GI Section III: MR Contrast - Hepatobiliary Considerations

Question 1

Gadolinium (super toxic) is bound to what agent to keep it from killing the patient?

Answer 1

chelation agent

Question 2

paramagnetic qualities of gadolinium cause what MRI findings?

Answer 2

SHort T1 relaxation time on neighboring molecules (shot t1 = Bright image)

Question 3

Two types of MRI contrast agents

Answer 3

1. Extracellular
2. Hepatocyte specific

Question 4

Extracellular contrast

Answer 4

These are nonspecific agents that are best thought of as Iodine contrast for CT

Blood flow dependent

imaging features in lesions will be the same as CT -

Question 5

Hepatocyte specific contrast

Answer 5

Taken by normal hepatocytes - excreted into the bile

Question 6

In hepatocyte specific contrast, the 20 min delay is the imaging sequence that should give you:

Answer 6

a homogenous bright liver

dark holes are things that don’t contain normal liver cells 0 COULDNOT DRINK CONTRAST - very non-specific

benign things taking it up - i.e. FNH, cyts..etc.

one bad thick taking it. up - well-differentiated HCC

Question 7

3 good reasons in using hepatocyte specific contrast =

Answer 7

1. it’s great for proving an FNH is an FNH - as most lesions won’t hold onto the Gd at 20 mins
2. Bile leaks
3. it’s excellent for picking up new mets (findings black holes on a white background is easy).