questions > Wrong output using dcm2niix with DWI images
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Sep 7, 2023  08:09 PM | María Torres
Wrong output using dcm2niix with DWI images

Hi experts, 


Hello experts,


I'm struggling with converting diffusion images from DICOM to NII format for data obtained from a Philips Intera MRI. The issue is that my bvec files are mostly zeros.


I get the following warnings: 


Warning: Volume number does not vary (0019,10A2; 0020,0100; 2005,1063; 2005,1413), assuming meaningful instance number (0020,0013).
Error: Check sorted order: 4D dataset has 34 volumes, but volume index ranges from 33..3960
Warning: Isotropic DWI series, all bvecs are zero (issue 405)
Warning: Volume 1 appears to be derived image ADC/Isotropic (non-zero b-value with zero vector length)


......


Warning: Saving 34 DTI gradients. Validate vectors (image slice orientation not reported, e.g. 2001,100B)


Any tips or guidance on this matter would be greatly appreciated.


Thanks in advance,


María José Torres


 

Sep 7, 2023  08:09 PM | Chris Rorden
RE: Wrong output using dcm2niix with DWI images

  1. I would ensure you are using the latest stable release of dcm2niix  v1.0.20230411 https://github.com/rordenlab/dcm2niix/re...
  2. You can find validation datasets for Philips DICOM images here:
    https://github.com/neurolabusc/dcm_qa_philips
  3. The warnings suggest some slices may be missing. I would try to export the DICOMs direct from your scanner before it has been touched by any PACS or anonymization tool to see if they are corrupting your data.
  4. I suggest you contact the Philips Clinical Scientist associated with your scanner. They can help guide you.