Imaging of the liver and biliary system Flashcards
ways to image the liver
Abdominal X-ray
Ultrasound 3.5MHz concave
CT
CT or MR angiography (contrast image subtracted from non-contrast image to veiw the vessel in great detail)
By a skilled operator, contrast enhanced ultrasound is about as sensitive to lesions as CT or contrast enhance MRI.
What is the echogenicity of normal liver tissue by US
Mildly hypoechoic
How to distinguish portal veins vs hepatic vessels by US
Portal vein branches have a Hyperechoic wall.
The bile ducts also have hyperechoic walls.
What patient position is best for viewing liver by US
On their back during deep inspiration
Ways to image the biliary system
What is a potential complication?
ERC, ERCP, PTC, colloid liver scitigraphy. PET-CT. MR angiography.
Endoscopic Retrograde Choliangiography - ERC
Endoscopic Retrograde CholangioPancreatography - ERCP
via retrograde filling of the bile system with contrast through the Papilla of Vater, under Fluroscopic guidance.
Complications:
1) Retrograde transport of bacteria up into the normally sterile bile tree, and cholecystitis. Thus, this is always performed with antibiotic prophylaxis.
2) Bacteria may also get into the pancreas, provoking
Pancreatitis is 5-15% of patients afterwards. So it is not done lightly.
Percutaneous Transhepatic cholangiography.
Percutaneous filling of the bile with contrast agent.
Complications, bleeding. Patient should have good hemostatic system.
PTC is also contraindicated if there is significant ascites.
colloid liver scitigraphy - no longer used because its resolution is worse than US and CT.
PET-CT. Administration Fluorodeoxyglucose (FDG) which is uptaken by hyperactive tissue (cancerous lesions) and the nthis PET image is combined with a CT image to localize the lesion. Very good at localizing cancer metastases.
Fatty liver is seen as hyperechoic regions, or homogenous tissue hyperchoic on US. Also seen as hyperintense signal on T1 or lower intensity on T2.
homogenous fibrosis does not change echoicity of the liver, but nodular firotic lesions can be seen, with regenerative nodules as hypoechoic regions.
