o Hepatitis: Acute and chronic
o Fatty Changes
o Diffuse hepato-cellar Carcinoma
o Infiltrative diseases i.e. Lymphoma, Leukemia,...
o Vascular insult (arterial or venous).
o Ultrasound does not normally play a prominent role in the diagnosis of acute hepatitis as the liver may appear normal. However, it is performed routinely in patients with jaundice to rule out bile duct obstruction.
o Hepatomegaly is the most common manifestation of acute hepatitis.
o Some patients with acute hepatitis present with a decrease in liver echogenicity due to swelling of hepatocytes and increased extra cellular fluid.
o The portal venule walls stand out in most areas of the liver, due to marked contrast between the hypoechoic liver parenchyma and the echogenic portal tracts. The so called "starry sky" appearance.
o The gallbladder wall is often oedematous and thickened (commonly seen in acute alcoholic hepatitis) and is a sign of acute hepatic insult, not infective cholecystitis.
o The gallbladder may not be visualized in neonatal hepatitis (due to lack of bile flow).
o In acute alcoholic hepatitis, the liver may appear " bright" (caused by coexistent fatty infiltration.
o Uncommonly, acute hepatitis may give rise to areas of focal echogenicity particularly in cytomegalovirus infection
Causes of "starry sky" appearance of the liver are:
o Acute hepatitis
o Leukemia infiltration.
o Diffuse lymphomatous infiltration
o Toxic shock syndrome.
o Heart failure.
o The liver may appear normal in chronic hepatitis.
o Generalized increased echogenicity of the liver is commonly seen together with areas of necrosis seen as hypoechoic foci giving rise to the generally heterogeneous appearance.
o The portal vein walls may lose their normal echogenic appearance relative to hepatic parenchyma and may become ill defined. The general pattern of parenchymal changes may thus vary depending on the stage of disease process
o Always look closely at the hepatic margin as the first sign may be loss of smooth and sharp hepatic margins with the development of a slightly lobulated contour.
Pathologically, cirrhosis is characterized by loss of liver cells, parenchymal fibrosis, and extensive disorganization of hepatic architexture.
o Early, the liver may be enlarged,then it returns to normal size or shrinks.
o The left and caudate lobes are enlarged relative to the Rt. Lobe.
o The surface of the liver appears irregular secondary to the nodular regeneration beneath the surface and these nodules appear deeper within the liver parenchyma giving its heterogeneous texture.
o Other sonographic findings of cirrhotic liver include: increased echogenicity of the liver, gallbladder-wall thickening, ascites, portal hypertension with splenomegaly, portal vein dilatation and varicose veins.
o The incidence of gall stones in patients with cirrhosis is increased.
o The accumulation of fat within the liver is a non- specific response to a wide variety of aetiologies i.e. Diabetes mellitus, obesity, malnutrition, alcohol, drugs (steroids..., chemotherapy...), Metabolic diseases (glycogen-storage and lipid-storage) and intravenous hyperalimentation.
o The liver is enlarged with increased strength and number of returning echoes resulting in a "bright" liver.
o The fatty infiltration can be patchy particularly in acute alcohol abuse, steroids and malnutrition.
o The Rt. Lobe is most often affected.
o Portal vein walls are less prominent than normal.
o There is increased attenuation of the ultrasound beam.
o The gallbladder wall may be ill-defined.
Grades of fatty infiltration:
Grade I: "mild" diffuse increase in liver echogenicity but normally visualized intra-hepatic vessels.
Grade II: "moderate" increase in hepatic echogenicity with slight impairment of visualization of hepatic vessels.
Grade III: "marked" increased in echogenicity with portal vein walls and the diaphragm hard to define.
Focal fatty infiltration and focal sparing of the liver:
o Features suggesting focal fatty infiltration or focal sparing are:
1. Geographic distribution of the fat.
2. Absence of mass effect, no vessel displacement or distortion.
3. Tendency to interdigitization of normal and fatty tissue,
o Focal fat infiltration may cause diagnostic problems, as it may mimic echogenic liver masses (such as haemangioma, H.C.C, adenoma, focal nodular hyperplasia or solitary metastatic deposit
o Alternatively "Spared" normal areas of the liver may mimic hypoechoic masses.
Recognition of typical sites for focal sparing: immediately anterior to the portal vein, medial to the falciform ligament and adjacent to the gallbladder.
11/05/2009 06:30 AM
To Be Completed.... ان شاء الله