The value of the gated 99m Tc- MIBI SPECT in differentiation of fixed myocardial lesions

Fixed myocardial defects in both stress and rest images, could be artifactual as a result of soft tissue attenuation. To increase specificity and identify the false positive results, we used gated technique to evaluate the wall motion and wall thickening as an index to differentiate real ischemic lesions from artifactual defects. 93 patients were studied. In 46 patients (48.8%) fixed perfusion defects were identified. Of these patients 10(21.7%) had definite evidence of previous MI, 6 of whom (60%) showed abnormal gated SPECT findings. Among 36 patients without history of MI, 11 case (30%) showed abnormal ventricular function (probably due to silent MI) and 25 patients(70%) had normal function. The latter group were comprised of 13 females (52%) with fixed perfusion defects seen in the anterior, septal and apical segments of the myocardium. The results of the investigation indicate that using gated SPECT method with 99m Tc- MIBI myocardial perfusion studies increases specificity of the fixed myocardial defects and is highly recommended