sigpy.mri.rf.trajgrad.spiral_varden¶
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sigpy.mri.rf.trajgrad.
spiral_varden
(fov, res, gts, gslew, gamp, densamp, dentrans, nl, rewinder=False)[source]¶ Variable density spiral designer. Produces trajectory, gradients, and slew rate. Gradient units returned are in g/cm, g/cm/s
Parameters: - fov (float) – imaging field of view (cm).
- res (float) – imaging isotropic resolution (cm).
- gts (float) – gradient sample time in sec.
- gslew (float) – max slew rate in g/cm/s.
- gamp (float) – max gradient amplitude in g/cm.
- densamp (float) – duration of full density sampling (# of samples).
- dentrans (float) – duration of transition from higher to lower (should be >= densamp/2).
- nl (float) – degree of undersampling outer region.
- rewinder (Boolean) – if True, include rewinder. If false, exclude.
Returns: (g, k, t, s, dens) tuple containing
- g - (array): gradient waveform [g/cm]
- k - (array): exact k-space corresponding to gradient g.
- time - (array): sampled time
- s - (array): slew rate [g/cm/s]
- dens - (array): undersampling factor at each time point.
Return type: tuple
References
Code and algorithm based on spiralgradlx6 from Doug Noll, U. of Michigan BME