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Feb 11, 2026  06:02 PM | Jose Raniery
DTI Phase Encoding Direction

Hello,


I am currently trying to use ARTS with my dataset, and I noticed that the script expects the DTI Phase Encoding Direction to be specified simply as either vertical or horizontal.


This terminology is confusing from an MR neuroimaging perspective, since phase encoding is usually defined either in image space (ROW/COL, i/j axes) or in anatomical space (AP/PA, LR/RL, SI/IS), rather than vertical/horizontal. 


In my dataset, the metadata shows for example "PhaseEncodingAxis": "j" and "InPlanePhaseEncodingDirectionDICOM": "COL". By conventions, this corresponds to the column direction (j axis), which in image space is the column axis, but depending on viewer orientation and world-coordinate mapping, this may appear visually vertical or horizontal.


So how can I set phase encoding safely as vertical or horizontal?


Thank you very much for your time.


Cheers,


Raniery

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Feb 12, 2026  04:02 PM | Konstantinos Arfanakis - Illinois Institute of Technology
RE: DTI Phase Encoding Direction
Dear Jose,

 

The ‘horizontal' and ‘vertical' terminology is exclusive to the TORTOISE software that is used inside ARTS. Based on our experience, the data should be processed with 'vertical'. We recommend that the processed diffusion data is checked to see if the distortions are corrected. We believe that 'horizontal' and 'vertical' correspond to 'row' and 'column' in image space, respectively. 

 

Regards,

Konstantinos

 
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Feb 17, 2026  02:02 PM | Jose Raniery
RE: DTI Phase Encoding Direction

Dear Dr. Arfanakis,


 

Thank you very much for your prompt response.

I will check the output using 'vertical' then.

 

Best,
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