Myocardial Blood Flow by PET and N-13 Ammonia During Regadenoson Stress

• Myocardial blood flow (MBF) [ Time Frame: 4 hours ] [ Designated as safety issue: No ]
  To quantify regadenoson-induced hyperemic PET N-13 ammonia MBF and compare to adenosine-induced hyperemic PET N-13 ammonia MBF.
  
  

Growing clinical experience and published studies support the comparable diagnostic accuracy, safety, and better subjective tolerability of regadenoson as compared to adenosine. Furthermore, while dipyridamole and adenosine are contraindicated in patients with asthma and significant chronic obstructive pulmonary disease (COPD), pilot data suggest overall safety of regadenoson in patients with mild or moderate asthma and in patients with stable moderate COPD.

The use of the cyclotron-produced and FDA-approved PET perfusion tracer, N-13 ammonia, with regadenoson has not been published. Among the nuclear perfusion tracers, N-13 ammonia provides the best image quality, high diagnostic accuracy, and the lowest total body radiation exposure. Quantification of myocardial blood flow (MBF) in ml per min per gm is also possible with N-13 ammonia, adding clinically useful information and powerful prognostic value and is increasingly utilized in clinical practice. In studies of PET with N-13 ammonia, MBF increases up to four-fold with adenosine or dipyridamole in healthy human volunteers and normal myocardium. However, the PET acquisition protocol for N-13 ammonia with regadenoson stress and the limits of normal PET measured hyperemic blood flow after regadenoson infusion have not been published. The optimal timing of N-13 ammonia administration and of PET image acquisition as well as acquisition duration following regadenoson bolus is not known. Different physical and biological properties of PET perfusion tracers necessitate specific protocols for each tracer.