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PET/CT exam 2 > exam 2 > Flashcards

exam 2 Flashcards

1
Q

whats is deoxyglucose

A

analog to glucose

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2
Q

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

A

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

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3
Q

what and how does f-18 decay

A

97% positron emission into O-18

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4
Q

normal f-18 fdg distrinution

A

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

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5
Q

physiology of tumor cells and why fdg goes there

A

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

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6
Q

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

A

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

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7
Q

define phosphorylation

A

attachment of a phosphate group to a molecule or ion

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8
Q

what do cancer cells overexpress

A

hexokinase

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8
Q

what does hexokinase do

A

converts glucose into next step for the citric acid cycle

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9
Q

whats the reverse enzyme

A

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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10
Q

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

A

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

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11
Q

f-18 fdg prep

A

-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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12
Q

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

A

proceed and just give a snack after

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13
Q

why no exercise for prep

A

glucose will preferentially move to the muscles

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14
Q

why low carb, high protein diet

A

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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15
Q

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

A

give glucose pill po and send home

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16
Q

can f-18 fdg be given orally

A

no very rarely

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17
Q

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

A

bc forcing heart to be in amino acid metabolism

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18
Q

admin steps for fdg

A

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

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19
Q

why is it important to keep pt warm

A

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

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20
Q

what is scout image for

A

to look for keys, metal objects, jewelery

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21
Q

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

A

port

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22
Q

fdg false positives

A

-inflammation: hematomas, granulomatous proccess, thyroiditis
-infection

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23
Q

whats granulotamous process

A

-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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24
Q

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

A

fdg will show up in bone marrow

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24
Q

why does infection pick up more fdg

A

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

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25
Q

what is bursitis

A

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

26
Q

what factors affect bio-distribution of fdg

A

serum insulin and glucose levels

27
Q

how does serum insulin affect bio disribution

A

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

28
Q

how does glucose levels affect bio-distribution

A

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

29
Q

if pt comes in with too high glucose

A

reschedule and if above 300 call doc and send to ER

30
Q

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

A

insulin if its all over

31
Q

what happens to pic if BG is 190

A

not much PET shown

32
Q

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

A

upatkes in intestines

33
Q

how does exercise affect bio distribution

A

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

34
Q

what does it look like if a pt gardenened day before

A

hands and quads lit up

35
Q

texting shows

A

in forearms and hands

36
Q

will a pulled muscle show

A

yes

37
Q

chewing gum and ate

A

uptake in salivary galnds and tummy

38
Q

how does chemo affect biodisrtibution

A

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

39
Q

why is a pet ordered day after chemo

A

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

40
Q

what happens if pt has splenomegaly

A

chemos causes this and then goes to bone then

41
Q

how does radiation therapy affect bio distribution

A

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

42
Q

what does rad tp look like on pet

A

homogenous incr in activity where xray converges

43
Q

how does surgery and biopsy affect biodistribution

A

cellular repair at incision site bc inflammatoin

44
Q

how do hemopoietins affect biodistribution

A

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

45
Q

what does hemopoeitn look like on pet scan

A

highlights all Bones

46
Q

how does muscle tension affect biodistribution

A

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

47
Q

how does hydration affect biodistribution

A

the circulatory system moves/ flows better when hydrated

47
Q

what muscles are often affected

A

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

48
Q

if a pt has sever lymphadema what will scan show

A

poor blood circulation so poor circulation of tracer

49
Q

what does a higher and lower suv mean

A

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

49
Q

what do we compare SUV’s for

A

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

49
Q

what does suv tell us

A

how metabolically active an area is

50
Q

need to see a suv of what percent if treatment working

A

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

50
Q

metabollically active MBq??

A

2.5 MBq/ml/mg or above

51
Q

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

A

weight because more reproducable than lean body mass

52
Q

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

A

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

53
Q

how to differentiate radiation necrosis vs tumor

A

overlay ct and pet and show exact location

54
Q

what happens in mesothelioma

A

lining of lung affected and spread to other organs= incurable

55
Q

radiation causes inflammation but is less…

A

bright on scan compared to new tumor

56
Q

what is thymus important for in kids

A

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

57
Q

in brain tumor imaging why would we wait longer

A

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

58
Q

what can also be named as “false positives”

A

artifcats

59
Q

where does brown fat store

A

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

60
Q

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

A

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

61
Q
A

PET/CT exam 2 (14 decks)

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