Experimental simulation evaluation of ECG-gated heart scans with a small number of views

Computed tomography (CT) scanning techniques designed to visualize the beating heart utilize the electrocardiogram (ECG) waveform to gate or select the phase of the cardiac cycle being imaged. Most such methods require that each slice to be imaged be scanned many times to obtain the usual number of projections in a single phase interval of the cardiac cycle. We are studying a new method in which only a single scan of 20 s should be required per imaged slice. The central problem in the proposed technique is to test the diagnostic utility of images reconstructed from a very limited number (about 25) of projections. An essential part of the proposed algorithm is the elimination of all material outside a circle chosen to contain only the heart and the structures immediately surrounding it. Experiments are reported here on scans of calf's heart in an 11-cm container of water, with most views deleted so as to simulate the results from this type of gated scan. The results show that if no high-contrast objects are within the chosen circle, then image quality is satisfactory and could be clinically useful.