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Rb82 is a monovalent cation and has ultra short base at the rim. Both relative and absolute flow re-
half life 75 sec. Sr-82 decays to an elution column. serve can be depicted on quantitative polar maps on
Rb82 is eluted with 25 to 50 ml of normal saline by Rb82 activity. In this manner the rest and stress imag-
a computer controlled elution pump, connected by es are functionally interrelated. Three dimensional (3-
IV tubing to the patient. This generator has almost D) topographic displays of Rb82 cardiac activity are
no breakthrough of strontium and has useful life of more quantitative with respect to the polar maps. An
4-6 weeks. Serial evaluations of regional myocardi- automated quantitative analysis programmed may
al perfusion can be made at intervals as short as 5 enhance accuracy and reproducibility of cardiac PET
minutes. The short half life of Rb82 taxes the perfor- flow studies.
mance limits of PET scanners; it facilitates the rapid The sensitivity and specificity of PET MPI are superi-
completion of a series of resting and stress myocar- or to other non-invasive tests. Four studies involving
dial perfusion studies. Rb-82 is a very efficient imag- a total of 342 patients have made direct comparisons
ing agent for routine clinical usage. Although the cost of Tl-201 SPECT and PET MPI. In addition a survey of
per patient at a low volume of studies per day is high, numerous studies of PET MPI in 1391 patients found
the cost with 6 to 10 studies per day is competitive excellent sensitivity (92%: C I = 90% to 94%) and spec-
with SPECT tracers.
ificity (90% C I = 88% to 92%). Church well et al has
The first pass extraction of Rb-82 at rest is approx- also shown greater accuracy in a blinded analysis of
imately 50-60% and it’s via Na+/K+ AT pase pump. the accuracy of 82 Rb PET in 194 patients with new
Myocardial extraction of Rb-82 is similar to thallium quantitative software developed in their laboratory.
– 201 and slightly less than N-13 ammonia, decreasing Patterson et al has also shown significantly better
during hyperemia .Rb- 82 extraction can be altered results with 82-Rb PET than their own SPECT Tl-201
by severe acidotic hypoxia and ischemia. (36). Thus results. These comparisons and Emory University’s
uptake of Rb-82. is a function of both blood flow and extensive clinical experiences (over 30,000 SPECT
of myocardial cell integrity. Rb-82 perfusion imaging Tl-201 and over 2000 MPI. Though all patients with
is usually performed before and after vasodilator intermediate risk of coronary artery disease can un-
stress rather than with exercise. Infracted myocar- dergo PET MPI, it is preferable to SPECT MPI in a
dium doesn’t retain intravenously administered Rb- subgroup of patients with attenuation problems i.e
82. After administration, it washes out rapidly from large patients, women, breast implants or left mas-
damaged myocardial cells following the initial uptake tectomy, chest wall deformity, left pleural or pericar-
phase. A mixture of reversible and irreversible myo- dial effusion. However it must be emphasized that
cardial tissue in the field of view results in an inter- attenuation problems in SPECT can not be predicted
mediate level of Rb-82 wash out that is proportional with confidence from examination of body habitus.
to the percentage of viable or infracted tissue. There is an incremental benefit caused by greater
specificity and sensitivity which gives rise to incre-
Imaging of Rb-82: mental economic benefit caused by more accurate
tests like Rb82 PET MPI.
Patient preparation for stress and rest myocardial
PET perfusion imaging is identical to SPECT perfu- During the last 10 to 15 years ,both SPECT and PET im-
sion imaging. Despite the short half-life of Rb82, aging have undergone significant improvements . A
modern PET gamma cameras are able to obtain good recent comparison between Tc-99m sestamibi SPECT
quality images. The usual protocol takes approxi- and Rb82 PET MPI revealed a significant margin of
mately 15 minutes with a BGO crystal PET scanner improvement for CAD detection accuracy with Rb82
and 35 minutes with LSO crystals PET scanner. The PET compared to SPECT (38). Given the proven value
proper positioning is done with a low dose (20mci) of PET myocardial perfusion imaging in the diagnosis
injection of Rb-82 and short 3 minutes scout acqui- of CAD, it is expected that the prognostic value of
sition and quick reconstruction. Subsequently, rest gated PET is also high, similar to SPECT imaging.
transmission imaging, rest perfusion 2D imaging and T in cardiac imaging is reduction in acquisition time
rest gated 3D imaging were done sequentially. Stress by 10-12 minutes in comparison to a dedicated PET
imaging is also done in similar manner. Transmission system. PET-CT imaging holds challenges and solu-
imaging is usually done with a germanium-68 pin or
rod source, which takes about 8 minutes. tion for the attenuation correction problem.
Tomographic data from Rb82 images can be dis-
played using polar maps utilizing the bulls eye ap-
proach with the apex located at the centre and the

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