# What's wrong with my DWI? Failed to convert from DWI to tensors

**URL:** <https://discourse.slicer.org/t/whats-wrong-with-my-dwi-failed-to-convert-from-dwi-to-tensors/26864>\
**Category:** Support\
**Tags:** diffusion, tractography, dwi\
**Created:** [December 21, 2022, 1:49am UTC](https://discourse.slicer.org/t/whats-wrong-with-my-dwi-failed-to-convert-from-dwi-to-tensors/26864 "2022-12-21T01:49:53Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![peter\_adidharma](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/peter_adidharma/32/10407_2.png) [@peter\_adidharma](https://discourse.slicer.org/u/peter_adidharma)\
**Post date:** [December 21, 2022, 1:49am UTC](https://discourse.slicer.org/t/whats-wrong-with-my-dwi-failed-to-convert-from-dwi-to-tensors/26864/1 "2022-12-21T01:49:53Z")

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Hi all,

I’ve been working to do some tractography using slicerDMRI, but seems to encounter the same problem with all DWI files that i have as i failed to convert it to tensors. Here, I attached the .nrrd file of our DWI.

> **[dwi.nrrd](https://www.dropbox.com/s/5uk42u9c3itt8ls/dwi.nrrd?dl=0)**
>
> Shared with Dropbox

Can anyone point out whats wrong with my DWI?

Really appreciate your help.

Regards,  
Peter

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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:** [December 21, 2022, 4:53pm UTC](https://discourse.slicer.org/t/whats-wrong-with-my-dwi-failed-to-convert-from-dwi-to-tensors/26864/2 "2022-12-21T16:53:45Z")

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If you look at the header you can see that there’s only one volume (a baseline, with gradient 0,0,0). For tractography you typically need dozens of gradients at different angles.

```plaintext
# Complete NRRD file format specification at:
# http://teem.sourceforge.net/nrrd/format.html
type: short
dimension: 3
space: right-anterior-superior
sizes: 160 160 25
space directions: (-1.3536703538588315,-0.23908993262719125,0.032211445171427509) (0.24112542786612504,-1.3467566568679989,0.13685771888390255) (0.029318512241917394,0.53090466025518757,5.1727440171111505)
kinds: domain domain domain
endian: little
encoding: gzip
space origin: (99.988388696114995,105.71384036457,-55.297402783850025)
measurement frame: (-1,0,0) (0,-1,0) (0,0,1)
DICOM_0008_0060_Modality:=MR
DICOM_0008_0070_Manufacturer:=SIEMENS
DICOM_0008_1090_ManufacturerModelName:=Skyra
DICOM_0018_0022_ScanOptions:=FS
DICOM_0018_0023_MRAcquisitionType:=2D
DICOM_0018_0080_RepetitionTime:=5500
DICOM_0018_0081_EchoTime:=64
DICOM_0018_0083_NumberOfAverages:=1
DICOM_0018_0087_MagneticFieldStrength:=3
DICOM_0018_1020_SoftwareVersions:=syngo MR E11
DICOM_0018_1314_FlipAngle:=180
DWMRI_b-value:=0
DWMRI_gradient_0000:=0 0 0
modality:=DWMRI

```

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<div class="post-metadata">

**Author:** ![peter\_adidharma](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/peter_adidharma/32/10407_2.png) [@peter\_adidharma](https://discourse.slicer.org/u/peter_adidharma)\
**Post date:** [December 22, 2022, 4:38am UTC](https://discourse.slicer.org/t/whats-wrong-with-my-dwi-failed-to-convert-from-dwi-to-tensors/26864/3 "2022-12-22T04:38:47Z")

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Thank you for the reply. Do you have any suggestion on what to change in the process of doing the MRI?

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<div class="post-metadata">

**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:** [December 22, 2022, 1:40pm UTC](https://discourse.slicer.org/t/whats-wrong-with-my-dwi-failed-to-convert-from-dwi-to-tensors/26864/4 "2022-12-22T13:40:38Z")

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Acquiring diffusion MRI in a form compatible with tractography is a complex process, and the detail vary a lot by scanner type. Generally speaking you would want dozens of gradient directions and usually there will be a standard sequence from the scanner vendor the provides good results.