Respiratory gating in cardiac PET: Effects of adenosine and dipyridamole

Respiratory motion due to breathing during cardiac positron emission tomography (pet) results in spatial blurring and erroneous tracer quantification. respiratory gating might represent a solution by dividing the pet coincidence dataset into smaller respiratory phase subsets. the aim of our study was to compare the resulting imaging quality by the use of a time-based respiratory gating system in two groups administered either adenosine or dipyridamole as the pharmacological stress agent. forty-eight patients were randomized to adenosine or dipyridamole cardiac stress 82rb-pet. respiratory rates and depths were measured by a respiratory gating system in addition to registering actual respiratory rates. patients undergoing adenosine stress showed a decrease in measured respiratory rate from initial to later scan phase measurements [12.4 (±5.7) vs 5.6 (±4.7) min−1, p < .001] and tended to have a lower frequency of successful respiratory gating compared to dipyridamole (47% vs 71%, p = .12). as a result, imaging quality was superior in the dipyridamole group compared to adenosine. if respiratory gating is considered for use in cardiac pet, a dipyridamole stress protocol is recommended as it, compared to adenosine, causes a more uniform respiration and results in a higher frequency of successful respiratory gating and thereby superior imaging quality.