DiffusionScheme-class: The DiffusionScheme class

In tractor.base: Read, Manipulate and Visualise Magnetic Resonance Images

The DiffusionScheme class

Description

This class represents a diffusion MRI acquisition scheme. It encapsulates a series of diffusion-weighted volume acquisitions, each with an associated diffusion-sensitising gradient direction, in one or more "shells" with a given weighting ("b-value").

Fields

bValues

A vector of b-values in seconds per square millimetre, one per volume acquired.

gradientDirections

A matrix of gradient directions, one row per volume acquired. Columns give the x, y and z components of the directions, relative to the image axes.

shellIndices

An integer vector giving the shell index associated with each volume. This is calculated internally and coded such that every volume with a b-value below unweightedThreshold gets an index of 0, and then others are grouped into shells with b-values differing by less than the relative tolerance specified (2 grouping is indicative only, and not stored in direction files.

shellValues

A vector of b-values associated with each shell. These are calculated as the mode of the assigned volume b-values in each case.

Methods

summarise()

Summarise key aspects of the object

tractor.base documentation built on Nov. 5, 2025, 6:18 p.m.