Liver

Question 1

Causes of hypoattenuating liver

Answer 1

Steatosis (focal or diffuse)
Hepatic amyloid (focal or diffuse)

Question 2

Causes of hyperattenuating liver (i.e. HU>75 on unenhanced scan)

Answer 2

Iron overload - most common
Medications - amiodarone, gold, methotrexate
Copper overload - Wilson’s
Glycogen excess

Question 3

Differentiating feature on imaging between hemochromatosis and hemosiderosis

Answer 3

MRI - both hypointense liver on all sequences (compared to skeletal muscle), will see low signal in IP, high signal on OOP

hemochromatosis - iron stored in hepatocytes, RES
spared, spleen and bone marrow normal
hemosiderosis - iron stored in RES, spleen and marrow
also hypointense, can cause secondary hemochromatosis

Question 4

Ddx multiple tiny hypoattenuating nodules in liver

Answer 4

Mets, micro-abscesses (candidiasis), biliary hamartomas (von Meyenburg complexes), Caroli disease**

Question 5

Imaging features of regenerative, dysplastic and siderotic nodules

Answer 5

Regenerative - isointense on all sequences; NO arterial enhancement (iso to liver, supplied by portal vein)

Dysplastic nodule - T2 hypo (usu), T1 hyper (fat drop out OOP), no DWI, high grade show arterial enhancement like HCC

Siderotic nodules - low T1, T2 (hyper on CT)

Question 6

Imaging features fibrolamellar HCC

Answer 6

Young patients, no cirrhosis, normal AFP**
Large mass, central fibrotic scar that is hypo on T1/T2 (unlike FNH which will have T2 bright central scar)
+/- capsular retraction

Question 7

DDx hypervascular liver mets

Answer 7

NETS (pancreas, carcinoid)
RCC
Thyroid 
Melanoma
Sarcoma

Question 8

Imaging features FNH

Answer 8

Stealth lesion - iso to liver on T1/T2, T2 bright central scar, avid arterial enhancement, central scar enhances on delayed phase, remainder of lesion fades to background liver

*asymptomatic, disorganized tissue (Kupffer cells and bile ducts - HIDA scan+, sulfur colloid +)

Question 9

Clinical and imaging features of hepatic adenoma

Answer 9

Benign neoplasm, contains hepatocytes, Kupffer cells but no bile ducts
F>M; OCPs (anabolic steroids in males)
High risk of bleeding, resected
Multiple –> think von Gierke disease (glycogen I storage disease)

Imaging - arterially hyperenhancing, may have late enhancing pseudocapsule, look for blood on T1 and fat on IP/OOP images

Question 10

Imaging findings Budd-Chiari

Answer 10

Occlusive and non-occlusive forms
Non-visualization of hepatic veins, or thrombus
Peripheral edema/reduced enhancement, caudate hypertrophy and peripheral atrophy, collaterals
Enlarged liver

Question 11

Imaging findings veno-occlusive disease

Answer 11

Periportal edema, hepatomegaly, narrowed hepatic veins (usually right), heterogeneous hepatic enhancement, caudate lobe also involved (not spared like Budd-Chiari)

Often occurs in bone marrow transplant/hemopoietic stem cell transplant patients (life threatening complication)

Question 12

List the subtypes of choledochal cysts (Todani classification)

Answer 12

Type 1 (most common) - fusiform dilation CBD
Type 2 - extra-hepatic saccular dilation
Type 3 - intra-duodenal dilation
Type 4 - multiple segments (intra and extra)
Type 5 - intrahepatic only - CAROLI DISEASE 

*do communicate with biliary tree, unlike hamartomas

Question 13

Caroli disease presentation, imaging findings, associations

Answer 13

AR, usu in kids
Present with RUQ pain, recurrent stones, fever, jaundice
Ass. ADPKD, ARPKD, medullary sponge kidney
Diffuse, lobar or segmental duct dilation, usu saccular
“Central-dot sign” - portal radicles in ducts

Question 14

Demographics and imaging findings in PSC

Answer 14

Most commonly associated with UC (other autoimmune d/o as well including Sjorgrens, AIH)
Imaging
- Multiple short strictures, intra or extra hepatic ducts
- Dilated ducts
- Biliary diverticula
- Mural irregularities
- Cirrhosis (no hypertrophy of left lobe)

Question 15

Complications of PSC

Answer 15

Cholangiocarcinoma (15% of pts)
Colorectal carcinoma (4x risk)
Cirrhosis, HCC

Question 16

DDx for PSC

Answer 16

• Cirrhosis from other causes
• IgG4 related sclerosing cholangitis (older, other organs involved, elevated IgG4 levels)
• Secondary sclerosing cholangitis (AIDS, biliary strictures from other causes -ischemia, infection/RPC, etc)

Question 17

Classic imaging features PBC

Answer 17

Middle aged women, jaundice and pruritus
AMA (anti-mitochondrial antibody) +
Lace-like fibrosis and periportal halo sign

Question 18

Risk factors for cholangiocarcinoma

Answer 18

• PSC, PBC
• RPC
• Asian liver flukes (Clonorchis sinensis)
• Caroli disease/choledochal cysts
• Cholangitis
• Hepatitis

Question 19

Subtypes of cholangiocarcinoma and imaging findings

Answer 19

Periductal infiltrating - grow along walls of ducts (Klatskin at the hilum), thickening and enhancing walls, longer segments of stricturing than benign causes

Mass-forming - low attenuation on non-contrast, gradual nodular centripetal enhancement with central fibrosis, capsular retraction*, distal ducts dilated

Intraductal - may present as subtle duct ectasia or enhancing polypoid mass

*Peripheral target appearance on MRI favours cholangiocarcinoma over HCC

Question 20

Imaging findings in focal confluent fibrosis and ddx

Answer 20

• Response to liver injury (cirrhosis, vascular, etc.)
• Medial and ant segments of liver extending to periphery
• Usually low on CT
• Moderate T2 hyperintensity, T1 hypo, progressive enhancement
• Capsular retraction

DDx: HCC, cholangio

Question 21

DDx fat-containing liver lesions

Answer 21

1) HCC (up to 30% have fat)
2) Liposarcoma mets
3) Adenoma
4) AML, lipoma (rare)
5) Focal fat deposition (different location/morphology)
6) Teratoma mets

Question 22

Ddx calcified liver mets

Answer 22

Mnemonic
B: breast cancer
O: osteosarcoma
T: papillary thyroid cancer
O: ovarian cancer (especially mucinous)
M: mucinous adenocarcinoma (especially colorectal carcinoma)