Currently coreMRI is based on .mat files (MATLAB files). All the coordinates are given in the Device Coordinate System (DCS). The .mat file should include the following variables:
dt: is the temporal step of the MR simulation experiment (in sec)
N_pulse: it holds the number of the total timesteps of the pulse sequence
pulse_sequence: it is an [8xN_pulse] matrix. The first row (pulse_sequence(1,:)) holds the time sequence of the magnitude of the RF events (B1), the second row (pulse_sequence(2,:)) holds the time sequence of the phase of the RF events (RFP), the third row (pulse_sequence(3,:)) holds the time sequence of the frequency of the RF events (RFfreq), the fourth row (pulse_sequence(4,:)) holds the time sequence of the gradients on the x axis, the fifth row (pulse_sequence(5,:)) holds the time sequence of the gradients on the y axis and the sixth row (pulse_sequence(6,:)) holds the time sequence of the gradients on the z axis. The last two rows are identical and each one is an array with increasing number from 1 to N_pulse (pulse_sequence(7,:) = 1:N_pulse and pulse_sequence(8,:) = 1:N_pulse). The last two rows are being used by an algorithm that allows for compression of the pulse sequence in order to accelerate the MR simulations (read more here CODE\fast-algorithm).
B1 is given in T (Tesla), RFP is given in radians, RFfreq is given in Hz and gradients are given in T/m (Tesla per meter).
times_fitting_single_point: it is an array of the timepoints for which the MR signal will be recorded in the database/dictionary of the simulated signals (for example the times_fitting_single_point = [1000, 2000, 3000, 4000, 5000] will record the simulated MR signal for timepoints 1000, 2000, 3000, 4000 and 5000. For a dt=0.000001 sec (1μsec), the simulated MR signal will be recorded for t = 1msec, 2msec, 3msec, 4msec and 5msec.)
soft_crushers: it is an array of 0s or 1s and of size [1xN_pulse]. This array is pointing out when a nullification of the transverse components of the magnetization should be induced. It is being used to avoid the introduction of strong gradients in the pulse sequence.
gamma: the gyromagnetic ratio in Hz/T. For example, the gyromagnetic ratio for the hydrogen nucleus is 42560000 Hz/T.
coordCenterSlice_mm: it is a [1x3] array that holds the center of the slice in millimeters.
normalVectorSlice: it is a [1x3] array that holds the normal vector of the slice. For example, a transversal slice would have a normalVectorCenterSlice equal to [0,0,1] in the DCS.
Tags: quantitative MR pulse sequence coreMRI