Multishot EPI‐SSFP in the heart

Abstract Refocused steady‐state free precession (SSFP), or fast imaging with steady precession (FISP or TrueFISP), has recently proven valuable for cardiac imaging because of its high signal‐to‐noise ratio (SNR) and excellent blood–myocardium contrast. In this study, various implementations of multiecho SSFP or EPI‐SSFP for imaging in the heart are presented. EPI‐SSFP has higher scan‐time efficiency than single‐echo SSFP, as two or more phase‐encode lines are acquired per repetition time (TR) at the cost of a modest increase in TR. To minimize TR, a noninterleaved phase‐encode order in conjunction with a phased‐array ghost elimination (PAGE) technique was employed, removing the need for echo time shifting (ETS). The multishot implementation of EPI‐SSFP was used to decrease the breath‐hold duration for cine acquisitions or to increase the temporal or spatial resolution for a fixed breath‐hold duration. The greatest gain in efficiency was obtained with the use of a three‐echo acquisition. Image quality for cardiac cine applications using multishot EPI‐SSFP was comparable to that of single‐echo SSFP in terms of blood–myocardium contrast and contrast‐to‐noise ratio (CNR). The PAGE method considerably reduced flow artifacts due to both the inherent ghost suppression and the concomitant reduction in phase‐encode blip size. The increased TR of multishot EPI‐SSFP led to a reduced specific absorption rate (SAR) for a fixed RF flip angle, and allowed the use of a larger flip angle without increasing the SAR above the FDA‐approved limits. Magn Reson Med 47:655–664, 2002. Published 2002 Wiley‐Liss, Inc.