# Intracranial 4D Flow MRI...Getting unknown error

**URL:** <https://discourse.slicer.org/t/intracranial-4d-flow-mri-getting-unknown-error/39481>\
**Category:** Support\
**Created:** [October 1, 2024, 10:32pm UTC](https://discourse.slicer.org/t/intracranial-4d-flow-mri-getting-unknown-error/39481 "2024-10-01T22:32:13Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![sannpeterson](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/sannpeterson/32/10892_2.png) [@sannpeterson](https://discourse.slicer.org/u/sannpeterson)\
**Post date:** [October 1, 2024, 10:32pm UTC](https://discourse.slicer.org/t/intracranial-4d-flow-mri-getting-unknown-error/39481/1 "2024-10-01T22:32:13Z")

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I’ve been using Siemens’ WIP (work-in-progress) 4D Flow MRI sequence for the past few months, and I’ve encountered an occasional issue. In 3 out of 20 cardiac phases, there is a complete reversal of flow in all vessels across the image, in every direction. Left-to-right flow appears as right-to-left, anterior-to-posterior shows as posterior-to-anterior, and so on. I haven’t been able to identify the cause of this anomaly. I’ve been scanning both the brain and chest, but this problem only occurs in some of the brain scans, despite using an adequate venc setting. Both Siemens and our techs suspect aliasing, but the issue seems different from typical aliasing artifacts. I’ve also attempted phase unwrapping with various commercial software, but it hasn’t resolved the problem.

Hoping for some insight as well as possible fixes. Tysm!

[link to dicom](https://we.tl/t-ZWak9F2eU1)

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**Author:** ![pieper](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/pieper/32/8_2.png) [@pieper](https://discourse.slicer.org/u/pieper)\
**Post date:** [October 4, 2024, 6:12pm UTC](https://discourse.slicer.org/t/intracranial-4d-flow-mri-getting-unknown-error/39481/2 "2024-10-04T18:12:39Z")

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How are you loading this data? It’s not loading as a sequence for me (maybe due to anonymization).

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**Author:** ![sannpeterson](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/sannpeterson/32/10892_2.png) [@sannpeterson](https://discourse.slicer.org/u/sannpeterson)\
**Post date:** [October 18, 2024, 6:27pm UTC](https://discourse.slicer.org/t/intracranial-4d-flow-mri-getting-unknown-error/39481/3 "2024-10-18T18:27:54Z")

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> [@pieper](#):
>
> ? It’s not loading as a sequence for me (maybe due to an

I’m using a 4d flow analysis software. I normally don’t anonymize it before importing into the software but I did to share the dataset.