def run(self, image):
if not verify_scanner_image(self, image):
return
fmap_file = clean_name(self.fmap_file)[0]
## if hasattr(image, 'n_chan'):
## fmap_file += '.c%02d'%image.chan
try:
fmapIm = readImage(fmap_file)
except:
self.log("fieldmap not found: " + fmap_file)
return -1
(nslice, npe, nfe) = image.shape[-3:]
# make sure that the length of the q1 columns of the fmap
# are AT LEAST equal to that of the image
regrid_fac = max(npe, fmapIm.shape[-2])
# fmap and chi-mask are swapped to be of shape (Q1,Q2)
fmap = np.swapaxes(
regrid_bilinear(fmapIm[0], regrid_fac, axis=-2).astype(np.float64),
-1, -2)
chi = np.swapaxes(regrid_bilinear(fmapIm[1], regrid_fac, axis=-2), -1,
-2)
Q1, Q2 = fmap.shape[-2:]
# compute T_n2 vector
Tl = image.T_pe
delT = image.delT
a, b, n2, _ = image.epi_trajectory()
K = get_kernel(Q2, Tl, b, n2, fmap, chi)
for s in range(nslice):
# dchunk is shaped (nvol, npe, nfe)
# inverse transform along nfe (can't do in-place)
dchunk = ifft1(image[:, s, :, :])
# now shape is (nfe, npe, nvol)
dchunk = np.swapaxes(dchunk, 0, 2)
for fe in range(nfe):
# want to solve Kx = y for x
# K is (npe,npe), and y is (npe,nvol)
#
# There seems to be a trade-off here as nvol changes...
# Doing this in two steps is faster for large nvol; I think
# it takes advantage of the faster BLAS matrix-product in dot
# as opposed to LAPACK's linear solver. For smaller values
# of nvol, the overhead seems to outweigh the benefit.
iK = regularized_inverse(K[s, fe], self.lmbda)
dchunk[fe] = np.dot(iK, dchunk[fe])
dchunk = np.swapaxes(dchunk, 0, 2)
# fft x back to kx, can do inplace here
fft1(dchunk, inplace=True)
image[:, s, :, :] = dchunk
def run(self, image):
if not verify_scanner_image(self, image):
return
fmap_file = clean_name(self.fmap_file)[0]
## if hasattr(image, 'n_chan'):
## fmap_file += '.c%02d'%image.chan
try:
fmapIm = readImage(fmap_file)
except:
self.log("fieldmap not found: " + fmap_file)
return -1
(nslice, npe, nfe) = image.shape[-3:]
# make sure that the length of the q1 columns of the fmap
# are AT LEAST equal to that of the image
regrid_fac = max(npe, fmapIm.shape[-2])
# fmap and chi-mask are swapped to be of shape (Q1,Q2)
fmap = np.swapaxes(regrid_bilinear(fmapIm[0], regrid_fac, axis=-2).astype(np.float64), -1, -2)
chi = np.swapaxes(regrid_bilinear(fmapIm[1], regrid_fac, axis=-2), -1, -2)
Q1, Q2 = fmap.shape[-2:]
# compute T_n2 vector
Tl = image.T_pe
delT = image.delT
a, b, n2, _ = image.epi_trajectory()
K = get_kernel(Q2, Tl, b, n2, fmap, chi)
for s in range(nslice):
# dchunk is shaped (nvol, npe, nfe)
# inverse transform along nfe (can't do in-place)
dchunk = ifft1(image[:, s, :, :])
# now shape is (nfe, npe, nvol)
dchunk = np.swapaxes(dchunk, 0, 2)
for fe in range(nfe):
# want to solve Kx = y for x
# K is (npe,npe), and y is (npe,nvol)
#
# There seems to be a trade-off here as nvol changes...
# Doing this in two steps is faster for large nvol; I think
# it takes advantage of the faster BLAS matrix-product in dot
# as opposed to LAPACK's linear solver. For smaller values
# of nvol, the overhead seems to outweigh the benefit.
iK = regularized_inverse(K[s, fe], self.lmbda)
dchunk[fe] = np.dot(iK, dchunk[fe])
dchunk = np.swapaxes(dchunk, 0, 2)
# fft x back to kx, can do inplace here
fft1(dchunk, inplace=True)
image[:, s, :, :] = dchunk
def run(self, image):
# Make sure it's an asems image
if not hasattr(image, "asym_times") and not hasattr(image, "te"):
self.log("No asym_time, can't compute field map.")
return
asym_times = image.asym_times
# Make sure there are at least two volumes
if image.tdim < 2:
self.log("Cannot calculate field map from only a single volume."\
" Must have at least two volumes.")
return
diffshape = (image.tdim-1,) + image.shape[-3:]
diffshape = image.tdim > 2 and diffshape or diffshape[-3:]
phase_map = image._subimage(np.zeros(diffshape, np.float32))
bytemask = image._subimage(np.zeros(diffshape, np.float32))
# Get phase difference between scan n+1 and scan n
# Then find the mask and unwrapped phase, and compute
# the field strength in terms of rad/s
fwhm = max(image.isize, image.jsize) * 1.5
for psub, msub in zip(phase_map, bytemask):
del_te = asym_times[msub.num+1] - asym_times[msub.num]
if self.haschans:
for c in range(image.n_chan):
image.load_chan(c)
dphs = image[msub.num+1] * np.conjugate(image[msub.num])
msk = build_3Dmask(np.power(np.abs(dphs), 0.5),
self.threshfactor)
msub[:] += msk
## psub[:] += (unwrap3D(np.angle(dphs)) * msk) #/ del_te
## psub[:] += gaussian_smooth(np.angle(dphs), 1.5, 3)
## smooth_phs = unwrap3D(gaussian_smooth(np.angle(dphs),
## sigma_y, sigma_x,
## gaussian_dims))*msk
smooth_phs = ReconImage(np.angle(dphs),
isize=image.isize,
jsize=image.jsize)
GaussianSmooth(fwhm=fwhm).run(smooth_phs)
psub[:] += smooth_phs[:]
#psub[:] = np.where(msub[:], psub[:]/msub[:], 0)
psub[:] /= image.n_chan
msub[:] = np.where(msub[:], 1, 0)
#psub[:] = (unwrap3D(psub[:]) * msub[:]) #/ del_te
image.use_membuffer(0)
else:
dphs = image[msub.num+1] * np.conjugate(image[msub.num])
msub[:] = build_3Dmask(np.power(np.abs(dphs), 0.5),
self.threshfactor)
#psub[:] = (unwrap3D(np.angle(dphs)) * msub[:]) #/ del_te
psub[:] = np.angle(dphs)
GaussianSmooth(fwhm=fwhm).run(psub)
psub[:] = unwrap3D(psub[:])*msub[:]
psub[:] /= del_te
# for each diff vol, write a file with vol0 = fmap, vol1 = mask
fmap_file = clean_name(self.fmap_file)[0]
if phase_map.ndim > 3:
for index in range(phase_map.tdim):
catIm = phase_map.subImage(index).concatenate(
bytemask.subImage(index), newdim=True)
catIm.writeImage(fmap_file+"-%d"%index,
format_type="nifti-single")
else:
catIm = phase_map.concatenate(bytemask, newdim=True)
catIm.writeImage(fmap_file, format_type="nifti-single")
def run(self, image):
# Make sure it's an asems image
if not hasattr(image, "asym_times") and not hasattr(image, "te"):
self.log("No asym_time, can't compute field map.")
return
asym_times = image.asym_times
# Make sure there are at least two volumes
if image.tdim < 2:
self.log("Cannot calculate field map from only a single volume."\
" Must have at least two volumes.")
return
diffshape = (image.tdim - 1, ) + image.shape[-3:]
diffshape = image.tdim > 2 and diffshape or diffshape[-3:]
phase_map = image._subimage(np.zeros(diffshape, np.float32))
bytemask = image._subimage(np.zeros(diffshape, np.float32))
# Get phase difference between scan n+1 and scan n
# Then find the mask and unwrapped phase, and compute
# the field strength in terms of rad/s
fwhm = max(image.isize, image.jsize) * 1.5
for psub, msub in zip(phase_map, bytemask):
del_te = asym_times[msub.num + 1] - asym_times[msub.num]
if self.haschans:
for c in range(image.n_chan):
image.load_chan(c)
dphs = image[msub.num + 1] * np.conjugate(image[msub.num])
msk = build_3Dmask(np.power(np.abs(dphs), 0.5),
self.threshfactor)
msub[:] += msk
## psub[:] += (unwrap3D(np.angle(dphs)) * msk) #/ del_te
## psub[:] += gaussian_smooth(np.angle(dphs), 1.5, 3)
## smooth_phs = unwrap3D(gaussian_smooth(np.angle(dphs),
## sigma_y, sigma_x,
## gaussian_dims))*msk
smooth_phs = ReconImage(np.angle(dphs),
isize=image.isize,
jsize=image.jsize)
GaussianSmooth(fwhm=fwhm).run(smooth_phs)
psub[:] += smooth_phs[:]
#psub[:] = np.where(msub[:], psub[:]/msub[:], 0)
psub[:] /= image.n_chan
msub[:] = np.where(msub[:], 1, 0)
#psub[:] = (unwrap3D(psub[:]) * msub[:]) #/ del_te
image.use_membuffer(0)
else:
dphs = image[msub.num + 1] * np.conjugate(image[msub.num])
msub[:] = build_3Dmask(np.power(np.abs(dphs), 0.5),
self.threshfactor)
#psub[:] = (unwrap3D(np.angle(dphs)) * msub[:]) #/ del_te
psub[:] = np.angle(dphs)
GaussianSmooth(fwhm=fwhm).run(psub)
psub[:] = unwrap3D(psub[:]) * msub[:]
psub[:] /= del_te
# for each diff vol, write a file with vol0 = fmap, vol1 = mask
fmap_file = clean_name(self.fmap_file)[0]
if phase_map.ndim > 3:
for index in range(phase_map.tdim):
catIm = phase_map.subImage(index).concatenate(
bytemask.subImage(index), newdim=True)
catIm.writeImage(fmap_file + "-%d" % index,
format_type="nifti-single")
else:
catIm = phase_map.concatenate(bytemask, newdim=True)
catIm.writeImage(fmap_file, format_type="nifti-single")
