Lung thallium-201 uptake after stress testing in patients with coronary artery disease.

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Abstract
Increased lung Tl-201 activity was observed on initial stress myocardial images in patients with coronary artery disease (CAD). To assess the clinical significance of this finding, initial and delayed 201Tl images were stored in a computer immediately after supine stress testing in 49 patients (39 with CAD and 10 controls). Regions of interest over the heart and lung were selected on the computer-generated images. Quantitative lung 201Tl activity was expressed as a percentage of maximal myocardial 201Tl activity/picture element (lung 201Tl index) for each imaging time. The lung 201Tl index was compared with the extent of CAD at catheterization, resting left ventricular ejection fraction by multigated blood pool scintigraphy, the results of the initial 201Tl stress myocardial perfusion images and qualitative assessment of initial lung 201Tl uptake after stress. In 10 control patients, the mean initial lung 201Tl index was 37.6 .+-. 2.5%. In 29 patients with 2 and 3 vessel CAD, the mean initial lung 201Tl index was elevated, at 53.5 .+-. 2.2% (P < 0.001 compared with controls). In 10 patients with 1 vessel CAD, the mean initial lung 201Tl index was 45.6 .+-. 3.6% (P = NS [not significant] compared with controls). Patients with CAD decreased their mean lung 201Tl index from initial to delayed images (P < 0.05), but control patients did not. When a lung 201Tl index of 54.5% was chosen as abnormal, patients who had CAD and an abnormal initial lung 201Tl index had significantly reduced resting ejection fractions (mean 58.2 .+-. 2.5%) compared with patients who had CAD and a normal lung 201Tl index (mean 66.0 .+-. 2.1%) (P < 0.05). Patients with CAD and 4 or 5 of 6 abnormal segments on the initial myocardial perfusion images had higher initial lung 201Tl indexes (mean 59.1 .+-. 13.0%) compared with patients with CAD and 1 or no abnormal segments on the initial myocardial perfusion images (mean 44.5 .+-. 10.3%) (P < 0.01). Initial lung 201Tl indexes determined quantitatively correlated with the qualitative assessment of initial lung 201Tl uptake after stress. The finding of elevated lung 201Tl activity on stress myocardial images correlates with increased severity of underlying cornary artery disease and left ventricular dysfunction. 201Tl lung activity after stress can be easily quantitated.

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