Advantages of list-mode acquisition of high resolution dynamic cardiac data

Frame-mode acquisition of MUGA studies is an imprecise means to study cardiac dynamics. List-mode acquisition offers significant advantages in temporal and spatial resolution as well as allowing flexibility in selecting those beats included in the final image sequence. Using list-mode, spatial coordinates (x and y), energy value (e), and an encoded physiologic/timing signal (p/t) are stored on an event-by-event basis as byte integer values. The four integers associated with each detected event (x,y,e, and p/t) are streamed onto a hard disk storage device allowing even stress gated blood pool studies to be recorded. Among the advantages we have been able to demonstrate are: Using the stored multispectral energy information to perform scatter correction on the dynamic images; measuring and correcting respirational displacement of the ventricle to minimize motion blurring; applying a variable zoom window after the fact to keep the ventricles centered for analysis; allowing formation of gated sequences representing only a specific aberrancy for detection of ectopic ventricular foci; and improving temporal precision necessary to analyze complex ventricular dynamics associated with aberrant neural conduction affecting the synchrony of muscle contraction. To demonstrate the improved resolution of the list-mode methodology, a dynamic phantom was used to simulate blurring due to respiration and segmental wall motion defects.