| 主权项 |
1. A method for acquiring magnetic resonance data, comprising:
in a processor, automatically calculating a flip angle and/or inversion time of a spectrum suppression pulse according to a steady state condition of a longitudinal magnetization component of a spectrum composition suppressed by a spectrum suppression pulse, to be generated in a magnetic resonance imaging sequence, and a zero crossing point condition of the longitudinal magnetization component; operating a magnetic resonance data acquisition unit to acquire magnetic resonance data by applying said magnetic resonance imaging sequence comprising the spectrum suppression pulse provided with the flip angle and/or the inversion time, to a subject in the data acquisition unit; entering said magnetic resonance data into memory locations in an electronic memory organized as k-space, and making k-space filled with said magnetic resonance data available in electronic form as a data file from said memory in a format suitable for further processing; emitting the spectrum suppression pulse in the magnetic resonance imaging sequence before one or more excitation pulses and using, as the zero crossing point condition of the longitudinal magnetization component, making the longitudinal magnetization component of the spectrum composition zero before an excitation pulse corresponding to a center line of k-space; and the inversion time comprising a first inversion time and a second inversion time, and calculating the flip angle or the inversion time of the spectrum suppression pulse, using a general formula, and the flip angle or the inversion time of the spectrum suppression pulse, wherein said general formula is:
{E+F·C·(DN-1−1)/(D−1)+F·A·DN-1}/(1−F·B·DN-1)={C·(DKSpaceCenterLine-1−1)/(D−1)+A·DKSpaceCenterLine-1}/(−B·DKSpaceCenterLine-1), where, A=1−ETl1 B=cos(β)·ETl1 C=1−ETrep D=cos(α)·ETrep E=1−ETr F=cos(α)·ETr ETl1=exp(−Tl1/T1) ETrep=exp(−Trep/T1) ETr=exp(−Tr/T1) Tl1=Tl1Min+TlFill Tr=TrMin+TrFill α is a flip angle of an excitation pulse, β is a flip angle of a spectrum suppression pulse, T1 is a longitudinal relaxation time of a spectrum composition suppressed by a spectrum suppression pulse, N is the number of excitation pulses between two spectrum suppression pulses, KSpaceCenterLine is the index number of a the center line of k-space, TI1Min is the minimum time interval between the center of a spectrum suppression pulse and the center of a first excitation pulse following the spectrum suppression pulse, Trep is the time between continuous excitation pulses, TrMin is the minimum time interval between the center of the last excitation pulse in a pulse train and the center of a spectrum suppression pulse in a next pulse string of the magnetic resonance imaging sequence, TIFill is the first inversion time, and TrFill is the second inversion time. |
