nifreeze.analysis.motion module

Motion analysis.

nifreeze.analysis.motion.compute_percentage_change(reference: ndarray, test: ndarray, mask: ndarray) → ndarray

Compute motion change between reference and test as a percentage.

If a mask is provided, the computation is only provided within the mask. Also, null values are ignored.

Parameters:

• reference (ndarray) – Reference imaging volume.

• test (ndarray) – Test (shifted) imaging volume.

• mask (ndarray) – Mask for value consideration.

Returns:

rel_diff – Motion change between reference and test.

Return type:

ndarray

nifreeze.analysis.motion.identify_spikes(fd: ndarray, threshold: float = 2.0)

Identify motion spikes in framewise displacement data.

Identifies high-motion frames as timepoint exceeding a given threshold value based on z-score normalized framewise displacement (FD) values.

Parameters:

• fd (ndarray) – Framewise displacement data.

• threshold (float, optional) – Threshold value to determine motion spikes.

Returns:

• indices (ndarray) – Indices of identified motion spikes.

• mask (ndarray) – Mask of identified motion spikes.