TC-99M TETROFOSMIN MYOCARDIAL PERFUSION SCAN - COMPARISON OF 1-DAY AND 2-DAY PROTOCOLS

Nineteen patients with angina were recruited in this study for compari son of two 1-day protocols (stress-4 h rest and rest-4-h stress) and a 2-day protocol of technetium-99m tetrofosmin single-photon emission t omography (SPET). All of them underwent coronary angiography before or after the study. Exercise stress-rest study and rest-stress study wer e performed on two consecutive days. Delayed imaging was performed bef ore the rest injection on the 2nd day. The stress study on the Ist day and rest study on the 2nd day were considered as a 2-day protocol. Th e I-day stress-rest protocol had a sensitivity of 100% (18/18) and an accuracy of 100% (19/19) in diagnosing ischaemic heart disease. The 1- day rest-stress protocol had a sensitivity of 94.4% (17/18) and an acc uracy of 94.7% (18/19), These differences were not statistically signi ficant (P=0.5 for sensitivity and accuracy). There was also no statist ically significant difference between the two protocols in the diagnos is of ischaemic heart disease in individual artery territories. For th e left descending artery, sensitivity was 88.2% (15/17) vs 76.5% (13/1 7) (P=0.48) for the stress-rest and rest-stress studies respectively. For the left circumflex artery, sensitivity was 90% (9/10) vs 80% (8/1 0) (P=1) and specificity was 66.7% (6/9) vs 77.8% (7/9) (P=1) respecti vely. For the right coronary artery, the sensitivity was 100% (16/16) vs 94% (15/16) (P=1) respectively, while the specificity was 33.3% (1/ 3) in both studies. Three hundred and forty-two myocardial segments we re analysed. The stress-rest and 2-day protocols showed no statistical ly significant difference in the overall identification of segments wi th reversible ischaemia (48/141 segments vs 48/141 segments) or in res pect of individual artery territories, There was also no significant d ifference in the identification of reversible ischaemic segments betwe en the rest-stress and 2-day protocols (48/141 segments vs 34/135 segm ents, P=0.14), Abdominal activity was seen in 36 studies and interpret ation was affected in five of them. Five patients with 24-h delayed im ages were evaluated and 24 segments with washout were identified. It i s concluded that Tc-99m-tetrofosmin is a valuable new tracer in the in vestigation of ischaemic heart disease. The 1-day stress-rest protocol is as good as the 1-day rest-stress protocol in diagnosing coronary h eart disease. The 1-day protocols and the 2-day protocol display no di fference in identifying segments with reversible ischaemia.