Can I measure the volume of white matter, hippocampus, pituitary and grey matter?
I think you can do the segmentation of the areas that you’re interested and then segment statistics module for measure the volume.
How? Can you show me?
You can use grow from seeds tool in the Segment editor module (ex: Brain segmentation in 3D Slicer via mask scalar volume (youtube.com)). And after having the final segmentation, you can calculate the volume of each segment (ex: Segment statistics - new module in 3D Slicer - YouTube)