Effect of patient motion on tomographic myocardial perfusion imaging

We evaluated the effect of patient motion on inducing false-positive tomographic 201Tl myocardial perfusion studies. The effects of the angle of camera rotation at which movement occurs, the direction of movement and the distance of movement were studied. Movement was stimulated by shifting the raw data from normal motion-free 201Tl tomographic myocardial perfusion studies. The visual detectability of motion artifact was evaluated with receiver-operating characteristic curve analysis. The clinical importance of patient movement was determined by measuring the incidence of quantitative bull's-eye abnormalities induced by motion. Visual artifacts were more detectable and quantitative abnormalities more frequent as the distance of movement increased. Artifacts from 3.25 mm of movement were not visually detectable. Artifacts from 6.5 mm of movement were visually detectable, but were infrequently clinically important. Movement of 13 mm or greater frequently caused quantitative abnormalities. Quantitative abnormalities from axial movement were more frequent than artifacts from lateral movement. Quantitative abnormalities were more frequent when the movement occurred at the beginning or end. We conclude that when patients move during 201Tl tomographic myocardial perfusion imaging, the incidence and character of false-positive results depend on the angle of camera rotation at which the movement occurs, the direction of the movement and distance of the movement.