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George Segall, M.D.

Stanford University. PET Myocardial Perfusion Imaging: Protocols and Procedures. George Segall, M.D. PET Perfusion Agents. Diffusible tracers. Radioisotope Form Half-life MeV. Rubidium-82 ( 82 Rb) Chloride 75 sec 3.15 Nitrogen-13 ( 13 N) Ammonia 10 min 1.19

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George Segall, M.D.

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

  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 110 sec 1.72 Copper-62 (62Cu) PTSM 9.8 min 2.94 Potassium-38 (38K) Chloride 7.6 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 1000 mCi

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

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

  10. Scheduling Rb-82 chloride N-13 ammonia 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 • 40-60 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 Tang. Phys Med Biol 2009;54:3161-3171 •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 NH3 -ketoglutarate 2 1 13NH4+ 13NH3 13NH3 glutamine glutamate glutamine urea

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

  20. Rb-82 40-60 mCi 60 55 50 45 40 35 30 25 0 20 15 10 5 N-13 ammonia 20-30 mCi Work Flow inject inject Pers scan CT scan min CT scan scan Pers inject inject

  21. 60 55 50 45 40 35 30 25 0 20 15 10 5 Rb-82 chloride inject inject Pers scan CT scan min scan scan Aden CT inject inject

  22. 60 55 50 45 40 35 30 25 0 20 15 10 5 Rb-82 chloride inject inject Pers scan CT scan min scan scan Reg CT inject inject

  23. inject inject scan CT scan Pers min 60 55 50 45 40 35 30 25 0 20 15 10 5 inject inject 25 0 20 15 10 5 CT scan Ex CT scan 90 85 80 75 70 65 60 ••• min N-13 ammonia

  24. = inject 60 55 50 45 40 35 30 25 0 20 15 10 5 Injection times Cyclotron starts production 23 minutes prior to calibration time Ex Reg Ad Per Dob

  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

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