Download Abdominal Sonography Part 1 Lecture 1 Liver . Normal

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
 The entire liver is covered in a thin fibrous
connective tissue layer called Glisson’s capsule
and is thickest around the IVC and the porta
hepatis.
 Morison’s pouch- potential space located
between the right kidney and liver
Size
 Size and shape variable, has a basic wedge shape, tapering toward the
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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
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
Liver lobes: Three lobes
 Right
lobe
 Left lobe
 Caudate lobe
Liver lobes cont.
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Right lobe:
 Right of an imaginary line between the GB fossa
and IVC
 Divided by right intersegmental fissure into:
 Anterior segment
 Posterior segment
Liver lobes cont.
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Left lobe:
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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.
Liver lobes cont.
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Caudate lobe:
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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.
Inferior surface of the liver
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:
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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.
Liver: anatomic relationship
 Superior, posterior and anterior surfaces: Dome of
diaphragm
 Left lobe:
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Anteriorly bounded by the ribs and abd. Wall
Posteriorly rests on the stomach
 Right lobe:
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Anteriorly bounded by the abdominal wall and ribs
Posteriorly rests on the GB, right adrenal gland,
upper pole of the Rt kidney.
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
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Liver
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.
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!!)
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
ligamentum venosum running posteriorly to the IVC.
 On Ultrasound:
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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.
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
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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).
Liver Circulation
 Hepatic arteries
 Hepatic veins
 Portal vein
Liver receives a dual blood supply:
 Hepatic arteries- Oxygenated blood from the
Aorta:
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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
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 .
Portal venous system
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.
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.
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:
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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.
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
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.
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
Protein Metabolism
 Liver process a variety of proteins:
1- Albumin
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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
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.
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.
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.
Bile production and function
 Bile is formed continuously by the hepatocytes
and transported to the duodenum via the bile
ducts.
 Bile function:
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Fat absorption
Aids in digestion and absorption of vitamin k and
other fat soluble vitamins
Removes toxins, cholesterol and metals
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.
Bile Secretion
 Bile drains from liver into Rt and Lt hepatic
ducts  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 the duodenum
via the Ampulla of Vater, which is controlled by
the Sphincter of Oddi.
Measurement of Bilirubin in the blood
 Unconjugated bilirubin = Indirect bilirubin (0.5)
 Conjugated bilirubin = Direct bilirubin (1.1)
 Note:
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Direct Bil. Increases in:
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Obstruction
Indirect Bil. Increases in :
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Hepatocellular disease
Anemia
Transfusion reactions
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
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.
Notes:
 SGOT and SGPT increased with hepatocellular
disease.
 Alkaline Phosphatase Increases more in
obstruction than in the hepatocellular damage.
 LDH (Lactic dehydrogenase):
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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)
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.
Lecture 1 Liver/Normal
Homework
 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