def test_crop_image_example(self):
fi = ants.image_read(ants.get_ants_data('r16'))
cropped = ants.crop_image(fi)
cropped = ants.crop_image(fi, fi, 100)
# image not float type
cropped = ants.crop_image(fi.clone('unsigned int'))
# label image not float
cropped = ants.crop_image(fi, fi.clone('unsigned int'), 100)
def test_decrop_image_example(self):
fi = ants.image_read(ants.get_ants_data('r16'))
mask = ants.get_mask(fi)
cropped = ants.crop_image(fi, mask, 1)
cropped = ants.smooth_image(cropped, 1)
decropped = ants.decrop_image(cropped, fi)
# image not float
cropped = ants.crop_image(fi.clone('unsigned int'), mask, 1)
# full image not float
cropped = ants.crop_image(fi, mask.clone('unsigned int'), 1)
def hippmapp3r_segmentation(t1,
do_preprocessing=True,
antsxnet_cache_directory=None,
verbose=False):
"""
Perform HippMapp3r (hippocampal) segmentation described in
https://www.ncbi.nlm.nih.gov/pubmed/31609046
with models and architecture ported from
https://github.com/mgoubran/HippMapp3r
Additional documentation and attribution resources found at
https://hippmapp3r.readthedocs.io/en/latest/
Preprocessing consists of:
* n4 bias correction and
* brain extraction
The input T1 should undergo the same steps. If the input T1 is the raw
T1, these steps can be performed by the internal preprocessing, i.e. set
do_preprocessing = True
Arguments
---------
t1 : ANTsImage
input image
do_preprocessing : boolean
See description above.
antsxnet_cache_directory : string
Destination directory for storing the downloaded template and model weights.
Since these can be resused, if is None, these data will be downloaded to a
~/.keras/ANTsXNet/.
verbose : boolean
Print progress to the screen.
Returns
-------
ANTs labeled hippocampal image.
Example
-------
>>> mask = hippmapp3r_segmentation(t1)
"""
from ..architectures import create_hippmapp3r_unet_model_3d
from ..utilities import preprocess_brain_image
from ..utilities import get_pretrained_network
from ..utilities import get_antsxnet_data
if t1.dimension != 3:
raise ValueError("Image dimension must be 3.")
if antsxnet_cache_directory == None:
antsxnet_cache_directory = "ANTsXNet"
if verbose == True:
print("************* Preprocessing ***************")
print("")
t1_preprocessed = t1
if do_preprocessing == True:
t1_preprocessing = preprocess_brain_image(
t1,
truncate_intensity=None,
brain_extraction_modality="t1",
template=None,
do_bias_correction=True,
do_denoising=False,
antsxnet_cache_directory=antsxnet_cache_directory,
verbose=verbose)
t1_preprocessed = t1_preprocessing[
"preprocessed_image"] * t1_preprocessing['brain_mask']
if verbose == True:
print("************* Initial stage segmentation ***************")
print("")
# Normalize to mprage_hippmapp3r space
if verbose == True:
print(" HippMapp3r: template normalization.")
template_file_name_path = get_antsxnet_data(
"mprage_hippmapp3r", antsxnet_cache_directory=antsxnet_cache_directory)
template_image = ants.image_read(template_file_name_path)
registration = ants.registration(
fixed=template_image,
moving=t1_preprocessed,
type_of_transform="antsRegistrationSyNQuickRepro[t]",
verbose=verbose)
image = registration['warpedmovout']
transforms = dict(fwdtransforms=registration['fwdtransforms'],
invtransforms=registration['invtransforms'])
# Threshold at 10th percentile of non-zero voxels in "robust range (fslmaths)"
if verbose == True:
print(" HippMapp3r: threshold.")
image_array = image.numpy()
image_robust_range = np.quantile(image_array[np.where(image_array != 0)],
(0.02, 0.98))
threshold_value = 0.10 * (image_robust_range[1] -
image_robust_range[0]) + image_robust_range[0]
thresholded_mask = ants.threshold_image(image, -10000, threshold_value, 0,
1)
thresholded_image = image * thresholded_mask
# Standardize image
if verbose == True:
print(" HippMapp3r: standardize.")
mean_image = np.mean(thresholded_image[thresholded_mask == 1])
sd_image = np.std(thresholded_image[thresholded_mask == 1])
image_normalized = (image - mean_image) / sd_image
image_normalized = image_normalized * thresholded_mask
# Trim and resample image
if verbose == True:
print(" HippMapp3r: trim and resample to (160, 160, 128).")
image_cropped = ants.crop_image(image_normalized, thresholded_mask, 1)
shape_initial_stage = (160, 160, 128)
image_resampled = ants.resample_image(image_cropped,
shape_initial_stage,
use_voxels=True,
interp_type=1)
if verbose == True:
print(" HippMapp3r: generate first network and download weights.")
model_initial_stage = create_hippmapp3r_unet_model_3d(
(*shape_initial_stage, 1), do_first_network=True)
initial_stage_weights_file_name = get_pretrained_network(
"hippMapp3rInitial", antsxnet_cache_directory=antsxnet_cache_directory)
model_initial_stage.load_weights(initial_stage_weights_file_name)
if verbose == True:
print(" HippMapp3r: prediction.")
data_initial_stage = np.expand_dims(image_resampled.numpy(), axis=0)
data_initial_stage = np.expand_dims(data_initial_stage, axis=-1)
mask_array = model_initial_stage.predict(data_initial_stage,
verbose=verbose)
mask_image_resampled = ants.copy_image_info(
image_resampled, ants.from_numpy(np.squeeze(mask_array)))
mask_image = ants.resample_image(mask_image_resampled,
image.shape,
use_voxels=True,
interp_type=0)
mask_image[mask_image >= 0.5] = 1
mask_image[mask_image < 0.5] = 0
#########################################
#
# Perform refined (stage 2) segmentation
#
if verbose == True:
print("")
print("")
print("************* Refine stage segmentation ***************")
print("")
mask_array = np.squeeze(mask_array)
centroid_indices = np.where(mask_array == 1)
centroid = np.zeros((3, ))
centroid[0] = centroid_indices[0].mean()
centroid[1] = centroid_indices[1].mean()
centroid[2] = centroid_indices[2].mean()
shape_refine_stage = (112, 112, 64)
lower = (np.floor(centroid - 0.5 * np.array(shape_refine_stage)) -
1).astype(int)
upper = (lower + np.array(shape_refine_stage)).astype(int)
image_trimmed = ants.crop_indices(image_resampled, lower.astype(int),
upper.astype(int))
if verbose == True:
print(" HippMapp3r: generate second network and download weights.")
model_refine_stage = create_hippmapp3r_unet_model_3d(
(*shape_refine_stage, 1), do_first_network=False)
refine_stage_weights_file_name = get_pretrained_network(
"hippMapp3rRefine", antsxnet_cache_directory=antsxnet_cache_directory)
model_refine_stage.load_weights(refine_stage_weights_file_name)
data_refine_stage = np.expand_dims(image_trimmed.numpy(), axis=0)
data_refine_stage = np.expand_dims(data_refine_stage, axis=-1)
if verbose == True:
print(" HippMapp3r: Monte Carlo iterations (SpatialDropout).")
number_of_mci_iterations = 30
prediction_refine_stage = np.zeros(shape_refine_stage)
for i in range(number_of_mci_iterations):
tf.random.set_seed(i)
if verbose == True:
print(" Monte Carlo iteration", i + 1, "out of",
number_of_mci_iterations)
prediction_refine_stage = \
(np.squeeze(model_refine_stage.predict(data_refine_stage, verbose=verbose)) + \
i * prediction_refine_stage ) / (i + 1)
prediction_refine_stage_array = np.zeros(image_resampled.shape)
prediction_refine_stage_array[lower[0]:upper[0], lower[1]:upper[1],
lower[2]:upper[2]] = prediction_refine_stage
probability_mask_refine_stage_resampled = ants.copy_image_info(
image_resampled, ants.from_numpy(prediction_refine_stage_array))
segmentation_image_resampled = ants.label_clusters(ants.threshold_image(
probability_mask_refine_stage_resampled, 0.0, 0.5, 0, 1),
min_cluster_size=10)
segmentation_image_resampled[segmentation_image_resampled > 2] = 0
geom = ants.label_geometry_measures(segmentation_image_resampled)
if len(geom['VolumeInMillimeters']) < 2:
raise ValueError("Error: left and right hippocampus not found.")
if geom['Centroid_x'][0] < geom['Centroid_x'][1]:
segmentation_image_resampled[segmentation_image_resampled == 1] = 3
segmentation_image_resampled[segmentation_image_resampled == 2] = 1
segmentation_image_resampled[segmentation_image_resampled == 3] = 2
segmentation_image = ants.apply_transforms(
fixed=t1,
moving=segmentation_image_resampled,
transformlist=transforms['invtransforms'],
whichtoinvert=[True],
interpolator="genericLabel",
verbose=verbose)
return (segmentation_image)
def sysu_media_wmh_segmentation(flair,
t1=None,
use_ensemble=True,
antsxnet_cache_directory=None,
verbose=False):
"""
Perform WMH segmentation using the winning submission in the MICCAI
2017 challenge by the sysu_media team using FLAIR or T1/FLAIR. The
MICCAI challenge is discussed in
https://pubmed.ncbi.nlm.nih.gov/30908194/
with the sysu_media's team entry is discussed in
https://pubmed.ncbi.nlm.nih.gov/30125711/
with the original implementation available here:
https://github.com/hongweilibran/wmh_ibbmTum
The original implementation used global thresholding as a quick
brain extraction approach. Due to possible generalization difficulties,
we leave such post-processing steps to the user. For brain or white
matter masking see functions brain_extraction or deep_atropos,
respectively.
Arguments
---------
flair : ANTsImage
input 3-D FLAIR brain image (not skull-stripped).
t1 : ANTsImage
input 3-D T1 brain image (not skull-stripped).
use_ensemble : boolean
check whether to use all 3 sets of weights.
antsxnet_cache_directory : string
Destination directory for storing the downloaded template and model weights.
Since these can be resused, if is None, these data will be downloaded to a
~/.keras/ANTsXNet/.
verbose : boolean
Print progress to the screen.
Returns
-------
WMH segmentation probability image
Example
-------
>>> image = ants.image_read("flair.nii.gz")
>>> probability_mask = sysu_media_wmh_segmentation(image)
"""
from ..architectures import create_sysu_media_unet_model_2d
from ..utilities import get_pretrained_network
from ..utilities import pad_or_crop_image_to_size
from ..utilities import preprocess_brain_image
from ..utilities import binary_dice_coefficient
if flair.dimension != 3:
raise ValueError("Image dimension must be 3.")
if antsxnet_cache_directory == None:
antsxnet_cache_directory = "ANTsXNet"
image_size = (200, 200)
################################
#
# Preprocess images
#
################################
def closest_simplified_direction_matrix(direction):
closest = (np.abs(direction) + 0.5).astype(int).astype(float)
closest[direction < 0] *= -1.0
return closest
simplified_direction = closest_simplified_direction_matrix(flair.direction)
flair_preprocessing = preprocess_brain_image(
flair,
truncate_intensity=None,
brain_extraction_modality=None,
do_bias_correction=False,
do_denoising=False,
antsxnet_cache_directory=antsxnet_cache_directory,
verbose=verbose)
flair_preprocessed = flair_preprocessing["preprocessed_image"]
flair_preprocessed.set_direction(simplified_direction)
flair_preprocessed.set_origin((0, 0, 0))
flair_preprocessed.set_spacing((1, 1, 1))
number_of_channels = 1
t1_preprocessed = None
if t1 is not None:
t1_preprocessing = preprocess_brain_image(
t1,
truncate_intensity=None,
brain_extraction_modality=None,
do_bias_correction=False,
do_denoising=False,
antsxnet_cache_directory=antsxnet_cache_directory,
verbose=verbose)
t1_preprocessed = t1_preprocessing["preprocessed_image"]
t1_preprocessed.set_direction(simplified_direction)
t1_preprocessed.set_origin((0, 0, 0))
t1_preprocessed.set_spacing((1, 1, 1))
number_of_channels = 2
################################
#
# Reorient images
#
################################
reference_image = ants.make_image((256, 256, 256),
voxval=0,
spacing=(1, 1, 1),
origin=(0, 0, 0),
direction=np.identity(3))
center_of_mass_reference = np.floor(
ants.get_center_of_mass(reference_image * 0 + 1))
center_of_mass_image = np.floor(
ants.get_center_of_mass(flair_preprocessed))
translation = np.asarray(center_of_mass_image) - np.asarray(
center_of_mass_reference)
xfrm = ants.create_ants_transform(
transform_type="Euler3DTransform",
center=np.asarray(center_of_mass_reference),
translation=translation)
flair_preprocessed_warped = ants.apply_ants_transform_to_image(
xfrm,
flair_preprocessed,
reference_image,
interpolation="nearestneighbor")
crop_image = ants.image_clone(flair_preprocessed) * 0 + 1
crop_image_warped = ants.apply_ants_transform_to_image(
xfrm, crop_image, reference_image, interpolation="nearestneighbor")
flair_preprocessed_warped = ants.crop_image(flair_preprocessed_warped,
crop_image_warped, 1)
if t1 is not None:
t1_preprocessed_warped = ants.apply_ants_transform_to_image(
xfrm,
t1_preprocessed,
reference_image,
interpolation="nearestneighbor")
t1_preprocessed_warped = ants.crop_image(t1_preprocessed_warped,
crop_image_warped, 1)
################################
#
# Gaussian normalize intensity
#
################################
mean_flair = flair_preprocessed.mean()
std_flair = flair_preprocessed.std()
if number_of_channels == 2:
mean_t1 = t1_preprocessed.mean()
std_t1 = t1_preprocessed.std()
flair_preprocessed_warped = (flair_preprocessed_warped -
mean_flair) / std_flair
if number_of_channels == 2:
t1_preprocessed_warped = (t1_preprocessed_warped - mean_t1) / std_t1
################################
#
# Build models and load weights
#
################################
number_of_models = 1
if use_ensemble == True:
number_of_models = 3
if verbose == True:
print("White matter hyperintensity: retrieving model weights.")
unet_models = list()
for i in range(number_of_models):
if number_of_channels == 1:
weights_file_name = get_pretrained_network(
"sysuMediaWmhFlairOnlyModel" + str(i),
antsxnet_cache_directory=antsxnet_cache_directory)
else:
weights_file_name = get_pretrained_network(
"sysuMediaWmhFlairT1Model" + str(i),
antsxnet_cache_directory=antsxnet_cache_directory)
unet_model = create_sysu_media_unet_model_2d(
(*image_size, number_of_channels))
unet_loss = binary_dice_coefficient(smoothing_factor=1.)
unet_model.compile(optimizer=keras.optimizers.Adam(learning_rate=2e-4),
loss=unet_loss)
unet_model.load_weights(weights_file_name)
unet_models.append(unet_model)
################################
#
# Extract slices
#
################################
dimensions_to_predict = [2]
total_number_of_slices = 0
for d in range(len(dimensions_to_predict)):
total_number_of_slices += flair_preprocessed_warped.shape[
dimensions_to_predict[d]]
batchX = np.zeros(
(total_number_of_slices, *image_size, number_of_channels))
slice_count = 0
for d in range(len(dimensions_to_predict)):
number_of_slices = flair_preprocessed_warped.shape[
dimensions_to_predict[d]]
if verbose == True:
print("Extracting slices for dimension ", dimensions_to_predict[d],
".")
for i in range(number_of_slices):
flair_slice = pad_or_crop_image_to_size(
ants.slice_image(flair_preprocessed_warped,
dimensions_to_predict[d], i), image_size)
batchX[slice_count, :, :, 0] = flair_slice.numpy()
if number_of_channels == 2:
t1_slice = pad_or_crop_image_to_size(
ants.slice_image(t1_preprocessed_warped,
dimensions_to_predict[d], i), image_size)
batchX[slice_count, :, :, 1] = t1_slice.numpy()
slice_count += 1
################################
#
# Do prediction and then restack into the image
#
################################
if verbose == True:
print("Prediction.")
prediction = unet_models[0].predict(np.transpose(batchX,
axes=(0, 2, 1, 3)),
verbose=verbose)
if number_of_models > 1:
for i in range(1, number_of_models, 1):
prediction += unet_models[i].predict(np.transpose(batchX,
axes=(0, 2, 1,
3)),
verbose=verbose)
prediction /= number_of_models
prediction = np.transpose(prediction, axes=(0, 2, 1, 3))
permutations = list()
permutations.append((0, 1, 2))
permutations.append((1, 0, 2))
permutations.append((1, 2, 0))
prediction_image_average = ants.image_clone(flair_preprocessed_warped) * 0
current_start_slice = 0
for d in range(len(dimensions_to_predict)):
current_end_slice = current_start_slice + flair_preprocessed_warped.shape[
dimensions_to_predict[d]]
which_batch_slices = range(current_start_slice, current_end_slice)
prediction_per_dimension = prediction[which_batch_slices, :, :, :]
prediction_array = np.transpose(np.squeeze(prediction_per_dimension),
permutations[dimensions_to_predict[d]])
prediction_image = ants.copy_image_info(
flair_preprocessed_warped,
pad_or_crop_image_to_size(ants.from_numpy(prediction_array),
flair_preprocessed_warped.shape))
prediction_image_average = prediction_image_average + (
prediction_image - prediction_image_average) / (d + 1)
current_start_slice = current_end_slice
probability_image = ants.apply_ants_transform_to_image(
ants.invert_ants_transform(xfrm), prediction_image_average,
flair_preprocessed)
probability_image = ants.copy_image_info(flair, probability_image)
return (probability_image)
translation = np.asarray(center_of_mass_image) - np.asarray(
center_of_mass_template)
xfrm = ants.create_ants_transform(transform_type="Euler3DTransform",
center=np.asarray(center_of_mass_template),
translation=translation)
warped_image = ants.apply_ants_transform_to_image(xfrm,
image,
reorient_template,
interpolation='linear')
warped_mask = ants.apply_ants_transform_to_image(xfrm,
mask,
reorient_template,
interpolation='linear')
warped_mask = ants.threshold_image(warped_mask, 0.4999, 1.0001, 1, 0)
warped_mask = ants.iMath(warped_mask, "MD", 3)
warped_cropped_image = ants.crop_image(warped_image, warped_mask, 1)
original_cropped_size = warped_cropped_image.shape
warped_cropped_image = ants.resample_image(warped_cropped_image,
resampled_image_size,
use_voxels=True)
end_time = time.time()
elapsed_time = end_time - start_time
print(" (elapsed time: ", elapsed_time, " seconds)")
batchX = np.expand_dims(warped_cropped_image.numpy(), axis=0)
batchX = np.expand_dims(batchX, axis=-1)
batchX = (batchX - batchX.mean()) / batchX.std()
print("Prediction and decoding")
start_time = time.time()
predicted_data = unet_model.predict(batchX, verbose=0)
