You can do your own Google search to learn more about these brain imaging technologies.  I would particularly recommend searching Google Images so you can see some of the scans and equipment.

The following sites will help you get started:

CT/ CAT Scan: Computed Tomography, from Radiology Info

EEG – Electroencephalogram, from the National Institutes of Health (USA)

ESB – Electrical Stimulation of the Brain, from Find Articles

fMRI – Functional Magnetic Resonance Imaging, from the Oxford Centre for Functional Magnetic Resonance Imaging of the Brain

MRI – Magnetic Resonance Imaging, from webMD

PET – Positron Emission Tomography, from webMD

Video:  TED Talk:  a look inside the brain