DWI vs ADC MRI sequences: EXPLAINED
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- čas přidán 9. 06. 2024
- High yield radiology physics past paper questions with video answers
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Understanding how to tell the difference between diffusion weighted imaging (DWI) and apparent diffusion coefficient (ADC) MRI images can be easy!
I use my trusty chopstick (!) to demonstrate the physics of MRI sequences. By the end, you'll confidently differentiate DWI vs ADC images (and know why this is important).
Chapters:
0:00 Intro
0:27 Why do people get confused?
1:58 Basic physics explanation
9:06 How is a DWI image created?
10:17 What contributes to signal?
12:26 How to eliminate T2 shine through
14:17 Clinical example
17:32 Outro
Case courtesy of Dr Ian Bickle, Radiopaedia.org, rID: 26111
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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
How many times have I come back to this video!! Thank you so much
Haha, even me 😂
This was SO helpful as I'm studying for boards. Thanks for such a clear simplified explanation!
Glad it was helpful!
Please do a comprehensive video on mri physics. You just demystified the physics behind DWI and its very well understood. thank you Doc
it is incredible how you managed to explain such difficult theme! Thank you so much!
Thank you! I'm glad it helped 😊
Amazing video, so well and easy explained. Thank you
Really simplified it. Thank you so much!
Keep making such videos!
It's a pleasure. Any topics in particular you want me to cover?
I am really amazed by the way you simplify difficult topics.Thanks so much.
That's great to hear! I never know if I'm actually making sense or not 😅 so it's very helpful to get comments like this. Thank you Hameed
Thank you so much for your simple yet beneficial explanation
Amazing video, can't wait to see the rest.
Thanks a lot (From a french intern)
Excellent video, very clear. Thank you for sharing
Excellent! So practical and applicable minus the complex physics ! Thank you
There's no getting away from the physics 😖 Thanks for watching!
Thank you for the video, I understand this process far more now.
Great! I'm glad it helped Jade 😊
You are truly phenomenal. Thank you for sharing!
Thank you!
Thank you so much. Excellent tutorial...
Thank you 🙏🏻
Thank you for sharing these explainations
I'm an undergrad just getting started in radiology with my first position as a clinical research assistant. This was ridiculously helpful, you're amazing! Thank you!
Ah, I’m so glad it helped! Good luck with the clinical research post 🙂
Great content! Truly helpful!
Thank you Andrés! Glad it helped 🙂
Thank you so much!Your videos really helps me for my exam preparation. Hello 👋🏼from Malaysia!😊
Hello from 🇿🇦 to 🇲🇾! I'm glad the videos are helping 😊
the best explanation out there. thanks a lot
Thank you Parastoo. That's very kind of you to say 😊
Really awesome explained ! Thank u
So glad to hear it. Thank you!
This was amazing. Thank you!
Pleasure Rodrigo 👍🏼 glad it was helpful!
great explanation, thanks a lot!
Yay! Glad it helped Olga 🙂
Thank you this was sooo helpful!
Yay! I'm glad!
Love this channel!
Thank you Matt. That really means a lot 😊
Well done!
Thanks Gregory!
I have read theoretical part of dwi and adc but was not correlating.now everything is crystal clear.Thanks a lot for transforming my life.One day I will start reporting mri by learning from your vedio only
I'm really happy it had started to make sense for you Ravi! Thank you for your kind words 😊
Thank you, very good.🤗
Excellent 👌
Extremely helpful! I am probably gonna speak the same words for my viva!
I always find myself coming back to this to remind myself 😅 glad it’s helpful Pallavi!
that is an excellent explanation!
Thank you Pallavi ☺️
Great teacher all the time
This helped me understand diffusion a lot. Thank you for preparing this! 😍
Thank you Masnla. I'm so glad it was helpful!
Excellent 👍
Thank you Alex 👍🏼
REALLY good, thanks
Thank you Iris 😊
Amazing, thank you!🙏
Yay! Glad it helped Anita 🙂
Thank you very much. It is important for clinician to get this intuition of MRI. Grateful for this.
Absolutely 👍
Thanks for sharing this
I wonder how you explain all complicated stuff in such a simple way
So glad you enjoyed it 😀. Takes quite a lot of preparation 😆
Your chanal is one of my favorit !
Thank you Ina 😊
Pls make one video of mri sequences in detail..btw ur videos r awesome ..Ty so much
Oh I just saw the module on the MRI physics🙌🙌🙌🙌🙌
Hi Michael, Great video again thank you very much. Please could you do more interpreting videos e.g. MRI findings in acute vs chronic stroke etc. ? Thank you
Acute Stroke:
1. Diffusion-weighted imaging (DWI): In the acute phase, DWI shows hyperintense (bright) signals, indicating restricted diffusion of water molecules in the affected brain tissue. This is a sensitive marker for early stroke detection.
2. Apparent diffusion coefficient (ADC) map: Corresponding to the DWI, the ADC map shows hypointense (dark) signals in the affected area, indicating reduced water diffusion.
3. T2-weighted imaging (T2WI) and fluid-attenuated inversion recovery (FLAIR): These sequences may show hyperintense signals due to edema and tissue swelling in the affected region.
Chronic Stroke:
1. T1-weighted imaging (T1WI): Chronic strokes typically appear as hypointense (dark) areas on T1WI, indicating tissue loss or cavitation in the affected region.
2. T2-weighted imaging (T2WI) and fluid-attenuated inversion recovery (FLAIR): These sequences may show hyperintense signals due to gliosis (reactive glial cell response) and hemosiderin deposition in the affected area.
3. T1-weighted post-contrast imaging: In some cases, chronic strokes may show enhancement or hyperintense signals on post-contrast images, indicating the presence of gliotic tissue or neovascularization.
It's important to note that the appearance of stroke lesions on MRI can vary depending on the time elapsed since the onset of the stroke and individual patient factors. These MRI findings are typically assessed by radiologists or neurologists who have expertise in interpreting brain imaging studies.
Thank you !!!
My pleasure 🙏🏻
Amazing, thank you.
How do you describe and interpret lesions that are high on DWI but isointense on ADC?
Thanks
Wow! Thank you 🙏🏻 really appreciate it!
Thanks alot 🙂
Most welcome 😊
You have no idea how much you've helped me!! These concepts have been confusing me for too long. Thank you very much.
That's great to hear Shiyuan!
Very nice
TY Dr! Great explanation.
One addendum to this could have been greatly useful is the b values, what do they represent and why certain Dr want 1000 or 800 for the same anatomy.
Thank you Mihai. You're right. I definitely could have included that. Didn't want to confuse the core message. For interest briefly, the b value represents the magnitude and timing of the diffusion gradient we apply. As you've said it is prechosen by the clinician. This choice controls for the degree of observed diffusion. Similar to how TE controls T2 weighting. In my experience the reason certain doctors want different values is based on preference or experience with looking for specific pathology. There may be more nuanced reasons that I have yet to learn. Thank you for watching and taking the time to leave a comment ☺️
I was just learning MRI image modalities for a Machine Learning project on brain Stroke detection, and this video was so much more helpful than so many blogs online on the same topic. Thanks man
Sounds very interesting Kaustabh. Hope the project is going well. I’m glad this video could be of some help. All the best from South Africa 🇿🇦
outstanding
1:33 DIFFUSION WEIGHTED IMAGE
I have a question what would be an example of T2 shine through that would be seen as white on both DWI and ADC ?
Pranam 🙏
Thanks a lot
Please upload some more topics like
MRI sequences and protocols
When and why
Khush Raho Sarvejana. Thank you for watching and taking the time to comment. Many more MRI videos planned. Hopefully more to come in the next few weeks!
@@radiologytutorials
I thank from bottom of my heart .
Sparing your precious time and energy in
Imparting knowledge to others is highest point of personal culture.
Gurudevo Maheshwara
(Teacher is equivalent to God for us ) 🙏
Sir colon or large intestine ulcers can be seen in MRI?
Is this image better for spine to?
I want to know the relationship between b value and dwi pls. explain for me if you dont mind
The b value in diffusion-weighted imaging (DWI) refers to the strength or level of diffusion sensitization applied during the image acquisition. It is a parameter that determines the extent to which the diffusion of water molecules is restricted or attenuated.
In DWI, water molecules in biological tissues undergo random thermal motion known as Brownian motion. The diffusion of water molecules can be quantified by applying magnetic gradients during the imaging process. The b value represents the strength and duration of these gradients.
A high b value corresponds to stronger diffusion sensitization, resulting in more signal attenuation from the diffusion of water molecules. This is useful for highlighting regions with restricted diffusion, such as areas affected by acute stroke or other pathologies.
Conversely, a low b value corresponds to weaker diffusion sensitization, allowing a greater contribution from other tissue properties, such as blood flow or perfusion. This can help in assessing different tissue characteristics and distinguishing between various types of pathology.
The choice of b value depends on the clinical application and the specific information required. In acute stroke imaging, higher b values (e.g., b = 1000-2000 s/mm²) are commonly used to enhance the visibility of restricted diffusion in the ischemic region. Lower b values (e.g., b = 0-100 s/mm²) are often employed in perfusion-weighted imaging to evaluate tissue perfusion.
It's worth noting that the relationship between b value and DWI signal intensity is complex and influenced by various factors, including tissue microstructure and diffusion time. Advanced diffusion models, such as diffusion tensor imaging (DTI), can provide additional information about tissue anisotropy and fiber directionality.
Overall, the selection of an appropriate b value in DWI depends on the clinical question, the specific imaging protocol, and the desired balance between diffusion sensitivity and other tissue properties of interest. Radiologists and clinicians use their expertise to optimize the b value selection for different clinical scenarios.
3:30 Nope, incorrect. The precessing hydrogen atom does not rotate to 90 degrees, the Net Magnetisation Vector does.
Correct. Thanks for pointing it out 👍🏼
I think it is T2 star and not T2 in that formula.
Audio is very low
Yeah, unfortunately my earlier video had low audio
please speak closer to your microphone
Noted
Call tumor brain
Só foi eu que achei muito prolixo e pouco objetivo?
L I F E. S A V E R. 🎉🎉🎉
I have learned this before but still end up forgetting about it. But I cant say the same after watching this. You are amazing Dr. Nel 👏🏼
Thank you Marc! I also end up forgetting it 😖 at least the video is here for when we inevitably forget again. Appreciate the kind words 🙏🏻
Thanks
Thank you so much!! Really appreciate your support 🤗