Question
Question Posted 04/20/26:
Dear ADNI team,
I am working with the ADNI-4 multi-shell diffusion MRI dataset (MSV21, Siemens Prisma), including both AP and PA acquisitions.
I would like to obtain the diffusion timing parameters, specifically the gradient duration (δ) and pulse separation / diffusion time (Δ) used in these acquisitions.
These parameters do not appear to be available in the DICOM headers (including CSA fields), and they are not specified in the ADNI protocol documentation.
For Siemens scanners, these values can typically be found in the diffusion sequence settings (e.g., by hovering over the “monopolar” diffusion gradient option in the sequence UI).
Could you please confirm exact values of these values?
Any clarification or reference documentation would be greatly appreciated.
Thank you for your help!
Best,
Hansol Lee
Dear ADNI team,
I am working with the ADNI-4 multi-shell diffusion MRI dataset (MSV21, Siemens Prisma), including both AP and PA acquisitions.
I would like to obtain the diffusion timing parameters, specifically the gradient duration (δ) and pulse separation / diffusion time (Δ) used in these acquisitions.
These parameters do not appear to be available in the DICOM headers (including CSA fields), and they are not specified in the ADNI protocol documentation.
For Siemens scanners, these values can typically be found in the diffusion sequence settings (e.g., by hovering over the “monopolar” diffusion gradient option in the sequence UI).
Could you please confirm exact values of these values?
Any clarification or reference documentation would be greatly appreciated.
Thank you for your help!
Best,
Hansol Lee
Response posted 04/20/26 by Rob Reid:
Hello, we have not been able to find them either except by using the method you described. I think you are the first to ask about them on the Ask The Experts page, though.
For a Prisma with the 127 volume protocol Delta is 34.6ms, and delta is 12.9ms.
For a Prisma with the 127 volume protocol Delta is 34.6ms, and delta is 12.9ms.
