Brain-Relevant Education

Computerized Axial Tomography (CT or CAT Scan)

In this technique dye injected into the bloodstream creates viewable contrast as x-rays pass through the brain during the scanning process. Resulting photographs can depict structural abnormalities. As this technique utilizes dye injection for contrast, it is classified as invasive.

Magnetic Resonance Imaging (MRI)

This technique applies a strong magnetic field—25,000 times stronger than Earth's magnetic field—in short, repetitive, staccato-like spurts as the subject being imaged passes through a circular tube. Atoms respond to the on–off spurts of magnetism in ways that allow the technology to create images of structures in the brain.

Electroencephalography (EEG)

By placing electrodes at various locations on the scalp, this technology records electrical activity within the brain. Physicians often provide a sensory stimulus—termed evoked potentials or evoked responses—to record differences in brain function as a result of the stimulation. This imaging provides approximate location of activity—within about a centimeter of space.

Magnetoencephalography (MEG)

Though similar to EEG, this technique differs in that it measures magnetic fields produced faintly in brain function. This process allows the advantage of observing a given effect in the brain as it travels—somewhat as a wave does on water.

Positron-Emission Tomography (PET)

This technique offers the advantage of high-definition imaging with the added feature of showing hotspots of activity in a live brain. This technique is more invasive that some other brain imaging technologies because it involves injecting chemicals containing radioactive atoms. This fact imposes limitations on the frequency of using this procedure.

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