Introduction to Multiphase CT & MRI of the Liver
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- čas přidán 31. 05. 2024
- In this video lecture, we review the appearance of the liver on multiphase CT & MRI. A basic approach to image interpretation is presented with pitfalls to avoid.
Key points include:
1) The three major liver postcontrast phases include the late hepatic arterial phase, portal venous phase, and delayed/equilibrium phases.
2) The hepatic artery enhances first, followed by the portal veins, then the hepatic veins along with the hepatic parenchyma.
3) An ideal late hepatic arterial phase sequence will have both hepatic artery and portal vein enhancement with no hepatic vein enhancement.
4) The late hepatic arterial phase occurs at about the same time as the corticomedullary phase, enteric phase, pancreatic phase, and splenic arciform enhancement phase.
5) The early arterial phase of an angiographic CT is NOT the same as the late hepatic arterial phase of a liver protocol study and may be too early to adequately assess hypervascular liver lesions.
6) “MRI CT” is a handy mnemonic for hypervascular liver metastases, lesions that will be best detected on a hepatic arterial phase series.
7) Portal venous phase images will have portal vein and hepatic vein enhancement, as well as liver parenchymal enhancement.
8) Hypovascular hepatic metastases (GI tract, pancreas) are usually best detected on the portal venous phase.
9) Delayed/equilibrium phase images allow detection of intralesional contrast washout and delayed capsular enhancement typical of hepatocellular carcinoma, as well as evaluation of delayed enhancement as seen with hemangiomas and intrahepatic cholangiocarcinoma.
10) CT has better spatial resolution, but MRI has better contrast resolution and is therefore superior to CT in the characterization of liver masses.
11) Pre- and postcontrast MRI sequences are typically obtained as a special T1 sequence known as a spoiled 3D gradient echo variant with fat saturation.
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Great and illuminating presentation , Dr Daniel!
Thank you, and so glad you enjoyed it!
wow ! Your presentation is amazing and smart. Very grateful of you. Thank you 🙏
Thank you, that's very kind! You're most welcome
These are gems that are great for initial study and short refreshers. Top notch
I'm thrilled to hear that Peregrine, thank you!
Great lecture
Glad you think so!
This is perfect for beginner radiologists. Thank you for your work 🙏
Glad it was helpful Hammer Radiology!
Excellent presentation !!! many thanks
OH, EXCELLENT LECTURE SIR, MUST APPRECIABLE.
Excellent lecture ! Thanks.
Great to learn some abdominal radiology knowledge. Great teacher.
Thank you kindly!
Wow, excellent, concise and very clear lecture for surgeons! Thank you very much 👍
Awesome, great to hear that Aldwin Ong, thank you!
You offer one of the best radiology resource available on the internet. You are my personal favourite. Concise but so much relevant information. Wishing you the best ❤️
Ps- if you could kindly upload content more often. God bless !
Wow, thank you for the kind words Dr. Fawaz Yousuf! Stay tuned :)
Great video because it's simple and yet, effective! Thx mate.
I try to keep the lectures simple and to the point, so that’s great to hear. Although tangents can be fun too ;) Thank you!
I just love the short format videos. The cases are excellent also. I think You really nailed the sweet spot regarding length, yet it is very information dense. Its also great that You repeat the crucial pieces of info multiple times.
Definitely one of the best radiology channels.
Awesome, thank you Tenzin Angio! Really appreciate that. I try to keep the videos short and high-yield, since time is our greatest commodity :)
Best lecture I have heard.
Thank you so much!
Excellent.
Thank you so so much for making such a great video! As an intraining newbie, this helps me a lot. Thank you!
Awesome, glad to hear that Ramita!
Very Nice explanation. Thankyou
You're welcome, and I'm glad you enjoyed it!
Very lucid presentation, thanks
Glad you liked it!
Thankyou so much! Amazing lecture.
You're most welcome Apoorva, and thanks for watching!
Amazing video!
Thanks Talia Cheng, appreciate that!
Informative lecture. Useful for us CT Techs. Thanks.
You’re welcome, glad you found it helpful!
The best one I have ever seen. Soooo easy to remember. Thanks!
Glad you liked it XING Xing!
Very helpful
great talk
Brilliant presentation! Thanks a lot!!!
You're very welcome Ivan, and thank you!
Your lecture is awesome. Thank u
Thank you RASHID MAHMOOD, glad you liked it!
That was an awesome lecture.....Thanks about
Most welcome!
Thank you for helpful lecture 🙂
Most welcome!
excellent presentation
Thank you!
a very nice video
That was a great presentation
Thanks so much Ashok!
very useful video from MRI technologist standpoint as we really need to take care of the timing and now I know more clearly about reasons behind it. Thanks
Glad it was helpful!
nicely explained,thanks
You’re welcome!
Great video ❤
Glad you liked it!
Very nice lecture
Thank you for watching suvarna latha Penukonda!
Well explained. Thanks for your help🇨🇩
Glad it was helpful!
Than you for the precious lecture!
You are welcome Jiyang Kim, glad you liked it!
extremely helpful. Thank you.
Glad to hear it, thank you KC Okoro!
The best video thank you
Thank you, greatly appreciated!
Great
Comprehensive
Consice
Thanx
Glad it was helpful!
Excellent video, this is the second time after a few months to review again. will come back again. Thanks a lot.Already subscribed.
Great to hear you found it useful enough to watch more than once!
Very nice
Thank you!
Nice presentation
Glad you liked it Rajesh, thanks!
Very nice 👌 thanks
Most welcome 😊
It helps a lot
Great to hear!
Thank you
You're welcome
Amazing
Thank you!
Very good
Thank you Anjali!
Awesome!
Thank you! Cheers!
just beautifully done merci bcp
Great video thanks so much!
I want to ask, when you talk about contrast media you mean the general MRI Contrast i.e Prohance or the liver specific i.e. Primovist?
Glad you enjoyed it!
Pure gold!
Great to hear, thank you Dean!
This video is very helpful. Thank you.Please do more liver and biliary track imaging.
Thank you! I'll work on that :)
Ooh perfekt . Thank you very much
You're welcome 😊
Subscribed sir
Thanks
You're welcome!
Thank you so much pro
You are welcome!
Great
Thank you!
Excellent.
Thanks for ur effort.
I just have a question.
During late hepatic arterial phase, how does contrast comes into PV? Is it from Aorta to SMA to capillary and then SMV & PV?
From splenic vein
great, great, great
Thank you Frank Robert, glad you enjoyed it!
That was neat!
Thank you!
With the late arterial phase (where hepatic veins are not opacified) how then can we differentiate the liver segments accurately for anatomical resection if there is already washout in PV phase?
While certain liver masses show washout in the PV phase, the hepatic and portal veins will be well opacified during this phase and can be used as landmarks to determine the anatomic segments.
Thank you Dr Kowal! Very informative video, though the MR info sounds like Greek to me as a CT tech ;-) I am wondering what your recommendations are for flow rate on this multi-phase liver protocol? As a traveler, standard injection rates vary greatly from facility to facility. For instance, where I am now their standard is 2ml/sec for routine abd/pel and such type of studies. To me, this seems too slow for this particular scan. I would think at least 3ml/sec, if not 4; making the rate closer to an angiogram. Do you find better enhancement using bolus tracking or fixed delay for late arterial phase? If using BT, where do you like to have the techs place the ROI (or visually watch it) and is there a post threshold delay? For instance, if tracking at the aorta near the hepatic artery, do you then wait several seconds to start the scan so that it is enhanced the way you describe? I work mostly in rural facilities and we rarely do any multiphase; with liver being the least performed (renal most often, pancreas second). Thank you for any and all input!
Glad you found it helpful Deana! Typically 2-3 mm/second is required to sufficient enhancement with multiphase liver CT. At my institution, we typically use bolus trigger for all angiograms, but just a fixed delay for late arterial phase.
Super!
Thank you!
Hi thanks for the nice presentation!
Can I ask If theres any challenge to distinguish between tumor and abscess @ liver on CT conclusively ?
Thanks Andy! There are a few CT findings with hepatic abscess that we don't typically see with tumor. The "double target" sign is when we see the enhancing wall of an abscess surrounded by hypodense parenchymal edema. Also, the "cluster" sign of an abscess is when we see multiple small locules giving a clustered appearance. Gas may also occasionally form in liver abscesses as well. Check out this RadioGraphics article for a nice example of these findings: pubs.rsna.org/doi/full/10.1148/rg.2016150196
The Best
Thank you!
da best!
Nice, thanks Vincent!
i don't quite understand why u mentiond that hypervascular tumors get most of the blood from the hepatic artery.not portal vein?
could y help me explain that,thanks a million
Although liver parenchyma is fed by both the hepatic artery and portal vein, hypervascular tumors such as hepatocellular carcinoma (HCC) may be fed primarily by the hepatic artery, and that is why they appear hypervascular. With HCC, angiogenesis can also occur, which is the creation of new blood vessels. This phenomenon leads to increased arterial flow and a gradual reduction of portal venous flow to the mass. It's not a hard and fast rule though, as the arterial supply to HCC has been shown to vary based on tumor grade.
What if you are someone who is getting an MRI on the liver because of lesions found but don't want to take the contrast. Can the MRI still be done?
Hi Liz. I’m in same situation. They found lesions in my liver from ultrasound and want me to do MRI for further investigation but I don’t want contrast. Any updates on yours?
@@LVH100 Hi Tony, she wouldn't do the MRI but just had another ultrasound and was thought to be hemangioma which is usually found incidentally on ultrasounds.
Excellent.Please do a video on THAD
Thanks Solon, I'll keep that in mind! I do show an example of THAD in my hepatic hemangioma part 2 lecture: bit.ly/Hepatic-Hemangioma-2. At minute 05:43, and I talk about THAD/THED (transient hepatic arterial difference/transient hepatic enhancement difference) as it relates to hemangiomas associated with arterial portal shunt, with CT and MRI examples.
patients might have different hyper or hypodinamic CO, do you adjust your timing to that . Do you note a differente in the timing of the arterial or portal phase between child A patients that to Child C patients because of Different cardiac Output ?
Good question Luis! When we use a fixed (AKA standard or empiric) contrast timing delay, we definitely see differences in the appearance of the immediate post-contrast phase depending on the patient's cardiac output. One way to prevent this variation is to use a trigger to delay for contrast using bolus tracking, where we sample the liver or aorta with an ROI at timed intervals after injection of a contrast test bolus, and then when the density reaches a certain threshold, the start of the scan is triggered. This technique give a more consistent, uniform pattern of contrast enhancement for each patient, but comes at the cost of a slightly increased radiation dose for the patient, technologist time, and increased contrast volume. Hope that helps!
@@Radquarters thanks a lot
নাইস বন্ধু
Thanks Prosanta!
Why the portal venous phase timing in ct is 80 sec and in mri 40?
The portal venous phase varies depending on using a fixed time delay (usually 60-90 seconds) versus bolus tracking (50-60 seconds), but otherwise looks similar on CT vs. MRI.
Can we do it in ge 16 slice machine.. we don't get this kind of scan ..our del ded is 8
Yes, a multiphase liver scan can be performed with a 16 slice scanner.
@@Radquarters yes sir but we r not getting proper arterial phase our scan del sec is 7 to 8 sec
Hello , The HQ of radiology . Please can you give me more precisions about Multiphasique Hepatic CT scan ? quantity of contrast ? and rate (Q) of injection ? what is best , bollus traquing or fixed delay ? Thanks a lot . We missssssssss you !!!!!
I scrolled through the comments looking for this exact info! It is one of the few that were unfortunately not answered 😕 I mainly need/want to know his recommendations about rate of injection, as it makes a difference to when the contrast will reach the specific phases. Also curious about bolus tracking, where to place roi (or visually watch it) and if there should be a post threshold delay. I am going to try and post my own comment and see if he answers.
Please do a videos on your search pattern on body mri .
Hi, I do plan on doing that type of video as part of a "How to Read" series in the near future. Thanks for the suggestion!
@@Radquarters Thank you . It's great . I have been struggling for year to find a method for reading those with confidence , I always have the feeling that I am misssing something !
🙏🏼🙏🏼🙏🏼
Thanks for watching Nagi!
5:35 delay phase
👍👍👍👍👍👏👏👏👏👏👏👏
Thanks!
Those first hypOvascular liver masses looked like cysts 😅
They do a look a bit deceptive, but their density measurement was above fluid. Thanks for watching!