This document summarizes several brain imaging techniques: Computerized Tomography uses X-rays to detect lesions, abnormalities, and structural differences. Magnetic Resonance Imaging produces detailed brain images using magnetic fields and radio waves to separate out features not visible on CT scans. Positron Emission Tomography injects radioactive isotopes to trace brain activity and localization of functions like blood flow, glucose uptake, and neurotransmitter binding in response to tasks. New techniques like Magnetic Resonance Spectroscopy and Diffusion Tensor Imaging provide chemical information and map white matter fibers. Electroencephalography measures electrical brain activity patterns using scalp electrodes, including during sleep. Brain Electroactivity Mapping extends EEG by generating activity maps. Event-related potentials measure tiny

1. Brain Imaging
• Imaging is a generic word to describe a range
of remarkable techniques to visualize internal
organs.

2. Computerized Tomography
• An x-ray beam (radiation exposure) is passed
through serial sections of the brain to look at
structural images.
• Detects possible lesions, abscesses, areas of
infarction, or aneurysm.
• Identifies anatomic differences in patients
with schizophrenia, organic mental disorder,
and bipolar disorders.

3. Magnetic Resonance Imaging
• Reconstructs detailed images of cerebral anatomy
from multiple perspectives.
• The head is placed into powerful magnetic field
,hydrogen atoms responds strongly to magnetic
fields and the has magnetically active hydrogen
atoms primarily in water molecules .
• Brief pulse of radio frequency energy is passed
through tissue expose to strong magnet,hydrogen
atoms release energy measured by detectors.
• MRI images can separate out features especial in
the brain that canot be visualzed by CT scans.

4. Cont...
• Detects brain oedema, ischemia,
infection,neoplasm, trauma and other
changes such demyelination.
• Used in the diagnosis of dementia, detects
morphological changes in schizophrenic
patient.

5. Positron Emission Tomography
• Unlike CT scanning PET scan requires the
injection of small amount of radioactive isotope
that is localized in brain tissue.
• PET scan allows the location of that isotope to be
traced while subject performs certain tasks.
• How it works
• Uses positrons as radioactive tracers or more
precisely uses positron generated tracers that are
bound to molecules(including glucose and certain
neurotransmitter analogues)

6. • Positrons are a form of antimatter electrons with positive
charge when antimatter and matter (in this case an
electron) meet they are both annihilated and produce two
gamma particles traveling in nearly opposite directions .
• This production of two diverging particles allows the
precise location of the original collision to be determined.
• Since human tissue are full of electrons, the collision occurs
very close to the site at which the positron generating
substance was concentrated.

7. • PET scan allows scientists to map function
such as the flow of blood within brain the
uptake of glucose and the binding of
neurotransmitters to synaptic membranes all
in response to specific real time.
• For example in normal individual, there are
major differences in where brain function
localize depending on whether an individual
does the following activities:

8. • Look at word :The metabolic activity is limited
to the visual cortex.
• Listen to word: The metabolic activity is
limited to parts of the temporal cortex.
• Speaks a word: The metabolic activity is
limited to the medial frontal cortex.
• Think about word meaning activity is widely
spread over areas of the association cortex

9. • PET scan provides a remarkable confimation
of the aspects of the biophysiological theory .
• Brain functions do link to mental processes
and are highly localized within the cortex.

10. Magnetic Resonance Spectroscopy
and Diffusion Tensor Imaging
• Two new MRI derived scanning techniques .
• MRS does not produce visual brain images but
allows scientists to determine which
neurotransmitters and other chemicals are
present at specific brain sites .DTI is an
extension of MRI that allows bran white
matter fibers.

11. Electroencephalogram(EEG)
• Measures electrical activity patterns of the
brain from leads connected to the surface
electrodes placed on the scalp and
nasopharyngeal area.
Polysomnography (sleep EEG)
• Measures electrial brain activity data during
all-night sleep.

12. Brain Electroactivity Mapping (BEAM)
• Extends theEEG by generating computerized
maps of brain electrial to produce
images;permits visualuzation of the brain
performing tasks or specific functions. Useful
in children.

13. Event-related potential(Eps)
Repeated auditory or visual stimuli associated
with tiny electrical events in the cerebral
cortex or sub cortical structures, measured by
surface electrodes.

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