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What are the 2 cell types located in the liver and what are their functions?
- 1. Hepatocytes(polygonal cells)
- -Metabolic functional cells (membrane transport)
- 2.Sinusoidal Cells
- -Endothelial cells
- -Kupffer's cells (phagocytic)
Are particulate agents for the liver used for morphological imaging or functional imaging?
- Particulate = morphological
- Hepatobiliary = Functional
What were 3 old radiocolloids used for liver imaging?
Gold, I-131, In-113 (produced in a tin generator)
What are the 3 components in the RXN vial of sulfur colloid and what do they each do? What are the other 2 vials
- VIAL A
- 1. Source of sulfur
- 2. Gelatin - Prevents overswelling (puts - charge around particles so they repel each other)
- 3. EDTA - Chelates Al+ (prevents excess Al reacts w/ phosphate which will cause a lung scan)
- VIAL C
- Buffer (inc pH to 6)
What is the average size of a SC particle?
80% of SC are .4-.6 um
What is the standard liver dosage, uptake, and distribution?
- 5 mCi
- 85% liver; spleen 5%; bone 10%
- Localized via phagocytosis by Kupffer cells
What is the old and current Hepatobiliary agents? Is the current a bifunctional chelate?
- Old: I-131 Rose Bengal
- Current: Tc 99m iminodiacetic acid analogs
- 1st FX: Drug portion (affects biologic distribution)
- 2nd FX: Chelate portion (binds Tc **necessary for organ localization**)
State biologic properties of Hepato Agents (5)
- 1. Anionic, fat loving, high extraction
- 2. Active transport
- 3. Compete w/ bilirubin uptake
- Lidofenin the least, Mebrofenin and Disofenin the most
- 4. ^ bilirubin=v liver uptake=^ kidney excretion
- 5. Critical Organ: large intestine
When will normal liver and GB be visualized? What diseases if they aren't?
- Normal liver: 5-10 min
- " GB: 10-20 min
- GB seen w/n 4 hr is CHRONIC cholecystitis
- " seen w/n after 4 hr ACUTE
No SB activity = OBSTRUCTION
Describe morphine dosage and findings
- .04 mg/kg over 3 min
- contracts sphincter of Oddi for GB visualization
- CHRONIC: GB shows
- ACUTE: GB NO show after 30 min
Describe phenobarbital dosage and findings
- 5mg/kg/day given 5 days prior
- enzyme inducer ^ bilirubin conjugation and excretion
- used to differentiate b/n biliary atresia and hepatitis
- HEPATITIS: bowel excretion occurs
- BILIARY ATRESIA: no bowel
Describe CCK dosage and findings
- .02 ug/kg over 60 min (too fast will cause pt to vomit)
- PRE-CCK to reduce false positives
- POST CCK to measure EF (<38% is abnormal)
What are the role of RBC's when it comes to spleen imaging?
- Old RBC's are destroyed in the spleen
- Radiolabeled RBC's look like old RBC's which is good for spleen imaging
*Size of RBC is 7.5 um*
Why do you seperate the plasma when labeling RBC's for spleen imaging? What happens if you heat it for too long?
Seperate plasma so you only have tinned RBC so that TC take place of tin and labels RBC.**Sodium hypochloride gets rid of extra tin in vial**
Heating for more than 15 min=^ destruction= ^ liver uptake=BAD
Describe localization in spleen imaging
- fragile cell membrane on RBC'S cause them to burst as they squeeze thu the 3 um sized fenestrae in the spleen sinusoids
- phagocytosis occurs
- 1 mCi
- DTST 30 MIN
- 70% uptake in spleen
What are the pros and cons of using RBC's vs SC for GI bleeds?
- Pros of SC:
- Fast blood clearance
- High target to bkgd
- Pros of RBC:
- Best for intermittent bleed (this makes it agent of choice since GI bleeds are INTERMITTENT)
Describe GI bleed procedure
- 20 mCi in vitro method
- 5min img/1 hr; 24 hr image delay
- Active bleeding:
- -^ accumulation a@ site
- -translocation of activity