Find AIF Voxels

Node Icon

Description

This node identifies candidate voxels that best represent the Arterial Input Function (AIF) in Dynamic Contrast-Enhanced MRI (DCE-MRI) data. The AIF is a crucial parameter in perfusion analysis as it describes how the contrast agent concentration evolves over time in arterial blood.

To find suitable AIF voxels, this node compares the enhancement time curves of all voxels to a predefined template AIF (either a standard Parker AIF or a user-provided custom AIF). It performs an inner product computation between the enhancement curves and the template AIF to quantify similarity. The top-ranked voxels based on this similarity measure are selected as AIF candidates.

Additionally, a Bolus Arrival Time (BAT) input should be provided to improve accuracy by referencing the time when contrast agent first arrives in the bloodstream. The BAT is used to define the duration of the baseline where no enhancement is occuring. Providing a BAT lower than the actual value is fine. Very few datapoints before the speciefied BAT may lead to less accurate results. An optional Mask input can be used to restrict the search area for AIF voxels to a specific region of interest.

The output of this node is a binary mask where selected AIF voxels are marked.

Inputs

Time Series

Time series image containing signal enhancement over time.

Type: Image, Required, Single

BAT

Bolus arrival time for reference in AIF extraction.

Type: Numeric Array, Required, Single

Mask

Optional mask to restrict AIF voxel selection.

Type: Mask, Optional, Single

Template AIF

Custom AIF, exposed only if that option is selected.

Type: Table, Single

Outputs

AIF Voxels

A binary mask highlighting the identified AIF voxels.

Type: Mask

Settings

Template AIF Selection

Select the template AIF used for voxel comparison. Custom AIF will expose an input for the custom template AIF.

Values: Parker Standard AIF, Custom AIF

Number of Voxels Integer

Number of voxels to select as AIF candidates.