Portal Scintigraphy Flashcards
What is the transit time for a trans-splenic portal scintigraphy? Per-rectal?
7 sec - Trans-splenic
12 sec - Per-rectal
What is the main advantages of trans-splenic portal scintigraphy vs per-rectal?
Less activity (1-2 mCi vs 10-20 mCi)
High counts
Morphology
What does 99mTc - MAA do?
Plugs up the first capillary bed
Goals of trans-splenic portal scintigraphy?
Multiple or single shunt
Where does it drain to
Can trans-splenic portal scintigraphy differentiate between intra and extra hepatic shunts?
No
What allows you to diagnose acquired vs congenital shunting?
- Acquired are usually slow transit due to portal hypertension
- Blush of activity behind the kidneys
What is the difference between the transit time in a congential shunt vs normal?
Congenital shunts have faster transit times
What is the only way to get a false positive on trans-splenic scinitigraphy?
Microvascular dysplasia
If you mess up the injection on a trans-splenic (ie intraperitoneum) what should you do?
Re-inject with a new dose
What sedation should you use when doing trans-splenic scintigraphy?
Ace to make the spleen bigger.
Dogs with left division shunts?
Irish wolfhounds
A left divisional intrahepatic shunt is asscoicated with what anatomic structure?
Patent ductus venosus
Why can’t 99mTc-sulfur colloid be used in cats and horses when looking for a PSS?
Because 99mTc-sulfur works by mononuclear phagocytic uptake in the reticuloendothelial system (liver, splee and bone marrow)…however, in cats and horse they have a resident population of mononuclear phagocytes in the Lungs and therefore it will stay there after first pass.
What type of collimator is used in trans spenic portal scin?
LEAP - cause it is 99mTc04-
What is the dose for Trans Splenic Portal scint?
0.5 - 2mCi
in 0.2 - 0.5 mL
What sedation could be used in trans splenic PS?
Ace….gets the spleen big
Is this normal?
Yes.. Injection site.. splenic vein… liver and lastly heart
From left to right
Is this normal?
Yes.. this is 99mTc Mebrofenin.. where, in a normal study, all the Tc goes to the liver and stays there.
What are the three main patterns of TSPS?
- Portoazygos
- Single portocaval/splenocaval
- Internal thoracic
Multiple acquire acquired shunts
Is this normal?
Portoazygos - look for the J-shape curve of coming to the cranial aspect of the heart
Transit time to the heart is 3 sec rather than 7
What type of shunt is this?
Portocaval/Splenocaval — no J-shape… just straight to the heart
What is the the disadvantage of TSPS?
Cannot tell the difference between intrahepatic vs extrahepatic.
what shunt does this dog have?
Internal thoracic along with top with multiple acquired shunts
What type of shunt is this?
Multiple acquired
