Comparative evaluation of the diagnostic accuracy of (99m)Tc-sestamibi gated SPECT using five different sets of image acquisitions at stress and rest phases for the diagnosis of coronary artery disease.

On the basis of some new evidences in favor of delayed (99m)Tc methoxy-isobutyl-isonitrile ((99m)Tc-MIBI) redistribution, doubts about the appropriate time of acquisition following radiotracer injection may be raised. The goal of this study was to find the best acquisition time at stress and rest phases to achieve the highest sensitivity and normalcy rate for (99m)Tc-MIBI SPECT. Ninety four patients with moderate pretest probability of coronary artery disease (CAD) according to "Framingham Risk Score" enrolled in the study. Myocardial perfusion imaging (MPI) with SPECT was performed on the basis of two-day protocol with stress- and rest-phase images obtained at 15, 60, 120 and 180 minutes after injection of 666-814 MBq (99m)Tc-MIBI. According to the time of image acquisition at stress/rest phases, five protocols were defined: A, 15/180 min, B, 15/15 min, C, 180/180 min, D, 180/15 min and E, 120/120 min for stress and rest images, respectively. The sensitivity of MPI for the diagnosis of angiographically proven CAD were 77.3%, 50%, 63.6%, 45.5%, 68.2% and normalcy rate were 72.1%, 72.1%, 75.5%, 70.6%, 92.6% in protocol A, B, C, D and E, respectively. A significant association between SSS and Gensini score was detected only with protocol A (p=0.038). The most sensitive and specific two-day protocols for MPI with (99m)Tc-MIBI were protocol A and E, respectively. In addition, the best relationship between scintigraphic score of ischemia and angiographic score of CAD was achieved using protocol A (i.e. early acquisition at stress phase and late acquisition at rest phase).