Hepatobiliary Imaging

Question 1

magnetic resonance cholangiopancreatography is good for what?

Answer 1

detecting stones without ductal dilation

Question 2

what are some form of invasive anatomical imaging for the GI?

Answer 2

PTHC - percutaneous transhepatic cholangiography
ERCP - endoscopic retrograde cholangiopancreatography

Question 3

how does a patient NOT FAST LONG enough cause false positives?

Answer 3

causes non-visualization of the GB due to contraction

Question 4

how does a patient who fasted >24 hours or on TPN cause a false positive?

Answer 4

causes non-visualization of GB due to no stimulation of contraction
GB is full of concentrated, viscous bile

Question 5

how does a patient who hasn’t stopped opiates for the required time show false positive?

Answer 5

sphincter of Oddi contracted; no visualization of bowel activity

Question 6

what enteroendocrine hormone stimulates contraction of the GB and relaxation of sphincter of Oddi?

Answer 6

cholecystokinin - CCK

Question 7

what stimulates the release of this enteroendocrine hormone?

Answer 7

presence of fatty acids in the chyme entering the small intestine

Question 8

which cells of the liver are responsible for the localization of the radiopharmaceutical?

Answer 8

hepatocytes

Question 9

what is the method of localization for these RPs?

Answer 9

active transport

Question 10

what is the primary route of excretion?

Answer 10

hepatobiliary (~90%)

Question 11

what is the alternative route of excretion?

Answer 11

kidneys (<10%)

Question 12

What can lead to an increase of RP being excreted via the alternative route?

Answer 12

hepatic dysfunction and increased bilirubin levels

Question 13

what is the LAO view good for in HIDA imaging?

Answer 13

separation of bile ducts from duodenum

Question 14

where do you find the GB in a RLAT view?

Answer 14

GB moves more anterior

Question 15

where do you find the GB in a LAO view?

Answer 15

GB moves to the right

Question 16

what is “rim sign”

Answer 16

increased liver uptake or RP adjacent to GB fossa due to inflammation of liver

Question 17

what percentage do we see the rim sign in pts with acute cholecystitis?

Answer 17

~25%

Question 18

no GB at 60 mins but has the rim sign =?

Answer 18

acute cholecystitis

Question 19

what is “cystic duct sign”

Answer 19

• cystic duct dilation proximal to obstruction

Question 20

cystic duct sign causes false negatives, why?

Answer 20

the activity is misinterpreted as GB but it’s not.

focal activity is usually smaller and more medial than typical GB activity

Question 21

what are “liver scan signs”?

Answer 21

no visualizaton of biliary tree with good visualization of liver

Question 22

what does the liver scan sign usually mean?

Answer 22

acute complete (high grade) CBD obstruction

Question 23

what does phenobarbital do?

Answer 23

stimulates liver excretion for better hepatic excretion of IDA agents

Question 24

what can be used as an alternative to phenobarbital?

Answer 24

ursodeoxycholic acid

Question 25

dose for phenobarbital?

Answer 25

5mg/kg/day (or 2.5 mg/kg BID) for minimum of 3-5 days prior to scan

Question 26

what is the dose for ursodeoxycholic acid?

Answer 26

20 mg/kg/d (or 10mg/kg BID) for 2-3 days and continued until study is complete

Question 27

when can biliary leaks occur?

Answer 27

after abdominal trauma, cholecystectomy, or biliary tract surgery

Question 28

what position do we scan for biliary leaks?

Answer 28

right lateral decubitus

Question 29

what do we see during biliary leaks?

Answer 29

progressive increasing collection of RP in region of GB fossa or hepatic hilum which may spread within the abdomen