# 4DCT registration - Hierarchical 3D Registration not recognizing "Sequence"

**URL:** <https://discourse.slicer.org/t/4dct-registration-hierarchical-3d-registration-not-recognizing-sequence/46026>\
**Category:** SlicerAutoscoperM\
**Created:** [February 1, 2026, 6:38pm UTC](https://discourse.slicer.org/t/4dct-registration-hierarchical-3d-registration-not-recognizing-sequence/46026 "2026-02-01T18:38:30Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![taylor\_t](https://avatars.discourse-cdn.com/v4/letter/t/e274bd/32.png) [@taylor\_t](https://discourse.slicer.org/u/taylor_t)\
**Post date:** [February 1, 2026, 6:38pm UTC](https://discourse.slicer.org/t/4dct-registration-hierarchical-3d-registration-not-recognizing-sequence/46026/1 "2026-02-01T18:38:30Z")

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I am trying to process 4DCT data using SlicerAutoscoper. I was able to load in the static CT images (Bone Thins Knee Bilateral), perform segmentations and export as STL files, and load in the 4D CT dynamic data (4D Knee\_1).

 ![image](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/2/4/24b9b1a07ee637a0c40626563fd5aa45646fece9.png)

When I try to register using “Hierarchical3DRegistration”, the dynamic image files are not being recognized as a sequence. When I try to use the dropdown next to “Input CT Sequence", the list is empty.

 ![image](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/6/5/650e98b51df2e9c8b52ed66f83a052b1908c943f.png)

I am wondering whether there are any pre-processing steps I need on the imported DICOM files for recognition as a sequence or conversion to .seq?

Thank you for your help.