I successfully registered MRI and CT, with minimal error, using a linear rigid registration after manually transforming the images. However, is there a way to localize electrodes using the newly registered CT image? I'd like to save the images in their original DICOM format, yet when the registration is finished, the matrix file saves, and I can't find an option to save or export the registered image. Can I apply the .matr file at a later point, perhaps in a different viewer? Additionally, after using the electrode editor to localize electrodes in a CT image (DICOM format), I'd like to use the .mgrid file (the saved electrode grid), to visualize on the registered MRI (DICOM) image. So all in all, I'm looking for a way to visualize electrodes on a registered MRI image, using the reference CT. 

thanks for any ideas!