1. PET Myocardial Perfusion Imaging: Protocols and Procedures
George Segall, M.D.
Stanford University

2. PET Perfusion Agents Diffusible tracers
Radioisotope Form Half-life MeV
Rubidium-82 (82Rb) Chloride 75 sec 3.15
Nitrogen-13 (13N) Ammonia 10 min 1.19
O-15 (15O) Water sec 1.72
Copper-62 (62Cu) PTSM min 2.94
Potassium-38 (38K) Chloride min 2.70
Carbon-11 (11C) Butanol 20 min 0.96
PTSM, pyruvaldehyde methylthiosemicarbazone

3. Medicare Coverage Policy
1995 Rb-82 PET for myocardial perfusion
1998 F-18 deoxyglucose PET and SPECT for myocardial viability
2003 N-13 ammonia for myocardial perfusion

4. Medicare Coverage Policy for
Rb-82 and N-13 ammonia
PET whether at rest alone, or rest with stress, is approved when PET is
• performed in place of SPECT, or
• used following SPECT when results are equivocal, technically uninterpretable, or discordant with clinical care
SPECT may not be used following an inconclusive PET

5. RAM License Strontium-82 200 mCi Rubidium-82 200 mCi Strontium-85
Generator contains mCi of Sr-82 at time of calibration (package insert)

6. Rb-82 Infusion System

7. Relative Advantages Rb-82 N-13 ammonia Availability Excellent Limited
Logistics Easy Difficult
Cost Fixed Variable

8. Decision Analysis Occasional Imaging On-site cyclotron Daily Imaging
N-13 ammonia
and
Daily Imaging
PET/CT capacity
Rb-82 chloride
and

9. Decision Analysis Flexibility Convenience Exercise Regadenoson
Adenosine
N-13 ammonia
Dipyridamole
Dobutamine
Convenience
Regadenoson
Rb-82 chloride
Adenosine
Dipyridamole

10. Scheduling N-13 ammonia Rb-82 chloride scheduled > 1D in advance √
• problematic cases
inconclusive SPECT
high BMI √
scheduled day of exam
• ED and inpatients

11. Emission protocol N-13 ammonia • 20-30 mCi • 2D gated emission
• start 10 min p injection
Rb-82 chloride
• mCi
• 2D gated emission
• start 90 sec p injection

12. 2D vs 3D Gated Rb-82 PET
Knesaurek. BMC Nucl Med 2007;7:4
16 normal volunteers had resting Rb-82 on a BGO PET camera
Low dose (20 mCi) 3D acquisition compared to high dose (60 mCi) 2D acquisition

13. Emission Reconstruction
Rb-82 chloride
• reconstruction filter: Butterworth 0.4 roll-off / power 10
• post reconstruction: axial smoothing
N-13 ammonia
• reconstruction filter: Butterworth 0.40 roll-off / power 10
• no post reconstruction smoothing

14. CT protocol • 140 keV • 30-210 mAs (noise index 25.0) • pitch 0.5
• ungated

15. PET Perfusion Agents
•Rb-82 Chloride and N-13 ammonia are both extractable agents which passively diffuse across cell membranes
•Both tracers have high first-pass myocardial extraction fractions, which are inversely related to flow is a non-linear manner.

16. Rb-82 chloride •Rb-82 is rapidly cleared from the circulation
Tang. Phys Med Biol 2009;54:
•Rb-82 is rapidly cleared from the circulation

17. N-13 ammonia
•N13 is rapidly cleared from the circulation

18. N-13 ammonia
•N-13 ammonia is trapped in the myocardium from the action of glutamate dehydrogenase1 and glutamine synthetase2
-ketoglutarate
NH3 1 2
13NH4+
13NH3
13NH3
glutamate
glutamine
glutamine
urea

19. PET Perfusion Agents Relationship to CBF Rb-82 Chloride N-13 ammonia
Bergman SR. In: PET of the Heart. Eds: Bergmann SR, Sobel BE. 1992
Schelbert Hr, Schwaiger M. In: PET and Autoradiography. Eds: Phelps ME, Mazziotta JC, Schelbert H 1986

20. Work Flow Rb-82 40-60 mCi min N-13 ammonia 20-30 mCi inject inject CT
scan
Pers
scan 5 10 15 20 25 30 35 40 45 50 55 60
min CT
scan
Pers
scan
inject
inject
N-13 ammonia
20-30 mCi

21. Rb-82 chloride min inject inject CT scan Pers scan 5 10 15 20 25 30 355 10 15 20 25 30 35 40 45 50 55 60
min CT
scan
Aden
scan
inject
inject

22. Rb-82 chloride min inject inject CT scan Pers scan 5 10 15 20 25 30 355 10 15 20 25 30 35 40 45 50 55 60
min CT
scan
Reg
scan
inject
inject

23. N-13 ammonia min 5 10 15 20 25 30 35 40 45 50 55 60 inject scan Pers5 10 15 20 25 30 35 40 45 50 55 60
inject
scan
Pers
min CT 65 70 75 80 85 90 Ex
•••

24. Injection times
Cyclotron starts production 23 minutes prior to calibration time Ex
Reg
= inject Ad
Per
Dob 5 10 15 20 25 30 35 40 45 50 55 60

25. Normal Rb-82 perfusion study

26. Normal Rb-82 perfusion study

27. Normal Rb-82 perfusion study

28. Normal Rb-82 perfusion study

29. Abnormal Rb-82 perfusion study

30. Abnormal Rb-82 perfusion study

31. Normal N-13 perfusion study

32. Normal N-13 perfusion study

33. Abnormal N-13 perfusion study
72 year old man with peripheral vascular disease.
Coronary arteriography:
•LAD: 60% ostial and 80% mid vessel stenoses
•LCX: 90% proximal stenosis and occluded OM
•RCA: 90% ostial stenosis

34. Summary
• PET myocardial perfusion protocols are simple and easy to incorporate in most practices
• Rb-82 and N-13 ammonia are qualitatively equivalent

35. Summary
• High throughput, and low cost per patient makes Rb-82 PET practical in a high volume practice
• NH3-ammonia PET is better suited for occasional use in patients with inconclusive SPECT, or as the test of choice in problematic patients

36. 3