 If, within one TR, either one of the gradient moments of magnetic gradients along three logical directions, including slice selection direction (Gss), phase encoding (Gpe) and readout (Gro), is not zero, then spins along such direction obtain different phases, making the signal intensity (SI) of a single voxel the vector sum of magnetizations therein.It causes some inevitable loss of signal.Such situations belong to ordinary SSFP imaging, with its commercial names listed below.