99mTc Sestamibi Myocardial Perfusion Imaging: Evaluation of the Effects of Patient Positioning on Image Quality
99mTc-Sestamibi (MIBI) is a widely used myocardial perfusion agent. However, extra-cardiac activity has the potential to diminish image quality. There are many different protocols regarding optimal patient preparation to minimise gastrointestinal uptake. This study evaluated the effect of patient positioning.
On the Picker 3000XP gamma camera patients are routinely scanned feet first with a bed extension used, which elevated the legs and forcing the bowel closer to the inferior wall of the heart. By removing the bed extension and scanning headfirst the patient is in a truly flat position. This study aims to evaluate if there is any qualitative difference between the two techniques.
Twenty (20) patients referred for One-Day protocol MIBI studies were randomly assigned a scanning position; 10 scanned head first, and 10 scanned feet first. Standard department protocol was adopted.
Four Physicians blinded to patient positioning evaluated the images based on a semi-quantitative scale. (1 – 4 with 1 being good quality and 4 being uninterpretable)
Results showed that the “feet in” group had a higher average score (2.22) compared to the “head in” group (2.01). When divided into outpatients and in-patients, the in-patient “feet in” group had a higher average score of 2.38 Vs. 1.74 for the “head in” group.
Also, analysis of the rest data, showed the “feet in” group was worse when scanned longer than 60 minutes post injection. (feet in = 2.76 head In = 2.03)
As a result of this study, the department has changed its protocol to scanning patients head in.