Certification Exam - Student Questions

Q2.  When doing myocardial perfusion study, patients are asked to fast for 3/4 hours before the study, either rest/stress. For stress, the purpose is to minimize the possibility of vomitting right? But what is the purpose of fasting during rest??

A2.  I thought they taught you this already at the school and in clinical.  

Anyway one of the main reasons why they need to fast for both rest and stress is to reduce the gut uptake.  Remember the biodistribution of sestamibi is uptake in the liver.  If they have eaten in the morning there is potential of obscuring the inferior portion of the left ventricle due to gallbladder secretions that help with the digestion of food.  The secretions into the small bowel can cause the loops of bowel to limit the visualization of the inferior wall.

However, with Myoview they claim that there is less liver uptake when imaging.... but most facilities still recommend that the patients fast before having their myocardial perfusion imaging.

Check this article out.  It's an older article.

Myocardial Technetium-99m-Tetrofosmin and Technetium-99m-Sestamibi Kinetics in Normal

Subjects and Patients with Coronary Artery Disease


And check this out as well, quantum, this gives an explanation of some of the things that I mentioned above in a case study.

I will follow up again with this answer with more details, later on.... but for the time being I'll leave with this.  The SNM guidelines do not provide much of an explanation.