MRI Studio Forum » DTI Studio

questions about Gradient vectors

(6 posts)
  • Started 7 years ago by wayne_qin
  • Latest reply from christineb1979
  1. wayne_qin
    Member

    Hello, every one. I encounter a question about the gradient vetors. The individual vectors extracted from the DICOM data seem some what different with the standard vectors provided by company. I have tried to use them to calculate the diffusion indices such as FA and MD,respectively. Diversities ranging from 0.5% to 5% were also manifested. My question are: what's the reason and which is best for the tensor calculation?
    Thanks!

    Posted 7 years ago #
  2. JHMI_Hangyi
    Member

    use the gradients from DICOM.

    Posted 7 years ago #
  3. wayne_qin
    Member

    Thanks! But in practice, standard gradients by compamies were more popular; furthermore, if we use gradients from DICOM, batch processing will difficult to be performed. How to make a resonable option?

    Posted 7 years ago #
  4. JHMI_Hangyi
    Member

    usually, "the standard vectors provided by company" is defined in scanner's coordinate system (or world-system, or physical system). since the image matrix is not always aligned with the scanner, the real-gradients (used for tensor calculation) applied to the patient should be adjusted according to oblique (or tilt) angle between the patient and scanner. usually, DICOM will save the oblique angles in the file header, and some DICOM files also save the adjusted gradients. if so, it is a better practice to use the adjusted gradients. or, if using DtiStudio, you can enable "adjusting the gradients if applicable" option (for DICOM files) with the original gradients. then the program will take care this issue.

    Posted 7 years ago #
  5. wayne_qin
    Member

    Thank you!

    Posted 7 years ago #
  6. christineb1979
    Member

    Thanks for this... i will try to use this...

    Posted 7 years ago #

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