Getting all custom variables for a custom variable (API)

How can i get a list of all the custom variables of an other custom variable?

I’ve got a visit scope UserId custom variable
And a page scope ImageId custom variable

How do i get a list of all the page scope custom variables for a visit scope custom variable
In other words how can i get the ImageIds visited by UserId?

Thanks in advance,

Not possible (yet) to get this automatically, but one could build a plugin for it.

is this not possible with the API?
What exactly do you mean by plugin? the call to the API comes from a web application, so i can create multiple API calls to get what I need.