George Segall, M.D.

VA Palo AltoHealth Care System

Stanford University

PET Myocardial Perfusion Imaging: Protocols and

Procedures

PET Perfusion Agents

Rubidium-82 (82Rb) Chloride 75 sec 3.15

Nitrogen-13 (13N) Ammonia 10 min1.19

O-15 (15O) Water 110 sec1.72

Copper-62 (62Cu) PTSM 9.8 min2.94

Potassium-38 (38K) Chloride 7.6 min 2.70

Carbon-11 (11C) Butanol 20 min0.96

Radioisotope Form Half-life MeV

Diffusible tracers

PTSM, pyruvaldehyde methylthiosemicarbazone

Medicare Coverage Policy

1995Rb-82 PET for myocardial perfusion

1998F-18 deoxyglucose PET and SPECT for myocardial

viability

2003N-13 ammonia for myocardial perfusion

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

RAM License

Strontium-82 200 mCi

Rubidium-82 200 mCi

Strontium-85 1000 mCi

Rb-82 Infusion System

Relative Advantages

Rb-82 N-13 ammonia

Availability Excellent Limited

Logistics Easy Difficult

Cost Fixed Variable

Decision Analysis

Occasional Imaging and

On-site cyclotron

N-13 ammonia

Daily Imaging and

PET/CT capacity

Rb-82 chloride

Decision Analysis

Flexibility Exercise

N-13 ammoniaAdenosine

DipyridamoleDobutamine

Convenience Adenosine

Rb-82 chloride

Dipyridamole

Regadenoson

Regadenoson

Scheduling

N-13 ammonia

scheduled > 1D in advance

• problematic cases

inconclusive SPECT

high BMI

Rb-82 chloride

scheduled day of exam

• ED and inpatients

√ √

√

Emission protocol

N-13 ammonia

Rb-82 chloride

• 20-30 mCi

• 2D gated emission

• start 10 min p injection

• 40-60 mCi

• 2D gated emission

• start 90 sec p injection

2D vs 3D Gated Rb-82 PETKnesaurek. 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

Emission Reconstruction

Rb-82 chloride

N-13 ammonia

• reconstruction filter: Butterworth 0.4 roll-off / power 10

• post reconstruction: axial smoothing

• reconstruction filter: Butterworth 0.40 roll-off / power 10

• no post reconstruction smoothing

CT protocol

• 140 keV

• 30-210 mAs (noise index 25.0)

• pitch 0.5

• ungated

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.

Rb-82 chloride

•Rb-82 is rapidly cleared from the circulation

Tang. Phys Med Biol 2009;54:3161-3171

N-13 ammonia

•N13 is rapidly cleared from the circulation

N-13 ammonia•N-13 ammonia is trapped in the myocardium from the

action of glutamate dehydrogenase1 and glutamine synthetase2

13NH313NH4

+

glutamineurea

-ketoglutarate

glutamate

NH3

glutamine1 2

13NH3

PET Perfusion Agents

Rb-82 Chloride N-13 ammonia

Relationship to CBF

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

Work Flow

0 5 10 15 20 25 30 35 40 45 50 55 60

inje

ct

scan

Pers

inje

ct

scan

inje

ct scan

Persin

ject sca

n

N-13 ammonia20-30 mCi

Rb-82 40-60 mCi

min

CT

CT

Rb-82 chloride

0 5 10 15 20 25 30 35 40 45 50 55 60

inje

ctscan

Pers

inje

ct

scan

inje

ct

min

CT

Aden

inje

ct

scan

scan

CT

Rb-82 chloride

0 5 10 15 20 25 30 35 40 45 50 55 60

inje

ctscan

Pers

inje

ct

scan

inje

ct

min

CT

Reg

inje

ct

scan

scan

CT

N-13 ammonia

0 5 10 15 20 25 30 35 40 45 50 55 60

inje

ct

scan

Pers

min

CT inje

ct

scan

scan

CT

60 65 70 75 80 85 90

Ex scan

CT

0 5 10 15 20 25

inje

ct

inje

ct

min•••

Cyclotron starts production 23 minutes prior to calibration time

Injection times

0 5 10 15 20 25 30 35 40 45 50 55 60

Ex

RegAd

Per

Dob

= inject

Nor

mal

Rb-

82 p

erfu

sion

stu

dy

Nor

mal

Rb-

82 p

erfu

sion

stu

dy

Nor

mal

Rb-

82 p

erfu

sion

stu

dy

Nor

mal

Rb-

82 p

erfu

sion

stu

dy

Abn

orm

al R

b-82

per

fusi

on s

tudy

Abn

orm

al R

b-82

per

fusi

on s

tudy

Nor

mal

N-1

3 pe

rfus

ion

stud

y

Nor

mal

N-1

3 pe

rfus

ion

stud

y

Abn

orm

al N

-13

perf

usio

n st

udy

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

Summary

• PET myocardial perfusion protocols are simple and easy to incorporate in most practices

• Rb-82 and N-13 ammonia are qualitatively equivalent

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