def test_estimate_radius_with_rtap(radius_gt=5e-3):
gtab = get_gtab_taiwan_dsi()
tau = 1 / (4 * np.pi**2)
# we estimate the infinite diffusion time case for a perfectly reflecting
# cylinder using the Callaghan model
E = cylinders_and_ball_soderman(gtab,
tau,
radii=[radius_gt],
snr=None,
angles=[(0, 90)],
fractions=[100])[0]
# estimate radius using anisotropic MAP-MRI.
mapmod = mapmri.MapmriModel(gtab,
radial_order=6,
laplacian_regularization=True,
laplacian_weighting=0.01)
mapfit = mapmod.fit(E)
radius_estimated = np.sqrt(1 / (np.pi * mapfit.rtap()))
assert_almost_equal(radius_estimated, radius_gt, 5)
# estimate radius using isotropic MAP-MRI.
# note that the radial order is higher and the precision is lower due to
# less accurate signal extrapolation.
mapmod = mapmri.MapmriModel(gtab,
radial_order=8,
laplacian_regularization=True,
laplacian_weighting=0.01,
anisotropic_scaling=False)
mapfit = mapmod.fit(E)
radius_estimated = np.sqrt(1 / (np.pi * mapfit.rtap()))
assert_almost_equal(radius_estimated, radius_gt, 4)
def test_estimate_radius_with_rtap(radius_gt=5e-3):
gtab = get_gtab_taiwan_dsi()
tau = 1 / (4 * np.pi ** 2)
# we estimate the infinite diffusion time case for a perfectly reflecting
# cylinder using the Callaghan model
E = cylinders_and_ball_soderman(gtab, tau, radii=[radius_gt], snr=None,
angles=[(0, 90)], fractions=[100])[0]
# estimate radius using anisotropic MAP-MRI.
mapmod = mapmri.MapmriModel(gtab, radial_order=6,
laplacian_regularization=True,
laplacian_weighting=0.01)
mapfit = mapmod.fit(E)
radius_estimated = np.sqrt(1 / (np.pi * mapfit.rtap()))
assert_almost_equal(radius_estimated, radius_gt, 5)
# estimate radius using isotropic MAP-MRI.
# note that the radial order is higher and the precision is lower due to
# less accurate signal extrapolation.
mapmod = mapmri.MapmriModel(gtab, radial_order=8,
laplacian_regularization=True,
laplacian_weighting=0.01,
anisotropic_scaling=False)
mapfit = mapmod.fit(E)
radius_estimated = np.sqrt(1 / (np.pi * mapfit.rtap()))
assert_almost_equal(radius_estimated, radius_gt, 4)