MRI MEASUREMENTS OF THE DEPENDENCE ON T-1 OF THE ECHO AMPLITUDES USING A MULTIPLE SPIN-ECHO SCHEME

Analytical calculations using the Bloch formalism were performed to as sess the dependence on T-1 of the echo amplitudes for the Phase-Altern ating Phase-Shift (PHAPS) multiple spin-echo protocol. Measurements in a 0.5 T MR imaging unit were performed to ratify the analytical resul ts. Especially for low T-2 values, the echo amplitudes were erroneous, with an increasing contribution from stimulated echo components with increasing T-1. Apart from affecting T-2 estimates, stimulated echoes generated a non-monoexponential signal decay of the echo trains. The r esults confirmed previous simulation studies as regards the dependence on T-1 of T-2 estimates from PHAPS.