Access to List of Segmented Organs

I needed access to the list so I could use the index related to the name of the organ of interest to set it as an input parameter for the “Mask Scalar Volume” module, specifically as the value of the Label Map to use in creating a new node. However, I might be able to work around this and solve it differently.

The aspect I need the most at the moment is the one discussed in this other topic:

I would be very grateful for any help with this!
Thanks a lot!