that liver is slightly lobulated, and the lateral segment left lobe is enlarged and approaching the
spleen, which itself is a little bit enlarged. This patient had two liver diseases, and over a course of three years, the developed accelerated cirrhosis. So as I press the button here you're going to see the changes in the liver over the course of three years. You can see that the liver is shrinking overall, but also that the distance between the lateral segment of the left
lobe and the right lobe has increased. Ansd this is due to the continuing atrophy of the medial segment of the left lobe, that is, segments for 4a and b. Segment 4b, in particular, shrinks significantly during cirrhosis. This patient's synthetic liver function also significantly worsened during the three year period. [BLANK_AUDIO] The diagnosis
of cirrhosis can be made on ultrasound by looking at the direct
signs that is, surface nodularity and parenchymal nodularity. Surface nodularity is best picked up by using a liner probe, parenchymal nodularity becomes apparent in advance cirrhosis due to fibrous bands that make the nodules more apparent. Heterogeneity of the echotexture is not a great sign in ultrasound because it has a lot of inter and intra observer
variability. The increasing stiffness of the liver makes the hepatic veins smaller, and also increases the pressure leading to portal hypertension. Therefore, the portal vein caliber can increase in size. There are also extrahepatic signs of portal hypertension such as multiple varices, and splenomegaly.
Another sign that we can see, indirectly, of cirrhosis is lobar redistribution. With cirrhosis, the lateral segment of the left lobe of the liver enlarges, that is segments 2 and 3, and also the caudate lobe enlarges. And with this enlargement, the tip of the left lobe approaches the spleen. The atrophy of the medial segment of the
liver, that is segments 4a and b, will lead to widening of the gallbladder fossa and also widening of the fossa for falciform ligament, and the falciform ligament venosum/g. Also there is atrophy of the right lobe of the liver, that is segments 5, 6, 7, and 8. So in this patient we can see that there is parenchymal
nodularity and it's best seen because of these linear echogenic
bands, which are bands of fibrosis. In this patient, the surface nodularity is not very apparent, using a curvilinear probe, but then we look at the same patient with a linear probe, we can start to appreciate the smooth angulations on the anterior surface of the liver that is definitive for cirrhosis, as a direct sign.
[BLANK_AUDIO] In this patient, we can see that the ascending branch of the left portal vein and the horizontal portion of the left portal vein have enlarged because of the portal hypertension. The medial segment of the left lobe, that lies to the right of the ascending branch of the left portal vein, has decreased in size, and this leads
to widening of the falciform ligament, and also the change in the axes of the ascending branch, which starts turning towards the right. [BLANK_AUDIO] In this patient we can also see that there is widening of the fossa for the ligamentum venosum because of some atrophy of the left
lateral lobe and the caudate lobe as well.
[BLANK_AUDIO] Here is the three different patients with advanced cirrhosis. So right here, in this patient, we can see that the tip of the left lobe of the liver is approaching an enlarged spleen. The tip of the left lobe touching the spleen is not an uncommon
thing to see in a tall woman, but is very unusual in men, and that would be a tip off that the lateral segment is enlarged and there is liver disease. In this patient, we can see that there is atrophy of the medial segment of the left lobe that is specifically here segment for 4b, and this leads to widening of the fossa for the falciform
for ligament and also the gallbladder fossa. We can also see that there is a change in the access of the ascending branch of the left portal vein. In this patient also, we can see that, not only there is generalized atrophy of the liver with enlargement of the lateral segment, but also there is widening of the fossa for ligamentum venosum. [BLANK_AUDIO] Okay, so we're going to change gears now and talk about
fatty infiltration of the liver. This is a patient that presented to us with no history of liver disease. On ultrasound exam we can see that there are numerous, well defined, echogenic foci distributed throughout the liver. These don't cause any kind of
distortion of the hepatic vasculature, and there is no change in size of the liver. And so this is a typical appearance for nodular fatty infiltration. This can be proven, in this patient, by just doing a follow up scan. And very commonly, either it will resolve or in his case we could see that diffused fatty infiltration of the liver appeared. [BLANK_AUDIO] On CT scanning, nodular fatty infiltration can
sometimes appear more sinister. We can see nodular fatty infiltration, especially in patients who are undergoing chemotherapy, and this pattern can appear like the patient's primary disease. To prove that this is fat infiltration and not malignant disease, MR would be the best modality. And in this patient, we can see that we performed a subtraction image between in and outer
phase gradient echo dual echo T1-weighted images. And so, anything that has any signal or bright within the liver has fat within it. So in the patient we can see that, not only there is diffused fatty infiltration in liver, but there are also multiple small increased areas of signal that are consistent with the nodular fatty infiltration. There are multiple different patterns of fatty infiltration within
the liver. Fatty infiltration can be diffused, as in this patient, where we can see, despite the contrast enhancement, the overall attenuation of liver is quite low and approaching that of water. Fat infiltration can also be lobar or lobulated angiographic, as in this patient. We can also get more well-defined geographic areas within the liver, and again, this is
a patient who's been on chemotherapy. And so this pattern of appearance can mimic malignant infiltration. We can show that this is fat infiltration by either doing MR or ultrasound, and here you can see on the patient's ultrasound, very easily, we can identify this geographic appearance to the fat in that region. Generally, infiltrative/g malignant/g disease will appear at hypoechoic to the [INAUDIBLE] parenchyma whereas,
the fat will appear as hyperechoic. In this patient we can see that there is subcapsular fatty infiltration, and this is really as a response to intraperitoneal insulin that was given in patients with peritoneal dialysis. [BLANK_AUDIO]
Assessment of hepatic fatty
Infiltration can be performed with ultrasound. We'll look at four parameters, these are overall echogenicity. Fat causes increase in echogenicity of the ultrasound, poor definition of the hepatic vessels, attenuation of the deep ultrasound beam, and a bright diaphragm. So in this patient we can see that there is fatty infiltration of the liver with increased echogenicity of the liver parenchyma
as compared to the normal renal cortex. This patient also happens to have area focal nodular hyperplasia. So we can see this is not fatty infiltration. So this lesion has normal hepatic echogenicity, and generally, the normal hepatic echogenicity is slightly more echogenic than the renal parenchyma. But also then the rest of the liver parenchyma has increase in echogenicity due to the fat.
In this patient, we can see that there is diffused fatty infiltration, and the intensity of the sound beam is dropping off causing this darker area within the posterior aspect of the liver. And also we can see that the diaphragm stands out brightly. And in this patient with severe fatty infiltration, we've lost most of the, liver due to the severe attenuation of the sound beam.
Ultrasound is overall okay in accuracy, in terms of assessment for fatty infiltration, it tends to have low sensitivity for mild fatty infiltration, but it has excellent specificity. And therefore, a good negative predictive value. So ultrasound is a useful modality to rule out hepatic fatty infiltration. CT is also used for hepatic
fatty infiltration, and the unenhanced scan is the best phase to
look at and measure attenuation of the liver. Attenuations of the liver can be a measured as an absolute number. So directly putting an RRI/g on the hepatic parenchyma, the normal liver parenchyma has attenuation of about 65 Hounsfield units, or the attenuation can be compared to the spleen. And so one can subtract the splenic attenuation from the hepatic attenuation. So the spleen
generally has attenuation about 10 Hounsfield units less than the liver, and the subtraction of spleen from the liver usually, in patients with no fat, will yield a difference of 10 Hounsfield units. As there is more and more fatty infiltration, of course, the attenuation of the liver decreases and so does the difference between the spleen and liver attenuations. The accuracy of CT is also similar to that
or ultrasound, but in terms of it's sensitivity, it has higher sensitivity than an ultrasound, but generally a lower specificity. [BLANK_AUDIO] MR is our most accurate modality in assessment of hepatic fatty infiltration. Semiquantitative techniques such as doing dual echo, in and out of phase gradient echo images, or quantitative techniques such as multi-echo gradient echo images with T2*
correction, or MR spectroscopy, which is the most accurate method of measurement of hepatic fat all exist. The quantitative techniques take a little bit longer and are difficult to do during routine practice. Most people end up doing semiquantitative techniques and dual phase in and out of phase images, and so here is an inphase image of the liver. And I'm going to project on top of this, the out
of phase image. And so if there is any fat within the liver the signal drops. And so here you can see that as I project this you can see that there is quite a bit of drop of signal within the hepatic parenchyma indicating that there is quite a bit of fat within the hepatocytes. An elegant way of showing fat within the liver is actually subtracting
the out of phase image from the in phase image. And in this patient we can see that there is no fat within the hepatic parenchyma, but that there is fat within this large mass, which is a hepatocellular carcinoma within the liver. As I mentioned MR is our most accurate modality, and is both sensitive and specific. Sometimes within the liver,
we see processes that look very aggressive, but in fact are quite
benign. In this patient on T2-weighted MR, we can see that there are numerous cystic lesions that are following the portal triads and branching out. These are peri-biliary cysts, and we can see them most often in patients who have hepatic cirrhosis. When they're very prominent such as this patient the
diagnosis is a little more apparent, but they can be relatively mild, as in this patient, and especially on CT scan, they can be mistaken for hepatic malignancy. So the important thing about peri-biliary cysts is to identify them and to ensure that they're not mistaken for malignancy. This is a 22-year-old female with chronic epigastric
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