Cord Follow-Up

The Cord Follow-Up tool can estimate the change in spinal cord atrophy between two time-points. The Cord Follow-Up tool first straightens the cord, then co-registers straightened cord images from the two time-points in a half-way registration space, and performs cord outlining for each of the two time-points in this registered space. The tool performs the analysis twice: once by registering the second time-point to the first, and then again by registering the first time-point to the second. This is done to reduce bias in the registration process. As an aid to visualising the results, the half-way registered straightened cord images are written to disk, together with the corresponding cord outline ROI files.

By default, the registered straightened cord images are only output for the forward registration direction (second time-point registered to the first), although there is an option to output registered images for both directions.

Start the Cord Follow-Up tool from the Toolkits menu: Launching the Cord Uollow-Up tool.

The Cord Follow-Up tool will now appear as shown below:

The spinal cord follow-up tool

Note that the ROI Toolkit also pops up when you start the Cord Follow-Up.

You can assess the change in spinal cord atrophy between two time-points in a similar way that you assess cord cross-sectional areas for individual scans. Prepare the images at each time-point as you would for the Cord Finder tool.

The cord cross-sectional areas will now be assessed, along with the change in area as a measure of progressive cord atrophy. Depending on the extent of the spinal cord segment being evaluated and the speed of your computer, processing will take around 20 minutes. When complete, you will see the results in a dialog like the one below:

Typical results from the spinal cord follow-up tool

This shows: You can create a more detailed report by clicking on the text_report_button button (to a get a report in text format) or the pdf_report_button button to get a report in PDF format. Click the dismiss_button button if you do not want a detailed report.

As well as the results above, a report will detail the the cross-sectional areas at regular intervals (in steps equal to the original slice thickness) down the cord, for both time-points, and produce a graph showing the same. The cross-sectional areas are measured in a plane that is perpendicular to the local cord centre-line.

Also produced are two straightened images of the cord, registered to their half-way location; these will have the same names as the input images but with the name prefixed by "hw" (half-way). The cord outlines are saved to ROI files with names taken from the input image name but prefixed by "hw", and suffixed by "_cord.roi".

Below are images of the cord acquired 1 year apart, with the cord registered to the half-way location, and with the cord outline ROIs loaded.

Half-way registered cord at baseline Half-way registered cord at 1 year follow-up

Baseline cervical cord and segmentation

1 year follow-up cervical cord and segmentation

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