Zonally magnified EPI in real time by NMR

To overcome the problems of gradient strength, large receiver bandwidth and computing time in nuclear magnetic resonance real-time echo-planar imaging (EPI) with large pixel arrays, the concept of zonal image magnification or zoomed EPI (ZEPI) is introduced. The image zone is defined by two selective RF pulses and the receiver bandwidth. For a fixed image array size it is shown that zooming requires less gradient strength to achieve a given spatial resolution than in an equivalent unzoomed image. Two different zoom techniques are described, ZEPI-1 and ZEPI-2, which employ a single and a double pulse sequence respectively. Experimental results obtained with these sequences on a phantom and a live piglet are presented.