PET CT

Question 1

pet radiotracer positron interaction?

Answer 1

positron and electron will meet, annihilate and create 2 511 keV photons traveling 180 degrees apart

Question 2

how are photons detected on PET CT?

Answer 2

circular crystal

Question 3

F18 half life?

Answer 3

110 min

Question 4

F18 FDG

Answer 4

F-18-fluorodeoxyglucose (F-18 FDG); glucose analog competing for transport into GLUT 1/3 trasnporters

FDG is phosphorylated by hexokinase and is trapped into cells

Question 5

what is SUV?

Answer 5

standardized uptake value; proportional to ROI activity x body weight/administered activity

Question 6

how does SUV change

Answer 6

equipment, time elapsed since FDG administered, amount of tracer extrav, muscle uptake, glucose, insulin levels at time of injection

Question 7

NPO time for PET

Answer 7

4 hrs for insulin to reach basal level; glucose < 1500 (200 upper limit)

Question 8

normal FDG uptake

Answer 8

brain, KUB, glands, liver, bowel, heart, muscle, brown fat

Question 9

smallest nodule that can be reliably evaluated by PET

Answer 9

8mm suspicious pulmonary nodule

Question 10

pulmonary nodules that may not be FDG avid

Answer 10

bronchioalveolar cell carcinoma or carcinoid

Question 11

how long to delay PET CT after colon cancer treatment?

Answer 11

2 months due to flare phenomenon

Question 12

how long to delay PET CT after H&N cancer treatment?

Answer 12

delay 4 months after treatment

Question 13

thyroid FDG avid?

Answer 13

undifferentiated or medullary thyroid cancer