Angiogram—X-ray of head with dye present in cerebral blood vessels Computerized axial tomography (CAT or CT)—a measure of X-ray absorption at several positions around the head, maps tissue density Computerized axial tomography (CAT or CT)—a measure of X-ray absorption at several positions around the head, maps tissue density

Magnetic resonance imaging (MRI) gives higher resolution images in three steps: Strong magnets cause protons in brain tissue to line up in parallel. A pulse of radio waves knocks protons over. Protons reconfigure themselves, emitting radio waves that differ by tissue density. Magnetic resonance imaging (MRI) gives higher resolution images in three steps: Strong magnets cause protons in brain tissue to line up in parallel. A pulse of radio waves knocks protons over. Protons reconfigure themselves, emitting radio waves that differ by tissue density.

MRI Tumor in Wernicke’s Area Magnetic resonance imaging (MRI) gives higher resolution images in three steps: Strong magnets cause protons in brain tissue to line up in parallel. A pulse of radio waves knocks protons over. Protons reconfigure themselves, emitting radio waves that differ by tissue density.         MRI is a noninvasive imaging technique that does not use x-rays.   The process involves passing a strong magnetic field through the head.  The magnetic field used is 30,000 + times that of the earth's magnetic field.  It's effect on the body, however, is harmless and temporary.  The MRI scanner can detect radiation from certain molecules, which are present in different concentrations in different tissues. 

Positron emission tomography (PET)—gives images of brain activity: Uses radioactive chemicals injected into the bloodstream and maps their destination by the radioactive emissions Identifies which brain regions contribute to specific functions Positron emission tomography (PET)—gives images of brain activity: Uses radioactive chemicals injected into the bloodstream and maps their destination by the radioactive emissions Identifies which brain regions contribute to specific functions

Functional MRI (fMRI) detects small changes in brain metabolism, such as oxygen use, in active brain areas. The amount of oxygen available is measured indirectly, on the basis of blood flow or the state of hemoglobin in blood (called the blood-oxygen-level-dependent, or BOLD, signal). fMRI can show how networks of brain structures collaborate Functional MRI (fMRI) detects small changes in brain metabolism, such as oxygen use, in active brain areas. The amount of oxygen available is measured indirectly, on the basis of blood flow or the state of hemoglobin in blood (called the blood-oxygen-level-dependent, or BOLD, signal). fMRI can show how networks of brain structures collaborate

Diffusion Tensor Imaging (DTI) uses the diffusion of water molecules within tissue to determine the orientation of fiber tracts within the brain. DTI provides a noninvasive method to map the fine axonal connections between different regions of the living human brain. Diffusion Tensor Imaging (DTI) uses the diffusion of water molecules within tissue to determine the orientation of fiber tracts within the brain. DTI provides a noninvasive method to map the fine axonal connections between different regions of the living human brain.

Optical imaging uses near-infrared light passed through the skull to reveal brain activity. Transcranial magnetic stimulation (TMS) briefly stimulates discrete cortical regions with magnets. Magnetoencephalography (MEG) measures the tiny magnetic fields given off by active neurons. Imaging can overcome the limitations of other methods of assessment. One question that can be addressed is the state of consciousness of people in comas. Brain areas in such people can show activation when prompted. Magnetoencephalography (MEG) measures the tiny magnetic fields given off by active neurons.