the liver. i.introduction/general information a. largest of viscera 1. ~ 2.5% body weight 2....

THE LIVER

I. Introduction/General Information

A. Largest of viscera

1. ~ 2.5% body weight

2. Completely covered by Glisson’s Capsule

3. Incomplete covering by peritoneum

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

General Information, continued …

B. Location:

1. right hypochondrium

2. epigastrium

C. Mostly covered by ribs

D. Contains numerous vascular structures

II. Detailed Anatomy

A. Four lobes

1. Divisions based on blood supply,

bile drainage

2. Anatomical lobes divided by falciform ligament

Inferior View of the Liver

A

P

Detailed Anatomy, con’t…

3. Functional Lobesa. right and left lobes

separated by imaginary line

b. from fossa for GB IVC

Right and Left Functional Lobes of the Liver

Right Lobe

Left Lobe

Detailed Anatomy, continued …

B. Functional Divisions

1. Right lobe with caudate process

2. Left lobe:

a. Caudate lobe

b. Quadrate lobe

Caudate Process


C. Fissures: 1. Right sagittal (main)2. Left sagittal (accessory)3. Portal4. Right oblique intersegmental5. Lateral intersegmental

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

Fissures of the Liver

Portal fissure T.S. on U/S Created by portal

veins (triads) R. main PV is //

to anterior body wall

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

Functional divisions, continued …

4. Fossae (Superficial)

a. IVC – posterior

b. Portal Vein – inferior

c. Gallbladder – inferior

Fossae, Inferior Surface of the Liver

Fossa for IVC

Fossa for Portal Vein

Fossa for Gall Bladder

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)

Visceral Impressions, continued …

•Esophageal

•Renal

•Gastric

•Adrenal

•Duodenal

•Right colic

•Left colic

L

P

R

A


D. Ligaments

1. Falciform (most superficial anteriorly)a. Divides left lobe in two

sections1. anatomical left lobe 2. caudate & quadrate lobes

b. Two layers of peritoneum c. Extends to umbilicus

Ligaments, continued …

2. Ligamentum teres hepatis

(fetal source??)

3. Ligamentum venosum

(fetal source??)

4. Right/Left Coronary Ligaments

Hepatic Ligaments

Falciform ligament L. coronary ligament L. triangular ligament

Ligamentum teres hepatis

Ligamentum venosum

Ligaments, continued …

5. Hepatophrenic & Hepatorenal ligaments:

a. Subdivisions of right coronary

ligament

b. hepatophrenic (superior) & hepatorenal

(inferior)

c. Surround BARE AREA

Hepatic Ligaments, con’t…

Hepatophrenic ligament

Hepatorenal ligament

Bare Area


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

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

Lesser Omentum

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

Detailed Anatomy, con’t…

E. Subphrenic Spaces

1. clinically important

2. common sites for abscesses

3. Between liver and diaphragm

Subphrenic Spaces, con’t…

4. Right superior posterior subphrenic space

a. Boundaries:- superior: right coronary ligament- anterior: liver- posterior: parietal peritoneum

covering diaphragm

b. Extends inferiorly to….

Subphrenic Spaces, continued …

5. Right posterior inferior subphrenic spacea. Boundaries - above: inferior surface of liver - below: transverse colon &

mesocolonb. Extends over right adrenal &

kidney

Subphrenic Spaces, continued …

c. AKA: Hepatorenal Pouch/Recess, Morrison’s Pouch

d. Patient lying supine:1. Lowest part of peritoneal

cavity is behind liver2. Fluid, pus, etc. collects here3. Can cause abscess

formation

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

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


F. Porta Hepatis: contains the following structures

1. Hepatic arteriesa. Usually two, sometimes oneb. Originate from common/proper

hepatic artery c. Course is variable

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

Porta Hepatis

Hepatic Artery

Portal Vein

Common Bile Duct


3. Hepatic & cystic ducts

4. Nerves:

a. Vagus X (parasympathetic)

b. Fibers from celiac ganglion


4. Lymph nodes:

a. most hepatic lymph vessels end in nodes around porta hepatis

b. From here, drain into celiac nodes


c. Some vessels pass through falciform ligament

1. through diaphragm

2. into mediastinal nodes

d. enlarged nodes may compress portal vein or hepatic duct


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


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

Hepatic Vessels

IVC

Right Portal Vein

Left Portal Vein

Main Portal Vein

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”

Computer-enhanced image of RPV, L.S.

Computer-enhanced 3-D image of RPV, L.S.

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)

Computer-enhanced 3-D image of Hepatic Vessels

Vascular structures, continued …

2. Hepatic Veins: a. Tubular structures b. Enlarge cephalad c. In superior half of liverd. Angles of hepatic vein

branches oriented toward IVCe. Walls not echogenic

Hepatic Veins

R. Hepatic Vein

Middle Hepatic Vein

L. Hepatic Vein


A. Bile Ducts

1. No “normal” anatomy 2. If dilated:

a. Echogenic collar b. Lobulated shapec. Highly branched over short

distancesd. Converge toward porta hepatis

Anatomy of the Biliary System (yeah, right…)

A

P

LR

III. Hepatic Masses

A. May be cystic, solid, or complex

B. Simple Cysts 1. solitary or multiple 2. sonolucent3. well-defined margins4. exhibit posterior acoustic

enhancement5. Congenital cysts may contain cellular debris

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

Hepatic Masses, continued …

C. Complex Masses

1. With central necrosis: irregular walls a. Associated with metastases from

rapidly-growing neoplasmsb. Blood supply can’t supply tumor

growthc. Central part of mass becomes

necrotic

Complex Masses,Hepatic Masses, continued …

2. With cellular or inflammatory debris: a. walls are irregular

b. Associated with hepatic abscessc. Internal bacterial infection

3. Due to echinococcal disease:a. Show irregular wall thicknessb. Parasitic bacteria in sheep feces

Complex Masses, continued …

4.Hematoma: ill-defined borders, sonolucent-to-complex masses

a. Early: appears sonolucent

b. After clot forms, echogenic

c. Due to liver trauma

Hepatic Masses, continued …

D. Solid Masses often represent carcinomas

1. Hepatoma: primary liver cancera. Central necrosis may be

presentb. Tumor thrombus may be

detected impinging on major veins

Solid Masses, Hepatic Masses, continued …

2. Metastatic Liver Diseasea. “Bull’s Eye” or “Target” pattern

[adenocarcinoma of GI Tract]

b. Adenocarcinomas from other sources more echogenic

c. Sonolucent metastases from lymphomas, sarcomas

more complex

IV. Parenchymal Disorders

A. Sonographic appearance: non-specific1. Stroma = supportive connective

tissue2. Parenychma = functional tissue3. Most liver tissue is parenchyma

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

Cirrhosis, Sonographic appearance, continued …

c. Peripheral intrahepatic vessels indistinct

1. reduced blood supply

2. peripheral vessels obscured by scar tissue


d. Lobes may show reduced size:

1. right lobe is more affected

2. left lobe enlargement a. compensation

b. decreased function of right lobe


e. As scar tissue develops, blood flow is affected

1. Blood backs up

2. Spleen and splenic vein enlarge

e. Portal Hypertension


f. Liver margin:

1. indentations

2. changes in contour

3. blunted edges

4. may be observed on U/S


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

Parenchymal Disorders, continued …

C. Fatty Replacement (prior to cirrhosis)1. Appearance similar to cirrhosis2. May be initial stage of cirrhosis3. Difference:

a. Intrahepatic vessels remain clearly defined

b. No portal HTN

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

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

Other disease conditions, continued …

6. Thrombosis of IVC may show similarities

-thrombus can be detected

7. Other signs:

a. Ascites

b. dilation of right atrium

Other diseases and conditions, continued …

B. Liver Abscesses:

1. Commonly found in hepatorenal pouch

2. Appear cystic with irregular borders and fine

precipitates


C. Obstructive Jaundice:

1. Result of obstruction of bile flow

2. Dilation of intrahepatic bile ducts

3. Ultrasound can differentiate between obstructive and hepatocellular jaundice

Dilated CBD: seen in Obstructive Jaundice


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


E. Klatskin Tumor:

1. Ducts are blocked or fused a. Tumor at junction of Right

and Left Hepatic Ducts

b. Causes obstructive jaundice


F. Courvasier’s Sign:

1. Refers to gallbladder “rate of fill” with tumor vs. stone

2. Hydrops (edema) of gallbladder due to tumor in head of

pancreas


G. Reidel’s Lobe:

1. Anomalous, tongue-like extension

2. From right lobe of liver to the gallbladder

Reidel’s Lobe

R. Lobe L. Lobe

GB

Reidel’s LobeReidel’s Lobe

VI. Miscellaneous Data

A. Portal Vein: Measurements

1. Length = 5.5 – 8.0 cm (average = 6.5)

2. Diameter = ~ 1 cm

Misc. Data, continued …

B. Ampulla of Vater

1. Length = 1 – 14 mm

2. Width = 1.5 – 4.5 mm

the liver. i.introduction/general information a. largest of viscera 1. ~ 2.5% body weight 2....

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