Gated (99m)Tc-tetrofosmin SPECT for discriminating infarct from artifact in fixed myocardial perfusion defects.
Soft-tissue attenuation artifacts generally appear as fixed perfusion-scan defects. Gated (99m)Tc-tetrofosmin SPECT may help differentiate myocardial infarction (MI) from artifacts, as fixed defects with decreased function (wall motion and thickening) probably represent MI, whereas attenuation artifacts represent preserved function.


METHODS
Ungated stress and gated rest (99m)Tc-tetrofosmin SPECT was performed on 153 consecutive patients referred for evaluation of coronary artery disease. From stress and summed gated rest images, 107 patients (70%) were identified with isolated fixed defects. The function of the defects was assessed semiquantitatively from gated stress images. The findings were correlated with clinical (history or electrocardiographic Q waves) evidence of MI.


RESULTS
Of 62 patients with fixed defects and clinical MI, 60 (97%) had an abnormal defect function. Of 45 patients with no clinical MI, 16 (36%) had decreased function of the defect, possibly indicating silent MI. In 29 of the 45 patients (64%) with no clinical MI, defect function was normal. Because most (90%) fixed defects with normal systolic function occurred in men with inferior fixed defects (87%) or women with anterior fixed defects (3%), these were most likely attenuation artifacts. By reclassifying the condition of patients with fixed defects and normal function as normal, patients with unexplained fixed defects (no clinical MI) decreased from 29% to 10%.


CONCLUSIONS
Gating adds considerable value to (99m)Tc-tetrofosmin SPECT myocardial perfusion imaging in characterizing fixed defects and potentially improves test specificity.
Fleischmann
Samuel
S
Cardiovascular Center, University Hospital Zurich, Zurich, Switzerland.
Koepfli
Pascal
P
Namdar
Mehdi
M
Wyss
Christophe A
CA
Jenni
Rolf
R
Kaufmann
Philipp A
PA
D000241:Adenosine; D016477:Artifacts; D004452:Echocardiography; D004562:Electrocardiography; D005080:Exercise Test; D005260:Female; D015637:Gated Blood-Pool Imaging; D006321:Heart / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D009200:Myocardial Contraction; D009203:Myocardial Infarction / Q000000981:diagnostic imaging*; D009943:Organophosphorus Compounds; D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; D012680:Sensitivity and Specificity; D015899:Tomography, Emission-Computed, Single-Photon
D009943:Organophosphorus Compounds; D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; C078700:technetium tc-99m tetrofosmin; D000241:Adenosine