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Transsplenic Portal Scintigraphy Mebrofenin vs. 99m TcO 4 -
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James Montgomery March 29, 2010 Transsplenic Portal Scintigraphy Mebrofenin vs. 99m TcO 4 -
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Transsplenic Portal Scintigraphy Mebrofenin vs. 99m TcO 4 -. James Montgomery March 29, 2010. Transsplenic Portal Scintigraphy. Two common radiopharmaceuticals for this procedure Na 99m TcO 4 99m Tc-Mebrofenin Dose 0.5 – 2.0 mCi in 0.2 – 0.5 mL volume - PowerPoint PPT Presentation
Transcript of Transsplenic Portal Scintigraphy Mebrofenin vs. 99m TcO 4 -
James MontgomeryMarch 29, 2010
Transsplenic Portal ScintigraphyMebrofenin vs. 99mTcO4
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Transsplenic Portal ScintigraphyTwo common radiopharmaceuticals for this
procedureNa99mTcO499mTc-Mebrofenin
Dose0.5 – 2.0 mCi in 0.2 – 0.5 mL volumeMuch smaller dose than PRPS (5 – 20 mCi)
Transsplenic Portal ScintigraphyNormal
Radioactivity travels from spleen and then seen in liver before the heart
127461PSS
See the radioactive isotope travel from the spleen through the shunt vessel to the vena cava
Activity in the heart before the liver125132
Technetium-99mThe first man-made element
Produced by atomic bombardment of Mo in 1937
Principal mode of decayIsometric transition – gamma ray emitter
Physical T1/26.02 hours
Principal photon energy140 keV
Production methodGenerator (Mo-99)
99mTc-MebrofeninLidocaine analog
Liver is the primary site of uptake and metabolism of lidocaine
High first pass extraction by the liver
Advantages of MebrofeninGives excellent images of the portal vein just
like 99mTcO4- but gives additional information…hepatic function
High first pass extraction by the liver>90% removed from blood pool on first pass
Will not pass through the liver to the heartRetained in the liver and gradually cleared into
the biliary systemHalf-time clearance rate of 19 minutesDogs with PSS have a conspicuously different
pattern from normal dogs
Advantages of MebrofeninEvaluate size and morphology of the liverAlso evaluate functionIn a normal dog, a static image at 5
minutes should have no activity anywhere except the liver and some residual in the spleen
Releasable at 1 hr
Comparison
TSPS - Mebrofenin
Hepatic Morphology
Sensitivity/SpecificityTSPSSensitivity
TSPSSpecificity
PRPSSensitivity
PRPSSpecificity
Single observer
100% 100% 100% 85.7%
Consensus 100% 100% 100% 95%
o Additionally, able to accurately determine shunt termination 97% of the timeo vs. 46% with PRPS
o Able to accurately determine number of shunt vessels 91% of the timeo vs. 71% with PRPS
o Cannot diagnose Microvascular Dysplasia
Portoazygous shunt
Portocaval or Splenocaval
Multiple acquired shunts
UTDo all of their TSPS with mebrofenin
$120
Hardly ever do US shunt huntsOnly for resident practice$210
CT those that are questionable with scintigraphy
Go to surgery based on scitigraphic results
NCSUAbdominal US
$262Abdominal CT
$537TSPS – pertechnetate
$163TSPS – mebrofenin
$220
Should we change our protocol?
ReferencesNuclear Medicine Short Course NotesMorandi F, et al. Transsplenic portal
scintigraphy using 99mTc-Mebrofenin in normal dogs. Veterinary Radiology & Ultrasound 2007(48):286-91.
