Liver

Question 1

What are the normal appearances of the liver on MRI scans, when compared to the spleen?

Answer 1

T1W:Normal liver is slightly higher signal intensity when compared to the spleen. Focal liver lesions are normally low signal on T1 weighted. T2W: Normal liver is less than or equal to the spleen in signal strength. most lesions are high intensity.

Question 2

What are some of the causes of fatty infiltration of the liver?

Answer 2

Steatosis is due to the hepatocytes becoming filled with cholesterol and triglycerides. Causes include: 1: obesity, 2: alcoholism, 3: steroid therapy, 4: diabetes, 5: pancreatitis, 6: glycogen storage diseases 7:chemotherapy.

Question 3

What is the role of trans-jugular intrahepatic portosystemic shunts (TIPS)?

Answer 3

1: Effective treatment for portal hypertension. 2: Long-term control of oesophageal varices.

Question 4

How can cirrhotic regenerative nodules be differentiated from malignant neoplastic lesions on CT

Answer 4

Regenerative nodules have the same imaging characteristics as normal hepatic parenchyma but stand out because of their surrounding fibrous bands They measure 3 to 10 mm in size. CT: most regenerative nodules are isointense to the surrounding liver parenchyma and are usually not detected. Occasionally they will appear hyperintense due to iron deposition (siderotic nodules).

Question 5

How can cirrhotic regenerative nodules be differentiated from malignant neoplastic lesions on MRI?

Answer 5

T1 weighted: variable signal intensity but they do not show early arterial enhancement unlike hepatocellular carcinoma. T2 weighted: May be hypo-intense (siderotic nodules), isointense but not hyperintense unlike most liver metastases and dysplastic nodules.

Question 6

DDx for patchy areas of low attenuation within the liver, post IV contrast?

Answer 6

1: Cirrhosis 2: Hepatitis 3: Portal Vein Thrombosis 4: Chr. Budd-Chiari 5: Lymphoma 6: Sarcoidosis

Question 8

DDx for Non-enhancing Cystic Liver Lesions

Answer 8

Top Differential Diagnoses:

• AD polycystic liver disease - Usually large and numerous.
• Multiple simple hepatic cysts - Variable size; often > 1.5 cm
• Caroli disease - “Central dot” sign on CECT ; Communicating bile duct abnormality
• Metastases: Usually nonuniform in size and distribution of lesions
• Microabscess (Candida)
• Biliary Hamartoma (This case)

Biliary Hamartoma:

Fx:

NECT

• Solitary or multiple, small, well-defined nodules of varied density
• Predominantly cystic: Water density
• Distribution: Relatively uniform compared to nonuniform metastases
• Varied size: 2-15 mm

CECT

• Varied enhancement based on cystic or solid component but usu NO enhancement.
• NB solid components do become isodense to liver

MR Findings

• T1WI: Hypointense (both cystic and solid lesions)
• T2WI: Hyperintense (cystic lesions) / Intermediate intensity (solid lesions)
• Heavily T2WI: Remains hyperintense (equal to fluid)
• T1WI C+: Predominantly cystic lesions: No enhancement ± thin rim enhancement on early and late post-gadolinium images. In rare predominantly solid lesions: Enhancement seen due to fibrous stroma

Clinical Mx:

• Rare but benign
• Follow imaging just to ensure stable appearance
• V.rare risk of transformation to cholangiocarcinoma