exam 2 Flashcards by Madi O’Dell

whats is deoxyglucose

analog to glucose

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what happens when you label deoxyglucose with F-18 and how is it used

you create F-18 fluorodeoxyglucose (FDG) and it is utilized as glucose would be in the body

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what and how does f-18 decay

97% positron emission into O-18

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normal f-18 fdg distrinution

brain, heart, thyroid, liver/spleen, stomach, intestines, bladder, kidneys, salivary glands

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physiology of tumor cells and why fdg goes there

cx cells have an 10 times incr metabolic rate compared to that of normal cells

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how is f-18 fdg trapped and what does it phosphorolate into

f-18 is phosphorylated into 2-FDG-6-phosphate by the enzyme hexokinase and phosphorylated into FDG

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define phosphorylation

attachment of a phosphate group to a molecule or ion

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what do cancer cells overexpress

hexokinase

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what does hexokinase do

converts glucose into next step for the citric acid cycle

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whats the reverse enzyme

glucose-6-phosphate and it allows it to leave the cx cells and cx cells will have no glucose-6-phosphate

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what is is f-18 fdg not the best for brain tumors

brains main food source is glucose so less differentiaiton of normal cells vs abnormal cells

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f-18 fdg prep

-npo 4-6 hours
-bg less than 200 (no lower limit but be cautious of too low)
-froedter bg standard= 70-210
-low carb, high protein diet
-no exercise

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if a pt is below 70 but not diabetic and feeling well what do we do

proceed and just give a snack after

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why no exercise for prep

glucose will preferentially move to the muscles

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why low carb, high protein diet

if no carbs, cells are starving, so they will take in FDG exceptionally well and will help with less cardiac uptake

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if a diabetic pt is less than 70 what do we do

give glucose pill po and send home

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can f-18 fdg be given orally

no very rarely

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why does low carb diet and high protein help lower cardiac uptake

bc forcing heart to be in amino acid metabolism

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admin steps for fdg

-inject via IV and make sure pt is warm and still
-wait 60 min to circulate b4 imaging

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why is it important to keep pt warm

brown fat keeps us warm and will eat sugar is it has to work aka if pt is cold

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what is scout image for

to look for keys, metal objects, jewelery

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what is a little round circle that is metal in chest area

port

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fdg false positives

-inflammation: hematomas, granulomatous proccess, thyroiditis
-infection

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whats granulotamous process

-bodies way of containing bacterial, fungal, or viral inf to keep from spreading
-form when immune cells clump together and create tiny nodules at inf or inflammation sites

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if pt had chemo in past 6 weeks, what will happen

fdg will show up in bone marrow

why does infection pick up more fdg

neutrophils and activated macrophages which are present in infections have increased fdg uptake

what is bursitis

inflammation and irritation of the jelly like pads distributed at the areas where bone meets tissue (hips are common)

what factors affect bio-distribution of fdg

serum insulin and glucose levels

how does serum insulin affect bio disribution

-insulin released to reduce glucose levels by pushing glucose into muscles> no insulin 4 hours prior to examh

how does glucose levels affect bio-distribution

increase in glucose levels means cells are already full of glucose and won't take p any f-18 fdg

if pt comes in with too high glucose

reschedule and if above 300 call doc and send to ER

if all muscles show up on scan then this is due to

insulin if its all over

what happens to pic if BG is 190

not much PET shown

what happens if choccy milk 2 hr prior to exam and bg is 103

upatkes in intestines

how does exercise affect bio distribution

muscles need sugar to repair themselves and will take it all up (can see for 24 hours)

what does it look like if a pt gardenened day before

hands and quads lit up

texting shows

in forearms and hands

will a pulled muscle show

yes

chewing gum and ate

uptake in salivary galnds and tummy

how does chemo affect biodisrtibution

chemo damages bone marrow -bm uses sugar to repair -wait 6 weeks from chemo b4 PET

why is a pet ordered day after chemo

to see if chemo is working a destroying bm and if not working siwtch chemo asapw

what happens if pt has splenomegaly

chemos causes this and then goes to bone then

how does radiation therapy affect bio distribution

xray converge on a tumor which create tumor inflammation on and around tumor site

what does rad tp look like on pet

homogenous incr in activity where xray converges

how does surgery and biopsy affect biodistribution

cellular repair at incision site bc inflammatoin

how do hemopoietins affect biodistribution

class of drug that incr production of bone marrow (usually cx patients) "colony stimulating drugs"

what does hemopoeitn look like on pet scan

highlights all Bones

how does muscle tension affect biodistribution

sitting upright activates muscles that need repair so lie pt back a bit

how does hydration affect biodistribution

the circulatory system moves/ flows better when hydrated

what muscles are often affected

tongue, vocalis, scalneus, laryngeal, sternocleidomastoid, esophogeal, heart, paraspinal, trapezius, rhomboid, colon, psoas, glutes, arms, legs, hands

if a pt has sever lymphadema what will scan show

poor blood circulation so poor circulation of tracer

what does a higher and lower suv mean

that higher suv is more metabolically active and lower is lower metabolic activity

what do we compare SUV's for

to tell if treatment is workinh (in 2 weeks) and if suv doesm't decr enough then switch therapies

what does suv tell us

how metabolically active an area is

need to see a suv of what percent if treatment working

25% or greater -calculated by taking mean activity in ROI over injected dose/wt (lean body mass vs weight)

metabollically active MBq??

2.5 MBq/ml/mg or above

is it better to use weight or lean body mass when calculating suv

weight because more reproducable than lean body mass

pov: lump in breast, LT breast bx was normal--> 2 wks later PET shows activity on outside of lump. why?

bc this tumor is necrotic and cut off blood flow to the inside of tumor so we need to re-bx and pt has invasive breast cx RIP

how to differentiate radiation necrosis vs tumor

overlay ct and pet and show exact location

what happens in mesothelioma

lining of lung affected and spread to other organs= incurable

radiation causes inflammation but is less...

bright on scan compared to new tumor

what is thymus important for in kids

growth of several organs and sleep patterns -normal to see active on PET in kids

in brain tumor imaging why would we wait longer

more time allows washout of tracer from normal tissue and can try looking at pic without attenuation correction applied

what can also be named as "false positives"

artifcats

where does brown fat store

around neck, chest, axilla, perinephric, intercostal, periaortic

what will a scan look like if pt is not warm enoigh

uptake in brown fat bc it feeds off of glucose, spots not warm on inj so shows on spine