THE LIVER. I.Introduction/General Information A. Largest of viscera 1. ~ 2.5% body weight 2....
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Transcript of 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
Detailed Anatomy, continued …
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
Detailed Anatomy, continued …
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
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
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
Detailed Anatomy, continued …
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
Porta Hepatis, continued …
3. Hepatic & cystic ducts
4. Nerves:
a. Vagus X (parasympathetic)
b. Fibers from celiac ganglion
Porta Hepatis, continued …
4. Lymph nodes:
a. most hepatic lymph vessels end in nodes around porta hepatis
b. From here, drain into celiac nodes
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
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
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
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
Detailed Anatomy, continued …
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
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
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
Cirrhosis, Sonographic appearance, continued …
f. Liver margin:
1. indentations
2. changes in contour
3. blunted edges
4. may be observed on U/S
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
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
Other Disease Conditions, continued …
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
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
Other Disease Conditions, continued …
E. Klatskin Tumor:
1. Ducts are blocked or fused a. Tumor at junction of Right
and Left Hepatic Ducts
b. Causes obstructive jaundice
Other Disease Conditions, continued …
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
Other Disease Conditions, continued …
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