Ch 7: Liver

Normal liver parenchyma sonographic appearance

homogeneous with medium level echoes. portal and hepatic veins appear as tubular fluid-filled structures. slightly more echogenic/isoechoic than renal cortex but less echogenic than pancreas and spleen

Liver Embryology: 4th week of development

Liver, GB, and bile duct system form from hepatic diverticulum

Liver Embryology: 6th week of development

right lobe increases in size, caudate forms from right lobe, and left lobe degenerates (becomes smaller). hemopoiesis occurs (formation of blood)

When does hemopoiesis occur, peak, and cease

occurs at week 6, peaks at 12-24 weeks, and ceases at birth

Liver Embryology: 10th week of development

Lymphocyte (WBC) formation and coagulation factors (10-12 weeks)

Liver Embryology: 13-16th week of development

Bile production begins

When does liver function in digestion

not until birth

What does the umbilical vein do

provides oxygenated blood and nutrients to fetus, and divides into left and right branches

Left branch of umbilical vein

Joins portal vein and enters the liver. after birth it becomes ligamentum teres (right ligament)

Right branch of umbilical vein

ductus venous, bypasses liver and flows directly into IVC. after birth it becomes ligamentum venosum

What ligaments can become recanalized and by what

ligamentum teres and venosum from portal hypertension

Why is color Doppler useful when evaluating a possible recanalized umbilical vessel

A recanalized vessel can resemble a contracted gallbladder, and color Doppler can confirm blood flow

Liver Physiology

It is an essential organ for life by performing >500 activities. some activities are:

• factory for many chemical compounds

• warehouse with short and long term storage capabilities

• power plant producing heat

• waste disposal plant excreting waste

• chemistry lab regenerating tissue not too severely damaged

The types of cells that carry out liver functions

Hepatocyte in parenchyma, biliary epithelial cells, and Kupffer cells

Function of Hepatocytes

most abundant cell carries out most metabolic functions

Function of Biliary epithelial cells

line biliary system, bile ducts, canaliculi, and gallbladder

Function of Kupffer cells

Phagocytic (breakdown/eat structures/toxins that are not good for liver), belong to the reticuloendothelial system, and line the sinusoids

What does hepatic disease do to cell function

It alters the functions and produce identifiable clinical manifestations

What is Hepatomegaly

Enlarged liver beyond normal size

Hepatomegaly causes/presentation

Has nonspecific findings (does not mean pathological process occurring), could be caused from infection, hepatic tumors, congenital, or metabolic disorders. Will often present as abdominal mass

What is fatty infiltration (steatosis)

An acquired and reversible (if cause is eliminated) condition of extra fat build up inside your liver cells

Causes of fatty infiltration (steatosis)

2 main causes are alcohol abuse or obesity but also comes from accumulation of triglycerides in blood, or diabetes, steroid use, pregnancy, metabolic disorders, or high cholesterol

fatty infiltration (steatosis) clinical findings

may be asymptomatic (unless there’s significant amount of damage that changes physiology), hepatomegaly, or elevated LFTs

fatty infiltration (steatosis) Sonographic appearance/features

Diffuse increased echogenicity and results with decreased penetration, poor delineation of vessel walls (blends with hyperechoic liver tissue), and may be focal.

can decrease frequency or turn off harmonics to improve penetration

What is focal fatty sparing

When the liver is all fatty with some spots not affected, specifically near porta hepatis

Image: 2 areas of focal fatty sparing are seen in classic location as hypoechoic, irregularly shaped areas anterior to GB and portal veins. b/c the liver is now hyperechoic from fatty infiltration, normal tissue appears hypoechoic

What is focal fatty infiltration

When only specific areas of liver are fatty but otherwise it is normal

Image: A local irregular increased echogenic area in right lobe of liver compatible with focal fatty infiltration. does not displace vessels, suggesting that it is not a mass

What are two important clues that favor focal fatty change over a true liver mass

Irregular shape and lack of vessel displacement/internal vascularity

What is Glycogen Storage Disease

An autosomal recessive disorder (genetic) that allows excessive deposits of glycogen to be stored in the liver, intestines, and kidneys. Glycogen is stored in tissues but the body cannot synthesize it into glucose

Glycogen storage disease symptoms

Hypoglycemia, abdominal distension, fatigue, and irritability

What is vonGierke disease and sonographic appearance

Type I glycogen storage disease and is the most common type.

Appears with diffuse increased echogenicity and hepatomegaly

What liver mass can occur in von Gierke disease

Liver cell adenomas (40% of cases)

Types 3 and 4 glycogen storage disease complications

More often associated with cirrhosis and hepatocellular carcinoma (HCC)

How can viral hepatitis range in severity

mild or extensive

Types of hepatitis and their transmission

• Hep A – parenteral or ingestion of contaminated food

• Hep B, C, and D – sexual contact, contaminated blood, needles, body fluid

• Hep E – contaminated water

Acute hepatitis clinical findings

Elevated LFTs, jaundice, RUQ pain, hepatomegaly, nausea/vomiting, and fever

Acute hepatitis Sonographic appearance

Normal to hypoechoic liver secondary to liver swelling, and “starry night” sign (portal vein walls seem more hyperechoic against liver parenchyma). Unlike fatty liver, this isn’t a penetration issue, we just need to adjust the gain.

Chronic Hepatitis sonographic appearance

Fibrosis causes course/hyperechoic parenchyma, and portal vein walls are less discrete

Complications from chronic hepatitis

Portal HTN and sequelae, or could progress to cirrhosis or liver failure

What machine adjustment can improve visualization of hepatitis

increase overall gain

What imaging-setting problem is more typical of fatty liver than hepatitis

Increased attenuation with poor sound penetration

What is Cirrhosis

Chronic and severe damage that destroys normal liver lobule architecture and leads to inflammation and subsequent necrosis. Is one of 3 types of alcoholic liver disease (other 2 being alcoholic fatty liver and alcoholic hepatitis)

What changes follow chronic inflammation in cirrhosis

Dense fibrous septa form, parenchymal cells degenerate, and regenerative nodules form.

Cirrhosis Clinical Presentation

RUQ pain, ascites, hepatomegaly, LFT abnormalities (depending on stage/extent of disease), or biliary/vascular channel blockage (which can lead to jaundice or portal HTN)

Cirrhosis Sonographic appearance

Varies during disease progression

early:hepatomegaly and possible textural changes indicative of diffuse disease (course/granular appearance)

Late: liver atrophy with caudate hypertrophy, surface nodularity (irregular border/edges, and can be seen bc of ascites outlining the liver), and loss of delineation of intrahepatic vasculature

Secondary findings to Cirrhosis

Portal HTN and splenomegaly, varies (abnormally enlarged/twisted blood vessels), or ascites

What are collateral shunts in cirrhosis

Secondary/accessory blood vessels that allow portal venous blood flow to bypass/route around blocked/damaged main vessel/damaged liver

Common collateral or varices found with cirrhosis

Recanalized umbilical vein, esophageal varices, and splenic varices

End-stage cirrhosis sonographic appearance

A small, lobulated or nodular liver with heterogeneous parenchyma, often outlined by ascites

Where may esophageal varices be seen sonographically

As anechoic vascular spaces posterior to the liver and anterior to the aorta. suspected esophageal varix should be confirmed with color doppler to demonstrate blood flow.

What can a recanalized umbilical vein be mistaken for and how to confirm it

the GB bc is can appear as a fluid-filled tubular structure near the liver if sonographer isn’t oriented to anatomy. it can be confirmed with color doppler and spectral doppler to show venous flow

Vascular changes with cirrhosis

Portal veins: reduced velocities and/or hepatofugal flow

Hepatic artery: enlarged with elevated velocities and turbulent flow (may have a corkscrew appearance with increased flow and aliasing)

Hepatic veins: become polarized (continuous flow and loss of multi-phasic appearance)

What is Hepatopetal flow

blood flow towards the liver. shows above the baseline on spectral doppler waveform

What is hepatofugal flow

blood flow away the liver. shows below the baseline on the spectral doppler waveform

What is assessed during a full abdominal doppler scan

3 hepatic veins, MPV, RPV, LPV, and hepatic arteries

Normal liver vascular flow

Arterial: hepatopetal, low resistance, continuous forward flow (above baseline)

Portal vein: hepatopetal, continuous monophasic flow

Hepatic vein: hepatofugal, triphasic and sensitive to respiration (below baseline)

What is Budd-Chiari syndrome and when is it clinically significant

Obstruction of hepatic veins and is clinically significant when at least 2 hepatic veins are occluded

Budd-Chiari syndrome symptoms

RUQ pain, jaundice, ascites, or hepatomegaly

Budd-Chiari syndrome acute clinical triad

ascites, hepatomegaly, and abdominal pain

Budd-Chiari syndrome etiology

Birth-control pills, tumor invasion from HCC (hepatocellular carcinoma), renal or adrenal carcinoma, severe metastatic liver disease, and Wilms tumor in pediatric patients

Can hepatic vein obstruction in Budd-Chiari be caused by external compression as well as intraluminal material

Yes. The lecture emphasizes that obstruction can result from material within the vein or compression from outside it

Budd-Chiari syndrome Sonographic Findings

varies depending on degree of obstruction/cause, hepatic veins are either not visible, narrow, or reversed flow (hepatopetal), or hypertrophy of caudate lobe. could also see portal HTN, intrahepatic collaterals, ascites, or splenomegaly.

color doppler may demonstrate enlarged caudate veins draining into IVC

What is passive liver congestion

Liver edema secondary to vascular congestion. commonly related to heart failure, especially right side

clinical findings of acute passive liver congestion

hepatomegaly or RUQ discomfort

Passive Liver congestion sonographic appearance

dilated veins, hepatic veins flow is reversed during systole and have a highly pulsatile W-type pattern, and portal veins become more pulsatile.

image shows “Canadian Moose sign” which is a dilated IVC and hepatic veins from right-sided heart failure

How can chronic passive congestion affect liver and veins

liver may shrink and become fibrotic while hepatic and systemic veins remain dilated/pulsatile

What are Congenital Hepatic Cyst

True hepatic cysts resulting from developmental anomalies. incidence increases with age

Congenital hepatic cyst symptoms

typically asymptomatic and discovered incidentally

Congenital hepatic cyst appearance

usually solitary lesions with varying size

Imaging modality of choice for congenital hepatic cysts

sonography

Classic sonographic features of a simple hepatic cyst

Thin walls, anechoic content, and posterior acoustic enhancement. May see reverberation artifact

What can give a hepatic cyst a complex appearance and how can CEUS help

hemorrhage or infection.

It can help distinguish a complicated cyst from malignant process

What is isolated polycystic liver disease (isolated PLD)

Multiple cysts are only in the liver

When does PLD cysts become detectable and who does it commonly affect

often detectable it 3-4th decade and women are more affected than men

What is autosomal dominant polycystic kidney disease (ADPKD)

It is 80-90% of PLD where cysts are present in both the liver and kidney

severe polycystic liver disease sonographic appearance

A “Swiss cheese” appearance with numerous cysts that may blend together.

Document “multiple cysts” and measure a clearly defined or largest representative cyst rather than every cyst

Acquired hepatic cyst causes/categories

trauma, parasites, or inflammatory reactions

would someone experience symptoms from Acquired hepatic cyst

yes

Sonographic appearance of acquired hepatic cysts

range from classic cystic to complex masses, and should always correlate your sonographic findings with clinical findings

Hepatic hematoma and how they are categorized

Collection of blood trapped inside the liver tissue or beneath its outer covering. they are categorized based on severity and location

Besides trauma, what causes hepatic hematoma

biopsy/interventional procedures, rupture of a vascular neoplasm or aneurysm, and pregnancy-induced hypertension

Hepatic Hematoma symptoms

a tender liver/abdominal pain and decreased hematocrit levels

What can occur if hepatic hematoma causes significant bleeding

patient can collapse with signs of shock

What clinical findings can you appear with significant hepatic hemorrhage

tender liver, collapse, shock with falling BP pulse and hematocrit

Hepatic hematoma sonographic findings

depends on age of the bleed (starts anechoic, then complex as its clotting then more solid mass appearance as it heals until it goes away).

can appear crescent shaped that displaces the liver medially.

left image is clotting stage and right is acute stage

hydatid cysts (echinococcal) cause

Most common cause is Taenia echinococcus or Echinococcus granulosus, which is a parasitic tapeworm. the larvae are ingested and travel to the liver through the SMV

Why is hydatid cyst rupture dangerous

it can cause severe anaphylactic shock and may be fatal

How can hydatid disease cause jaundice or portal HTN

cyst can obstruct bile ducts and larvae can invade or obstruct portal venous structures

hydatid cysts (echinococcal) sonographic appearance

varies depending on larval maturation but could be simple cyst or cyst with worms in it.

Active cyst can look like a large cyst containing daughter cysts (honeycomb appearance)

Inactive cyst can have more solid-appearing lesion with rim calcifications

What is a pyogenic hepatic abscess

A localized collection of pus

What organism is most commonly isolated from a pyogenic hepatic abscess

E. Coli

Most common source of pyogenic hepatic abscess and how

biliary tract. bile flow obstruction allows bacteria to grow and proliferate which can produce multiple abscesses

How does pyogenic bacteria enter liver

via portal vein or hepatic artery or direct extension from adjacent organs

What conditions are listed as sources of portal-vein seeding for a pyogenic abscess

Appendicitis, diverticulitis, or inflammatory bowel disease

What conditions are listed as sources of hepatic artery seeding for a pyogenic abscess

bacterial endocarditis and urinary sepsis

Pyogenic hepatic abscess symptoms/lab findings

Fever, elevated LFTs (AST, ALT, ALP, Bilirubin), RUQ pain, pleuritic pain, leukocytosis, and hepatomegaly

Pyogenic Hepatic abscess sonographic appearance

usually less echogenic than hepatic parenchyma, single or multiple masses usually >1cm, variable is shape (round, ovoid, poorly defined), and internal echo depends on debris, adhesions, or gas microbubbles. posterior acoustic enhancement differentiates debris filled pyogenic abscess from solid mass. irregular walls, peripheral hyperemia and heterogeneous

How severe is an untreated pyogenic liver abscess

it can reach 100% mortality rate

What is an Amebic abscess and where is it mostly located

a pus-filled mass in the liver caused by the parasite Entamoeba histolytica. most commonly in right lobe

Amebic abscess symptoms

usually asymptomatic when parasite is confined to GI tract.

Once it has developed (parasite is in the liver), you could experience RUQ pain and reactive hepatomegaly, diarrhea or black tarry stool, fever, jaundice, or moderate leukocytosis and elevated LFTs

Amebic abscess Sonographic appearance

newly formed abscess appears echogenic and becomes hypoechoic as it matures.

color doppler usually shows no flow

image shows 4.5cm complex cystic mass in right lobe