# How the tensor is stored in NRRD
**URL:** https://discourse.slicer.org/t/how-the-tensor-is-stored-in-nrrd/34084
**Category:** Support
**Tags:** dicom
**Created:** [February 1, 2024, 12:03pm UTC](https://discourse.slicer.org/t/how-the-tensor-is-stored-in-nrrd/34084 "2024-02-01T12:03:47Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@Yixun\_Liu](https://discourse.slicer.org/u/Yixun_Liu)
#### Post date: [February 1, 2024, 12:03pm UTC](https://discourse.slicer.org/t/how-the-tensor-is-stored-in-nrrd/34084/1 "2024-02-01T12:03:47Z")
Hi,
I use the 3DSlicer Diffusion module to load DWI, estimate its tensor and then store the tensor image into NRRD. I want to know how the tensor is stored in NRRD?
Is it stored as 6 upper triangle elements of the 3x3 tensor matrix or the lower triangle or others?
I also want to know which VTK class can be used to correctly load the tensor image?
Thanks.
Yixun
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### Author:  [@pieper](https://discourse.slicer.org/u/pieper)
#### Post date: [February 1, 2024, 3:36pm UTC](https://discourse.slicer.org/t/how-the-tensor-is-stored-in-nrrd/34084/2 "2024-02-01T15:36:36Z")
[https://teem.sourceforge.net/nrrd/format.html](https://teem.sourceforge.net/nrrd/format.html)
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### Author:  [@Yixun\_Liu](https://discourse.slicer.org/u/Yixun_Liu)
#### Post date: [February 6, 2024, 4:30am UTC](https://discourse.slicer.org/t/how-the-tensor-is-stored-in-nrrd/34084/3 "2024-02-06T04:30:45Z")
Thank you very much！