Liver Anatomy (2) - Day 1 PDF

1 oThe liver is the largest organ in the body and is quite accessible to sonographic evaluation oThe parenchyma of the normal liver is used to evaluate other organs in the body 2 The kidneys are equally echogenic or less echogenic than the liver 3 What do we call it...

1 oThe liver is the largest organ in the body and is quite accessible to sonographic evaluation oThe parenchyma of the normal liver is used to evaluate other organs in the body 2 The kidneys are equally echogenic or less echogenic than the liver 3 What do we call it when the liver appears echogenic (brighter) than the kidney parenchyma? Answer: Fatty liver, echogenic liver, hepatic/liver steatosis. 4  Liver measurement A normal liver usually measures less than 16cm. 5 The pancreas is equally echogenic or slightly more echogenic than the liver 6  Normal Sonographic Anatomy A. Sagittal image of right liver lobe demonstrates homogeneous echo pattern of hepatic parenchyma as isoechoic or mildly hyperechoic in comparison to renal parenchyma. B. Transverse image demonstrates the homogeneous echo pattern with hepatic veins and inferior vena cava identified within normal hepatic parenchyma. Occupies almost all the right hypochondrium, the greater part of epigastrium and the left hypochondrium as far as the mammillary line 8 9  Liver is Inferior to the diaphragm The stomach lies posterior and lateral to the left lobe Duodenum are located adjacent to the right lobe 10 11 12 13 14 The anterior, superior,and posterior aspects of the liver are related to the diaphragm and follow its configuration 15 Diaphragm on ultrasound 16 The liver is suspended from the diaphragm and anterior abdominal wall by the falciform ligament. 17 The falciform ligament and the ligamentum teres divide the right and left lobes of the liver by surface anatomy 18 19 Most of the liver is enclosed in the peritoneum. An exception to this is a triangular space on the posterior surface, called the bare area 20  a l e n r e a ito a e r re a p b a r t he in t an for i s t e r e p il v exc h e n T ga or 21 22 Right lobe: Six times larger than the left lobe Has three fossae along the posterior and visceral surface: porta hepatis, gallbladder and IVC Left lobe: Lies left of the falciform ligament Caudate lobe: Lies posterior to the porta hepatis Anterior to the IVC Posterior to the ligamentum venosum Superior to the main portal vein 23  Porta hepatis SAG Porta hepatis Trans 24 25 26 27 28 29 30 31 oA Riedel’s lobe is a congenital variant. oCan be seen as an anterior projection of the liver and may extend to the iliac crest 32 oA tonguelike process occasionally extending downward from the right lobe of the liver laterally to the gallbladder. 33 A B A. An image of a Riedel lobe on a 36-year-old woman demonstrating this normal variant as an extension of liver tissue past the right kidney. B. Using the extended field of view option to demonstrate the entire length of a patient with a Riedel lobe. Copyright © 2018 Wolters Kluwer All Rights Reserved  COUINAUD’S SEGMENTS oIs a system that provides the anatomic basis for hepatic surgical resections. oIs based on the portal and hepatic venous segments oDivide the liver into 8 segments 35 36  Liver segmentation creates 8 functionally separate liver segments, counted in a clockwise fashion. Caudate lobe is segment I Left lobe makes up segments II through IV Right lobe makes up segments V through VIII. Division is based on hepatic veins and portal vein branches. Each segment has a central portal vein branch, hepatic artery, and bile duct. Hepatic veins provide boundaries of each segment. Copyright © 2018 Wolters Kluwer All Rights Reserved  CT and MRI report pathology based on the 8 segments. Nomenclature provides critical knowledge regarding hepatic surgery —potential to perform large resections while minimizing blood loss and morbidity. Allows major resections up to 75% of liver tissue, providing 2 or 3 segments remain uncompromised. 38 39 40 41 42 Anatomy—Lobes—Segmental Divisions A. A “see-through” anterior to posterior profile. B. A sectional illustration through vertical plane B. B C. Parasagittal scan displays a portion of the main lobar fissure (MLF), a linear echogenic line extending from RPV to GB separating the right lobe (RL) C from left lobe (LL). Copyright © 2018 Wolters Kluwer All Rights Reserved Anatomy—Lobes—Segmental Divisions Anatomy—Lobes—Segmental Divisions H I Anatomy—Lobes—Segmental Divisions Anatomy—Lobes—Segmental Divisions L M Anatomy—Lobes—Segmental Divisions N LIGAMENTS AND FISSURES oGlisson’s capsule oMain lobar fissure oFalciform ligamentus oLigamentus Teres oLigamentum venosum 49 oGlisson’s capsule: is a thin connective tissue layer that surround the liver oThe main lobar fissure: is the boundary between the right and left lobes of the liver. On the longitudinal scan, it may be seen as a hyperechoic line extending from the Portal vein to the neck of the GB 50 Parasagittal scan displays a portion of the main lobar fissure, a linear echogenic line extending from RPV to GB separating the right lobe from left lobe. 51 MAIN LOBAR FISSURE 52 53 oThe falciform ligament: extends from the umbilicus to the diaphragm. Within this ligament is a ligamentum teres which is a remnant of the old umbilical vein. 54 In patients with ascites, falciform ligament (arrow) can be identified coursing between the anterior abdominal wall and the left lobe of the liver 55 oThe ligamentus Teres: appears as a bright triangular shaped, echogenic fossa. oIs the rounded termination of the falciform ligament oIs the umbilical vein in fetal life oDivide the medial and lateral segments of the left lobe of the liver 56 LIGAMENTUS TERES 57 58 oThe fissure for the ligamentum venosum separetes the left lobe from the caudate lobe. oOn ultrasound, it may be seen anterior to the IVC oThe caudate lobe is located on the posterior-superior surface of the right lobe. It is located posterior to the porta hepatis between the fissure for the ligamentum venosum and the IVC 59 LIGAMENTUM VENOSUM 60 61 62 63 Parasagittal image demonstrates a small vein (arrows) draining directly from the CL into the IVC. 64 65 66 Transducer in TRANS 67 Transducer in SAG 68 Landmarks to divides the right and left lobes: Main lobar fissure The Gallbladder fossa inferiorly The IVC posteriorly The middle hepatic vein superiorly 69 Ligament Description Connects posterosuperior liver surface to diaphragm and consists of an anterior and a posterior layer. The anterior layer is formed by reflection of the parietal peritoneum and the posterior layer is reflected from the caudal margin of the bare area onto the right adrenal gland and right kidney Coronary (hepatorenal ligament). These two layers are continuous on each side with the right and left triangular ligaments and anteriorly with the falciform ligament. Broad, thin anteroposterior fold of the parietal peritoneum. It originates from the midportion of the coronary ligament; inserts itself in a parasagittal plane anteriorly and shifts obliquely to its posterior surface; separates right and left liver lobes at the anterior surface; and extends from the liver to the Falciform abdominal wall between the diaphragm and the umbilicus. At its base or free edge, the ligamentum teres is released from between its layers. Is a fibrous cord resulting from the obliterated left umbilical vein. It ascends from the umbilicus in free margin of the falciform ligament to the notch in Ligamentum teres anterior liver border. Here, it courses along a fissure on the visceral surface aka: Round ligament and continues as the ligamentum venosum as far back as the inferior vena cava. Obliterated ductus venosus is usually attached to the left branch of the portal vein. It is a continuance of the ligamentum teres within the left Ligamentum intersegmental fissure on the superior, visceral surface of the liver. The venosum upper part of the lesser omentum is also attached to the margins of the Copyright © 2018 Wolters Kluwer All Rights Reserved fissure. Ligament Description Right and left triangular ligaments have a triangular shape. They are formed by apposition of the upper and lower ends of the coronary ligament and extend from the liver to the diaphragm. The right ligament is attached to the border at the right extremity of the bare area and passes to the diaphragm. The left ligament is the larger of the two and attaches to the Triangular superior surface of the left lobe, where it lies anterior to the esophageal opening in the diaphragm. Its anterior layer is continuous with the left layer of the falciform ligament. Composed of two folds of visceral peritoneum. Originates on the undersurface of the liver, is continuous with the ligamentum venosum, and Gastrohepatic courses caudally to attach to the lesser curvature of the stomach and to the aka: Lesser omentum first portion of the duodenum. Surrounds portal triad (portal vein, hepatic artery, and bile duct) prior to entering the porta hepatis. Located on the right free edge of the gastrohepatic ligament forming the anterior boundary of the epiploic foramen (foramen of Winslow), a potential space representing the only communication of the lesser sac with the rest of the peritoneal cavity. The IVC and caudate lobe form the posterior wall of the lesser sac. The size of Hepatoduodenal caudate process, in part, determines the length of the hepatoduodenal ligament and its proximity to the IVC. Below the caudate process, the portal vein, within the hepatoduodenal ligament, is contiguous with the posteriorly located IVC. Copyright © 2018 Wolters Kluwer All Rights Reserved 72  Microanatomy The hepatic parenchyma consists of hepatocytes intermixed with reticuloendothelial cells called Kupffer cells. Within the lobule, the hepatocytes are arranged radially in cords around a central hepatic venule with adjacent arteriole 73 VASCULAR SUPPLY: oThe liver received a dual blood supply from the portal vein and the hepatic artery oThe PV carries poor oxigenated blood from the intestines and spleen but rich in nutrients. o It supplies the half oxygen requirements of the hepatocytes because of its greater flow oThis dual blood supply explains the low incidence of hepatic infarction 75  1.Hepatic arterial blood is oxygen rich. 2.Portal venous blood is nutrient rich after it traverses the walls of the gastrointestinal tract. Blood from portal vein and hepatic arteries mixes in liver sinusoids. Hepatic veins drain the blood into the IVC. 76 Nutrient-rich blood flows in from the hepatic portal vein Oxygenated blood flows from the hepatic artery 77  1. Main portal vein: approaches the porta hepatics in rightward. It then divides into the right and left portal veins Portal venous system 2. Right portal vein: is the larger of the branches. More posterior The normal diameter of 3. Left portal vein: is the portal vein ranges more anterior and between 1.0 and 1.6 cm. The average is 1.3 cm. cranial than the right. 78 Measuring the main portal vein 79 The portal venous system is responsible for the draining of blood from the spleen, digestive system, pancreas and gallbladder. 80 Main Portal Vein (MPV) with and without color 81 Normal hepatopetal portal vein flow (toward the liver: from the intestines to the liver) 82 The main portal vein divides into right and left branches The IVC is seen posteriorly. 83  I J Portal Veins I. Transverse image: main portal vein (MPV) is seen entering liver. Inferior vena cava (IVC). J. Transverse scan demonstrates left portal vein (LPV) dividing into the Copyright medial andKluwer © 2018 Wolters lateral branches. All Rights Reserved  L K K.Transverse scan shows right portal vein (RPV) dividing into anterior (ANT) and posterior (POST) segmental branches. L.Oblique color Doppler scan through RPV and LPV demonstrates flow away from the transducer (blue) in RPV branch and flow toward transducer (red) in the LPV branch. IVC, inferior vena cava. Copyright © 2018 Wolters Kluwer All Rights Reserved  P O O.Normal architecture of relationship of common bile duct (CBD) with portal vein (PV) and hepatic artery (HA). P.Gray-scale image and color Doppler image. The parallel-channel sign represents dilated bile ducts (structures void of color) and the portal veins (vessels with color). Copyright © 2018 Wolters Kluwer All Rights Reserved  ARTERIAL CIRCULATION: The liver receives its nutrients from the portal vein and hepatic artery. The portal vein provides 70-75 % of the total volume of incoming blood to the liver. It is 80 % saturated with oxygen, allowing for 50-60 % of the oxygen requirements of the hepatocytes. 87  Common hepatic artery branches off celiac axis, passes anterior, and to the right to enter right margin of gastrohepatic ligament. Hepatic artery lies to left of common bile duct and anterior to portal vein. It turns cephalad and gives three branches: Gastroduodenal artery Supraduodenal artery Right gastric artery 88 89 Hepatic artery The hepatic artery is pulsatile and can therefore appear to have both blue and red when you put color on it. 90 E F  Hepatic Veins Best visualized on transverse scans in superior portion of liver. Drain directly into the superior aspect of IVC and all 3 (RHV, MHV, LHV) should be demonstrated routinely. RHV is largest and courses between anterior and posterior branches of RPV Located in the right intersegmental fissure Divides the right hepatic lobe into its anterior and posterior segments. Copyright © 2018 Wolters Kluwer All Rights Reserved The right, middle and left hepatic veins divide the liver in four segments LEFT LH LOBE V MH LS V RIGHT MS LOBE AS RHV IVC PS 93  LHV MS MHV LS AS RHV IVC PS 94 Hepatic vein doppler 95  Q R Q. Right hepatic vein (RHV), middle hepatic vein (MHV), and left hepatic vein (LHV) are seen in transverse scan draining into inferior vena cava (IVC). Transducer placement is high in the liver. R. On this transverse color Doppler image, all three hepatic veins are seen with hepatofugal flow, which represents flow exiting the liver. Copyright © 2018 Wolters Kluwer All Rights Reserved Porta (gate) Hepatis (liver) A fissure where portal vein and hepatic artery enter liver and bile duct exits liver. In normal relationship, three structures within hepatoduodenal ligament are: 1. Bile duct is ventral and lateral, 2. Hepatic artery is ventral and medial, and 3. Portal vein is dorsal. Evaluate structures and measure bile duct placing calipers along inner duct wall to opposing inner duct wall. Copyright © 2018 Wolters Kluwer All Rights Reserved  Published values for normal internal diameter of bile duct vary from 4 mm to 8 mm. Hepatic artery maximum internal diameter is reported to be 2 mm to 6 mm. Color Doppler helps in distinguishing bile duct from hepatic artery due to the presence of flow in the artery and absence of flow in the bile duct. Copyright © 2018 Wolters Kluwer All Rights Reserved 99 Physiology Liver is essential to life performing >500 separate activities. Single liver cell diverse activities analogous to: Factory for many chemical compounds Warehouse with short- and long-term storage capabilities Power plant producing heat Waste disposal plant excreting waste Scientist is able to regenerate tissue not too severely damaged Copyright © 2018 Wolters Kluwer All Rights Reserved  Physiology Three types of cells carry out these functions: Hepatocyte in parenchyma Most abundant cell carries out most metabolic functions Biliary epithelial cells Line biliary system, bile ducts, canaliculi, gallbladder Kupffer cells Phagocytic Belong to the reticuloendothelial system Line the sinusoids Hepatic diseases alter these functions and produce identifiable clinical manifestations  Microscopic Structures 103 Quiz Which ligament surrounds the portal triad? A. Hepatoduodenal B. Gastrohepatic C. Triangular D. Ligamentum teres Quiz Which scanning plane is best to visualize hepatic veins? A. Parasaggital B. Transverse C. Oblique D. Coronal Quiz Which universal nomenclature is used for hepatic lesion localization? A. Anatomic divisions B. Right, left, and caudate lobular C. Couinaud’s hepatic segment D. Vascular branching Quiz Which cell type is most abundant in the liver parenchyma and carries out most metabolic functions? A. Epithelial B. Hepatocyte C. Lobule D. Kupffer The portal vein carry blood from the LIVER BOWEL to the ________. ________ The hepatic veins drain the blood fromLIVER IVC the ______ into the _______ The hepatic arteries carry OXYGENATED AORTA ____________ blood from the ______ to LIVER the ______ The ____________ BILE DUCTStransport the bile manufactured in theLIVER ________ to the DUODENUM __________ 108 This anatomical variant can be seen as an anterior, tongue like projection of the liver that may extend to the iliac crest: A.Hepatomegaly B.Riedel’s lobe C.Cirrhosis D.Fatty Liver 109 Flow in the portal vein can best be described as: A.Hepatopetal B.Hepatofugal 110 The common bile duct is found anterior to which anatomical structure in the liver? a.Hepatic vein b.Hepatic artery c.Portal vein d.Cystic vein 111