PET

Question 1

Calcium score >399-<1000 risk of ischemia on PET stress

Answer 1

~50% and on the Schenker study provided a small but incremental benefit for predicting ischemia on the PET scan over patient age and gender and other traditional risk factors

Question 2

2D PET scanner - Septa In scanner

Answer 2

lead or tungsten septa inbetween detector rings (reduces coincidence events) to try to decrease scatter or reduce noise. Down side is increasing imaging times

Question 3

3D PET scanner- Seota Out

Answer 3

this allows more coincidence events between detectors, increasing sensitivity 5xs but increases scatter, less radioactive traces

Question 4

imaging pediatric patients PET 2D vs 3D

Answer 4

3D- reductionin radiation

Question 5

imaging oncologic PET 2D vs 3D

Answer 5

3D- increases sensitivity for detection of abnormal tracer uptake.

Question 6

considering dosimetry which organ receives the highest dose of radiation

Answer 6

urinary bladder, encourage emptying of the bladder

Question 7

energy of the annihilation photons emit regardless of isotope is

Answer 7

511keV

Question 8

Time of flight means

Answer 8

The time difference between two annihilation photons reaching corresponding detector. PET scanner use the slight difference in timing of scintillation events in paired opposite detectors to improve localization

Question 9

which organ recieves highest radiation dose in rubidium 82 study

Answer 9

kidney as it is K analog followed by the heart

Question 10

hormesis

Answer 10

presumptive protective effect of expsure to low amounts of ionizing radiation (upregulartion of molecular cell repair mechanisms)

Question 11

deterministic effect

Answer 11

exposure to ionizing radiation is one in which dose is related to the severity of the effect (min dose to see x affect )

Question 12

stochastic effect

Answer 12

probability of occurance (as opposed to severity of effect) is determined by dose

Question 13

PET SCAN Rest stress -FDG protocol

Answer 13

Rest stress–glucose manipulation (60-90mins), Inject tracer over 10-15 imns then allow 60 mins then imagin
– image 2 hours post infusion

Question 14

PET/CT Scan Protocol

Answer 14

Rest CT 30 secs, inject tracer then prescan delay, stress then inject 7-20 mins for stress mpi

Question 15

Calcium score > 400

Answer 15

Aggressive risk factor modification and consider ischemia evaluation

Question 16

137 Cs HVL in lead

Answer 16

0.6cm

Question 17

18F HVL in lead

Answer 17

0.4cm

Question 18

FFR

Answer 18

FFR =Mean pressure distal to stenosis/ mean aortic pressure

Question 19

CFR equation and normal

Answer 19

CFR= Stress myocardial blood flow/rest myocardial flow , normal is >2

Question 20

hibernating myocaradium functionally definition

Answer 20

functionally defined by improvement of contraction with reperfusion or inotropic stimulation

Question 21

hibernating myocardium metabolic defintion

Answer 21

switch from fat to glucose metabolism, accompanied by reactivation of fetal gene program

Question 22

why do we preform glucose loading and insulin adminitration in PET FDG

Answer 22

improves uptake in normal segments that serve as reference - oral glucose load with 50G dextrose prior to FDG, IV load with hydrocortisone, priming with 50Ml of dextrose and 5 u of insulin