Hepatobiliary Imaging Flashcards
magnetic resonance cholangiopancreatography is good for what?
detecting stones without ductal dilation
what are some form of invasive anatomical imaging for the GI?
PTHC - percutaneous transhepatic cholangiography
ERCP - endoscopic retrograde cholangiopancreatography
how does a patient NOT FAST LONG enough cause false positives?
causes non-visualization of the GB due to contraction
how does a patient who fasted >24 hours or on TPN cause a false positive?
causes non-visualization of GB due to no stimulation of contraction
GB is full of concentrated, viscous bile
how does a patient who hasn’t stopped opiates for the required time show false positive?
sphincter of Oddi contracted; no visualization of bowel activity
what enteroendocrine hormone stimulates contraction of the GB and relaxation of sphincter of Oddi?
cholecystokinin - CCK
what stimulates the release of this enteroendocrine hormone?
presence of fatty acids in the chyme entering the small intestine
which cells of the liver are responsible for the localization of the radiopharmaceutical?
hepatocytes
what is the method of localization for these RPs?
active transport
what is the primary route of excretion?
hepatobiliary (~90%)
what is the alternative route of excretion?
kidneys (<10%)
What can lead to an increase of RP being excreted via the alternative route?
hepatic dysfunction and increased bilirubin levels
what is the LAO view good for in HIDA imaging?
separation of bile ducts from duodenum
where do you find the GB in a RLAT view?
GB moves more anterior
where do you find the GB in a LAO view?
GB moves to the right
what is “rim sign”
increased liver uptake or RP adjacent to GB fossa due to inflammation of liver
what percentage do we see the rim sign in pts with acute cholecystitis?
~25%
no GB at 60 mins but has the rim sign =?
acute cholecystitis
what is “cystic duct sign”
- cystic duct dilation proximal to obstruction
cystic duct sign causes false negatives, why?
the activity is misinterpreted as GB but it’s not.
focal activity is usually smaller and more medial than typical GB activity
what are “liver scan signs”?
no visualizaton of biliary tree with good visualization of liver
what does the liver scan sign usually mean?
acute complete (high grade) CBD obstruction
what does phenobarbital do?
stimulates liver excretion for better hepatic excretion of IDA agents
what can be used as an alternative to phenobarbital?
ursodeoxycholic acid
dose for phenobarbital?
5mg/kg/day (or 2.5 mg/kg BID) for minimum of 3-5 days prior to scan
what is the dose for ursodeoxycholic acid?
20 mg/kg/d (or 10mg/kg BID) for 2-3 days and continued until study is complete
when can biliary leaks occur?
after abdominal trauma, cholecystectomy, or biliary tract surgery
what position do we scan for biliary leaks?
right lateral decubitus
what do we see during biliary leaks?
progressive increasing collection of RP in region of GB fossa or hepatic hilum which may spread within the abdomen
