A comparison of same day and separate day injection protocols for myocardial perfusion SPECT using 99Tcm-MIBI

Three dose administration protocols for 99Tcm-MIBI were applied to groups of 15 patients with known or suspected ischaemic heart disease. Firstly, injections were given on consecutive days, with 300 MBq at rest and 500 MBq 24 h later at exercise. Secondly, both injections on the same day with 200 MBq at rest followed 1.5 h later by 1000 MBq during exercise. Finally, both injections on the same day with 200 MBq at rest followed 1.5 h later by 600 MBq during exercise. The diagnostic accuracy was significantly better when the administrations were on separate days than when given on the same day. There was no difference in diagnostic accuracy between the two same day protocols. The same day protocols gave a significantly higher false negative reporting rate than the separate day protocol.