Phase encoding direction

[syunchoi]

Hi,

I am using the dcm2niix command to convert dwi dcm to nifti file, and I'm having trouble with phase encoding direction.
I'm sure my data is L->R direction because I set the phase encoding parameter as L->R. However, when I use dcm2niix and check json file, the phase encoding direction is in 'j', which makes me confused because I think 'j' indicates 'AP' and not 'LR'.
Below is some fo the information of dicom image header. Also, MSMA is in S(R>>L)-C(A>>P)-T(F>>H).
It would be great if anyone could help me with this issue.

Thank you

(0018, 0020) Scanning Sequence CS: 'EP'

(0018, 0025) Angio Flag CS: 'N'
(0018, 0050) Slice Thickness DS: '2.2999999523163'
(0018, 0080) Repetition Time DS: '3200.0'
(0018, 0081) Echo Time DS: '110.0'
(0018, 0083) Number of Averages DS: '1.0'
(0018, 0084) Imaging Frequency DS: '123.177387'
(0018, 0085) Imaged Nucleus SH: '1H'
(0018, 0086) Echo Number(s) IS: '1'
(0018, 0087) Magnetic Field Strength DS: '3.0'
(0018, 0088) Spacing Between Slices DS: '2.299999961907'
(0018, 0089) Number of Phase Encoding Steps IS: '83'
(0018, 0091) Echo Train Length IS: '1'
(0018, 0093) Percent Sampling DS: '100.0'
(0018, 0094) Percent Phase Field of View DS: '100.0'
(0018, 0095) Pixel Bandwidth DS: '1299.0'
(0018, 1000) Device Serial Number LO: '35422'
(0018, 1020) Software Versions LO: 'syngo MR B19'
(0018, 1030) Protocol Name LO: 'DTI_BLIP_LR'
(0018, 1251) Transmit Coil Name SH: 'Body'
(0018, 1310) Acquisition Matrix US: [110, 0, 0, 110]
(0018, 1312) In-plane Phase Encoding Direction CS: 'COL'
(0018, 1314) Flip Angle DS: '90.0'
(0018, 1315) Variable Flip Angle Flag CS: 'N'
(0018, 1316) SAR DS: '0.20510281195378'
(0018, 1318) dB/dt DS: '0.0'
(0018, 5100) Patient Position CS: 'HFS'

(0051, 100b) [AcquisitionMatrixText] LO: '110p110'
(0051, 100c) [Unknown] LO: 'FoV 23032303'
(0051, 100e) [Unknown] LO: 'Tra>Cor(-8.2)>Sag(-1.9)'

[neurolabusc]

Feel free to share your images with my institutional email. For Siemens V* EPI axial acquisitions saved as mosaics we typically expect 0018,1312 to be COL for A>>P and P>>A while [ ROW for L>>R and R>>L. There was a long-standing bug with Siemens consoles that using Copy References would cause a 90-degree flip on phase encoding polarities where a 180 degree reversal was specified. You may want to contact your sites Siemens Research Collaboration Manager for more insight.

[neurolabusc]

Closing: dcm2niix handles validation datasets correctly. Without seeing an example dataset, it is unclear if the root cause for this issue.