@giemmecci I completely agree with you about the importance of this feature. In fact, just earlier today we discussed this topic with @wlongabaugh @spaquett and @george.white, and I am very happy you independently added another use case for justifying the effort to support more granular definition of the cohort and modification of the cohort.
To give you the background as to why we spend so much time discussing whether this is important, here are few points, and I will let other folks comment on this further:
- the concept of the portal is to support quick facet counting, and due to the limitations of the backend implementation on the size of the filter it can support. When we define the filter as a set of identifiers (at the series or study level), the filter will grow very big, and will push the limits. It is also my understanding that it may not be possible to combine facet selection with the cohort defined by a set of identifiers.
- there are storage implications maintaining large cohorts defined as lists (while cohort definition is very compact when defined as facet selection).
It is very attractive from developer’s standpoint to think that cohorts can always be defined by selecting certain facet values. But for anyone familiar with the imaging domain, this approach becomes very limiting very quickly.
Independently from supporting the ability to define cohort as a set of identifiers (and more specifically, at the level of
SOPInstanceUID granularity), I believe it is absolutely critical to be able to support persistence of cohorts at the level of identifiers to support reproducibility of analysis. Of course, the user defining the cohort can always maintain that final list of identifiers in BQ, but I think it is desirable to be able to maintain that list somewhere in IDC and not defer it to the user.
Would you be open at some point to join a meeting where we brainstorm the approaches (and limitations of those) related to granular definition of the cohort? I believe your voice and perspective could be very valuable.