Adenosine is routinely used as a pharmacologic stressor in myocardial perfusion imaging, but its effects on other organs have not been comprehensively studied. The aim of this study was to investigate the effects of adenosine on the perfusion of different organs using a long-axial-field-of-view (LAFOV) PET scanner.

Methods: Ninety-one patients with suspected coronary artery disease who did not have myocardial ischemia or a history of stroke underwent [¹⁵O]H₂O LAFOV PET perfusion imaging at rest and during adenosine stress. Analysis was performed using an in-house open-source total-body pipeline, including CT-based segmentation of organs other than the heart. Organ-specific absolute perfusion values were measured.

Results: Adenosine increased global myocardial blood flow, with a median of 1.01 mL/min/g at rest and 3.47 mL/min/g during stress. Perfusion in other organs was measured in milliliters of blood per minute per milliliter of tissue and significantly increased with adenosine stress in the liver (from 1.10 mL/min/mL at rest to 3.32 mL/min/mL during stress, P < 0.0001), duodenum (from 0.37 mL/min/mL at rest to 0.53 mL/min/mL during stress, P < 0.0001), and colon (from 0.09 mL/min/mL at rest to 0.13 mL/min/mL during stress, P < 0.0001). In contrast, perfusion significantly decreased with adenosine stress in the brain (from 0.43 mL/min/mL at rest to 0.32 mL/min/mL during stress, P < 0.0001) and kidneys (from 0.87 mL/min/mL at rest to 0.65 mL/min/mL during stress, P < 0.0001). In the spleen, perfusion was reduced by 71% as a sign of splenic switch-off (from 1.11 mL/min/mL at rest to 0.31 mL/min/mL during stress, P < 0.0001).

Conclusion: The perfusion response to adenosine appears to be organ-specific. Adenosine increases perfusion in the heart, liver, colon, and duodenum, whereas perfusion is reduced by adenosine in the brain, spleen, kidneys, skeletal muscle, and bone.