def test_bounding_box():
vol = np.zeros((100, 100, 50), dtype=int)
# Check the more usual case
vol[10:90, 11:40, 5:33] = 3
mins, maxs = bounding_box(vol)
assert_equal(mins, [10, 11, 5])
assert_equal(maxs, [90, 40, 33])
# Check a 2d case
mins, maxs = bounding_box(vol[10])
assert_equal(mins, [11, 5])
assert_equal(maxs, [40, 33])
vol[:] = 0
with warnings.catch_warnings(record=True) as w:
warnings.simplefilter("always")
# Trigger a warning.
num_warns = len(w)
mins, maxs = bounding_box(vol)
# Assert number of warnings has gone up by 1
assert_equal(len(w), num_warns + 1)
# Check that an empty array returns zeros for both min & max
assert_equal(mins, [0, 0, 0])
assert_equal(maxs, [0, 0, 0])
# Check the 2d case
mins, maxs = bounding_box(vol[0])
assert_equal(len(w), num_warns + 2)
assert_equal(mins, [0, 0])
assert_equal(maxs, [0, 0])
def test_bounding_box():
vol = np.zeros((100, 100, 50), dtype=int)
# Check the more usual case
vol[10:90, 11:40, 5:33] = 3
mins, maxs = bounding_box(vol)
assert_equal(mins, [10, 11, 5])
assert_equal(maxs, [90, 40, 33])
# Check a 2d case
mins, maxs = bounding_box(vol[10])
assert_equal(mins, [11, 5])
assert_equal(maxs, [40, 33])
vol[:] = 0
with warnings.catch_warnings(record=True) as w:
warnings.simplefilter("always")
# Trigger a warning.
num_warns = len(w)
mins, maxs = bounding_box(vol)
# Assert number of warnings has gone up by 1
assert_equal(len(w), num_warns + 1)
# Check that an empty array returns zeros for both min & max
assert_equal(mins, [0, 0, 0])
assert_equal(maxs, [0, 0, 0])
# Check the 2d case
mins, maxs = bounding_box(vol[0])
assert_equal(len(w), num_warns + 2)
assert_equal(mins, [0, 0])
assert_equal(maxs, [0, 0])
def test_mask():
vol = np.zeros((30, 30, 30))
vol[15, 15, 15] = 1
struct = generate_binary_structure(3, 1)
voln = binary_dilation(vol, structure=struct, iterations=4).astype('f4')
initial = np.sum(voln > 0)
mask = voln.copy()
thresh = otsu(mask)
mask = mask > thresh
initial_otsu = np.sum(mask > 0)
assert_equal(initial_otsu, initial)
mins, maxs = bounding_box(mask)
voln_crop = crop(mask, mins, maxs)
initial_crop = np.sum(voln_crop > 0)
assert_equal(initial_crop, initial)
applymask(voln, mask)
final = np.sum(voln > 0)
assert_equal(final, initial)
# Test multi_median.
median_test = np.arange(25).reshape(5, 5)
median_control = median_test.copy()
medianradius = 3
median_test = multi_median(median_test, medianradius, 3)
medarr = np.ones_like(median_control.shape) * ((medianradius * 2) + 1)
median_filter(median_control, medarr, output=median_control)
median_filter(median_control, medarr, output=median_control)
median_filter(median_control, medarr, output=median_control)
assert_equal(median_test, median_control)
def test_mask():
vol = np.zeros((30, 30, 30))
vol[15, 15, 15] = 1
struct = generate_binary_structure(3, 1)
voln = binary_dilation(vol, structure=struct, iterations=4).astype('f4')
initial = np.sum(voln > 0)
mask = voln.copy()
thresh = otsu(mask)
mask = mask > thresh
initial_otsu = np.sum(mask > 0)
assert_equal(initial_otsu, initial)
mins, maxs = bounding_box(mask)
voln_crop = crop(mask, mins, maxs)
initial_crop = np.sum(voln_crop > 0)
assert_equal(initial_crop, initial)
applymask(voln, mask)
final = np.sum(voln > 0)
assert_equal(final, initial)
# Test multi_median.
median_test = np.arange(25).reshape(5, 5)
median_control = median_test.copy()
medianradius = 3
median_test = multi_median(median_test, medianradius, 3)
medarr = np.ones_like(median_control.shape) * ((medianradius * 2) + 1)
median_filter(median_control, medarr, output=median_control)
median_filter(median_control, medarr, output=median_control)
median_filter(median_control, medarr, output=median_control)
assert_equal(median_test, median_control)
def bound_data(self):
min_indicies, max_indicies = bounding_box(self.mask)
min_x, min_y, min_z = min_indicies
max_x, max_y, max_z = max_indicies
self.data = self.data[min_x:max_x, min_y:max_y, min_z:max_z, :]
self.mask = self.mask[min_x:max_x, min_y:max_y, min_z:max_z]
def compute_nifti_bounding_box(img):
"""Finds bounding box from data and transforms it in world space for use
on data with different attributes like voxel size."""
data = img.get_fdata(dtype=np.float32, caching='unchanged')
affine = img.affine
voxel_size = img.header.get_zooms()[0:3]
voxel_bb_mins, voxel_bb_maxs = bounding_box(data)
world_bb_mins = voxel_to_world(voxel_bb_mins, affine)
world_bb_maxs = voxel_to_world(voxel_bb_maxs, affine)
wbbox = WorldBoundingBox(world_bb_mins, world_bb_maxs, voxel_size)
return wbbox
def compute_masks_crop_bet(reference_scan, other_scan1, ref_scan_path,
ref_dir_path, other_dir_path, starting_dir):
# Use bet for generating brain masks for each of the scans
# Get the mask of the reference scan
os.chdir(ref_dir_path)
subprocess.call([
"bet",
os.path.basename(ref_scan_path), "Brain_temp", "-m", "-n", "-R", "-f",
"0.2", "-t"
])
reference_scan_mask = nib.load("Brain_temp_mask.nii.gz")
reference_scan_mask = reference_scan_mask.get_data()
# Delete the created files
os.remove('Brain_temp.nii.gz')
os.remove('Brain_temp_mask.nii.gz')
# Go back to the original directory. We do this because the file paths specified are not
# Required to be absolute
os.chdir(starting_dir)
# Similarly get the masks of the other scans
os.chdir(other_dir_path)
subprocess.call([
"bet", "Full_Registered_Scan.nii.gz", "Brain_temp", "-m", "-n", "-R",
"-f", "0.2", "-t"
])
other_scan1_mask = nib.load("Brain_temp_mask.nii.gz")
other_scan1_mask = other_scan1_mask.get_data()
os.remove('Brain_temp.nii.gz')
os.remove('Brain_temp_mask.nii.gz')
#Get the intersection of the masks
mask_union = np.logical_and(reference_scan_mask, other_scan1_mask)
#Apply the combined mask to the scans
reference_scan_brain = applymask(reference_scan, mask_union)
other_scan1_brain = applymask(other_scan1, mask_union)
#Crop the scans using the unioned mask
(mins, maxs) = bounding_box(mask_union)
reference_scan_brain = crop(reference_scan_brain, mins, maxs)
return (reference_scan_brain, other_scan1_brain)
and (0, 0.1) in the y and z axes respectively.
These values work well in practice to isolate the very RED voxels of the cfa map.
Then, as assurance, we want just RED voxels in the CC (there could be
noisy red voxels around the brain mask and we don't want those). Unless the brain
acquisition was badly aligned, the CC is always close to the mid-sagittal slice.
The following lines perform these two operations and then saves the computed mask.
"""
print('Computing worst-case/best-case SNR using the corpus callosum...')
threshold = (0.6, 1, 0, 0.1, 0, 0.1)
CC_box = np.zeros_like(data[..., 0])
mins, maxs = bounding_box(mask)
mins = np.array(mins)
maxs = np.array(maxs)
diff = (maxs - mins) // 4
bounds_min = mins + diff
bounds_max = maxs - diff
CC_box[bounds_min[0]:bounds_max[0], bounds_min[1]:bounds_max[1],
bounds_min[2]:bounds_max[2]] = 1
mask_cc_part, cfa = segment_from_cfa(tensorfit,
CC_box,
threshold,
return_cfa=True)
cfa_img = nib.Nifti1Image((cfa * 255).astype(np.uint8), affine)
def rumba_deconv_global(data,
kernel,
mask,
n_iter=600,
recon_type='smf',
n_coils=1,
R=1,
use_tv=True,
verbose=False):
r'''
Fit fODF for all voxels simultaneously using RUMBA-SD.
Deconvolves the kernel from the diffusion-weighted signal at each voxel by
computing a maximum likelihood estimation of the fODF [1]_. Global fitting
also permits the use of total variation regularization (RUMBA-SD + TV). The
spatial dependence introduced by TV promotes smoother solutions (i.e.
prevents oscillations), while still allowing for sharp discontinuities
[2]_. This promotes smoothness and continuity along individual tracts while
preventing smoothing of adjacent tracts.
Generally, global_fit will proceed more quickly than the voxelwise fit
provided that the computer has adequate RAM (>= 16 GB should be more than
sufficient).
Parameters
----------
data : 4d ndarray (x, y, z, N)
Signal values for entire brain. None of the volume dimensions x, y, z
can be 1 if TV regularization is required.
kernel : 2d ndarray (N, M)
Deconvolution kernel mapping volume fractions of the M compartments to
N-length signal. Last two columns should be for GM and CSF.
mask : 3d ndarray(x, y, z)
Binary mask specifying voxels of interest with 1; fODF will only be
fit at these voxels (0 elsewhere).
n_iter : int, optional
Number of iterations for fODF estimation. Must be a positive int.
Default: 600
recon_type : {'smf', 'sos'}, optional
MRI reconstruction method: spatial matched filter (SMF) or
sum-of-squares (SoS). SMF reconstruction generates Rician noise while
SoS reconstruction generates Noncentral Chi noise. Default: 'smf'
n_coils : int, optional
Number of coils in MRI scanner -- only relevant in SoS reconstruction.
Must be a positive int. Default: 1
use_tv : bool, optional
If true, applies total variation regularization. This requires a brain
volume with no singleton dimensions. Default: True
verbose : bool, optional
If true, logs updates on estimated signal-to-noise ratio after each
iteration. Default: False
Returns
-------
fit_array : 4d ndarray (x, y, z, M)
fODF and GM/CSF volume fractions computed for each voxel. First M-2
components are fODF, while last two are GM and CSf respectively.
Notes
-----
TV modifies our cost function as follows:
$J(\textbf{f}) = -\log{P(\textbf{S}|\textbf{H}, \textbf{f}, \sigma^2, n)})+
\alpha_{TV}TV(\textbf{f})$
where the first term is the negative log likelihood described in the notes
of `rumba_deconv`, and the second term is the TV energy, or the sum of
gradient absolute values for the fODF across the entire brain. This results
in a new multiplicative factor in the iterative scheme, now becoming:
$\textbf{f}^{k+1} = \textbf{f}^k \circ \frac{\textbf{H}^T\left[\textbf{S}
\circ\frac{I_n(\textbf{S}\circ\textbf{Hf}^k/\sigma^2)} {I_{n-1}(\textbf{S}
\circ\textbf{Hf}^k/\sigma^2)} \right ]} {\textbf{H}^T\textbf{Hf}^k}\circ
\textbf{R}^k$
where $\textbf{R}^k$ is computed voxelwise by:
$(\textbf{R}^k)_j = \frac{1}{1 - \alpha_{TV}div\left(\frac{\triangledown[
\textbf{f}^k_{3D}]_j}{\lvert\triangledown[\textbf{f}^k_{3D}]_j \rvert}
\right)\biggr\rvert_{x, y, z}}$
Here, $\triangledown$ is the symbol for the 3D gradient at any voxel.
The regularization strength, $\alpha_{TV}$ is updated after each iteration
by the discrepancy principle -- specifically, it is selected to match the
estimated variance after each iteration [3]_.
References
----------
.. [1] Canales-Rodríguez, E. J., Daducci, A., Sotiropoulos, S. N., Caruyer,
E., Aja-Fernández, S., Radua, J., Mendizabal, J. M. Y.,
Iturria-Medina, Y., Melie-García, L., Alemán-Gómez, Y., Thiran,
J.-P., Sarró, S., Pomarol-Clotet, E., & Salvador, R. (2015).
Spherical Deconvolution of Multichannel Diffusion MRI Data with
Non-Gaussian Noise Models and Spatial Regularization. PLOS ONE,
10(10), e0138910. https://doi.org/10.1371/journal.pone.0138910
.. [2] Rudin, L. I., Osher, S., & Fatemi, E. (1992). Nonlinear total
variation based noise removal algorithms. Physica D: Nonlinear
Phenomena, 60(1), 259–268.
https://doi.org/10.1016/0167-2789(92)90242-F
.. [3] Chambolle A. An algorithm for total variation minimization and
applications. Journal of Mathematical Imaging and Vision. 2004;
20:89–97.
'''
# Crop data to reduce memory consumption
dim_orig = data.shape
ixmin, ixmax = bounding_box(mask)
data = crop(data, ixmin, ixmax)
mask = crop(mask, ixmin, ixmax)
if np.any(np.array(data.shape[:3]) == 1) and use_tv:
raise ValueError("Cannot use TV regularization if any spatial" +
"dimensions are 1; " +
f"provided dimensions were {data.shape[:3]}")
epsilon = 1e-7
n_grad = kernel.shape[0] # gradient directions
n_comp = kernel.shape[1] # number of compartments
dim = data.shape
n_v_tot = np.prod(dim[:3]) # total number of voxels
# Initial guess is iso-probable
fodf0 = np.ones((n_comp, 1), dtype=np.float32)
fodf0 = fodf0 / np.sum(fodf0, axis=0)
if recon_type == "smf":
n_order = 1 # Rician noise (same as Noncentral Chi with order 1)
elif recon_type == "sos":
n_order = n_coils # Noncentral Chi noise (order = # of coils)
else:
raise ValueError("Invalid recon_type. Should be 'smf' or 'sos', " +
f"received f{recon_type}")
mask_vec = np.ravel(mask)
# Indices of target voxels
index_mask = np.atleast_1d(np.squeeze(np.argwhere(mask_vec)))
n_v_true = len(index_mask) # number of target voxels
data_2d = np.zeros((n_v_true, n_grad), dtype=np.float32)
for i in range(n_grad):
data_2d[:, i] = np.ravel(
data[:, :, :, i])[index_mask] # only keep voxels of interest
data_2d = data_2d.T
fodf = np.tile(fodf0, (1, n_v_true))
reblurred = np.matmul(kernel, fodf)
# For use later
kernel_t = kernel.T
f_zero = 0
# Initialize algorithm parameters
sigma0 = 1 / 15
sigma2 = sigma0**2
tv_lambda = sigma2 # initial guess for TV regularization strength
# Expand into matrix form for iterations
sigma2 = sigma2 * np.ones(data_2d.shape, dtype=np.float32)
tv_lambda_aux = np.zeros((n_v_tot), dtype=np.float32)
reblurred_s = data_2d * reblurred / sigma2
for i in range(n_iter):
fodf_i = fodf
ratio = mbessel_ratio(n_order, reblurred_s).astype(np.float32)
rl_factor = np.matmul(kernel_t, data_2d * ratio) / \
(np.matmul(kernel_t, reblurred) + _EPS)
if use_tv: # apply TV regularization
tv_factor = np.ones(fodf_i.shape, dtype=np.float32)
fodf_4d = _reshape_2d_4d(fodf_i.T, mask)
# Compute gradient, divergence
gr = _grad(fodf_4d)
d_inv = 1 / np.sqrt(epsilon**2 + np.sum(gr**2, axis=3))
gr_norm = (gr * d_inv[:, :, :, None, :])
div_f = _divergence(gr_norm)
g0 = np.abs(1 - tv_lambda * div_f)
tv_factor_4d = 1 / (g0 + _EPS)
for j in range(n_comp):
tv_factor_1d = np.ravel(tv_factor_4d[:, :, :, j])[index_mask]
tv_factor[j, :] = tv_factor_1d
# Apply TV regularization to iteration factor
rl_factor = rl_factor * tv_factor
fodf = fodf_i * rl_factor # result of iteration
fodf = np.maximum(f_zero, fodf) # positivity constraint
# Update other variables
reblurred = np.matmul(kernel, fodf)
reblurred_s = data_2d * reblurred / sigma2
# Iterate variance
sigma2_i = (1 / (n_grad * n_order)) * \
np.sum((data_2d**2 + reblurred**2) / 2 - (
sigma2 * reblurred_s) * ratio, axis=0)
sigma2_i = np.minimum((1 / 8)**2, np.maximum(sigma2_i, (1 / 80)**2))
if verbose:
logger.info("Iteration %d of %d", i + 1, n_iter)
snr_mean = np.mean(1 / np.sqrt(sigma2_i))
snr_std = np.std(1 / np.sqrt(sigma2_i))
logger.info("Mean SNR (S0/sigma) estimated to be %.3f +/- %.3f",
snr_mean, snr_std)
# Expand into matrix
sigma2 = np.tile(sigma2_i[None, :], (data_2d.shape[0], 1))
# Update TV regularization strength using the discrepancy principle
if use_tv:
if R == 1:
tv_lambda = np.mean(sigma2_i)
if tv_lambda < (1 / 30)**2:
tv_lambda = (1 / 30)**2
else: # different factor for each voxel
tv_lambda_aux[index_mask] = sigma2_i
tv_lambda = np.reshape(tv_lambda_aux, (*dim[:3], 1))
fodf = fodf.astype(np.float64)
fodf = fodf / (np.sum(fodf, axis=0)[None, ...] + _EPS) # normalize fODF
# Extract compartments
fit_array = np.zeros((*dim_orig[:3], n_comp))
_reshape_2d_4d(fodf.T,
mask,
out=fit_array[ixmin[0]:ixmax[0], ixmin[1]:ixmax[1],
ixmin[2]:ixmax[2]])
return fit_array
fbvec = input_directory + "/bvecs" # Load the data img = nib.load(fdwi) img_data = img.get_data() # Load the mask mask = nib.load(fmask) mask_data = mask.get_data() #load bvals, bvecs and gradient files bvals, bvecs = read_bvals_bvecs(fbval, fbvec) gtab = gradient_table(bvals, bvecs) # Apply the mask to the volume mask_boolean = mask_data > 0.01 mins, maxs = bounding_box(mask_boolean) mask_boolean = crop(mask_boolean, mins, maxs) cropped_volume = crop(img_data, mins, maxs) data = applymask(cropped_volume, mask_boolean) fw_runner = FreewaterRunner(data, gtab) fw_runner.LOG = True # turn on logging for this example fw_runner.run_model(num_iter=100, dt=0.001) # save the loss function to the working directory #freewater_runner.plot_loss() # Save the free water map somewhere fw_file = output_directory + "/freewater.nii.gz" nib.save(nib.Nifti1Image(fw_runner.get_fw_map(), img.affine), fw_file)
def run(self, data_files, bvals_files, bvecs_files, mask_file,
bbox_threshold=[0.6, 1, 0, 0.1, 0, 0.1], out_dir='',
out_file='product.json', out_mask_cc='cc.nii.gz',
out_mask_noise='mask_noise.nii.gz'):
"""Compute the signal-to-noise ratio in the corpus callosum.
Parameters
----------
data_files : string
Path to the dwi.nii.gz file. This path may contain wildcards to
process multiple inputs at once.
bvals_files : string
Path of bvals.
bvecs_files : string
Path of bvecs.
mask_file : string
Path of a brain mask file.
bbox_threshold : variable float, optional
Threshold for bounding box, values separated with commas for ex.
[0.6,1,0,0.1,0,0.1]. (default (0.6, 1, 0, 0.1, 0, 0.1))
out_dir : string, optional
Where the resulting file will be saved. (default '')
out_file : string, optional
Name of the result file to be saved. (default 'product.json')
out_mask_cc : string, optional
Name of the CC mask volume to be saved (default 'cc.nii.gz')
out_mask_noise : string, optional
Name of the mask noise volume to be saved
(default 'mask_noise.nii.gz')
"""
io_it = self.get_io_iterator()
for dwi_path, bvals_path, bvecs_path, mask_path, out_path, \
cc_mask_path, mask_noise_path in io_it:
data, affine = load_nifti(dwi_path)
bvals, bvecs = read_bvals_bvecs(bvals_path, bvecs_path)
gtab = gradient_table(bvals=bvals, bvecs=bvecs)
mask, affine = load_nifti(mask_path)
logging.info('Computing tensors...')
tenmodel = TensorModel(gtab)
tensorfit = tenmodel.fit(data, mask=mask)
logging.info(
'Computing worst-case/best-case SNR using the CC...')
if np.ndim(data) == 4:
CC_box = np.zeros_like(data[..., 0])
elif np.ndim(data) == 3:
CC_box = np.zeros_like(data)
else:
raise IOError('DWI data has invalid dimensions')
mins, maxs = bounding_box(mask)
mins = np.array(mins)
maxs = np.array(maxs)
diff = (maxs - mins) // 4
bounds_min = mins + diff
bounds_max = maxs - diff
CC_box[bounds_min[0]:bounds_max[0],
bounds_min[1]:bounds_max[1],
bounds_min[2]:bounds_max[2]] = 1
if len(bbox_threshold) != 6:
raise IOError('bbox_threshold should have 6 float values')
mask_cc_part, cfa = segment_from_cfa(tensorfit, CC_box,
bbox_threshold,
return_cfa=True)
save_nifti(cc_mask_path, mask_cc_part.astype(np.uint8), affine)
logging.info('CC mask saved as {0}'.format(cc_mask_path))
mean_signal = np.mean(data[mask_cc_part], axis=0)
mask_noise = binary_dilation(mask, iterations=10)
mask_noise[..., :mask_noise.shape[-1]//2] = 1
mask_noise = ~mask_noise
save_nifti(mask_noise_path, mask_noise.astype(np.uint8), affine)
logging.info('Mask noise saved as {0}'.format(mask_noise_path))
noise_std = np.std(data[mask_noise, :])
logging.info('Noise standard deviation sigma= ' + str(noise_std))
idx = np.sum(gtab.bvecs, axis=-1) == 0
gtab.bvecs[idx] = np.inf
axis_X = np.argmin(
np.sum((gtab.bvecs-np.array([1, 0, 0])) ** 2, axis=-1))
axis_Y = np.argmin(
np.sum((gtab.bvecs-np.array([0, 1, 0])) ** 2, axis=-1))
axis_Z = np.argmin(
np.sum((gtab.bvecs-np.array([0, 0, 1])) ** 2, axis=-1))
SNR_output = []
SNR_directions = []
for direction in ['b0', axis_X, axis_Y, axis_Z]:
if direction == 'b0':
SNR = mean_signal[0]/noise_std
logging.info("SNR for the b=0 image is :" + str(SNR))
else:
logging.info("SNR for direction " + str(direction) +
" " + str(gtab.bvecs[direction]) + "is :" +
str(SNR))
SNR_directions.append(direction)
SNR = mean_signal[direction]/noise_std
SNR_output.append(SNR)
data = []
data.append({
'data': str(SNR_output[0]) + ' ' + str(SNR_output[1]) +
' ' + str(SNR_output[2]) + ' ' + str(SNR_output[3]),
'directions': 'b0' + ' ' + str(SNR_directions[0]) +
' ' + str(SNR_directions[1]) + ' ' +
str(SNR_directions[2])
})
with open(os.path.join(out_dir, out_path), 'w') as myfile:
json.dump(data, myfile)
def main():
parser = buildArgsParser()
args = parser.parse_args()
image = nib.load(args.image)
affine = image.get_affine()
data = image.get_data()
if args.savename is None:
temp, _ = str.split(os.path.basename(args.image), '.', 1)
filename = os.path.dirname(os.path.realpath(args.image)) + '/' + temp
else:
filename, _ = str.split(args.savename, '.', 1)
# If the file already exists, check if the user want to overwrite it. If
# not, simply exit.
filename_CC = filename + '_mask_CC.nii.gz'
if os.path.exists(filename_CC):
if not args.overwrite:
raise ValueError("File " + filename_CC +
" already exists. Use -f option to overwrite.")
print(filename_CC, " already exist and will be overwritten.")
if args.mask is not None:
mask = nib.load(args.mask).get_data()
else:
b0_mask, mask = median_otsu(data)
nib.save(nib.Nifti1Image(mask.astype('int16'), affine),
filename + '_mask.nii.gz')
# Rough box estimation of the corpus callosum, since we do not want to
# include noise that appears on the boundaries of the skull
CC_box = np.zeros_like(data[..., 0])
if args.loc is None:
mins, maxs = bounding_box(mask)
mins = np.array(mins)
maxs = np.array(maxs)
diff = (maxs - mins) // 4
bounds_min = mins + diff
# Min in z goes down to the neck, so we need to further restrict
# the bounding to not get random voxel at the bottom
bounds_min[2] = np.floor(1.5 * bounds_min[2])
bounds_max = maxs - diff
else:
bounds_min = np.array(literal_eval(args.loc))[0::2]
bounds_max = np.array(literal_eval(args.loc))[1::2]
CC_box[bounds_min[0]:bounds_max[0], bounds_min[1]:bounds_max[1],
bounds_min[2]:bounds_max[2]] = 1
threshold = np.array(literal_eval(args.t))
print("Threshold in RGB is :", threshold)
print("ROI used spans from :", bounds_min, "to", bounds_max)
if args.is_rgb is True:
# The example works on threshold between 0 and 1, so we divide the RGB
# by 255, which is the max value
data = data.astype('float32') / 255.
CC_mask = segment_from_RGB(data, CC_box, threshold)
else:
CC_mask = segment_from_dwi(image, args.bvals, args.bvecs, CC_box,
threshold, mask, filename, args.overwrite)
nib.save(nib.Nifti1Image(CC_mask, affine), filename_CC)
print("Mask of the corpus callosum was saved as", filename_CC)
def show(self, rescale=False, fps=10, output=''):
self._visuVolume = self._qVolume.astype("uint8")
# Scale data direction wise or globally
if rescale:
log.info("Scaling data for every direction individually...")
for i in range(0, self._qVolume.shape[2]):
diff_dir_image = np.copy(self._qVolume[:, :, i].astype(float))
mini, maxi = np.amin(diff_dir_image), np.amax(diff_dir_image)
self._visuVolume[:, :, i] = (255.0 * (diff_dir_image - mini) /
maxi).astype("uint8")
else:
image = np.copy(self._qVolume.astype(float))
mini, maxi = np.amin(image), np.amax(image)
self._visuVolume = (255.0 * (image - mini) / maxi).astype("uint8")
if output:
# Output the animation
images = self._visuVolume
crop_image = np.copy(images)
# Cropping volume
t = 0.05
log.info("Cropping volume in a bounding box from pixels below " +
str(int(t * 100.0)) + " % intensity threshold ...")
crop_image[crop_image <= int(t * 255.0)] = 0
min_bounds, max_bounds = mask.bounding_box(crop_image)
images = mask.crop(images, min_bounds, max_bounds)
# Swap axes for gif writer
images = np.swapaxes(images, 0, 2)
images = np.swapaxes(images, 1, 2)
if output.find(".gif") < 0:
output = output + ".gif"
imageio.mimwrite(output, images)
log.info(output + " file created.")
else:
# Initialize figure
fig = plt.figure()
# Add current frame to figure
plt.subplot(121)
self._currentFrame = plt.imshow(self._visuVolume[:, :, 0],
cmap='gray')
if not rescale:
plt.colorbar()
self._currentFrame.set_interpolation('nearest')
plt.axis('off')
# Add text display to figure
plt.subplot(122)
plt.text(0.5,
0.7,
"Data : " + str(self._data.shape) + "\n" +
"Q-Space volume : " + str(self._qVolume.shape),
horizontalalignment='center',
verticalalignment='center')
self._currentText = plt.text(
0.5,
0.5,
"Position , action='store_true': Value, Mean\n" +
str(self._currentPosition),
horizontalalignment='center',
verticalalignment='center',
fontsize='x-large')
plt.axis('off')
# Connect the callback functions
fig.canvas.mpl_connect('motion_notify_event', self._onMove)
fig.canvas.mpl_connect('button_press_event', self._onClick)
fig.canvas.mpl_connect('scroll_event', self._onScroll)
# Create the animation in the figure
anim = animation.FuncAnimation(fig,
self._updateImage,
frames=self._qVolume.shape[2],
interval=1000.0 / fps)
plt.show()
def run(self, data_files, bvals_files, bvecs_files, mask_files,
bbox_threshold=[0.6, 1, 0, 0.1, 0, 0.1], out_dir='',
out_file='product.json', out_mask_cc='cc.nii.gz',
out_mask_noise='mask_noise.nii.gz'):
"""Compute the signal-to-noise ratio in the corpus callosum.
Parameters
----------
data_files : string
Path to the dwi.nii.gz file. This path may contain wildcards to
process multiple inputs at once.
bvals_files : string
Path of bvals.
bvecs_files : string
Path of bvecs.
mask_files : string
Path of brain mask
bbox_threshold : variable float, optional
Threshold for bounding box, values separated with commas for ex.
[0.6,1,0,0.1,0,0.1]. (default (0.6, 1, 0, 0.1, 0, 0.1))
out_dir : string, optional
Where the resulting file will be saved. (default '')
out_file : string, optional
Name of the result file to be saved. (default 'product.json')
out_mask_cc : string, optional
Name of the CC mask volume to be saved (default 'cc.nii.gz')
out_mask_noise : string, optional
Name of the mask noise volume to be saved
(default 'mask_noise.nii.gz')
"""
io_it = self.get_io_iterator()
for dwi_path, bvals_path, bvecs_path, mask_path, out_path, \
cc_mask_path, mask_noise_path in io_it:
data, affine = load_nifti(dwi_path)
bvals, bvecs = read_bvals_bvecs(bvals_path, bvecs_path)
gtab = gradient_table(bvals=bvals, bvecs=bvecs)
logging.info('Computing brain mask...')
_, calc_mask = median_otsu(data)
mask, affine = load_nifti(mask_path)
mask = np.array(calc_mask == mask.astype(bool)).astype(int)
logging.info('Computing tensors...')
tenmodel = TensorModel(gtab)
tensorfit = tenmodel.fit(data, mask=mask)
logging.info(
'Computing worst-case/best-case SNR using the CC...')
if np.ndim(data) == 4:
CC_box = np.zeros_like(data[..., 0])
elif np.ndim(data) == 3:
CC_box = np.zeros_like(data)
else:
raise IOError('DWI data has invalid dimensions')
mins, maxs = bounding_box(mask)
mins = np.array(mins)
maxs = np.array(maxs)
diff = (maxs - mins) // 4
bounds_min = mins + diff
bounds_max = maxs - diff
CC_box[bounds_min[0]:bounds_max[0],
bounds_min[1]:bounds_max[1],
bounds_min[2]:bounds_max[2]] = 1
if len(bbox_threshold) != 6:
raise IOError('bbox_threshold should have 6 float values')
mask_cc_part, cfa = segment_from_cfa(tensorfit, CC_box,
bbox_threshold,
return_cfa=True)
save_nifti(cc_mask_path, mask_cc_part.astype(np.uint8), affine)
logging.info('CC mask saved as {0}'.format(cc_mask_path))
mean_signal = np.mean(data[mask_cc_part], axis=0)
mask_noise = binary_dilation(mask, iterations=10)
mask_noise[..., :mask_noise.shape[-1]//2] = 1
mask_noise = ~mask_noise
save_nifti(mask_noise_path, mask_noise.astype(np.uint8), affine)
logging.info('Mask noise saved as {0}'.format(mask_noise_path))
noise_std = np.std(data[mask_noise, :])
logging.info('Noise standard deviation sigma= ' + str(noise_std))
idx = np.sum(gtab.bvecs, axis=-1) == 0
gtab.bvecs[idx] = np.inf
axis_X = np.argmin(
np.sum((gtab.bvecs-np.array([1, 0, 0])) ** 2, axis=-1))
axis_Y = np.argmin(
np.sum((gtab.bvecs-np.array([0, 1, 0])) ** 2, axis=-1))
axis_Z = np.argmin(
np.sum((gtab.bvecs-np.array([0, 0, 1])) ** 2, axis=-1))
SNR_output = []
SNR_directions = []
for direction in ['b0', axis_X, axis_Y, axis_Z]:
if direction == 'b0':
SNR = mean_signal[0]/noise_std
logging.info("SNR for the b=0 image is :" + str(SNR))
else:
logging.info("SNR for direction " + str(direction) +
" " + str(gtab.bvecs[direction]) + "is :" +
str(SNR))
SNR_directions.append(direction)
SNR = mean_signal[direction]/noise_std
SNR_output.append(SNR)
data = []
data.append({
'data': str(SNR_output[0]) + ' ' + str(SNR_output[1]) +
' ' + str(SNR_output[2]) + ' ' + str(SNR_output[3]),
'directions': 'b0' + ' ' + str(SNR_directions[0]) +
' ' + str(SNR_directions[1]) + ' ' +
str(SNR_directions[2])
})
with open(os.path.join(out_dir, out_path), 'w') as myfile:
json.dump(data, myfile)
Then, as assurance, we want just RED voxels in the CC (there could be
noisy red voxels around the brain mask and we don't want those). Unless the brain
acquisition was badly aligned, the CC is always close to the mid-sagittal slice.
The following lines perform these two operations and then saves the computed mask.
"""
print("Computing worst-case/best-case SNR using the corpus callosum...")
from dipy.segment.mask import segment_from_cfa
from dipy.segment.mask import bounding_box
threshold = (0.6, 1, 0, 0.1, 0, 0.1)
CC_box = np.zeros_like(data[..., 0])
mins, maxs = bounding_box(mask)
mins = np.array(mins)
maxs = np.array(maxs)
diff = (maxs - mins) // 4
bounds_min = mins + diff
bounds_max = maxs - diff
CC_box[bounds_min[0] : bounds_max[0], bounds_min[1] : bounds_max[1], bounds_min[2] : bounds_max[2]] = 1
mask_cc_part, cfa = segment_from_cfa(tensorfit, CC_box, threshold, return_cfa=True)
cfa_img = nib.Nifti1Image((cfa * 255).astype(np.uint8), affine)
mask_cc_part_img = nib.Nifti1Image(mask_cc_part.astype(np.uint8), affine)
nib.save(mask_cc_part_img, "mask_CC_part.nii.gz")
import matplotlib.pyplot as plt
def run(self,
data_file,
data_bvals,
data_bvecs,
mask=None,
bbox_threshold=(0.6, 1, 0, 0.1, 0, 0.1),
out_dir='',
out_file='product.json',
out_mask_cc='cc.nii.gz',
out_mask_noise='mask_noise.nii.gz'):
""" Workflow for computing the signal-to-noise ratio in the
corpus callosum
Parameters
----------
data_file : string
Path to the dwi.nii.gz file. This path may contain wildcards to
process multiple inputs at once.
data_bvals : string
Path of bvals.
data_bvecs : string
Path of bvecs.
mask : string, optional
Path of mask if desired. (default None)
bbox_threshold : string, optional
Threshold for bounding box, values separated with commas for ex.
[0.6,1,0,0.1,0,0.1]. (default (0.6, 1, 0, 0.1, 0, 0.1))
out_dir : string, optional
Where the resulting file will be saved. (default '')
out_file : string, optional
Name of the result file to be saved. (default 'product.json')
out_mask_cc : string, optional
Name of the CC mask volume to be saved (default 'cc.nii.gz')
out_mask_noise : string, optional
Name of the mask noise volume to be saved
(default 'mask_noise.nii.gz')
"""
if not isinstance(bbox_threshold, tuple):
b = bbox_threshold.replace("[", "")
b = b.replace("]", "")
b = b.replace("(", "")
b = b.replace(")", "")
b = b.replace(" ", "")
b = b.split(",")
for i in range(len(b)):
b[i] = float(b[i])
bbox_threshold = tuple(b)
io_it = self.get_io_iterator()
for data_path, data_bvals_path, data_bvecs_path, out_path, \
cc_mask_path, mask_noise_path in io_it:
img = nib.load('{0}'.format(data_path))
bvals, bvecs = read_bvals_bvecs('{0}'.format(data_bvals_path),
'{0}'.format(data_bvecs_path))
gtab = gradient_table(bvals, bvecs)
data = img.get_data()
affine = img.affine
logging.info('Computing brain mask...')
b0_mask, calc_mask = median_otsu(data)
if mask is None:
mask = calc_mask
else:
mask = nib.load(mask).get_data().astype(bool)
mask = np.array(calc_mask == mask).astype(int)
logging.info('Computing tensors...')
tenmodel = TensorModel(gtab)
tensorfit = tenmodel.fit(data, mask=mask)
logging.info('Computing worst-case/best-case SNR using the CC...')
threshold = bbox_threshold
if np.ndim(data) == 4:
CC_box = np.zeros_like(data[..., 0])
elif np.ndim(data) == 3:
CC_box = np.zeros_like(data)
else:
raise IOError('DWI data has invalid dimensions')
mins, maxs = bounding_box(mask)
mins = np.array(mins)
maxs = np.array(maxs)
diff = (maxs - mins) // 4
bounds_min = mins + diff
bounds_max = maxs - diff
CC_box[bounds_min[0]:bounds_max[0], bounds_min[1]:bounds_max[1],
bounds_min[2]:bounds_max[2]] = 1
mask_cc_part, cfa = segment_from_cfa(tensorfit,
CC_box,
threshold,
return_cfa=True)
cfa_img = nib.Nifti1Image((cfa * 255).astype(np.uint8), affine)
mask_cc_part_img = nib.Nifti1Image(mask_cc_part.astype(np.uint8),
affine)
nib.save(mask_cc_part_img, cc_mask_path)
logging.info('CC mask saved as {0}'.format(cc_mask_path))
mean_signal = np.mean(data[mask_cc_part], axis=0)
mask_noise = binary_dilation(mask, iterations=10)
mask_noise[..., :mask_noise.shape[-1] // 2] = 1
mask_noise = ~mask_noise
mask_noise_img = nib.Nifti1Image(mask_noise.astype(np.uint8),
affine)
nib.save(mask_noise_img, mask_noise_path)
logging.info('Mask noise saved as {0}'.format(mask_noise_path))
noise_std = np.std(data[mask_noise, :])
logging.info('Noise standard deviation sigma= ' + str(noise_std))
idx = np.sum(gtab.bvecs, axis=-1) == 0
gtab.bvecs[idx] = np.inf
axis_X = np.argmin(
np.sum((gtab.bvecs - np.array([1, 0, 0]))**2, axis=-1))
axis_Y = np.argmin(
np.sum((gtab.bvecs - np.array([0, 1, 0]))**2, axis=-1))
axis_Z = np.argmin(
np.sum((gtab.bvecs - np.array([0, 0, 1]))**2, axis=-1))
SNR_output = []
SNR_directions = []
for direction in ['b0', axis_X, axis_Y, axis_Z]:
if direction == 'b0':
SNR = mean_signal[0] / noise_std
logging.info("SNR for the b=0 image is :" + str(SNR))
else:
logging.info("SNR for direction " + str(direction) + " " +
str(gtab.bvecs[direction]) + "is :" +
str(SNR))
SNR_directions.append(direction)
SNR = mean_signal[direction] / noise_std
SNR_output.append(SNR)
data = []
data.append({
'data':
str(SNR_output[0]) + ' ' + str(SNR_output[1]) + ' ' +
str(SNR_output[2]) + ' ' + str(SNR_output[3]),
'directions':
'b0' + ' ' + str(SNR_directions[0]) + ' ' +
str(SNR_directions[1]) + ' ' + str(SNR_directions[2])
})
with open(os.path.join(out_dir, out_file), 'w') as myfile:
json.dump(data, myfile)
def get_bounded_image(self, vol):
min_indicies, max_indicies = bounding_box(vol)
bounded_image = crop(vol, min_indicies, max_indicies)
return bounded_image
def crop_using_mask(data, mask):
mins, maxs = bounding_box(mask)
cropped_data = crop(data, mins, maxs)
return cropped_data
