title: Regadenoson versus dipyridamole hyperemia for cardiac PET imaging.
abstract: OBJECTIVE
  The goal of this study was to compare regadenoson and dipyridamole hyperemia for quantitative myocardial perfusion imaging.
  
  
  BACKGROUND
  Regadenoson is commonly used for stress perfusion imaging. However, no study in nuclear cardiology has employed a paired design to compare quantitative hyperemic flow from regadenoson to more traditional agents such as dipyridamole. Additionally, the timing of regadenoson bolus relative to tracer administration can be expected to affect quantitative flow.
  
  
  METHODS
  Subjects underwent 2 rest/stress cardiac positron emission tomography scans using an Rb-82 generator. Each scan employed dipyridamole and a second drug in random sequence, either regadenoson according to 5 timing sequences or repeated dipyridamole. A validated retention model quantified absolute flow and coronary flow reserve.
  
  
  RESULTS
  A total of 176 pairs compared regadenoson (126 pairs, split unevenly among 5 timing sequences) or repeated dipyridamole (50 pairs). The cohort largely had few symptoms, only risk factors, and nearly normal relative uptake images, with 8% typical angina or dyspnea, 20% manifest coronary artery disease, and a minimum quadrant average of 80% (interquartile range: 76% to 83%) on dipyridamole scans. Hyperemic flow varied among regadenoson timing sequences but showed consistently lower stress flow and coronary flow reserve compared with dipyridamole. A timing sequence most similar to the regadenoson package insert achieved about 80% of dipyridamole hyperemia, whereas further delaying radiotracer injection reached approximately 90% of dipyridamole hyperemia. Because of the small numbers of pairs for each regadenoson timing protocol and a paucity of moderate or large perfusion defects, we did not observe a difference in relative uptake.
  
  
  CONCLUSIONS
  With the standard timing protocol from the package insert, regadenoson achieved only 80% of dipyridamole hyperemia quantitatively imaged by cardiac positron emission tomography using Rb-82. A nonstandard protocol using a more delayed radionuclide injection after the regadenoson bolus improved its effect to 90% of dipyridamole hyperemia.
authors: Weatherhead PET Center for Preventing and Reversing Atherosclerosis, Division of Cardiology, Department of Medicine, University of Texas Medical School and Memorial Hermann Hospital, Houston, Texas. Electronic address: Nils.Johnson@uth.tmc.edu.
authors: Nils P
authors: NP
authors: Johnson
authors: Weatherhead PET Center for Preventing and Reversing Atherosclerosis, Division of Cardiology, Department of Medicine, University of Texas Medical School and Memorial Hermann Hospital, Houston, Texas.
authors: K Lance
authors: KL
authors: Gould
mesh_terms: D058908:Adenosine A2 Receptor Agonists / Q000008:administration & dosage*; D000328:Adult; D000368:Aged; D004176:Dipyridamole / Q000008:administration & dosage*; D005260:Female; D006331:Heart Diseases / Q000000981:diagnostic imaging*; D006439:Hemodynamics; D006801:Humans; D006940:Hyperemia / Q000139:chemically induced*; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography / Q000379:methods*; D011687:Purines / Q000008:administration & dosage*; D011720:Pyrazoles / Q000008:administration & dosage*; D014665:Vasodilator Agents / Q000008:administration & dosage*
chemical_list: D058908:Adenosine A2 Receptor Agonists; D011687:Purines; D011720:Pyrazoles; D014665:Vasodilator Agents; C430916:regadenoson; D004176:Dipyridamole
keywords: absolute flow; dipyridamole; positron emission tomography; regadenoson