Liver and Hepatic Doppler Flashcards
What are some signs of portal hypertension?
- enlarged portal vein
- splenomegaly
- varices
- portosystemic shunts
- patent umbilical vein
Name all the liver infections
- Viral hepatitis
- Pyogenic abscess
- Amebic abscess
- Echinococcal cyst (hydatid disease)
- Candidiases
- Hepatic Pneumocystis jiroveci
What is the most common US finding in viral hepatitis?
What is a classic finding of viral hepatitis?
What is another US finding associated with viral hepatitis?
- The most common ultrasound finding is a normal liver.
- Occasionally periportal edema produces the characteristic starry sky pattern of increased portal triad echogenicity.
- Acute hepatitis is often associated with diffuse severe gallbladder wall thickening.
What are pyogenic abscesses of the liver caused by and where are they usually spread from?
What do they look like on US?
- Pyogenic abscess is caused by pus-forming organisms and is usually due to spread from intestinal or biliary infection (most commonly E. coli).
- Infection starts as an ill-defined area of altered echogenicity (phlegmon stage) that evolves into a well-defined hypoechoic structure with internal echoes (mature abscess).
What are amebic abscesses caused by?
Common presentation? Common location?
US finding?
- An amebic abscess is caused by Entamoeba histolytica.
- A near-universal presenting symptom is pain, seen in 99% of pa ents. The most common location is near the dome of the right lobe.
- On ultrasound, an amebic abscess is indistinguishable from a pyogenic abscess and appears as a hypoechoic structure with low-level internal echoes.
What are Echinococcal cysts caused by?
Endemic areas? Medical treatment?
Classic ultrasound appearance?
- Echinococcal cyst is caused by larvae of Echinococcus granulosus.
- Endemic areas in the Middle East, Mediterranean, and South America.
- Classic ultrasound appearance is a large liver cyst with numerous peripheral daughter cysts. A highly suggestive finding is the change in position of daughter cysts as the patient is repositioned.
- The water-lily sign is an undulating membrane within the hydatid cyst.
- Hydatid sand is a fine sediment caused by separation of the membranes from the endocyst.
What is the US finding of hepatic candidiasis?
The presence of what is highly suggestive of this infection?
- Hepatic candidiasis is a rare infection in the immunocompromised due to Candida albicans or Candida glabrata.
- On imaging, there are multiple tiny targetoid lesions.
- The presence of concurrent similar-appearing lesions in the spleen is highly suggestive of hepatosplenic candidiasis.
Hepatic PCJ infection - When do we see it and what does it look like?
- Hepatic Pneumocystis jiroveci is seen in disseminated disease in the severely immunocompromised.
- Hepatic infection is classically secondary to the use of inhaled pentamidine as pentamidine is not absorbed systemically and thus would not prevent hepatic infection.
- Ultrasound shows multiple punctate echogenic calcifications in the liver and o en spleen.
Name the benign hepatic neoplasms in order of frequeny
MNEMONIC: “Benign CHALC in the liver”
- Cavernous hemangioma
- Focal nodular H yperplasia
- Hepatic Adenoma
- Hepatic Lipoma
- Biliary Cystadenoma
Hepatic Cavernous Hemangioma
What is the classic US finding?
The classic ultrasound appearance of hemangioma is a solitary, circumscribed, homogeneously echogenic mass with no flow on color Doppler. Posterior acoustic enhancement is nonspecific but may be present. When seen, posterior acoustic enhancement is thought to correlate with hypervascularity. A hypoechoic halo should never be seen - this finding suggests malignancy.
Focal Nodular Hyperplasia
What is it?
Ultrasound findings? Doppler finding?
Confirmatory testing?
- FNH is a benign hyperplastic hepatic mass with a central non- fibrotic stellate scar consisting of biliary ductules and venules.
- Ultrasound findings are nonspecific. The central scar is rarely seen on ultrasound, and even when it is, this finding can be seen in other lesions, including hepatocellular carcinoma, giant hemangioma, or adenoma.
- FNH is difficult to detect on sonography. It may be nearly isoechoic to normal liver and manifest on imaging as a subtle displacement of the hepatic contour.
- Doppler findings of FNH include a spoke-wheel configuration of arterial vessels.
- MRI or Tc-99m sulfur colloid scintigraphy can confirm (classically, FNH has increased uptake of sulfur colloid). MRI is by far the more useful test.
Hepatic Adenoma
What is it?
What is it associated with?
What do you do with them?
Ultrasound findings?
What other scan can you do?
- Hepatic adenoma is a benign liver tumor associated with oral contraceptives, anabolic steroids, and type I glycogen storage disease (von Gierke’s disease - in which case adenomas will be multiple).
- Due to the high incidence of hemorrhage, adenomas are usually resected.
- There are no specific ultrasound features to distinguish an adenoma from other hepatic masses. An adenoma may be hyperechoic, isoechoic, or hypoechoic relative to normal liver.
- Adenoma is usually photopenic on Tc-99m sulfur colloid scintigraphy (in contrast to FNH).
Hepatic Lipomas
What are they?
What do they look like on US?
Associations?
- Hepatic lipoma is a benign neoplasm composed of fat that appears as a well-defined hyperechoic mass.
- It may appear identical to hemangioma or hyperechoic hepatocellular carcinoma.
- When multiple, may be associated with tuberous sclerosis and renal angiomyolipomas.
Biliary Cystadenoma
What are they?
What do you do with them?
US appearance?
What finding indicates a higher risk of malignant transformation?
- Biliary cystadenoma is a benign cystic mass lined with biliary-type epithelium.
- Although benign, most are surgically resected since malignant transformation may occur.
- Biliary cystadenoma appears as a multi-septated cystic mass on all imaging modalities.
- Mural nodules should be regarded with suspicion. The presence of mural nodularity suggests malignant transformation to cystadenocarcinoma.
Hepatic Malignancy
What is the most common neoplasm found in the liver?
Name all the neoplasms found in liver.
- Mets is by far most common than primary hepatocellular CA
- Hepatocellular CA
- Fibrolamellar CA
- Hepatic lymphoma
- Post-transplant lymphoproliferative disorder
Classic US finding for neoplasms metastatic to the liver
The classic finding is a hypoechoic rim producing a target sign.
Hypoechoic hepatic mets include:
- Breast (can be either hypoechoic or hyperechoic).
- Pancreas.
- Lung.
- Lymphoma.
Hyperechoic hepatic mets include:
- Breast (can be either hyperechoic or hypoechoic)
- Colon cancer is hyperechoic in greater than 50% of cases. A hypeRechoic appearance may suggest a better prognosis
- Renal Cell Carcinoma
- Carcinoid
- Choriocarcinoma
Calcified hepatic mets (hyperechoic with acoustic shadowing) include:
- Colon cancer (especially mucinous type).
- Gastric Adenocarcinoma.
- Osteosarcoma (very rare)
Cystic hepatic mets include:
- Ovarian cystadenocarcinoma
- Gastrointestinal sarcoma
Infiltrative hepatic metastasis include:
- Breast. In particular, treated breast cancer may cause a pseudo-cirrhosis appearance.
- Lung.
- Prostate.
What is hepatocellular CA?
Ultrasound appearance?
What should be evaluated in the presence of a hepatic mass?
- HCC is a hepatic malignancy arising in the setting of chronic inflammation.
- Patients with cirrhosis or chronic viral hepatitis are regularly screened for HCC with serum alpha-fetoprotein levels and ultrasound.
- Ultrasound is not very sensitive to detect small HCC in end-stage cirrhotic livers.
- HCC has a variety of ultrasound appearances therefore, a mass in a cirrhotic liver is considered HCC until proven otherwise. High Doppler flow may be present, especially at the periphery of the mass, due to arteriovenous shunting.
- HCC has a propensity for venous invasion. The portal veins should always be carefully evaluated in the presence of a hepatic mass. Internal doppler flow within a venous clot suggests a tumor thrombus.
What is fibrolamellar CA?
- Fibrolamellar carcinoma is a variant of HCC seen in young adults without cirrhosis and is not associated with elevated alpha-fetoprotein.
- Fibrolamellar carcinoma has a much better prognosis compared to typical HCC.
Hepatic Lymphoma
What does it look like on US?
- Primary hepatic lymphoma may present as a single mass or multiple masses.
- Lymphoma tends to be hypoechoic and may demonstrate the target sign typical of metastases.
What is Post-Transplant Lymphoproliferative Disorder (PTLD)?
What is the treatment?
What is the US appearance?
- Post-transplant lymphoproliferative disorder (PTLD) is a type of lymphoma caused by EBV that arises after solid organ or bone marrow transplant.
- Patients with renal transplants are at particular risk.
- PTLD may occur anywhere, regardless of which organ was transplanted.
- Treatment is reduction/withdrawal of immunosuppression.
- PTLD appears as a mass with a variable and nonspecific ultrasound appearance. Therefore, it is important to mention PTLD if a liver mass is seen in a transplant patient.
Liver: Common Imaging Patterns:
Multicystic liver
- Multiple simple cysts.
- Caroli disease (saccular dilation of the intrahepatic bile ducts).
- Autosomal dominant polycystic kidney disease (AdPkd): Liver cysts seen in >50% of patients.
Liver: Common Imaging Patterns:
Multiple echogenic liver lesions
- Prior granulomatous disease exposure.
- Disseminated pneumocystis in AIdS. Classic history is treatement with inhaled pentamidine, which does not have systemic absorption.
Liver: Common Imaging Patterns:
Liver cyst with internal echoes
- Simple cyst with internal hemorrhage.
- Liver abscess.
- Hematoma.
- Necrotic or cystic metastasis (ovarian cystadenocarcinoma or gastrointestinal sarcoma)
Describe pre-sinusoidal, sinusoidal, and post-sinusoidal portal HTN
- Portal hypertension is increased pressure in the portal venous system. It can be classified in relation to the hepatic capillary bed as pre-sinusoidal, sinusoidal, or post-sinusoidal:
- Pre-sinusoidal: Insult is proximal to the hepatic parenchyma, such as portal vein thrombosis.
- Sinusoidal: Insult is hepatic in origin, such as cirrhosis.
- Post-sinusoidal: Insult is beyond the liver, such as Budd-Chiari (hepatic vein thrombosis) or IVC thrombosis.
Normal flow of portal veins
- Normally, the portal veins and hepatitic arteries flow in the same direction, toward the liver.
- This direction is called hepatopetal flow (-petal = toward). The normal portal venous waveform is above the baseline (hepatopetal) and gently undulating.
Differential diagnosis for a pulsatile portal venous waveform:
- Tricuspid regurge
- Right-sided heart failure
What is hepatofugal flow?
- When portal venous pressure is higher than forward pressure, the portal venous flow will reverse, which is diagnostic for portal hypertension. Reversal of portal venous flow is called hepatofugal flow (-fugal = away, same Latin root as fugitive).
- Hepatic arteries and portal veins flow in opposite directions.
In addition to portal vein flow reversal, what are several secondary findings of portal HTN?
- Low portal venous velocity (<16 cm/sec)
- Dilated portal vein (13 mm is the maximal normal diameter in quiet respiration).
- Portosystemic shunts are often present, most commonly gastro-esophageal, paraumbilical, or splenorenal. Note that an isolated portosystemic shunt may not be caused by portal hypertension. For instance, isolated obstruction of the splenic vein from pancreatitis or neoplasm may lead to a shunt.
- A recanalized umbilical vein is a portosystemic shunt that is diagnostic of portal hypertension
- Splenomegaly
- Varices
What will flow in a patent TIPS be like?
- Flow in a patent TIPS will be towards the hepatic veins, and ow in the portal veins will be towards the TIPS. Therefore, ow in the main portal vein will be hepatopetal and flow in the right and left portal veins will be hepatofugal.
What flow velocities suggest TIPS stenosis?
- High intra-TIPS velocity >190 cm/sec or low intra-TIPS velocity of <90 cm/sec suggests stenosis.
- Intra-TIPS velocity change of +/->50 cm/sec since the baseline study is also concerning for stenosis.
- Low main portal vein velocity (<30 cm/sec) suggests TIPS stenosis.
Blood flow in liver if a TIPS becomes occluded
ask one of the seniors why the CORE is confusing here. . .
Long-standing portal vein thrombosis leads to _________.
US appearance?
Cavernous Transformation = formation of multiple periportal collaterals.
What does portal venous gas signify?
What does it look like?
Contrast to pneumobilia.
- Portal venous gas is due to abdominal catastrophe (ischemia and infarction) until proven otherwise.
- If the cause of the portal venous gas is unknown, CT should be performed emergently.
- Ultrasound shows peripheral patchy branching foci of hyperechogenicity that are often transient. Spectral doppler of the portal vein features numerous characteristic spikes.
- In contrast to portal venous gas, pneumobilia tends to be more central.
Normal Hepatic Vein Waveform
What are the distinct components?
- A-wave: Atrial systole, during which blood is forced retrograde (away from the heart) into the liver.
- S-wave: ventricular systole, during which a large volume of blood returns to the right atrium.
- D-wave: ventricular diastole, during which a smaller volume of blood returns to the right atrium.
Increased Hepatic Vein Pulsatility:
Accentuated A-wave
What does waveform look like in tricuspid regurgitation?
- Both conditions (tricuspid regurgitation and right-sided heart failure) are characterized by accentuation of the A-wave due to increased retrograde flow during atrial systole.
- In tricuspid regurgitation, there is some degree of blood flow from the right ventricle into the right atrium during ventricular systole, allowing less blood to return to the right atrium from the hepatic veins and IVC during ventricular systole. This results in a decreased or even retrograde S-wave.
Increased Hepatic Vein Pulsatility:
Accentuated A-wave
What does waveform look like in right-sided heart failure?
- Both conditions (tricuspid regurgitation and right-sided heart failure) are characterized by accentuation of the A-wave due to increased retrograde flow during atrial systole.
- In right-sided heart failure, the tall A-wave is due to increased right atrial pressure; however, in contrast to tricuspid regurgitation, the S-wave is normal since the tricuspid valve remains competent.
What are some causes of hepatic steatosis?
US appearance?
Where does focal fat sparing usually occur?
- Hepatic steatosis is the accumulation of excess fat within hepatocytes due to a metabolic derangement (obesity or diabetes), hepatotoxins (EtOH, chemothearpy), or prolonged fasting.
- Ultrasound shows a diffuse increase in hepatic echogenicity. Normally, the liver and kidney should have the same echogenicity. With fatty infiltration, the liver appears more echogenic than the kidney. Hepatic steatosis also causes increased sound attenuation, leading to poor visualization of deeper structures.
- Focal fat sparing is a geographic area of hypoechogenicity in an otherwise fatty liver.
- A characteristic location of focal fat sparing is the gallbladder fossa.
Portal Vein Thrombosis
Causes?
US appearance?
- Thrombosis of the portal vein can be bland (simple thrombosis) or may be due to tumor invasion.
- Bland portal vein thrombus can be caused by general hypercoagulable state or may be due to local inflammation from pancreatitis or hepatitis.
- In infants, omphalitis or dehydration may also lead to portal vein thrombosis.
- Tumor thrombus is most commonly caused by hepatocellular carcinoma.
