AUTOMATED REGION SELECTION FOR ANALYSIS OF DYNAMIC CARDIAC SPECT DATA

Dynamic cardiac SPECT using Tc-99m labeled teboroxime can provide kine tic parameters (washin, washout) indicative of myocardial blood flow. A time-consuming and subjective step of the data analysis is drawing r egions of interest to delineate blood pool and myocardial tissue regio ns. The time-activity curves of the regions are then used to estimate local kinetic parameters. In this work, the appropriate regions are fo und automatically, in a manner similar to that used for calculating ma ximum count circumferential profiles in conventional static cardiac st udies. The drawbacks to applying standard static circumferential profi le methods are the high noise level and high liver uptake common in dy namic teboroxime studies. Searching along each ray for maxima to locat e the myocardium does not typically provide useful information. Here w e propose an iterative scheme in which constraints are imposed on the radii searched along each ray. The constraints are based on the shape of the time-activity curves of the circumferential profile members and on an assumption that the short axis slices are approximately circula r. The constraints eliminate outliers and help to reduce the effects o f noise and liver activity. Kinetic parameter estimates from the autom atically generated regions were comparable to estimates from manually selected regions in dynamic canine teboroxime studies.