Incorporate sliceband in oxford_asl call for multiband ASL

[tsalo]

Closes #536.

Changes proposed in this pull request

• For multiband ASL data, determine if slice times within bands are monotonically increasing. If so, pass the slice spacing and multiband factor to BASIL.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 76.08%. Comparing base (5bbe278) to head (7269326).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #548      +/-   ##
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+ Coverage   75.91%   76.08%   +0.17%     
==========================================
  Files          38       38              
  Lines        4082     4107      +25     
==========================================
+ Hits         3099     3125      +26     
+ Misses        983      982       -1     

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[tsalo]

@tientong98 the two ruff commands I use are:

pipx run ruff format .
pipx run ruff check . --fix

[tsalo]

Just a couple of very minor suggestions.

[Copilot]

Pull Request Overview

This PR refactors slice-timing handling for multiband ASL by extracting it into a utility and wiring slice-spacing and multiband factors into the BASIL interface.

• Extract inline slice-timing logic into prepare_basil_kwargs
• Update the ASL workflow to call prepare_basil_kwargs(metadata)
• Extend BASILCBF interface with a sliceband input trait

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
aslprep/workflows/asl/cbf.py	Replaced inline slice-timing code with a call to prepare_basil_kwargs
aslprep/utils/asl.py	Added prepare_basil_kwargs to compute slice_spacing and sliceband
aslprep/tests/test_utils_asl.py	Added parametrized tests for prepare_basil_kwargs
aslprep/interfaces/cbf.py	Introduced sliceband trait to _BASILCBFInputSpec

Comments suppressed due to low confidence (2)

aslprep/utils/asl.py:314

• The code references np but the module does not import NumPy. Add import numpy as np at the top of this file to avoid a NameError.

slicetime_diffs = np.unique(np.round(np.diff(band_slice_times), 10))

aslprep/utils/asl.py:347

• The returned key slice_spacing does not match the _BASILCBFInputSpec trait slicedt. Rename the key to slicedt (or map it before passing) so that the value is correctly applied to the interface.

return basil_kwargs

[aptinis]

Reading the docs I think the interpretation of sliceband is the number of slices in each band and not the MB factor.

[tsalo]

The changes look good to me, but since I created the PR I can't review it.