Clinical concept of PET-CT

Question 1

Why do we combine PET with CT/MRI?

Answer 1

• Improved anatomical localisation
• Reduction in dose by doing the scans together

Question 2

What does PET stand for?

Answer 2

Positron emission tomography

Question 3

What is PET scanning?

Answer 3

It’s a technique measures positron admitted from radionuclide that have been injected into a patient and reconstruct 3-D image of radiotracer concentration

Question 4

What do we need to ask prior to PET scan?

Answer 4

• allergies/adverse reactions
• Pregnancy status
• If interpreters are needed
• bring list of medication

Question 5

What is the prep for pET-CT?

Answer 5

• Limited carbohydrate diet 24 hours prior appointment
• nothing to eat/drink for 6 hours prior - lots of water
• take medication
• Arrive 15-30 min before appointment
• eGFR

Question 6

What should patients expect during the PET scan?

Answer 6

Average 2 hours
After FDG injection 60 min wait before scan

Question 7

What is a typical imaging protocol for PET-CT?

Answer 7

1. Pt injected with tracer them waits 1-2 hours
2. Scout performed for planning
3. Pt automatically moved to CT gantry and a low dose spiral CT is obtained
4. PT automatically through the PET Gantry to obtain slices - about 5-7 beds each 5-7 min
5. CT based attenuation correction (CTAC) are generated
6. Attenuation- corrected PET emmision data reconstructed
7. Pet- and CT images fused

Question 8

What is the process of PET-CT?

Answer 8

• positron emitter injected into the patient
• Annihilation of a positron with an electron occurs and 2 511 kev photons are created travelling in opposite directions in order to conserve momentum
• the coincident detection of the pair of photons is used to localise their source along the Line of Response (LOR)
  Not done