Sex differences in the tracer distribution on stress thallium-201 imaging, (1)

To determine the sex differences in the tracer distribution on stress thallium-201 imaging, the studies of 18 normal males and 18 normal females were subjected to quantitative circumferential profile analysis in each projection image. Although the exercise duration was shorter in females (11±3 min) than in males (14±3 min) (p<0.01), the peak heart rate, peak systolic pressure and the lung-to-myocardial count ratio were similar between them. The averaged profile curves in female showed a significant reduction in tracer uptake in anterior and upper septal regions, particularly in the study of lateral view, which may be attributed to breast attenuation. In addition, the percent washout of thallium in 3 hours was higher in females (48±8%) than in males (43±7%) (p<0.01), particularly in the study of anterior view. We conclude that important differences in the pattern of thallium uptake and washout between males and females should be considered for interpretation of stress thallium imaging. (author)