Week One Flashcards
In clinical practice, the primary application of neuroimaging in paitents management is for
diagnoses purposes where neuroimaging procedures are used to facilitate the diagnoses of disease conditions such as stroke (CVA), epilepsy, space-occupying lesions, tumours, Alzheimer’s disease, intra/extra cranial haemorrhages etc. the monitoring of disease progress cal also be achieved by the use of neuroimaging
What are the common neuroimaging tools for investigating cerebral changes?
- Electroencephalography (EEG)
- Computed axial Tomography scan (CT)
- Magnetic resonance imaging (MRI)
- functional magnetic resonance imaging (fMRI)
- Positron Emission Tomography (PET)
- Single photon emission computed tomography (SPECT)
Electroencephalography (EEG)
is an important neuroimaging tool used in neuroscience to investigae brain electrical activity and cerebral changed that usually accompany many pathological and psychological conditions. the most widely used neuroimaging tool in neuropsychiatry research, in many neurophysiological and neuropsychological studies on depression.
How does EEG work
electrodes are attached to scalp, measures voltage fluctuations resulting from ionic current flows within the neurons of the brain. records brains spontaneous activity over a short period of time (usually less than 40 minutes) from multiple electrodes placed on the scalp at the same time.
General use of EEG
-sleep studies and diagnosis of epilemsy, coma, encephalopathies, focal brain disorders (tumors and stroke, and to make a diagnosis of brain death.
EEG advantages
being able to determine the relative strengths and locations of electrical activity arising from different brain regions, painless, cheap and risk free. higher spatial resolution than (SPECT) and (PET)
EEG Disadvantages
resolution is poor and does not record interior brain activity as a result of this researcher use EEG in combination with MRI scans to better pinpoint the location of the brain activity.
Computed Axial Tomography scan (CT Scan)
Utilized a series of x-rays applied from different directions to produce quick and clear two-dimensional images of organs, bones and tissues of the body
How a CT scan works
the x-rays which are passed through the body are detected by a computerized scanner which has been programmed to process the data and display it ac cross-sectional images or “slices” of the internal structure of the organ under investigation. the computer scanner uses a set of algebraic calculations to estimate how much x-ray is absorbed by an organ. therefore the harder the material is the whiter it will appear on the CT scan so bones appear whiter than soft tissues
CT Scan use
they are used to investigate a variety of abnormalities such as identifying blood clot or intracranial bleeding in patients with stroke, detecting bone and vascular irregularities, confirming the presence of brain tumors and cysts. evaluating swelling and tissue damage in the brain, investigating brain and spinal cord damage from trauma, assessment of ventricle size in patients with hydrocephalus and for assisting in the diagnosis of other disorders such as herniated discs, epilepsy, encephalitis and spinal canal stenosis
CT scan neuro research
extensively used ti investigate various neurophysiological and neuropsychological factors associated with depression which include
- neuropsychological deficits and cognitive impairments associated with depression
- association of depressive symptoms and medical condition such as acute stroke and Alzheimers disease and depressive symptoms following traumatic brain injury.
CT scan advantages
-non-invasive, painless which is quick to carry out. regular scan takes 20 minutes but brain scan may take up to one hour. usually done in hospital or imaging centre as day procedure, so no extensice pre-procedure preperation is required, and images are avalible for use nearly immediately. apart from differentiating soft and hard and soft tissues in the body the CT scan is also capible of differentiating various brain regions and such it is very helpful in differentiating many neurological disorders which share similar characteristics.
CT Scan disadvantages
- relatively expensive
- obese and claustrophobic patients will find it hard to undergo CT as they will be spending time in a close space.
- Pregnant women cannot undergo CT scan because of the high exposure to ionizing radiation
- individuals whom are restless may require sedation to stay still during the procedure
- if contrast dye is used (helps to highlight different areas) it has been known to give unwanted side effects such as allergic reactions, patients may also experience slight metallic taste or feeling of warm or cold sensation as dye circulates through their bloodstream.
Megnetic Resonance Imaging (MRI)
uses a combination of powerful magnetic field and computer generated radio waves to produce high quality two or three dimensional detailed images of body strructures including tissues, organs, bones and nerves
How MRI works
MRI scan generated images by the temporary realignment of water molecules as a result of the high magnetic field created around the body.
- As radio waves are passed through the body the “relaxation” of the molecules back to a random alignment is detected and resonance signal at different angles within the body are acquired through the aid of sensors which lead the frequencies and a computer uses the information to construct the required image. The computer processing of th triggered resonance is able to create either a two dimensional slice or a three dimensional picture of the tissues under investigation
