IS DIAPHRAGMATIC ATTENUATION A MISNOMER - EVALUATION OF THE ANATOMIC CAUSE OF DIAPHRAGMATIC ATTENUATION IN SPECT THALLIUM SCANNING

The most common artifact on thallium scans in our laboratory has been posterior myocardial attenuation, mostly in males. In the past this ha s been thought due to the position of the diaphragm. Methods: To evalu ate this concept, matching chest x-rays were examined and measured. El even examples of posterior myocardial attenuation were consecutively p ulled from our files and compared to eleven consecutive controls. Resu lts: It was found that the diaphragm did not differ significantly. The ratio of the PA diameter of the chest to chest width was significantl y (p < 0.03) less than controls. Conclusions: It is suggested that a m ale with a flat, wide chest is more prone to posterior myocardial atte nuation. If a posterior defect is present in this type of patient it i s suggested he be further evaluated to rule out artifact.