Assessing the Adequacy of and Differences between Adenosine and Adenosine Triphosphate (ATP) as Stress Inducing Drugs using the Splenic Signal Intensity Ratio in Patients Undergoing Stress Perfusion Cardiac MR Imaging

1296 Background : During stress cardiac MRI ( CMR ) , if there is su‹cient adenosine, a splenic switch-oŠ phenomenon ( SSO ) occurs. In Japan, adenosine triphosphate ( ATP ) is more commonly used as a stressor drug than adenosine. Aims : We aimed to examine whether the eŠect of these drugs was adequate and whether there is a diŠerence between adenosine and ATP with respect to changes in splenic blood ‰ow and signals of stress and rest ( stress / rest splenic signal intensity ratio ; SIR ) . Methods : We visually analyzed stress perfusion CMR scans in a total of 71 patients. In total 33 patients were administered adenosine ( 0.12 mg / kg / min ) , and 38 patients with ATP ( 0.16 mg / kg / min ) underwent stress / rest perfusion CMR examination after intravenous injection of 0.1 ml / kg of 38  meglumine gadoterate at 4.0 ml / sec. After comparing coronary angiogram ( CAG ) ˆndings per-formed within 2 months of CMR and stress CMR images, we divided the patients into 3 groups ; positive CAG and CMR ( true positive ) , both negative ( true negative ) , and CAG positive CMR negative ( false negative ) . SIR was then compared across all groups. Results : No SSO was identiˆed in 25  of patients ( adenosine 21  , ATP 29 ) . The optimal threshold for SIR as an CI, 0.012 In adenosine, the SIR for negative was signiˆcantly higher than the  p ＝ 0.001 . In ATP, a trend towards an increase in SIR in negative group compared to the positive group,