ADVANTAGES OF LIST-MODE ACQUISITION OF DYNAMIC CARDIAC DATA

Conventional frame-mode acquisition of multigated blood-pool (MUGA) st udies is an imprecise means to study cardiac dynamics in part because the energy and ECG waveform information is not retained Early methods for list-mode acquisition were also somewhat limited in that only the (x,y) coordinate, a timing pulse and an R-wave detect pulse were store d. We have extended list-mode capability to include full storage of th e ECG waveform and the energy value associated with each spatial coord inate. The spatial coordinates (x and y), energy value (E), and an enc oded physiologic/timing signal (p/t) are stored on an event-by-event b asis as 8-bit values. These four bytes are streamed onto a hard disk s torage device allowing even stress gated blood pool studies to be reco rded. List-mode acquisition gives greater flexibility than frame-mode. Among the demonstrable advantages this flexibility provides are the a bility to: 1) Measure and correct respirational displacement of the ve ntricle to minimize motion blurring; 2) Form gated sequences represent ing only a specific aberrancy for detection of ectopic ventricular foc i; and 3) Use the stored multispectral energy information to perform s catter correction on the dynamic images. To conclusively demonstrate t he improved resolution of the list-mode methodology, a dynamic phantom was used to simulate blurring-due to respiration. The advantages of l ist-mode warrant its further use, and it may be especially valuable fo r wall thickness measurements.