Hi all. I have a question regarding the times stored in a DICOM header of a functional.
I have four times in my header (with examples of values of one of my participants):
Study time: 140626.322000
Series time: 152514.303000
Acquisition time: 152454.345000
Content time: 152514.306000
What do the different times mean exactly?
I guess study time is the beginning of the whole scanning session (this stays the same in all of my runs). But how do series and acquisition time differ?
Which of those times relates to my first volume being scanned?
Thanks a lot!
You can find the DICOM standard here.
The participant comes to the scanner
- patient loaded and study starts: this is the StudyTime (0008,0030).
- Every time a series starts (T1 scan, T2 scan, fMRI run) all subsequent images of the series use the same series time (0008,0031)
- In theory, acquisition time (0008,0032) refers to the start of acquisition of 2D image, e.g. for a EPI fMRI dataset this would refer to the start of acquisition for the slice. Be aware that not all manufacturers record this with precision, and for some systems it may not even reveal actual slice order. You need to work with your vendor to understand what this value means.
- When a new DICOM file is created (for fMRI, this is after reconstruction) a Content Time stamp is generated.
Thank you very much
So in an EPI fMRI dataset the “acquisition time” I get in my header should roughly relate to the first slice that was scanned, correct?
Depends on the manufacturer and scanner software version. In my experience, this is not a reliable tag, but for your equipment it might work.