diff --git a/dmriprep/interfaces/reports.py b/dmriprep/interfaces/reports.py
index fecf8dd8..4842724e 100644
--- a/dmriprep/interfaces/reports.py
+++ b/dmriprep/interfaces/reports.py
@@ -35,7 +35,7 @@
\t\tSummary
\t\t
\t\t\t- Phase-encoding (PE) direction: {pe_direction}
-\t\t\t- Distinct shells: {shells_dist}
+\t\t\t- Shell distribution: {shell_dist}
\t\t
\t\t
"""
@@ -133,7 +133,7 @@ class DiffusionSummaryInputSpec(BaseInterfaceInputSpec):
pe_direction = traits.Enum(
None, "i", "i-", "j", "j-", "k", "k-", desc="Phase-encoding direction detected"
)
- shells_dist = traits.Dict(mandatory=True, desc="Number of distinct shells")
+ shell_dist = traits.Dict(mandatory=True, desc="Number of distinct shells")
class DiffusionSummary(SummaryInterface):
@@ -141,10 +141,14 @@ class DiffusionSummary(SummaryInterface):
def _generate_segment(self):
pe_direction = self.inputs.pe_direction
- shells_dist = self.inputs.shells_dist
+ shell_dist = self.inputs.shell_dist
+ shell_dist_text = ", ".join(
+ f"{shell_dist[key]} directions at b={key} s/mm\u00B2"
+ for key in shell_dist
+ )
return DIFFUSION_TEMPLATE.format(
- pe_direction=pe_direction, shells_dist=shells_dist
+ pe_direction=pe_direction, shell_dist=shell_dist_text
)
diff --git a/dmriprep/interfaces/vectors.py b/dmriprep/interfaces/vectors.py
index a3592087..b13d4bcb 100644
--- a/dmriprep/interfaces/vectors.py
+++ b/dmriprep/interfaces/vectors.py
@@ -20,6 +20,7 @@ class _CheckGradientTableInputSpec(BaseInterfaceInputSpec):
in_rasb = File(exists=True, xor=["in_bval", "in_bvec"])
b0_threshold = traits.Float(B0_THRESHOLD, usedefault=True)
bvec_norm_epsilon = traits.Float(BVEC_NORM_EPSILON, usedefault=True)
+ b_mag = traits.Int(None, usedefault=True)
b_scale = traits.Bool(True, usedefault=True)
@@ -30,7 +31,7 @@ class _CheckGradientTableOutputSpec(TraitedSpec):
full_sphere = traits.Bool()
pole = traits.Tuple(traits.Float, traits.Float, traits.Float)
num_shells = traits.Int
- shells_dist = traits.Dict
+ shell_dist = traits.Dict
b0_ixs = traits.List(traits.Int)
@@ -51,7 +52,7 @@ class CheckGradientTable(SimpleInterface):
True
>>> check.outputs.num_shells
3
- >>> check.outputs.shells_dist
+ >>> check.outputs.shell_dist
{0.0: 12, 1200.0: 32, 2500.0: 61}
>>> check = CheckGradientTable(
@@ -64,7 +65,7 @@ class CheckGradientTable(SimpleInterface):
True
>>> check.outputs.num_shells
3
- >>> check.outputs.shells_dist
+ >>> check.outputs.shell_dist
{0: 12, 1200: 32, 2500: 61}
>>> newrasb = np.loadtxt(check.outputs.out_rasb, skiprows=1)
>>> oldrasb = np.loadtxt(str(data_dir / 'dwi.tsv'), skiprows=1)
@@ -84,6 +85,7 @@ def _run_interface(self, runtime):
bvecs=_undefined(self.inputs, "in_bvec"),
bvals=_undefined(self.inputs, "in_bval"),
rasb_file=rasb_file,
+ b_mag=self.inputs.b_mag,
b_scale=self.inputs.b_scale,
bvec_norm_epsilon=self.inputs.bvec_norm_epsilon,
b0_threshold=self.inputs.b0_threshold,
@@ -92,7 +94,7 @@ def _run_interface(self, runtime):
self._results["pole"] = tuple(pole)
self._results["full_sphere"] = np.all(pole == 0.0)
self._results["num_shells"] = len(table.count_shells)
- self._results["shells_dist"] = table.count_shells
+ self._results["shell_dist"] = table.count_shells
self._results["b0_ixs"] = np.where(table.b0mask)[0].tolist()
cwd = Path(runtime.cwd).absolute()
diff --git a/dmriprep/utils/vectors.py b/dmriprep/utils/vectors.py
index 6eeb206c..c86479b1 100644
--- a/dmriprep/utils/vectors.py
+++ b/dmriprep/utils/vectors.py
@@ -17,6 +17,7 @@ class DiffusionGradientTable:
__slots__ = [
"_affine",
"_b0_thres",
+ "_b_mag",
"_b_scale",
"_bvals",
"_bvec_norm_epsilon",
@@ -30,6 +31,7 @@ class DiffusionGradientTable:
def __init__(
self,
b0_threshold=B0_THRESHOLD,
+ b_mag=None,
b_scale=True,
bvals=None,
bvec_norm_epsilon=BVEC_NORM_EPSILON,
@@ -46,12 +48,14 @@ def __init__(
----------
b0_threshold : :obj:`float`
The upper threshold to consider a low-b shell as :math:`b=0`.
+ b_mag : :obj:`int`
+ The order of magnitude to round the b-values.
b_scale : :obj:`bool`
Automatically scale the *b*-values with the norm of the corresponding
*b*-vectors before the latter are normalized.
bvals : str or os.pathlike or numpy.ndarray
File path of the b-values.
- b_vec_norm_epsilon : :obj:`float`
+ bvec_norm_epsilon : :obj:`float`
The minimum difference in the norm of two *b*-vectors to consider them different.
bvecs : str or os.pathlike or numpy.ndarray
File path of the b-vectors.
@@ -93,6 +97,7 @@ def __init__(
"""
self._affine = None
self._b0_thres = b0_threshold
+ self._b_mag = b_mag
self._b_scale = b_scale
self._bvals = None
self._bvec_norm_epsilon = bvec_norm_epsilon
@@ -195,6 +200,7 @@ def normalize(self):
self.bvals,
b0_threshold=self._b0_thres,
bvec_norm_epsilon=self._bvec_norm_epsilon,
+ b_mag=self._b_mag,
b_scale=self._b_scale,
raise_error=self._raise_inconsistent,
)
@@ -290,6 +296,7 @@ def normalize_gradients(
bvals,
b0_threshold=B0_THRESHOLD,
bvec_norm_epsilon=BVEC_NORM_EPSILON,
+ b_mag=None,
b_scale=True,
raise_error=False,
):
@@ -361,7 +368,7 @@ def normalize_gradients(
raise ValueError(msg)
config.loggers.cli.warning(msg)
- # Rescale b-vals if requested
+ # Rescale bvals if requested
if b_scale:
bvals[~b0s] *= np.linalg.norm(bvecs[~b0s], axis=1) ** 2
@@ -369,9 +376,17 @@ def normalize_gradients(
bvecs[b0s, :3] = np.zeros(3)
# Round bvals
- bvals = round_bvals(bvals)
+ bvals = round_bvals(bvals, bmag=b_mag)
- # Rescale b-vecs, skipping b0's, on the appropriate axis to unit-norm length.
+ # Ensure rounding bvals doesn't change the number of b0s
+ rounded_b0s = bvals == 0
+ if not np.all(b0s == rounded_b0s):
+ msg = f"Inconsistent b0s before ({b0s.sum()}) and after rounding ({rounded_b0s.sum()})."
+ if raise_error:
+ raise ValueError(msg)
+ config.loggers.cli.warning(msg)
+
+ # Rescale bvecs, skipping b0's, on the appropriate axis to unit-norm length.
bvecs[~b0s] /= np.linalg.norm(bvecs[~b0s], axis=1)[..., np.newaxis]
return bvecs, bvals.astype("uint16")
diff --git a/dmriprep/workflows/dwi/base.py b/dmriprep/workflows/dwi/base.py
index 180c2c0f..c0f9f841 100644
--- a/dmriprep/workflows/dwi/base.py
+++ b/dmriprep/workflows/dwi/base.py
@@ -161,7 +161,7 @@ def init_dwi_preproc_wf(dwi_file, has_fieldmap=False):
("in_bvec", "in_bvec"),
("in_bval", "in_bval")]),
(inputnode, dwi_reference_wf, [("dwi_file", "inputnode.dwi_file")]),
- (gradient_table, summary, [("shells_dist", "shells_dist")]),
+ (gradient_table, summary, [("shell_dist", "shell_dist")]),
(gradient_table, dwi_reference_wf, [("b0_ixs", "inputnode.b0_ixs")]),
(gradient_table, outputnode, [("out_rasb", "gradients_rasb")]),
])