Some factors that influence the steady state in steady-state free precession

✍ Scribed by Samuel Patz

• Publisher: Elsevier Science
• Year: 1988
• Tongue: English
• Weight: 986 KB
• Volume: 6
• Category: Article
• ISSN: 0730-725X
• DOI: 10.1016/0730-725x(88)90477-8

✦ Synopsis

Steady-state free precession (SSFP) and particularly the spatially periodic magnetization response with wavelength A that results in the presence of an applied gradient is discussed. The maximum SSFP magnetization does oot always occur at the Larmor frequency hut rather depends on both the phase cycling of the rf pulses and on the rf tip angle. The slow flow sensitivity of SSFP also depends on X. Experimental data of the flow sensitivity is shown to be parameterized by a dimensionless dephasing parameter d defined as the ratio of the distance traveled by a spin in one cycle of the SSFP sequence as compared to A. An example of the creation of a moving reference frame with the SSFP sequence is given. The modulation in image intensity that results when the gradients are nearly but not exactly compensated and X becomes large (i.e., tens of pixels long) is demonstrated. The pixel length must be an integral number of X's in order to have a uniform image intensity from a uniform phantom.