T1 and T2 effects during radio-frequency pulses in spoiled gradient echo sequences.
Finite pulse durations in diverse pulse schemes lead to the reduction of the magnitude of the magnetization vector due to T(1) and T(2) effects during the radio-frequency pulses. This paper presents an analysis of the steady state signal in the presence of relaxation effects during radio-frequency pulses in MRI spoiled gradient echo sequences. It is shown that minor attenuations of the magnetization vector can have dramatic consequences on the measured signal, and may thus entail a loss in SNR benefits at high static magnetic fields if a careful analysis is not performed. It is emphasized that it is the time-integrated magnetization vector trajectory that matters for these effects and not only the pulse duration. Some experimental results obtained on a phantom at 3T verify this analysis.
Boulant
Nicolas
N
CEA, DSV, I2BM, NeuroSpin, LRMN, Gif sur Yvette 91191, France. nicolas.boulant@cea.fr
D000465:Algorithms; D004574:Electromagnetic Fields; D008279:Magnetic Resonance Imaging / Q000379:methods* / Q000706:statistics & numerical data; D008872:Microwaves; D011522:Protons; D014867:Water / Q000737:chemistry
D011522:Protons; D014867:Water