Stomach interference in ⁸²Rb-PET myocardial perfusion imaging

Background: ⁸²Rubidium( ⁸²Rb)-positron-emission-tomography (PET) is prone to some of the same imaging artifacts as single-photon-emission-computed-tomography myocardial perfusion imaging (MPI) including interference from excessive subdiaphragmatic activity. Our aim was to determine associations between clinical parameters and MPI interference including any potential correlation between interference severity and stomach volume. Methods and results: Two hundred men and women fasted two hours prior to standard clinical ⁸²Rb myocardial perfusion rest/stress PET. Images were analyzed for radiotracer interference between left ventricle myocardium and extracardiac activity. Furthermore, volume of the stomach was measured. Interference, predominantly caused by ⁸²Rb activity in the stomach, was less severe in stress PET compared to rest (absent in 46% vs 31% of patients during stress and rest, P < 0.05). In addition, a large stomach volume was associated with more severe interference in rest (P < 0.05) while a high body mass index was associated with less interference. Conclusion: Among clinical parameters associated with patient size, BMI was the strongest predictor of MPI interference. Furthermore, a large stomach volume was associated with more severe MPI interference, suggesting that sufficient fasting prior to imminent ⁸²Rb PET may be important to reduce interference from adjacent radiotracer activity and consequently improve interpretation of MPI results, especially in small patients.