Working synb0 wrapper in scilpy

scilpy/image/volume_operations.py

@@ -194,17 +194,55 @@ def transform_dwi(reg_obj, static, dwi, interpolation='linear'):
 
 
 def register_image(static, static_grid2world, moving, moving_grid2world,
-                   transformation_type='affine', dwi=None):
+                   transformation_type='affine', dwi=None, fine=False):
+    """
+    Register a moving image to a static image using either rigid or affine
+    transformations. If a DWI (4D) is provided, it applies the transformation
+    to each volume.
+
+    Parameters
+    ----------
+    static : ndarray
+        The static image volume to which the moving image will be registered.
+    static_grid2world : ndarray
+        The grid-to-world (vox2ras) transformation associated with the static
+        image.
+    moving : ndarray
+        The moving image volume that needs to be registered to the static image.
+    moving_grid2world : ndarray
+        The grid-to-world (vox2ras) transformation associated with the moving
+        image.
+    transformation_type : str, optional
+        The type of transformation ('rigid' or 'affine'). Default is 'affine'.
+    dwi : ndarray, optional
+        Diffusion-weighted imaging data (if applicable). Default is None.
+    fine : bool, optional
+        Whether to use fine or coarse settings for the registration.
+        Default is False.
+
+    Raises
+    ------
+    ValueError
+        If the transformation_type is neither 'rigid' nor 'affine'.
+
+    Returns
+    -------
+    ndarray or tuple
+        If `dwi` is None, returns transformed moving image and transformation
+        matrix.
+        If `dwi` is not None, returns transformed DWI and transformation matrix.
+    """
+
     if transformation_type not in ['rigid', 'affine']:
         raise ValueError('Transformation type not available in Dipy')
 
     # Set all parameters for registration
-    nbins = 32
+    nbins = 64 if fine else 32
     params0 = None
     sampling_prop = None
-    level_iters = [50, 25, 5]
-    sigmas = [8.0, 4.0, 2.0]
-    factors = [8, 4, 2]
+    level_iters = [250, 100, 50, 25] if fine else [50, 25, 5]
+    sigmas = [8.0, 4.0, 2.0, 1.0] if fine else [8.0, 4.0, 2.0]
+    factors = [8, 4, 2, 1.0] if fine else [8, 4, 2]
     metric = MutualInformationMetric(nbins, sampling_prop)
     reg_obj = AffineRegistration(metric=metric, level_iters=level_iters,
                                  sigmas=sigmas, factors=factors, verbosity=0)

scilpy/io/fetcher.py

@@ -1,5 +1,6 @@
 # -*- coding: utf-8 -*-
 
+import inspect
 import logging
 import hashlib
 import os
@@ -131,3 +132,20 @@ def fetch_data(files_dict, keys=None):
         else:
             # toDo. Verify that data on disk is the right one.
             logging.warning("Not fetching data; already on disk.")
+
+
+def get_synb0_template_path():
+    """
+    Return MNI 2.5mm template in scilpy repository
+    Returns
+    -------
+    path: str
+        Template path
+    """
+    import scilpy  # ToDo. Is this the only way?
+    module_path = inspect.getfile(scilpy)
+    module_path = os.path.dirname(os.path.dirname(module_path))
+
+    path = os.path.join(module_path, 'data/',
+                        'mni_icbm152_t1_tal_nlin_asym_09c_masked_2_5.nii.gz')
+    return path

scilpy/preprocessing/distortion_correction.py

@@ -1,9 +1,12 @@
 # -*- coding: utf-8 -*-
 
+import logging
+
 import numpy as np
 
 
-def create_acqparams(readout, encoding_direction, nb_b0s=1, nb_rev_b0s=1):
+def create_acqparams(readout, encoding_direction, synb0=False,
+                     nb_b0s=1, nb_rev_b0s=1):
     """
     Create acqparams for Topup and Eddy
 
@@ -23,13 +26,18 @@ def create_acqparams(readout, encoding_direction, nb_b0s=1, nb_rev_b0s=1):
     acqparams: np.array
         acqparams
     """
+    if synb0:
+        logging.warning('Using SyNb0, untested feature. Be careful.')
+
     acqparams = np.zeros((nb_b0s + nb_rev_b0s, 4))
     acqparams[:, 3] = readout
 
     enum_direction = {'x': 0, 'y': 1, 'z': 2}
     acqparams[0:nb_b0s, enum_direction[encoding_direction]] = 1
     if nb_rev_b0s > 0:
-        acqparams[nb_b0s:, enum_direction[encoding_direction]] = -1
+        val = -1 if not synb0 else 1
+        acqparams[nb_b0s:, enum_direction[encoding_direction]] = val
+        acqparams[nb_b0s:, 3] = readout if not synb0 else 0
 
     return acqparams
 

scilpy/tractanalysis/afd_along_streamlines.py

@@ -33,7 +33,6 @@ def afd_map_along_streamlines(sft, fodf, fodf_basis, length_weighting):
         rdAFD map (weighted if length_weighting)
     """
 
-
     afd_sum, rd_sum, weights = \
         afd_and_rd_sums_along_streamlines(sft, fodf, fodf_basis,
                                           length_weighting)
@@ -112,7 +111,8 @@ def afd_and_rd_sums_along_streamlines(sft, fodf, fodf_basis,
 
         normalization_weights = np.ones_like(seg_lengths)
         if length_weighting:
-            normalization_weights = seg_lengths / np.linalg.norm(fodf.header.get_zooms()[:3])
+            normalization_weights = seg_lengths / \
+                np.linalg.norm(fodf.header.get_zooms()[:3])
 
         for vox_idx, closest_vertex_index, norm_weight in zip(vox_indices,
                                                               closest_vertex_indices,
@@ -130,5 +130,4 @@ def afd_and_rd_sums_along_streamlines(sft, fodf, fodf_basis,
             weight_map[vox_idx] += norm_weight
 
     rd_sum_map[rd_sum_map < 0.] = 0.
-
     return afd_sum_map, rd_sum_map, weight_map

scripts/scil_dwi_prepare_topup_command.py

@@ -34,6 +34,9 @@ def _build_arg_parser():
     p.add_argument('--config', default='b02b0.cnf',
                    help='Topup config file [%(default)s].')
 
+    p.add_argument('--synb0', action='store_true',
+                   help='If set, will use SyNb0 custom acqparams file.')
+
     p.add_argument('--encoding_direction', default='y',
                    choices=['x', 'y', 'z'],
                    help='Acquisition direction of the forward b0 '
@@ -119,8 +122,8 @@ def main():
     fused_b0s_path = os.path.join(args.out_directory, args.out_b0s)
     nib.save(nib.Nifti1Image(fused_b0s, b0_img.affine), fused_b0s_path)
 
-    acqparams = create_acqparams(
-        args.readout, args.encoding_direction, b0.shape[-1], rev_b0.shape[-1])
+    acqparams = create_acqparams(args.readout, args.encoding_direction,
+                                 args.synb0, b0.shape[-1], rev_b0.shape[-1])
 
     if not os.path.exists(args.out_directory):
         os.makedirs(args.out_directory)

scripts/scil_volume_b0_synthesis.py

@@ -0,0 +1,142 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+"""
+Wrapper for SyNb0 available in Dipy, to run it on a single subject.
+Requires Skull-Strip b0 and t1w images as input, the script will normalize the
+t1w's WM to 110, co-register both images, then register it to the appropriate
+template, run SyNb0 and then transform the result back to the original space.
+
+This script must be used carefully, as it is not meant to be used in an
+environment with the following dependencies already installed (not default
+in Scilpy):
+- tensorflow-addons
+- tensorrt
+- tensorflow
+"""
+
+
+import argparse
+import logging
+import os
+import sys
+import warnings
+
+# Disable tensorflow warnings
+with warnings.catch_warnings():
+    os.environ['TF_CPP_MIN_LOG_LEVEL'] = '3'
+    warnings.simplefilter("ignore")
+    from dipy.nn.synb0 import Synb0
+
+from dipy.align.imaffine import AffineMap
+from dipy.segment.tissue import TissueClassifierHMRF
+import nibabel as nib
+import numpy as np
+from scipy.ndimage import gaussian_filter
+
+from scilpy.io.fetcher import get_synb0_template_path
+from scilpy.io.utils import (add_overwrite_arg,
+                             add_verbose_arg,
+                             assert_inputs_exist,
+                             assert_outputs_exist)
+from scilpy.image.volume_operations import register_image
+
+
+def _build_arg_parser():
+    p = argparse.ArgumentParser(
+        description=__doc__,
+        formatter_class=argparse.RawTextHelpFormatter)
+    p.add_argument('in_b0',
+                   help='Input b0 image.')
+    p.add_argument('in_b0_mask',
+                   help='Input b0 mask.')
+    p.add_argument('in_t1',
+                   help='Input t1w image.')
+    p.add_argument('in_t1_mask',
+                   help='Input t1w mask.')
+    p.add_argument('out_b0',
+                   help='Output b0 image without distortion.')
+
+    add_verbose_arg(p)
+    add_overwrite_arg(p)
+
+    return p
+
+
+def main():
+    parser = _build_arg_parser()
+    args = parser.parse_args()
+    assert_inputs_exist(parser, [args.in_b0, args.in_t1])
+    assert_outputs_exist(parser, args, args.out_b0)
+
+    logging.getLogger().setLevel(logging.getLevelName(args.verbose))
+    logging.info('The usage of synthetic b0 is not fully tested.'
+                 'Be careful when using it.')
+
+    template_img = nib.load(get_synb0_template_path())
+    template_data = template_img.get_fdata()
+
+    b0_img = nib.load(args.in_b0)
+    b0_skull_data = b0_img.get_fdata()
+    b0_mask_img = nib.load(args.in_b0_mask)
+    b0_mask_data = b0_mask_img.get_fdata()
+
+    t1_img = nib.load(args.in_t1)
+    t1_skull_data = t1_img.get_fdata()
+    t1_mask_img = nib.load(args.in_t1_mask)
+    t1_mask_data = t1_mask_img.get_fdata()
+
+    b0_bet_data = np.zeros(b0_skull_data.shape)
+    b0_bet_data[b0_mask_data > 0] = b0_skull_data[b0_mask_data > 0]
+    t1_bet_data = np.zeros(t1_skull_data.shape)
+    t1_bet_data[t1_mask_data > 0] = t1_skull_data[t1_mask_data > 0]
+
+    # Crude estimation of the WM mean intensity and normalization
+    logging.info('Estimating WM mean intensity')
+    hmrf = TissueClassifierHMRF()
+    t1_bet_data = gaussian_filter(t1_bet_data, 2)
+    _, final_segmentation, _ = hmrf.classify(t1_bet_data, 3, 0.25,
+                                             tolerance=1e-4, max_iter=5)
+    avg_wm = np.mean(t1_skull_data[final_segmentation == 3])
+    t1_skull_data /= avg_wm
+    t1_skull_data *= 110
+
+    # SyNB0 works only in a standard space, so we need to register the images
+    logging.info('Registering images')
+    # Use the BET image for registration
+    t1_bet_to_b0, t1_bet_to_b0_transform = register_image(b0_bet_data,
+                                                          b0_img.affine,
+                                                          t1_bet_data,
+                                                          t1_img.affine,
+                                                          fine=True)
+    affine_map = AffineMap(t1_bet_to_b0_transform,
+                           b0_skull_data.shape, b0_img.affine,
+                           t1_skull_data.shape, t1_img.affine)
+    t1_skull_to_b0 = affine_map.transform(t1_skull_data.astype(np.float64))
+
+    # Then register to MNI (using the BET again)
+    _, t1_bet_to_b0_to_mni_transform = register_image(template_data,
+                                                      template_img.affine,
+                                                      t1_bet_to_b0,
+                                                      b0_img.affine,
+                                                      fine=True)
+    affine_map = AffineMap(t1_bet_to_b0_to_mni_transform,
+                           template_data.shape, template_img.affine,
+                           b0_skull_data.shape, b0_img.affine)
+
+    # But for prediction, we want the skull
+    b0_skull_to_mni = affine_map.transform(b0_skull_data.astype(np.float64))
+    t1_skull_to_mni = affine_map.transform(t1_skull_to_b0.astype(np.float64))
+
+    logging.info('Running SyN-B0')
+    SyNb0 = Synb0(args.verbose)
+    rev_b0 = SyNb0.predict(b0_skull_to_mni, t1_skull_to_mni)
+    rev_b0 = affine_map.transform_inverse(rev_b0.astype(np.float64))
+
+    dtype = b0_img.get_data_dtype()
+    nib.save(nib.Nifti1Image(rev_b0.astype(dtype), b0_img.affine),
+             args.out_b0)
+
+
+if __name__ == "__main__":
+    main()

scripts/tests/test_volume_b0_synthesis.py

@@ -0,0 +1,47 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+from scilpy.io.fetcher import fetch_data, get_home, get_testing_files_dict
+import os
+import tempfile
+
+import pytest
+import nibabel as nib
+import numpy as np
+tensorflow = pytest.importorskip("tensorflow")
+
+
+# If they already exist, this only takes 5 seconds (check md5sum)
+fetch_data(get_testing_files_dict(), keys=['others.zip', 'processing.zip'])
+tmp_dir = tempfile.TemporaryDirectory()
+
+
+def test_help_option(script_runner):
+    ret = script_runner.run('scil_volume_b0_synthesis.py', '--help')
+    assert ret.success
+
+
+@pytest.mark.skipif(tensorflow is None, reason="Tensorflow not installed")
+def test_synthesis(script_runner):
+    os.chdir(os.path.expanduser(tmp_dir.name))
+    in_t1 = os.path.join(get_home(), 'others',
+                         't1.nii.gz')
+    in_b0 = os.path.join(get_home(), 'processing',
+                         'b0_mean.nii.gz')
+
+    t1_img = nib.load(in_t1)
+    b0_img = nib.load(in_b0)
+    t1_data = t1_img.get_fdata()
+    b0_data = b0_img.get_fdata()
+    t1_data[t1_data > 0] = 1
+    b0_data[b0_data > 0] = 1
+    nib.save(nib.Nifti1Image(t1_data.astype(np.uint8), t1_img.affine),
+             't1_mask.nii.gz')
+    nib.save(nib.Nifti1Image(b0_data.astype(np.uint8), b0_img.affine),
+             'b0_mask.nii.gz')
+
+    ret = script_runner.run('scil_volume_b0_synthesis.py',
+                            in_t1, 't1_mask.nii.gz',
+                            in_b0, 'b0_mask.nii.gz',
+                            'b0_synthesized.nii.gz', '-v')
+    assert ret.success