how to determine the pre-contrast and post-contrast through series time, acquisition time and content time in DCE-MRI dicom images

I was studying the DCE-MRI image on Multi-center breast DCE-MRI data and segmentations from patients in the I-SPY 1/ACRIN 6657 trials (ISPY1) - The Cancer Imaging Archive (TCIA) Public Access - Cancer Imaging Archive Wiki

It seems that they have pre-contrast, early post-contrast, and late post-contrast images, all of which are stored in the same DICOM series or multiple folders. However, I cannot determine which image is pre-contrast and which ones are post-contrast. In the DICOM tags, I found four time-related tags: study time, series time, acquisition time, and content time. I assume that the series time indicates the time when the pre-contrast image was collected. So, how can I determine which series belongs to pre-contrast and which series belongs to post-contrast using these time tags?

Determining this info is not always straightforward, and for older DICOM data (the data in the ISPY1 study is from 1980s) it can be non-standard. The TCIA does a great job of including supporting documentation. The link you sent has a link to the Study Protocol and it states that
“multiple quantitative parameters are extracted for estimation of
tumor volume and parameters related to contrast kinetics: initial percent
enhancement, PE = (S1-S0)/S0, and signal enhancement ratio (SER)=(S1-S0)/(S2-
S0), where S0, S1 and S2 are the pre-contrast, first post-contrast and second-post
contrast signal intensities of the three time-point data acquisition.27”

Looking through the dicom data, for each patient there is DICOM series labeled
It contains all three time points, in sequence. It has 180 time-sequential slices representing 3 passes over the breast. These are the S0, S1, and S2 images described in the study. You can view the data using this link.

There are then two secondary/derived series:
Dynamic-3dfgre: PE1
These were computed as defined in the study protocol.

I haven’t verified, but the acquisition time for each of the DICOM objects (slices) in the Dynamic-3dfgre series should allow you to differentiate S0 from S1 from S2.

Hope that helps.

Great. Though some error exists, for instance, 095917 and 095918 for the acquisition time of one pre-contrast series. But Seems like the acquisition time is the only information to differentiate this. Cannot find other related tags.Thank you so much for your help.