A comparison between 99Tcm-tetrofosmin and 99Tcm-MIBI myocardial perfusion imaging in detection of silent myocardial ischemia

Objective To compare 99Tcm-tetrofosmin (TF) and 99Tcm-MIBI adenosine stress/resting MPI in detection of silent myocardial ischemia (SMI).Methods According to the WHO diagnostic criteria for coronary heart disease (CHD),306 SMI patients were classified to three groups as type Ⅰ (n =122),type Ⅱ (n =112) and type Ⅲ (n =72).The subjects of each type were randomly divided into 2 subgroups; one subgroup underwent adenosine stress/rest MPI with 99Tcm-MIBI and another subgroup with 99Tcm-TF.The clinical diagnosis of CHD was proven with electrocardiogram (46 cases),dynamic electrocardiogram (219 cases) or CAG (41 cases).Comparison factors between the two tracers included image quality and diagnostic efficacy.The image quality was graded into three classes:excellent,good and moderate.x2 test and analysis of variance were used to analyze data.Results The sensitivities of detecting myocardial ischemia with 99Tcm-MIBI MPI and 99Tcm-TF MPI in group type Ⅰ were 57.38％ (35/61) vs 60.66％ (37/61) (x2 ＝ 0.136,P ＞ 0.05) ; in group type Ⅱ 69.64％ (39/56) vs 64.29％ (36/56) (x2 =0.363,P ＞ 0.05) and in group type Ⅲ 83.33％ (30/36) vs 88.89％ (32/36) (x2 =0.465,P ＞ 0.05),respectively.There was no significant difference between the sensitivities of the two imaging modalities in all three types of SMI patients.In image quality grading,99Tcm-MIBI and 99Tcm-TF demonstrated excellent images with 41.18％ (63/153) vs 48.37％ (74/153) (x2 =1.599,P =0.206),good with 45.10％ (69/153) vs34.64％(53/153) (x2 =3.489,P=0.062) and moderate with 13.72％ (21/153) vs 16.99％(26/153) (x2 =0.628,P =0.428).There was no unqualified image with either modality.99Tcm-TF displayed quicker radioactivity clearance in liver and lungs.Thereby there was less interference or pitfalls present in the ventricle base or interior wall that may result from higher liver radioactivity retention.The waiting time between the tracer injection and imaging was at least 1 h shorter with 99Tcm-TF compared to 99Tcm-MIBI.Conclusions 99Tcm-TF is comparable with 99Tcm-MIBI in detection of silent myocardial ischemia as a MPI tracer.Meanwhile,99Tcm-TF MPI may reduce MPI pitfalls and save time during the imaging protocol. Key words: Myocardial ischemia; Tomography emission-computed,single-photon; Technetium; Tetrofosmin; MIBI