMed
Thanks a lot for making MRI miles more understandable than most other explanations.
Thank you so much you dont know how much this helps me as an MRI student. I rewatch your videos multiple times a day everyday! Please continue posting MRI contents!
I'm so glad you find the videos helpful! Working on some more content right now 🙌
Thanks!
Thank you so much ☺️
Thank you for your excellent work. Your teaching style is second to none.
Cheers Simon. That means a lot. Thanks mate 🙂
Words are not enough to appreciate your efforts, u made MRI physics so interesting n easy, big applause 👏 🎉❤
Hold on, If the band with is smaller then the Image HiGHER freq will be CUT OFF. There for the RIGHT SIDE OF THE IMAGE MUST BE CUT OFF.
really hope this series and the mri q bank is all ready before the part 1 in September.
Excellent content and clear explanations, Thank you! Can you tell me when the MRI question bank will be available?
Thank you @boomtown1020! Working on it at this very moment - hoping it will be available soon 🤞
9344 Reynolds Mountain
The way you explain and illustrate these concepts is truly amazing. I can visualize my learnings because of your videos. Thank you, Sir Michael. I will be taking the ARMRIT soon, I hope the MRI Question bank will be ready in a few days.
Thank you! I hope your studying has gone well 🙂
Are you planning to bring for CT also?
Hi, your videos are usefull.can you make video on pulse sequences like diifferent types of all pulse sequences in mri . Can you please tell about cardiac ,fuctional and diffusion tensor imaging in mri.
Thank you. Will be making pulse sequence videos next week 😊
Hello Michael,
you have a great way of explaining things! But I have a question regarding this video. I understand how a higher BW shortens the echo duration and that you need a higher sampling rate. Therefore you´re faster collecting all your data points you need. But wouldn´t it be possible to just use the same high sampling rate for a lower BW. Then you would need the same short time? Or asked in another way. Why not always using the highest sampling rate that is technically possible to be faster or at least have more data?
Where is my mistake? Thanks in advance!
Hi Christian. Excellent question! You’re one step ahead. Indeed what most sequences do is oversample in the frequency encoding direction. This helps to prevent aliasing occurring because we sample at a high enough rate to accurately localise signal that is beyond the nyquist limit for the FOV. So there is definitely benefit in using a higher sampling rate. There are limitations though. 1. Machines have a sampling rate limit and nearing the limit can make data acquisition less accurate. 2. Sampling at a higher rate does not speed up acquisition time - the echo still takes longer in lower bandwidths irrespective of sampling rate (which is also a good thing because we get better signal to noise). Hope this makes sense 👍🏼
@@radiologytutorials Thanks a lot for the detailed answer! So you always have to sample the whole echo, if I understand it correctly. It is not possible just to sample the middle part of an echo with low BW to save some time?
You can just sample the middle part (provided you have enough samples) but it wouldn’t save time, because you still have to wait until the TR and repeat the process for multiple phase encoding steps. Only processes that reduce TR/phase encoding steps/NEX will actually save time. Hope that makes sense 🙂
God blessing you... عاشت ايديك يابطل
Sir how many videos to go before ct module?:)
I'm pretty sure 30khz bandwidth will give you 4.3ms - dont forget the nyquist theorem. Also the readout prephase gradient should be before the 180 to avoid adding the FID from the 180 😊
Hi Tyson. I’m not sure I’m following your calculation. Are you referring to 4.3ms for the sampling time (in a 30khz bandwidth slice with 256 pixels)? A 30khz bandwidth slice has a nyquist limit of 15khz because the relative frequency changes are measured from the null point. These formulas take into account the nyquist limit. Perhaps I’ve made a mistake and am happy to hear you explanation and calculations.
Ok I guess it depends on how you frame it. For us, if the operator requests 30kHz readout bandwidth, our acq time (s) = read points * (1 / (30000*2))
Question: does the $14 review questions only apply to current video or does that purchase cover questions for all the sections for this series? Thank you!
Hi 👋 Sorry for the delay! Missed this comment. The review questions cover topics covered in the entire MRI series.
@@radiologytutorials awesome! Thank you! Incredibly helpful I'll be getting those
Do you have books you suggest to understand quantum mechanics and calculus?
Type in pdf syllabus… xyz. However, applied explanations are sometimes best.
Wow this is sooo helpful thank you so much!!
Glad it was helpful!
Amazing ❤
Hi sir❤
Great❤❤
Thankyou sir🎉🎉
Cheers Sohail 🙏🏻
Thank you doctor
My pleasure 🙂🙏🏻
Best explain
Thank you 🙏🏻
Amazing🎉
Thank you! 🙌🏼
Wow❤❤
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I like that❤❤
Thank you ❤️
@@radiologytutorialsplz put new cases also...u teach in very simple and most understandible way...
Thanks a lot sir Michael 🎉
Pleasure Fazal. Hope you’re well 🙂
Sir we are desperately waiting for new video of MRI physics,,,,
@@radiologytutorialssir Michael we are waiting for the new video of MRI 😂, any updates plzz 🙏
Hoping to film a new one tomorrow. I’ve been extremely busy the last 10 days. Just had no time to sit down and film 😣😣
@@radiologytutorialsstay blessed sir Michael,,, your videos are very very helpful for us ❤🎉😊