Introduction to Multiphase CT & MRI of the Liver

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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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wow ! Your presentation is amazing and smart. Very grateful of you. Thank you 🙏

losadotough
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Wow, excellent, concise and very clear lecture for surgeons! Thank you very much 👍

AldO-HPB
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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 !

MrFawaz
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These are gems that are great for initial study and short refreshers. Top notch

peregrinedalziel
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Great and illuminating presentation, Dr Daniel!

madhuguptan
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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.

tenzinangio
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This is perfect for beginner radiologists. Thank you for your work 🙏

hammerradiology
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Great to learn some abdominal radiology knowledge. Great teacher.

caiyu
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Informative lecture. Useful for us CT Techs. Thanks.

nategalindojr
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Thank you so so much for making such a great video! As an intraining newbie, this helps me a lot. Thank you!

ramitac.
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Excellent presentation !!! many thanks

icosum
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Great video because it's simple and yet, effective! Thx mate.

nutellapringles
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The best one I have ever seen. Soooo easy to remember. Thanks!

xingxing
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OH, EXCELLENT LECTURE SIR, MUST APPRECIABLE.

syedzaman
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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

SO-blet
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Excellent video, this is the second time after a few months to review again. will come back again. Thanks a lot.Already subscribed.

javedahmad
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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?

dr.md.shalahuddin
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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!

deana
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This video is very helpful. Thank you.Please do more liver and biliary track imaging.

sweetstreetcats
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Brilliant presentation! Thanks a lot!!!

ivanmamontov