# Slicer ACPC Transformation Instructions

**URL:** <https://discourse.slicer.org/t/slicer-acpc-transformation-instructions/16244>\
**Category:** Support\
**Tags:** mri\
**Created:** [February 26, 2021, 4:55pm UTC](https://discourse.slicer.org/t/slicer-acpc-transformation-instructions/16244 "2021-02-26T16:55:19Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![shebaelena](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/shebaelena/32/9708_2.png) [@shebaelena](https://discourse.slicer.org/u/shebaelena)\
**Post date:** [February 26, 2021, 4:55pm UTC](https://discourse.slicer.org/t/slicer-acpc-transformation-instructions/16244/1 "2021-02-26T16:55:19Z")

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1. Begin by opening the ACPC module in the upper left. Under the ‘Transform Panel’, create a new markups line.  

2. Use this line to define the posterior border of the anterior commissure as well as the anterior border of the posterior commissure in the axial slice. You will need to toggle between slices before you place the second point to do this. Verify in the sagittal slice that this line is accurate. 

3. To create the midline, select ‘Create New MarkupsFiducial’ from the dropdown. 

4. Under output transform, select ‘Create New Transform,’ and then Apply.  
 ![Screen Shot 2021-02-26 at 11.47.56 AM](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/5/1/519fcd27efe4da24074c0018d1dd11aa50719ed6.png)

5. Open ‘Data’ in the dropdown to navigate to the Subject hierarchy. ![Screen Shot 2021-02-26 at 11.49.14 AM](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/a/0/a035de08f916158717739b919fe2763f69cdb620.png)

6. Right click on the grid along your original MRI scan and select ‘Output transform’. Then, reselect this same scan, and select ‘Harden transform’.  

You have now completed your AC-PC transformation!

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<div class="post-metadata">

**Author:** ![lassoan](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/lassoan/32/13_2.png) [@lassoan](https://discourse.slicer.org/u/lassoan)\
**Post date:** [February 28, 2021, 3:18pm UTC](https://discourse.slicer.org/t/slicer-acpc-transformation-instructions/16244/2 "2021-02-28T15:18:06Z")

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A post was merged into an existing topic: [ACPC Transform for MRI scans- Slicer 4.11](https://discourse.slicer.org/t/acpc-transform-for-mri-scans-slicer-4-11/15762)

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<div class="post-metadata">

**Author:** ![lassoan](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/lassoan/32/13_2.png) [@lassoan](https://discourse.slicer.org/u/lassoan)\
**Post date:** [February 28, 2021, 3:18pm UTC](https://discourse.slicer.org/t/slicer-acpc-transformation-instructions/16244/3 "2021-02-28T15:18:06Z")

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