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So our first case is a 20-year-old female.

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The history provided is biliary obstruction suspected.

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And for that, uh, the ordering providers ordered

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an MRI of the abdomen without intravenous contrast.

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And I wanted to showcase this case to simply go

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through some normal gallbladder anatomy, and over

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the course of this master course, I'm going to show

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you about 30 odd cases. And I have to tell you, the

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one that was the most difficult to find cases for

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was the normal gallbladder because there are so

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many little variants within the gallbladder, and

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it's challenging to get a gallbladder that

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looks distended enough but not too distended in

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order to showcase the normal anatomy. But this is a

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pretty good representation of a normal gallbladder.

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The sequence over here is a

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typical T2-weighted axial image.

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Over here, we have a T2-weighted coronal image.

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Both of them are non-fat-saturated.

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As you scroll downwards, you

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can see the liver over here.

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And as we scroll just inferiorly,

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tucked away here is the gallbladder,

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sort of an oval, or some people

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describe it as a pear-shaped structure.

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It's located along the undersurface of the liver.

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That sort of anatomic relationship is perhaps

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better appreciated on the coronal images

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where you can see the gallbladder over here.

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Again, oval-shaped, pear-shaped,

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uh, it's also been described.

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And I'm not one to remember sizes of organs.

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I think it, you know, it can get kind of confusing.

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But if you're somebody who likes to remember sizes,

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in general, uh, you know, gallbladder length can

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measure up to seven centimeters, uh, gallbladder

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transverse dimension up to four centimeters.

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And in my experience, that transverse

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dimension becomes more important.

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Once it gets more than four centimeters, we

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start to think about gallbladder distension.

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Now, the gallbladder itself can

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be split into different portions.

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As we can see over here on this 3D,

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uh, coronal MRCP image, this is MIPT.

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Uh, so you have a very thick slab

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showcasing the gallbladder all at once.

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We can see over here, this is

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the fundus of the gallbladder.

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That's followed by the body of the gallbladder.

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As it starts to taper, this is known as the

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infundibular portion of the gallbladder.

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That leads into the neck of the

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gallbladder right over here.

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And finally, you have the cystic duct that

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extends outwards from the neck of the gallbladder,

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which then meets the common hepatic duct.

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I'm going to zoom in on the cystic duct for a second.

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You can see as you look at the cystic duct, if

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you were to take your finger and just sort of

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run across it, it has this sort of undulating

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appearance going up and down, up and down.

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It looks quite different from any of the other

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sort of surfaces of the gallbladder and any of the

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bile ducts, and that sort of appearance is caused by

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uh, what is known as the spiral valves of Heister.

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These are concentric mucosal bands located along

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the endoluminal surface of the cystic ducts, and

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that appearance is quite normal, and you'll see

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that from time to time within the gallbladder.

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You can see on the T2-weighted imaging,

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generally, the gallbladder is T2 hyper-

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intense, pretty homogeneous in its appearance.

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On the T1-weighted images that I'm showing you here,

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this is a T1-weighted image with fat saturation. The

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gallbladder will be generally hypo-intense, but there

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is variability within this. Certainly, if patients

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are fasting, having not eaten for a few hours, some

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of the water in the gallbladder is reabsorbed, the

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bile gets concentrated, and as a result, on the T1-

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weighted sequences, you may see more hyper-intense

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signal, or it may be more iso-intense signal.

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On the T2-weighted images, you'll see more relative

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hypo-intense signal, and sometimes you'll have a

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layering effect, like with that hypo-intense signal,

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uh, layer sort of on the dependent portions, and we'll

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see examples of that, uh, on the next few, uh, images.

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And it's important to remember that when you have

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that sort of concentrated appearance of the bile, it

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is challenging to differentiate that from sludge, so

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oftentimes I'll say concentrated bile sludge is seen

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in the gallbladder if I need to make a reference to it.

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So there you have it.

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This is the normal appearance of the

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gallbladder with all its different parts.

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The normal appearance of the cystic duct in this

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patient who is presenting with biliary obstruction.