High reproducibility of myocardial perfusion defects in patients undergoing serial exercise thallium-201 tomography (original) (raw)
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European Journal of Nuclear Medicine and Molecular Imaging, 2007
Introduction The precise clinical utility of lung 201 Tl uptake in exercise SPECT myocardial perfusion imaging remains open to research. This study validates an optimal index for lung 201 Tl uptake measurement and assesses its value in the prediction of higher-risk coronary artery disease (CAD). Method Three hundred and ninety-eight patients underwent exercise SPECT myocardial perfusion imaging. They were separated into derivation (n=217) and validation (n=186) groups, both including sub-populations of lower-and higher-risk CAD, according to coronary angiography. Another 56 individuals with a low probability of CAD comprised the control group. From a planar, anterior, postexercise acquisition, the lung (L) to heart (H) maximal (L/H max), total (L/H mean) and background-subtracted total (L/H net) ratios were calculated. These were also adjusted for confounding variables, as assessed from the control group. ROC analysis was used to compare the L/H ratios and define thresholds of abnormality. The performance of the optimal index was assessed in the derivation group and was then tested in the validation population. Subsequently, it was compared with other scintigraphic, exercise electrocardiography and clinical variables. Results In the derivation group L/H net was a better discriminator for higher-risk CAD than both L/H max and L/H mean. Similarly, the adjusted L/H net was a better discriminator than both the adjusted L/H max and the adjusted L/H mean. No significant difference was attained between L/H net and the adjusted L/H net. At the upper defined threshold of abnormality, sensitivity and specificity of L/H net in the detection of higher-risk CAD in the derivation and the validation cohorts were 52% and 92% versus 47% and 94%, respectively (p= ns). The results were similar at other defined thresholds. Moreover, L/H net was found to be a significant predictor of higher-risk CAD, superior to myocardial perfusion images, transient ventricular dilation measurements, and clinical and exercise testing variables (ROC analysis and logistic regression). By raising the threshold of abnormality of L/H net , specificity and positive predictive value increased, whereas sensitivity and negative predictive value decreased. Conclusion Lung 201 Tl assessment assists substantially in the identification of higher-risk CAD in exercise SPECT myocardial perfusion imaging and this is best achieved by L/H net. This index is a significant predictor of higher-risk CAD, superior to myocardial perfusion images, and its value is associated with the probability of a disease state.