How to get spatial coordinate information of an anatomical structure?

[yiyang]

Hello,

I am using a script to place some electric dipoles within some structures in an anatomical model, e.g., the gastrointestinal (GI) tract (stomach, small intestine, etc.). The question is how can I get the coordinates of the space occupied by the model of the GI tract, or in other words, how can I verify that the electric dipoles I place are inside the tissue of the GI tract? Thanks for your help!