Ghost artifact cancellation using phased array processing

In this article, a method for phased array combining is formulated which ma y be used to cancel ghosts caused by a variety of distortion mechanisms, in cluding space variant distortions such as local flow or off-resonance. This method is based on a constrained optimization, which optimizes SNR subject to the constraint of nulling ghost artifacts at known locations. The resul tant technique is similar to the method known as sensitivity encoding (SENS E) used for accelerated imaging; however, in this formulation it is applied to full field-of-view (FOV) images. The method is applied to multishot EPI with noninterleaved phase encode acquisition. A number of benefits, as com pared to the conventional interleaved approach, are reduced distortion due to off-resonance, in-plane flow, and EPI delay misalignment, as well as eli minating the need for echo-shifting. Experimental results demonstrate the c ancellation for both phantom as well as cardiac imaging examples. Published 2001 Wiley-Liss, Inc.(dagger)