In-111 WBC labeling

Question 1

what is 8-hydroxyquinoline (oxine)

Answer 1

a weak organic chelate (-)

Question 2

what happens when 8-hydroxyquinoline (oxine) bind with In-111(+3)

Answer 2

they bind in a 3:1 ratio and produce a large neutral molecule that can pass easily through cell membrane

Question 3

In-111 mixed with WBC then the ______ passes through the _______ and into the ________ where _______ displaces In-111 from ______ and permanently bind the isotope.

Answer 3

chelate, cell membrane, cytoplasm, intracellular proteins, oxine

Question 4

what does it mean that In-111 oxine is an indiscriminate label

Answer 4

WBC must be seperated from other cells to prevent cross labeling

Question 5

because oxine is a weak chelate and easily displace by other materials, what iron binding proteins in plasma prevent mislabeling

Answer 5

lactoferrin and transferrin will bind to In-111 and make it incapable of labeling cells so they must be removed early on

Question 6

what must be determined prior to in wbc labeling

Answer 6

pt wbc count

Question 7

upper and lower limit allowed for wbc count

Answer 7

too low= <2,000 mm^3
too high= 40,000 mm^3
nothing higher than 25,000 pref

Question 8

what do you do if pt wbc count too low

Answer 8

you can double amount of whole blood and combine with already drawn wbc or use donor matched wbc

Question 9

what do you do if pt wbc count is too high

Answer 9

> 40,000 mm3 indicates leukemic patients whihc means poor functioning cells so poor locating and labeling

Question 10

labeling % avg and what alters this

Answer 10

75% of indium binds to cells dependent on technique and pt status (75-80%)

Question 11

how long can i delay wbc reinjection

Answer 11

4 hours max but reinject asap and invert gently to suspend cells. store in hard capped syringe.

Question 12

when should we use PET or Ga-67

Answer 12

brain/transaxial system

Question 13

what is the benefit of In

Answer 13

weak chelate so binds well and crosses cell membrane easier

Question 14

what is tc exametazine

Answer 14

a lipophilic tc labeled material is introduced that penetrates the cell and energy of tc and has the ability to administer 10-15 times greater activity compared to In-111. This allows quicker and better imaging

Question 15

what is tc hmpao good for

Answer 15

well suited bc of its ability to cross the cell membrane easily and wash out quickly

Question 16

how to minimize cross cell labeling

Answer 16

WBC isolated from whole blood

Question 17

why is the presence of plasma during labeling not an issue

Answer 17

because the tc is not bound by plasma ion binding protiens and other plasma proteins have no affinity for tc

Question 18

practical considerations of tc

Answer 18

-wbc count
-labeling %
-reinject asap

Question 19

labeling % of tc wbc

Answer 19

50-60% which is low and why we use In-111

Question 20

In labeling procdures

Answer 20

7 mL of ACD (heparin) to 60 mL syringe>draw pt blood>invert syringe>position syringe in holder and remove needle and pull back plunger far as possible>add 6% hetastarch and attach needle and invert>position at 45 degree for 30 min> straighten syringe when 2 min left so solid sink to bottom>baxter tubing extension and centrifuge for 10 min @1000rpm>pippette plasma to new centrifuge tube to isolate wbc> button wash and spin 5 min @750 rpm>draw 650-680 uCi In-111 oxine>discard hot supernatant

Question 21

while labeling with tc how old can tc be

Answer 21

less than 2 hours old and milked from gen that has been eluted in past 24 hours

Question 22

how much activity used for Tc

Answer 22

12 mCi in 2 mL

Question 23

incubate Tc labeled for how long

Answer 23

15 min

Question 24

how long to incubate Tc kit

Answer 24

1-2 min

Question 25

how long to incubate In

Answer 25

15 min