Efficiency comparison between ^99mTc-tetrofosmin and ^99mTc-sestamibi myocardial perfusion studies

The purpose of this investigation was to compare the efficiency of two different imaging protocols using two different clinically available ^99mTc labelled myocardial perfusion tracers. One thousand one hundred and thirty-four imaging studies were performed prospectively, using either ^99mTc-tetrofosmin or ^99mTc-sestamibi, alternating the use of each tracer for a total period of 8 months. ^99mTc-tetrofosmin rest studies were performed with injections of 259 MBq-370 MBq and imaging 30 min later. Exercise studies were performed with injections of 777 MBq-1.11 GBq and imaging 20 min later. ^99mTc-sestamibi studies used doses similar to those in the ^99mTc-tetrofosmin studies. Imaging followed a standard procedure, at 60 min after rest injection, and 30 min after exercise. For patients undergoing pharmacological stress testing,^99mTc-sestamibi was imaged 45 min after injection and ^99mTc-tetrofosmin was imaged 30 min after injection. Variables analysed were (1) injection-to-imaging time for the procedure, and (2) the number of repeated scans because of extra cardiac activity. The completion time for the rest study was significantly shorter for ^99mTc-tetrofosmin compared to ^99mTc-sestamibi (47.7±21.7 min vs 74.3±25.8 min P<0.0001). Likewise, the total study time was shorter for ^99mTc-tetrofosmin compared to ^99mTc-sestamibi (90±32.7 min vs 124±37 min, P<0.0001). More importantly, the number of repeated scans was higher with ^99mTc-sestamibi compared to ^99mTc-tetrofosmin, 21.4% vs 10%, P = 0.001 for rest studies and 19.7% vs 7.9% P = 0.1 for rest and stress. It was concluded that, using a same day rest/stress protocol, ^99mTc-tetrofosmin provided higher patient throughput with fewer repeat scans. These factors may be considered for efficiency improvement in nuclear cardiology laboratories using ^99mTc perfusion tracers.