MYOCARDIAL SPET IMAGING WITH TC-99(M)-TETROFOSMIN IN CLINICAL-PRACTICE - COMPARISON OF A 1 DAY AND A 2 DAY IMAGING PROTOCOL

Tc-99(m)-tetrofosmin is a new myocardial perfusion agent with the adva ntage that it can be reconstituted at room temperature. Because two se parate injections are required for rest and stress images, a separate- day imaging protocol with one injection each day would be optimal in t erms of image quality. From the logistical point of view, a 1 day prot ocol may be more convenient for the majority of those referred as outp atients. The main aim of this study was to determine whether the detec tion of myocardial ischaemia would be impeded by the use of a 1 day pr otocol instead of a 2 day protocol. A secondary aim was to establish t he relative diagnostic accuracy of the two imaging strategies. Tc-99(m )-tetrofosmin SPET imaging was performed in 157 patients. Sixty-nine ( 44%) patients were administered 250 MBq (7 mCi) Tc-99(m)-tetrofosmin a t rest followed 4 h later by 750 MBq (21 mCi) during stress (the 1 day protocol), whereas 88 (56%) patients had rest and stress imaging stud ies on two separate days, receiving a 500 MBq (14 mCi) dose of Tc-99(m )-tetrofosmin on each occasion (the 2 day protocol). With the 1 day pr otocol, 135 of 621 (22%) abnormal segments (i.e. both reversible and p ersistent defects) were observed, compared with 195 of 792 (25%) segme nts with the 2 day protocol. Also, the occurrence of reversible defect s only did not differ between the two protocols (both 9%). The sensiti vity for the detection of coronary artery disease was 83 and 90% for t he 1 and 2 day protocols respectively. We conclude that the 1 and 2 da y protocols provide similar scintigraphic information and are equally sensitive and specific for the detection of coronary artery disease. T herefore, the imaging protocol can be adjusted as appropriate for the patient in question.