THE LIVER

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THE LIVER
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• Introduction/General Information
• A. Largest of viscera
• 1. 2.5 body weight
• 2. Completely covered by Glissons
  Capsule
• 3. Incomplete covering by peritoneum

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General Information, continued 4.
Measurements are a. 21 23 cm
transverse b. 15 18 cm superior
to inferior c. 10 13 cm anterior
to posterior
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• General Information, continued
• Location
• 1. right hypochondrium
• 2. epigastrium
• C. Mostly covered by
  ribs
• D. Contains numerous
  vascular structures

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II. Detailed Anatomy A. Four lobes 1.
Divisions based on blood
supply, bile
drainage 2. Anatomical lobes divided by
falciform ligament
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Inferior View of the Liver
A
P
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Detailed Anatomy, cont 3. Functional
Lobes a. right and left lobes separated by
imaginary line b. from fossa for GB ?
IVC
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Right and Left Functional Lobes of the Liver
Left Lobe
Right Lobe
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• Detailed Anatomy, continued
• Functional Divisions
• Right lobe
  with caudate process
• Left lobe
• a. Caudate lobe
• b. Quadrate lobe

Caudate Process
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(No Transcript)
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Detailed Anatomy, continued C. Fissures
1. Right sagittal (main) 2. Left sagittal
(accessory) 3. Portal 4. Right oblique
intersegmental 5. Lateral intersegmental
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Fissures of the Liver

• Main lobar fissure
• Boundary between R and L lobes
• L.S. on U/S seen as hyperechoic line from PV to
  neck of GB
• Used to ID GB when it is packed with stones

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Fissures of the Liver

• Portal fissure
• T.S. on U/S
• Created by portal veins (triads)
• R. main PV is // to anterior body wall

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Segments of the Liver

• Hepatic segments
• I caudate lobe
• II III superior and inferior lateral
  segments, L. lobe
• IV medial segment, L. lobe
• V VI caudal to transverse plane
• VII VIII cephalad to transverse plane

I
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Functional divisions, continued 4. Fossae
(Superficial) a. IVC posterior b. Portal
Vein inferior c. Gallbladder inferior
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Fossae, Inferior Surface of the Liver

• Fossa for IVC
• Fossa for Portal Vein
• Fossa for Gall Bladder

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Functional Divisions, continued 5.
Impressions (visceral surface) produced by
abdominal viscera a. Gastric (fundus of
stomach) b. Renal (right kidney) c. Adrenal
(right adrenal gland) d. Duodenal (bulb of
duodenum) e. Esophageal (esophagus) f.
Right and left colic (flexures of the
colon)
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Visceral Impressions, continued
P

• Esophageal
• Renal
• Gastric
• Adrenal
• Duodenal
• Right colic
• Left colic

L
R
A
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Detailed Anatomy, continued D. Ligaments
1. Falciform (most superficial
anteriorly) a. Divides left lobe in two
sections 1. anatomical left lobe 2.
caudate quadrate lobes b. Two layers of
peritoneum c. Extends to umbilicus

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Ligaments, continued 2. Ligamentum teres
hepatis (fetal source??) 3. Ligamentum
venosum (fetal source??) 4. Right/Left
Coronary Ligaments
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Hepatic Ligaments

• Falciform ligament
• L. coronary ligament
• L. triangular ligament
• Ligamentum teres hepatis
• Ligamentum venosum

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Ligaments, continued 5. Hepatophrenic
Hepatorenal ligaments a. Subdivisions
of right coronary ligament b.
hepatophrenic (superior) hepatorenal
(inferior) c. Surround BARE AREA
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Hepatic Ligaments, cont

• Hepatophrenic ligament
• Hepatorenal ligament

Bare Area
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Detailed Anatomy, continued E. Lesser
Omentum 1. Sleeve-like structure 2. Connects
lesser curvature of stomach bulb of duodenum
to inferior surface of liver 3. AKA
Gastrohepatic or Hepatoduodenal ligament
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Lesser Omentum, continued 3.
Attachment surrounds Porta Hepatis 4.
Continues on each side of ligamentum
venosum 5. Extends to caudate left lobes
on posterior surface of liver
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Lesser Omentum

• Lesser Omentum (R) Anterior view, (L) Inferior
  view

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• Detailed Anatomy, cont
• E. Subphrenic Spaces
• clinically important
• common sites for abscesses
• Between liver and diaphragm

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Subphrenic Spaces, cont 4. Right superior
posterior subphrenic space a.
Boundaries - superior right coronary
ligament - anterior liver - posterior
parietal peritoneum covering
diaphragm b. Extends inferiorly to.
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Subphrenic Spaces, continued 5. Right
posterior inferior subphrenic space a.
Boundaries - above inferior surface of
liver - below transverse colon
mesocolon b. Extends
over right adrenal kidney
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Subphrenic Spaces, continued c. AKA
Hepatorenal Pouch/Recess, Morrisons
Pouch d. Patient lying supine 1. Lowest
part of peritoneal cavity is behind
liver 2. Fluid, pus, etc. collects
here 3. Can cause abscess formation
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Subphrenic spaces, continued 6. Right
superior anterior subphrenic space a.
Boundaries - right side of falciform
ligament - upper layer of right coronary
ligament - underside of diaphragm -
superior surface of liver b. Found when
patient lying prone
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Subphrenic spaces, continued 7. Most
sources of peritoneal contamination are on
the right 8. Right posterior right
inferior spaces are most significant sites
9. Infection may spread via
diaphragmatic lymphatics
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Detailed Anatomy, continued F. Porta
Hepatis contains the following
structures 1. Hepatic arteries a.
Usually two, sometimes one b. Originate from
common/proper hepatic artery c.
Course is variable
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Porta Hepatis, continued 2. Portal vein
(supplies 1100 ml/blood per minute) a.
Largest structure in porta b. Formed by
confluence of mesenteric veins
splenic vein
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Porta Hepatis
Hepatic Artery Portal Vein Common Bile Duct
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• Porta Hepatis, continued
• 3. Hepatic cystic ducts
• 4. Nerves
• a. Vagus X (parasympathetic)
• b. Fibers from celiac ganglion

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• Porta Hepatis, continued
• 4. Lymph nodes
• a. most hepatic lymph vessels end in
  nodes around porta hepatis
• b. From here, drain into celiac nodes

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Porta Hepatis, continued c. Some vessels
pass through falciform ligament 1.
through diaphragm 2. into mediastinal
nodes d. enlarged nodes may compress
portal vein or hepatic duct
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Detailed Anatomy, continued G. Vascular
Structures in Liver 1. Largest vessels are
portal vein and IVC a. Portal Vein 1.
appears on T.S. as tubular, echolucent
structure 2. courses horizontally
from porta hepatis
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Detailed Anatomy, continued 3. walls
echogenic due to structures in
portal triad b. Left Portal Vein 1.
has more variable course 2. May be
difficult to trace on transverse scans
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Hepatic Vessels

• IVC
• Right Portal Vein
• Left Portal Vein
• Main Portal Vein

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Vascular Structures, continued c.
Right Portal Vein 1. anatomical
landmark 2. extends into right lobe 3.
branches after porta hepatis 4. L.S. shows
dumbbell or circular structure with
echogenic collar
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Computer-enhanced image of RPV, L.S.
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Computer-enhanced 3-D image of RPV, L.S.
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Vascular Structures, continued d. IVC
1. To right of aorta 2. Appears to pass
through liver 3. Diameter enlarges after
renal veins join (L-1)
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Computer-enhanced 3-D image of Hepatic Vessels
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Vascular structures, continued 2. Hepatic
Veins a. Tubular structures b. Enlarge
cephalad c. In superior half of liver d.
Angles of hepatic vein branches
oriented toward IVC e. Walls not echogenic
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Hepatic Veins
R. Hepatic Vein Middle Hepatic Vein L. Hepatic
Vein
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• Detailed Anatomy, continued
• Bile Ducts
• 1. No normal anatomy
• 2. If dilated
• a. Echogenic collar
• b. Lobulated shape
• c. Highly branched over short
  distances
• d. Converge toward porta hepatis

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Anatomy of the Biliary System (yeah, right)
P
L
R
A
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III. Hepatic Masses A. May be cystic, solid,
or complex B. Simple Cysts 1. solitary or
multiple 2. sonolucent 3. well-defined
margins 4. exhibit posterior acoustic
enhancement 5. Congenital cysts may contain
cellular debris
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Simple Cysts, Hepatic Masses, continued 6.
Polycysts usually accompany cysts of
kidney, spleen, and/or pancreas 7. Appearance
a. Wall is distinct, sharp
border, crisp edges b. Shape
spherical
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Hepatic Masses, continued C. Complex
Masses 1. With central necrosis irregular
walls a. Associated with metastases from
rapidly-growing neoplasms b. Blood
supply cant supply tumor
growth c. Central part of mass becomes
necrotic
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Complex Masses,Hepatic Masses, continued
2. With cellular or inflammatory debris
a. walls are irregular b. Associated
with hepatic abscess c. Internal bacterial
infection 3. Due to echinococcal
disease a. Show irregular wall
thickness b. Parasitic bacteria in sheep feces
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• Complex Masses, continued
• Hematoma ill-defined borders,
  sonolucent-to-complex masses a. Early
  appears sonolucent
• b. After clot forms, echogenic
• c. Due to liver trauma

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Hepatic Masses, continued D. Solid Masses
often represent carcinomas 1. Hepatoma
primary liver cancer a. Central necrosis may
be present b. Tumor thrombus may be detected
impinging on major veins
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Solid Masses, Hepatic Masses, continued 2.
Metastatic Liver Disease a. Bulls Eye or
Target pattern adenocarcinoma of GI
Tract b. Adenocarcinomas from other
sources more echogenic c. Sonolucent
metastases from lymphomas, sarcomas
more complex
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• IV. Parenchymal Disorders
• A. Sonographic appearance non-specific
• 1. Stroma supportive connective
  tissue
• 2. Parenychma functional tissue
• 3. Most liver tissue is parenchyma

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Parenchymal disorders, continued B.
Cirrhosis Most common 1. Due to hepatitis or
alcoholism 2. Sonographic appearance a.
Moderately echogenic b. Liver denser than
normal c. Due to formation of scar tissue
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Cirrhosis, Sonographic appearance, continued
c. Peripheral intrahepatic vessels
indistinct 1. reduced blood supply 2.
peripheral vessels obscured by scar
tissue
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• Cirrhosis, Sonographic appearance, continued
• d. Lobes may show reduced size
• 1. right lobe is more affected
• 2. left lobe enlargement a.
  compensation
• b. decreased function of right
  lobe

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Cirrhosis, Sonographic appearance, continued
e. As scar tissue develops, blood
flow is affected 1. Blood backs up 2.
Spleen and splenic vein enlarge e.
Portal Hypertension
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Cirrhosis, Sonographic appearance, continued
f. Liver margin 1. indentations 2.
changes in contour 3. blunted edges 4. may
be observed on U/S
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Cirrhosis, Sonographic appearance, continued
g. Increased incidence of hepatoma in
advanced cirrhosis h. detection of ascites
aids in differential diagnosis 1.
Ascites fluid in peritoneal cavity 2.
Due to portal HTN
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Parenchymal Disorders, continued C. Fatty
Replacement (prior to cirrhosis) 1.
Appearance similar to cirrhosis 2. May be
initial stage of cirrhosis 3. Difference
a. Intrahepatic vessels remain clearly
defined b. No portal HTN
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V. Other Diseases and Conditions A.
Congestive Hepatomegaly 1. Enlargement of
liver secondary to congestive heart
failure 2. Homogeneous liver rarely shows
echo changes 3. Tissue attenuation may
decrease as liver fills with blood
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• Other Disease Conditions, continued
• 4. Marked dilation of IVC without
  respiratory influence is proof of right
  heart failure
• 5. Hepatic vein branches may show
  enlargement

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Other disease conditions, continued 6.
Thrombosis of IVC may show similarities -th
rombus can be detected 7. Other signs
a. Ascites b. dilation of right atrium
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Other diseases and conditions, continued B.
Liver Abscesses 1. Commonly found in
hepatorenal pouch 2. Appear cystic
with irregular borders and fine
precipitates
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• Other Disease Conditions, continued
• Obstructive Jaundice
• 1. Result of obstruction of bile flow
• 2. Dilation of intrahepatic bile ducts
• 3. Ultrasound can differentiate
  between obstructive and hepatocellular
  jaundice

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Dilated CBD seen in Obstructive Jaundice
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Other Disease Conditions, continued
D. Hepatic Artery Aneurysm 1. May
stimulate hepatic abscess 2. Usually appears as
sonolucency with surrounding
echogenic area (thrombus) 3. Flow of blood
changes as blood swirls and clots
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• Other Disease Conditions, continued
• Klatskin Tumor
• 1. Ducts are blocked or fused
  a. Tumor at junction of Right and
  Left Hepatic Ducts
• b. Causes obstructive jaundice

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Other Disease Conditions, continued F.
Courvasiers Sign 1. Refers to gallbladder
rate of fill with tumor vs.
stone 2. Hydrops (edema) of gallbladder
due to tumor in head of pancreas
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Other Disease Conditions, continued G.
Reidels Lobe 1. Anomalous, tongue-like
extension 2. From right lobe of liver
to the gallbladder
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Reidels Lobe
R. Lobe
L. Lobe
GB
Reidels Lobe
Reidels Lobe
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VI. Miscellaneous Data A. Portal Vein
Measurements 1. Length 5.5 8.0 cm
(average 6.5) 2. Diameter 1
cm
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Misc. Data, continued B. Ampulla of
Vater 1. Length 1 14 mm 2. Width 1.5
4.5 mm