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

• Published in: Japanese Journal of Magnetic Resonance in Medicine Vol. 40; no. 1; pp. 7 - 13
• Main Authors: ABE, Masahiro, IIJIMA, Syouta, FUJINAWA, Manabu, IINO, Hitoshi, UCHIKOSHI, Hiroyuki, TAKESHIMA, Hiroshi, YAMASAKI, Akira, KURIHARA, Masato
• Format: Journal Article
• Language: Japanese; English
• Published: Japanese Society for Magnetic Resonance in Medicine 15.02.2020
• Subjects: adenosine; ATP; cardiac MRI; splenic signal intensity ratio; splenic switch-off
• ISSN: 0914-9457; 2434-0499
• DOI: 10.2463/jjmrm.2019-1687

Background : During stress cardiac MRI (CMR), if there is sufficient adenosine, a splenic switch-off 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 effect of these drugs was adequate and whether there is a difference between adenosine and ATP with respect to changes in splenic blood flow 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) findings performed 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 identified in 25% of patients (adenosine 21%, ATP 29%). The optimal threshold for SIR as an indicator of SSO was 0.87 AUC 0.957 for adenosine (0.888-1.000 95%CI, p=0.003) and 0.96 AUC 0.806 for ATP (0.659-0.954 95%CI, p=0.012). In patients administered adenosine, the SIR for the false negative group was significantly higher than in the true positive group and the true negative group (0.50±0.20, vs 0.58±0.36 vs 1.24±0.35* : p=0.001). In patients administered ATP, there was a trend towards an increase in SIR in the false negative group compared to the true positive group, but there was no statistically significant difference among the three groups (0.79±0.20 vs 0.86±0.32 vs 1.06±0.24 : p=0.074).Conclusion : In stress CMR, SIR is a useful indicator stressor effectiveness. In addition, SIR was found to be different between patients administered adenosine or ATP, which suggests a difference in the coronary vasodilator effect. Assessment of CMR after ATP requires more caution than with adenosine.