Transformation to just one of the items in iterfield in MapNode


I ve just started to use nipype to perform my preprocessing pipelines and therefore am still trying to understand the syntax and how it works.

My question has to do with the application a specific transformation to just one of items of the iterfield in a MapNode. Imagine that I have a number of different images and as I want to apply a BET transformation to all of them, I pass them to ‘in_file’ as a iterfield in a MapNode. Before passing all these images to a further node, If I wanted to perform a specific transformation to just one of these BET transformed images, how could I do it? Is there any way to pass to a Node just one element of the list in the iterfield in a MapNode and then merge this result with the rest of the iterfield items?