title: T1 and T2 effects during radio-frequency pulses in spoiled gradient echo sequences.
abstract: 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.
authors.affiliation: CEA, DSV, I2BM, NeuroSpin, LRMN, Gif sur Yvette 91191, France. nicolas.boulant@cea.fr
authors.forename: Nicolas
authors.initials: N
authors.lastname: Boulant
mesh_terms: D000465:Algorithms; D004574:Electromagnetic Fields; D008279:Magnetic Resonance Imaging / Q000379:methods* / Q000706:statistics & numerical data; D008872:Microwaves; D011522:Protons; D014867:Water / Q000737:chemistry
chemical_list: D011522:Protons; D014867:Water