How is it handled if a user specifically wants to calculate a new concentration image, i.e. when testing different conversion methods or a varying number of baseline images? This should be taken into account when setting up the rules when a new concentration image is generated.
This point should kept in mind also for refactoring of the signal concentration conversion in task https://phabricator.mitk.org/T27128 . If the concentration images would be generated only in a separate plugin, they would not have to be generated at all in the DCE MRI Datafit View.

This is why I proposed rules. More precisely:

1. one would derive from SourceImageRelationRule.
2. And then one can encode different conversion strategies or their configuration in the PurposeTag of the rule. So can always search for the availablity of the right Concentration Node.
3. To standardize the purpose definition one would implement for all currently known conversion strategies a create helper function; e.g.:

namespace mitk
{
  ConcentrationImageRelationRule::Pointer CreateTurboFlashConcentrationRule(double recoveryTime);
  ConcentrationImageRelationRule::Pointer CreateRelativeConcentrationRule();
}

Or we derive special sub classes for each conversion strategie from ConcentrationImageRelationRule. Might be even better...

This would address all your points. It is the same way how it is done in the new statistics infrastucture.