Liver Flashcards
Name LI-RADS major imaging criteria for HCC
Arterial phase hyper-enhancement
PV/delayed venous phase washout
capsular enhancement
threshold growth (new lesion >10mm)
When can you call fatty liver on T2
Compare to spleen. If liver hyperintense then there is fatty infiltration
Name of FNH specific MRI contrast
Primovist
Pathological difference between FNH and hepatic adenoma? (Cell that is absent)
Kupffer cells are absent in hepatic adenoma. Otherwise they both contain normal hepatocytes in an abnormal configuration
Name the top 3 differential diagnoses of a hyperdense liver on C-
Amiodarone therapy Iron deposition (oral intake, blood transfusions, thalassemia/sideroblastic anemia, hemochromatosis) Glycogen storage disease (types 1 and 4)
What is T2 signal of regenerative nodules in cirrhosis?
Hypointense, which allows differentiation from metastases (hyper T2)
Daughter cysts within a larger cyst are pathognomonic of which pathology?
Hydatid cyst (echinococcal infection)
Name the different types of choledochal cysts (Todani)
type I: most common, accounting for 80-90%
Ia: dilatation entire of extrahepatic bile duct
Ib: focal dilatation of extrahepatic bile duct
Ic: dilatation of the common bile duct portion of extrahepatic bile duct
type II: true diverticulum from extrahepatic bile duct
type III: dilatation of extrahepatic bile duct within duodenal wall (choledochocoele)
type IV: next most common
IVa: cysts involving both intra and extrahepatic ducts
IVb: multiple dilatations/cysts of extra hepatic ducts only
type V: multiple dilatations/cysts of intra hepatic ducts only (Caroli disease)
What contrast timing and speed demonstrates hypervascular liver masses best?
Late arterial phase (35 sec, PV opacified)
Injection rate of 5cc/sec allows more contrast to reach liver
Radiologyassistant
How do you differentiate benign hypervascular liver lesions (regen nodules, FNH, adenoma) from HCC on CT?
Delayed phase will demonstrate washout in HCC whereas the other masses will remain isodense to liver parenchyma
Ddx of liver masses with retained contrast on delayed phase (10min)?
Hemangioma - blood pool HCC - fibrous capsule FNH - central scar Cholangiocarcinoma - scar Fibrolamellar carcinoma - scar
How is the scar of FNH different from scar of other tumors on imaging?
On MRI, the scar of an FNH will be hyperT2 because of oedema whereas in other masses it will be hypoT1T2
Ddx of hypervascular liver metastases?
Breast Sarcoma RCC Melanoma Neuroendocrine (carcinoid, islet cell, pheochromocytoma)
Most common liver tumor with a capsule?
HCC
The capsule is fibrous and enhances on delayed views
Other masses with a capsule are adenoma, cystadenoma and cystadenocarcinoma
Central calcifications are seen in what type of liver masses?
Hemangioma
Metastases (especially colon)
Cholangiocarcinoma
Fibrolamellar carcinoma
How do you differentiate benign hypervascular liver lesions (regen nodules, FNH, adenoma) from HCC on CT?
Delayed phase will demonstrate washout in HCC whereas the other masses will remain isodense to liver parenchyma
Ddx of liver masses with retained contrast on delayed phase (10min)?
Hemangioma - blood pool HCC - fibrous capsule FNH - central scar Cholangiocarcinoma - scar Fibrolamellar carcinoma - scar
How is the scar of FNH different from scar of other tumors on imaging?
On MRI, the scar of an FNH will be hyperT2 because of oedema whereas in other masses it will be hypoT1T2
Ddx of hypervascular liver metastases?
Breast Sarcoma RCC Melanoma Neuroendocrine (carcinoid, islet cell, pheochromocytoma)
Most common liver tumor with a capsule?
HCC
The capsule is fibrous and enhances on delayed views
Other masses with a capsule are adenoma, cystadenoma and cystadenocarcinoma
Central calcifications are seen in what type of liver masses?
Hemangioma
Metastases (especially colon)
Cholangiocarcinoma
Fibrolamellar carcinoma
Ddx of fat containing liver tumor? (4)
Adenoma
HCC
Metastatic liposarcoma
Angiomyolipoma
Describe nutmeg liver appearance and Ddx
Due to perfusion abnormality usually as a result of hepatic venous congestion. It is a mottled pattern of enhancement in arterial and early PV phases with decreased enhancement of liver periphery. The liver becomes more uniform on delayed images.
Ddx:
Hepatic veno-occlusive disease
Budd-Chiari syndrome
Congestive hepatopathy - right heart failure, constrictive pericarditis
What is characteristic MR appearance of primary sclerosing cholangitis
Multiple stenoses
Minor dilatations (from periductal fibrosis)
Beaded appearance of bile ducts
Findings of cirrhosis can also be present
What are some causes of portal vein thrombosis? (8)
Cirrhosis (most common cause of intrahepatic thrombosis) Neoplasm (HCC, cholangio, mets, pancreas) Trauma hematological disorders Pancreatitis Thrombophlebitis from sepsis Diverticulitis Appendicitis
In portal vein thrombosis, where can you find collateral vessels?
Portal vein (formation of periportal/intramural collaterals in location of PV, i.e. hypertrophic vasa vasorum in wall of portal vein)
wall of the gallbladder (pericholecystic varices)
wall of the bile ducts (pericholedocal varices)
What is ddx for starry sky liver appearance on US (5)
Acute hepatitis
Hepatic congestion
Infiltrating neoplasm
Toxic shock syndrome
Biliary or portal venous gas
How does the distribution of organ involvement on MR differ between hemochromatosis and hemosiderosis?
In hemochromatosis, a low signal intensity on T2-WI and T2*-WI is found in the liver, pancreas, myocardium, and endocrine glands, but the spleen remains normal.
In hemosiderosis, spleen, liver, and bone marrow reveal decreased intensity on MRI studies, and the pancreas tends to be spared.
What is hepatic peliosis?
Etiology?
Rare benign vascular condition characterised by multiple mottled blood-filled cyst-like spaces within the liver.
Most commonly idiopathic (20-50%). toxins drugs AIDS transplantation (cardiac, renal) Chronic illness (cancer, TB, celiac, diabetes)
What is CT/MRI appearance of hepatic peliosis?
CT:
multiple hypodense lesions of variable size. Can contain areas of hyperdensity (hemorrhage) and dystrophic calcification.
Centrifugal (centripetal also but less likely) arterial enhancement with no washout, remains slightly hyperdense on PV phase.
MRI is variable, but in general:
T1 hypo
T2 hyper
C+: centrifugal enhancement
What are the veins of sappey? In what pathology are they dilated, giving the appearance of a pseudolesion due to increased enhancement?
Small veins around the falciform ligament that drain the venous blood from the anterior part of the abdominal wall directly into the liver.
In SVC obstruction, they dilate as a collateral pathway, with formation of a liver pseudolesion due to increased enhancement (hot quadrate lobe)
What patient population should Li-Rads be used for?
Patients at increased risk for HCC. Should not be used in general population.
What are the 5 features of Li-Rads evaluation?
1- Masslike configuration 2- Arterial phase hyperenhancement 3- Portal venous or later phase washout 4- Increase in size of 10mm or more in diameter within 1 year 5- Tumor within lumen of vein
When using Li-Rads, what criteria determine if there is significant increase in size (6mo, any timing)
6mo: 100% increase
Any time: new lesion 10mm or more
What are the enhancement characteristics of the capsule of an HCC?
The capsule represents fibrous tissue that enhances slowly
Hypo on arterial and PV phase, will enhance on delayed phase
What ancilliary features support malignity in Li-Rads?
Peritumoral fat Iron sparing in iron overloaded liver Mild T2 hyper Capsule with delayed enhancement \+ve DWI
In Li-Rads, what is the highest category a lesion can be upgraded to using ancilliary findings?
Li-Rads 4
TRUE OR FALSE
FNH and adenoma are very rare in cirrhotic liver and should not be considered in the ddx
True
According to Li-Rads, FNH and adenoma are not part of ddx
What is a turtle back appearance in the liver, and what pathology does it present in?
Periportal fibrotic bands that extend to the liver surface
Best imaging clue of hepatic schistosomiasis
Give 3 criteria that you can use to call fatty liver on CT scan
Less than 40HU on NECT
10HU less than spleen on NECT
25HU less than spleen on CECT
If the intensity of the liver increases on out of phase image, what is the pathology?
Hemochromatosis
The presence of increased iron affects the magnetic field in a way that causes an increase in the signal of the liver on out of phase imaging
What is primary budd chiari syndrome
Membranous weblike obstruction of the hepatic veins or IVC (more common in asian population)
What are the findings in acute budd chiari syndrome?
Diffusely hypodense and enlarged liver
Modified perfusion with early enhancement of caudate lobe
Non enhancement of hepatic veins
What are the 4 mecanisms of THAD-THID
Directly by siphoning effect
Portal hypoperfusion due to compression
Portal thrombosis
Flow diversion due to arterio-portal shunt
If you see both perfusion anomalies and arterio-venous shunting in the liver, what pathology should you consider?
HHT (osler weber rendu)
True or false
Regenerative liver nodules are hyperenhancing
False
They are iso-hyperdense on NECT, but disappear after contrast administration
If they hyperenhance on arterial phase it is HCC until proven otherwise
What is the most common location of focal confluent fibrosis
90% involve medial segment of left lobe or anterior segment of right lobe
MRI findings in focal confluent fibrosis?
HypoT1
Slightly HyperT2
Delayed enhancement
Capsular retraction
What is usual timeline for development of post radiation hepatitis?
2 weeks to 4 months after hepatic irradiation
What finding on contrast enhanced MRI is most useful in differentiating FNH from hepatocellular adenoma?
On the hepatobiliary phase (delayed), FNH is iso-hyper whereas hepatocellular adenoma is hypointense
What is the imaging appearance of mucinous cystic neoplasm (biliary cystadenoma)?
multiloculated cystic mass with smooth fibrous capsule. the capsule and septa enhance, which increases on delayed phase
What enhancement characteristic allows you to differentiate a hydatid cyst from a mucinous cystic neoplasm (biliary cystadenoma)?
In hydatid cyst, the septa do not enhance
How do hepatobiliary MR contrast agents help you differentiate FNH from a metastasis?
These agents are taken up by functioning hepatocytes and excreted in the bile. On the hepatobiliary phase (delayed phase), lesions that are hepatocellular in nature (FNH, hepatoma), will be isointense whereas non-hepatocellular lesions (mets, cysts, hemangioma), will be hypointense because of lack of uptake.
TRUE OR FALSE
Hepatobiliary MR contrast agents help differentiate a benign lesion such as FNH from a well differentiated HCC
FALSE
Low-grade/well-differentiated HCC cannot be differentiated from a benign liver lesion with hepatobiliary MR contrast agents because it will also enhance.
What is the ultrasound imaging appearance of multiple biliary hamartomas?
They can be too small to properly visualize and appear as diffuse heterogeneous liver echotexture. Otherwise, they can present as multiple echogenic foci.
If they are large enough (10mm), they can present as hypo-anechoic foci with comet tail artifact.
They can be indistinguishable from metastases
What are the imaging findings of biliary cystadenoma?
Large, uni or multilocular cystic liver mass with multiple internal septations.
Its appearance ranges from cystic contents to hemorrhage/proteinaceous contents.
There can be calcification of wall and septations. mural nodules can be present.
On post contrast imaging, the septa may enhance.
How do you differentiate biliary cystadenoma from biliary cystadenocarcinoma on imaging?
Imaging cannot reliably differentiate cystadenoma from cystadenocarcinoma, but the presence of septal nodularity may favour the diagnosis of biliary cystadenocarcinoma.
The calcifications can be more coarse and thick. The presence of discrete soft tissue masses is also an important clue.
What are the types of choledochal cysts?
Type 1: fusiform dilatation of the extrahepatic bile duct
Type 2: Saccular diverticulum, arising from the supraduodenal extrahepatic bile duct or the intrahepatic bile ducts.
Type 3: protrusion of a focally dilated, intramural segment of the distal common bile duct into the duodenum.
Type 4: Multiple communicating intra- and extrahepatic duct cysts. It can also be purely extra-hepatic, with multiple cysts.
Type 5: Caroli disease. Multiple intrahepatic bile duct cystic dilatations.
What 2 liver tumors can create an AV fistula?
Hemangioma
HCC
Gallix
TRUE OR FALSE
FNH never contains fat
FALSE
20% of FNH can contain fat
Gallix
What is the differential diagnosis of multifocal biliary strictures?
Sclerosing cholangitis Primary biliary cirrhosis Multifocal cholangiocarcinoma Chronic bacterial cholangitis AIDS cholangitis
Name the 2 most common causes of hepatic veno-occlusive disease?
Bone marrow transplantation
Chemotherapy
