The Effect of a Shortened Fasting State Prior to Radiotracer Administration on Upper Abdominal Artifacts in Myocardial Perfusion Scan: A Pilot Study

Abstract

Objective: To evaluate the effect of shortened fasting state prior to radiotracer administration on upper abdominal artifacts, study duration, and patient side effects in myocardial perfusion study and to identify any factors that may correlate with the presence of upper abdominal artifacts on imaging.
Methods: Pilot study in twenty eligible patients who underwent myocardial perfusion was done. All patients were instructed to have a light meal between 2-4 hours prior to radiotracer administration, both for rest and stress studies. Other preparation and protocol were performed according to our division’s protocol. Visual analysis of myocardial
perfusion images were evaluated by two nuclear medicine physicians using raw data images (anterior, LAO45 and left lateral views) and SPECT short axis images. The images were scored from 0-3 regarding the artifacts in liver, gallbladder and intestines. Quantitative analysis was done using mean radioactivity counts in inferior myocardial wall, right lobe of liver, gallbladder and intestines and count ratio between myocardial wall and these organs.
Results: The visual analysis in up to 80% of patients showed no artifact in liver, gallbladder and intestine, while 10% showed some artifacts without disturbing scan interpretation and 10% showed artifacts which could be corrected by reconstruction technique without the needed for re-acquisition. The myocardial-to-intestinal ratio in patients without abdominal artifact tended to be higher than in those with abdominal artifacts in both rest and stress studies. Only one patient had transient dizziness after stress, which was most likely due to side effect from adenosine.
Conclusion: There was neither significant effect on the presence of upper abdominal artifacts nor side effect in the patients who had meal until 2 h prior to radiotracer administration in MPS. Thus, this study can be performed in patients who did not fast as instructed by delaying radiotracer administration to 2 h thereafter. This shortening
of fasting period may be considered to reduce patient’s discomfort and the risk from prolonged fasting state for several hours.