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Abdominal Sonography Part 1 Lecture 1 Normal Liver Holdorf

Abdominal Sonography Part 1 Lecture 1 Normal Liver Holdorf. Introduction. Liver is the largest organ in the human body, providing an acoustic window for viewing the upper abdominal and retroperitoneal structures. In adults weighs about : 1500 g

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Abdominal Sonography Part 1 Lecture 1 Normal Liver Holdorf

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  1. Abdominal Sonography Part 1 Lecture 1 Normal Liver Holdorf

  2. Introduction • Liver is the largest organ in the human body, providing an acoustic window for viewing the upper abdominal and retroperitoneal structures. • In adults weighs about : 1500 g • The entire liver is covered in a thin fibrous connective tissue layer called Glisson’scapsule and is thickest around the IVC and the porta hepatis. • Morison’s pouch- potential space located between the right kidney and liver

  3. Size • Size and shape variable, has a basic wedge shape, tapering toward the left lobe. • Measurement; • Longitudinal diameter is taken at midclavicular line: NL Rt lobe measures 13 cm or less, but in some literatures 15-17 cm has also been stated as NL longitudinal length. • AP measurement at the same level should also be taken in heavy patients to avoid under- or overestimations • Note-In 75% of patients Hepatomegaly is present if midclavicular liver length is greater than 15.5 cm (according to Rumack). • Indicators of hepatomegaly: • Lower edge of the Rt lobe become rounded as opposed to a sharp wedge shape. • Extension of the inferior portion of the Rt lobe to overlie a significant portion of the RT kidney in the midclavicular line. • Normal Caudate/ right lobe ratio < 0.65 : • In Cirrhosis > 0.65

  4. Location • Situated in the RUQ extending from right hypochondiac region to hypogastrium and frequently extends to the left hypochondrium. • Except for the bare area (most of its posterior surface) liver is an intraperitoneal organ. • Reidel’s lobe: Normal variant, tongue-like projection of the right lobe which extends to the iliac crest

  5. Liver lobes: Three lobes • Right lobe • Left lobe • Caudate lobe

  6. Liver lobes cont. • Right lobe: • Right of an imaginary line between the GB fossa and IVC • Divided by right intersegmental fissure into: • Anterior segment • Posterior segment

  7. Liver lobes cont. • Left lobe: • Left of an imaginary line formed by the Lig. Teres anteriorly and Lig. Venosum posteriorly. • Divided by the left Intersegmental fissure into (Note-The Falciform lig. , lig. Teres/Round lig. and LHV are located within this fissure): • Medial segment= Quadrate Lobe: Located between lig. Teres and GB fossa and Lies on anterior midportion of the inferior aspect of liver. • Lateral segment.

  8. Liver lobes cont. • Caudate lobe: • Located on the posterior midportion of the inferior aspect of the liver; Posterior and superior to the porta hepatis • Lies between the ligamentum venosum anteriorly and IVC posteriorly • The papillary process is an anteromedial extension of the caudate lobe, may appear separate from the liver and mimic a lymph node. • It is supplied by left and right portal veins and HA and it is drained by emissary veins which directly enter into the IVC.

  9. Inferior surface of the liver

  10. Segmental division of the liver • Liver segments are determined by the blood supply. They are clinically significant for localizing potentially resectable liver lesions. • The major hepatic veins course between the lobes and the segments: • RHV course in the Right intersegmental fissure • MHV course in the Interlobar fissure • LHV course in the Left intersegmental fissure • The major branches of the RT and LT portal veins run centrally within the segments, with the exception of the ascending part of the LPV which runs in the LT intersegmental fissure.

  11. Liver: anatomic relationship • Superior, posterior and anterior surfaces: Dome of diaphragm • Left lobe: • Anteriorly bounded by the ribs and abd. Wall • Posteriorly rests on the stomach • Right lobe: • Anteriorly bounded by the abdominal wall and ribs • Posteriorly rests on the GB, right adrenal gland, upper pole of the Rt kidney.

  12. Liver surfaces • Posterior surface: • Caudate lobe • Bare area • Most of this surface is not covered by the peritoneum • Anterior surface: • Covered by the peritoneum • The lig. Teres ascends from the umbilicus to the umbilical notch of the anterior surface • Superior surface: • Intraperitoneal • Covered by the diaphragmatic dome • Inferior surface; • Covered by the peritoneum except at the porta hepatis and GB fossa • Anterior mid portion is the Quadrate lobe (medial portion of LLL) • Posterior mid portion is the Caudate lobe

  13. Liver

  14. Liver ligaments • Coronary ligament: • The visceral peritoneum around the bare area turns upward (Coronary ligaments) on to the diaphragm to become parietal peritoneum. • They attach the liver post. surface to the diaphragm. • They are continuous anteriorly with the falciform ligament and laterally with the triangular ligaments. • RT and LT Triangular ligament: • The edges of the coronary ligaments are called the Triangular ligaments. • They attach the Rt and Lt lateral borders of the liver to the diaphragm.

  15. Liver ligaments cont. • Falciform ligament: • The two anterior leaves of the coronary ligaments join to become the Falciform ligament in the anterior surface of the liver (the two posterior leaves become the lesser omentum, which encircle the porta hepatis). • FL is an anteroposterior fold of parietal peritoneum extending from the bare area of the liver to the diaphragm and from the diaphragm to the umbilicus • FL on the superior surface of the liver is an anatomical divider of the RT and Lt lobes • FL conducts the umbilical vein to the LPV in liver during fetal development. After birth, the umbilical vein atrophies, forming the lig. Teres. (NOTE: This ligament can be seen if ascites is present!!)

  16. Liver ligaments cont. • Ligamentum Teres: • Fibrous, round ligament formed by obliterated fetal umbilical vein, which runs from the umbilicus to the left PV. • Arise from the umbilicus, courses within the free border of FL, in left intersegmental fissure, to the umbilical notch on the ant. surface of the liver. • Continue its course on the inf. surface of the liver as the ligamentumvenosum running posteriorly to the IVC. • On Ultrasound: • Hyperechoic structure in left lobe of liver in caudal aspect of the left intersegmental fissure. • In transverse scan seen as a round hyperechoic density just to the Rt of midline.

  17. Liver ligaments cont. • Ligamentum Venosum: • Obliterated ductus venosus, which until birth shunts the blood from left portal vein to the IVC. • Located between the caudate lobe and the left hepatic lobe. • Anterior to the IVC. • Contains hepatogasteric ligament, • On US- in sag. Echogenic line anterior to the CL and in trans. echogenic. line extending from porta hepatis • Hepatogasteric ligament: • It is continuous with the lig. venosum at the inferior surface of the liver. • Hepatoduodenal ligament: • Surrounds the portal triad at the porta hepatis

  18. Liver Fissures • Main lobar fissure: • Separates the RT and the LT lobes. • Contains the MHV. • Runs obliquely between the neck of the GB and the RPV. • Right intersegmental fissure • Subdivides the Rt lobe into Ant. and Post. segments. • Contains the RHV • Left intersegmental fissure • Contains the LHV • Subdivides the Lt lobe into lateral and medial segments superiorly (Note- lig. Teres forms this boundary inferiorly).

  19. Liver Circulation • Hepatic arteries • Hepatic veins • Portal vein

  20. Liver receives a dual blood supply: • Hepatic arteries-Oxygenated blood from the Aorta: • Celiac axis Common Hepatic art. anterior to the PV and CBD divides into  gastroduodenal artery and the Proper Hepatic artery divides into Right and Left Hepatic arteries. • The Middle Hepatic artery arises from the Lt hepatic art. • The Cystic artery arise from the Rt hepatic art. • Portal vein

  21. Portal venous system • Carries the blood from the spleen and bowel to the liver. • Supply the greatest percentage of total blood flow to the liver (75%). • Formed by the confluence of Splenic vein, IMV, and SMV. • The main portal vein enters the liver posterior to the hepatic artery and CBD  then it divides into RPV and LPV .

  22. Portal venous system

  23. Portal venous system cont. • RPV divides into Rt anterior and Rt posterior branches which supply the ant. and post. segments of the Rt lobe of liver. • LPV initially courses horizontally, ant. to the caudate lobe (Horizontal sag); separates CL posteriorly from medial sag. of Lt lobe anteriorly. • Then the ascending branch of the LPV travels anteriorly in the left intersegmental fissure to divide the medial and lateral segments of the left lobe • a H shape of LPV bifurcation is made from the ascending and horizontal LPV and the segmental branches.

  24. Hepatic veins • Blood perfuses the liver parenchyma through the sinusoids  enters the terminal venules which unite to form the larger veins  Rt, middle, and Lt hepatic veins  drain into IVC. • Hepatic veins like PVs are without valves. • RHV- usually single, runs in the Rt intersegmental fissure, separating the ant. and post. seg. of the Rt lobe. • In most people MHV (which courses in the main lobar fissure) forms a common trunk with the LHV. • LHV forms the most cephalad boundary between the medial and lateral seg. of the left lobe.

  25. Portal Triad • Refers to the hepatic artery, bile duct, and portal vein at the level of the porta hepatis. • At the level of the porta hepatis: • The portal vein lies posterior to the hepatic artery (most posterior vessel in the triad) • HA courses anterior and medial (Rt) to the PV, usually located between PV and CBD. • CBD located anterior and lateral (left) to the PV.

  26. Liver histology • Hexagonal or cylindrical shaped hepatic lobules are the functional unit of the liver. Cellular plates radiate centrifugally from central vein(CV) like spokes of wheel. At each 6 corner is a portal triad containing a portal venule, a bile ductile, and a hepatic arteriole. • Sinusoids are small capillaries with highly permeable endothelial lining located between the cellular plates. It receives mix of PV & HA blood. Blood drains into CV in the middle of each lobule

  27. Liver histology cont. • Unlike other capillaries sinusoids are lined with phagocytes known as Kupffer cells. • Note - Lymphatic system is also included in the Portal Triad which lie in the Hepatoduodenal ligament, and covered by a collagenous sheath which is echogenic on US.

  28. Liver Function • Arterial and venous blood mix in the sinusoids where oxygen, nutrients, and toxic substances are extracted by the hepatic cells. • Liver maintains body’s metabolism by: • storage and release of nutrients • Protein metabolism • Fat metabolism • Carbohydrate metabolism • Bile production and release • Processing of the vitamins • Detoxification- liver is responsible for biotransformation of harmful substances into harmless products which are then excreted by kidneys • Blood volume regulation: in sinusoids

  29. Protein Metabolism • Liver process a variety of proteins: 1-Albumin • Acts as a factor to maintain fluid within the vessels • In sever liver disease  Hypoalbuminemia fluid escapes from the vessels and get collected in body’s cavities  edema in the lower extremities, Ascites

  30. Protein Metabolism cont. 2-Globulin 3- Fibrinogen 4- Prothrombin 5- Factors V, VII, IX, and X • Note- Decrease in production of these proteins may cause hemorrhage due to inadequate blood coagulation. • Deficiency of clotting factors may result from failure of absorption of vitamin K which is a fat soluble vitamin. And is essential for PT synthesis. • PTT and INR are the tests to detect coagulopathies in the patients with liver disease.

  31. Carbohydrate Metabolism • Liver is the major organ to convert sugar to the glucose. • If there is too much glucose, liver store it in the form of glycogen. • In sever liver disease hypoglycemia happens, which may cause dizziness.

  32. Fat Metabolism • Liver converts fats into lipoproteins. • Sever liver disease  hypocholesterolemia. • Fatty liver may happen due to failure of liver to convert fat to lipoproteins.

  33. Bile production and function • Bile is formed continuously by the hepatocytes and transported to the duodenum via the bile ducts. • Bile function: • Fat absorption • Aids in digestion and absorption of vitamin k and other fat soluble vitamins • Removes toxins, cholesterol and metals

  34. Bile Composition: • Water • Cholesterol • Bile salts • Bile pigments- Bilirubin, which is formed from breakdown of hemoglobin (Hb) in spleen and get conjugated (soluble) in liver and excreted in bile.

  35. Bile Secretion • Bile drains from liver into Rt and Lt hepaticducts  that converge to form the Common Hepatic duct  CHD meets the Cystic duct of the GB and this union forms the Common bile duct (CBD). • CBD enters the second portion of theduodenum via the Ampulla of Vater, which is controlled by the Sphincter of Oddi.

  36. Measurement of Bilirubin in the blood • Unconjugated bilirubin = Indirect bilirubin (0.5) • Conjugated bilirubin = Direct bilirubin (1.1) • Note: • Direct Bil. Increases in: • Obstruction • Indirect Bil. Increases in : • Hepatocellular disease • Anemia • Transfusion reactions

  37. Urea Detoxification • Ammonium is toxic product of nitrogen metabolism. • Liver converts it to urea. • Urea is eliminated by kidneys. • Failure of ammonium detoxification is a serious consequence of liver disease

  38. Hepatic Enzymes • Enzymes are protein catalysts utilized by body for protein metabolism and large quantities are present in hepatocytes • If liver cell are damaged  high level of liver enzymes get released in the blood stream, particularly SGOT( AST), SGPT(ALT), and Alkaline phosphatase.

  39. Notes: • SGOT and SGPT increased with hepatocellular disease. • Alkaline Phosphatase Increases more in obstruction than in the hepatocellular damage. • LDH (Lactic dehydrogenase): • Increases in liver disease. • Decreases in bile obstruction • Alpha feto protein: increases in the liver CA • Note- In hepatoma of liver CEA increases. (Carcinoembryonic antigen)

  40. Ultrasound appearance of the liver • Parenchyma: • Homogeneously fine-medium level of echogenicity • Hyperechoic or isoechoic compared to the renal cortex • Hypoechoic compared to the spleen • Fissures: Echogenic • Vessels: PVs and HVs and HA. PVs and HVs are echo-free tubular structures, traveling in the liver lobes and dumping into the main PV and IVC. (Note their differences) • Ducts: Echo free tubular structures, traveling in the liver lobes and dumping into the hepatic ducts, contain echogenic collar, post. enhancement and usually not vis. except when dilated.

  41. Lecture 1 Liver/NormalHomework • Show an image of the ligamentum Teres • Describe the bare area of the liver • Show an image of the coronary ligament • Show an image of the triangular ligaments • Show an image of the falciform ligament • Show an image of the hepatogasteric ligament • Show an image of the Hepatoduodenal ligament • Show an image of the main lobar fissure • Show an image of the right intersegmental fissure • Some an image of the left intersegmental fissure

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