Arterial spin labelling (ASL) analysis

Two ASL analysis methods are supported:

• Pseudo-continuous ASL (pCASL)
• Pulsed ASL (PASL - QIPPS II)

The module provides different approaches for quantitative ASL analysis, and a flexible interface for specifying ASL-related parameters and for outlier-detection and elimination.

To start the ASL module a compatible ASL dataset, containing multiple series of label and control images should be selected in the main window. Additionally, a reference (Mo) series can be specified for quantitative perfusion analysis.

The main ASL interface appears as follows:

How to do ASL analysis:

1. Open the ASL input data and start the module.

2. In the Parameters tab, check that image order is correctly detected: The program will attempt to automatically detect the image and slice order, and will display the resulting image.

3. Check that parameters are correct and correspond to the input data.

4. Set labelling method.

5. Check that processing settings are set correctly. Do motion correction, if required.

6. For quantitative analysis:

I. Open the M0 series.

II. Select the M0 image specification and drag the M0 image into the window (note that coregistration should be done).

III. Specify parameters and options.

7. Hit Create perfusion maps. This will produce a blood flow map.

The left part of the window will show a preview of the perfusion image.

Note: ASL can be done with or without including an M0 image (e.g. quantitative or qualitative analysis). When a M0 image is added, the Mean of current slice unit will change from arbitrary units to [mL/100g/min].

Note that correct sorting of the label/control series is essential for correct analysis. This can be set from the “Input Data” parameters where image and slice order are defined: The left image below shows correct setting of image and the right shows incorrect setting of slice order. The preview image is automatically updated when changing these settings for easy identification of correct and incorrect settings.

Read more details about the ASL analysis in the links below.

Subtopics in this section:

Process
Parameters
Quantitative analysis