Ghazale Boroumand

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Spin Echo (SE)

Using two RF pulse to generate an echo.

Produce the best image quality.

Having long scan times.

Gradian Echo (GE)

Using an RF pulse and gradient pulse to generate an echo.

Having short scan times.

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Repetition Time(TR)

the amount of time that exists between successive pulse sequences applied to the same slice.

Echo Time (TE)

the time between the start of the RF pulse and the maximum in the signal.

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T1-Weighted MRI

T2-Weighted MRI

PD(Proton Density)

FLAIR(Fluid Attenuated Inversion Recovery )

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T1-weighted imaging (T1-WI) in which cerebrospinal fluid (CSF) has a low signal intensity in relation to brain tissue.

Applications :

After gadolinium injection in Axial and coronal slices:

Tumors.

Infection.

Inflammation.

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T2-weighted imaging (T2-WI) in which CSF has a high signal intensity in relation to brain tissue.

Application :

Sagittal images to determine optimal brightness variations T2 in Multiple Sclerosis.

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Spin density–weighted imaging in which CSF has a density similar to brain tissue.

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Gradient echo imaging, which has the highest sensitivity in detecting early hemorrhagic changes.

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DWI in which the images reflect the microscopic random motion of water molecules.

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Trace(DWI) ADC map

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After infarction.

Display reversible and irreversible ischemic injury.

Distinguish between malignant and benign injury.

Distinguish between tumors from edema and infarction.

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Map of myelinated nerve patterns in pre-term infants.

Distinguish between pathological and traumatic fractures.

Assessment of bone bruises.

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Perfusion-weighted imaging (PWI) in which hemodynamicallyweighted MR sequences are based on passage of MR contrast through brain tissue .

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Assessment of tissue viability.

Metabolism of vascular organs and Visceral brain structures.

Characteristic patterns of perfusion in hepatocellular carcinoma, Metastasis and Hemangioma.

Assessment of ischemia.

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MRS creates a graph or "spectrum" arraying the types and quantity of chemicals in the brain or other organs.

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Helping prognosis.

Biopsy Guide.

Treatment planning and monitoring of treatment.

metabolic changes in brain tumors.

Strokes.

seizure disorders.

Alzheimer's disease.

Recognition and diagnosis of epilepsy, depression and Schizophrenia.

and other diseases affecting the brain

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No peak of NAA at 2.01ppm.

No peak of Cr at 3.02ppm.

Choline peak at 3.2ppm.

Manitol peak at 3.8ppm.

manitol is used as part of treatment to reduce cerebral odema.

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FMRI31

Blood-Oxygenation-

Level Dependent

contrast

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Uses a standard MRI scanner to acquire images of functionally meaningful brain activity.

Typically measures changes in blood oxygenation.

Non-invasive, no ionizing radiation.

Good combination of spatial / temporal resolution.◦ Voxel sizes ~4mm

◦ Time of Repetition (TR) ~1s

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Understanding Cognition.

Improving Clinical procedures.

Studying Brain Development.

Investigating Brain Physiology.

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Brain imaging improves models for cognitive processes.◦ Activation-based dissociations.

Brain imaging guides understanding of the relative timing/structure of cognitive processes.

Brain imaging facilitates integration of information from other techniques.◦ Lesion studies, animal work, brain disorders.

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Brain Tumors◦ Direct: Mapping of functional properties of adjacent tissue◦ Indirect: Understanding of likely consequences of a

treatment

Drug Abuse/Addiction◦ Understanding of brain effects of long-term use◦ Development of treatment strategies for abusers

Drug Studies◦ What are the effects of a given medication on the brain?◦ How does a drug affect cognition? … our measures of

cognition?

Neuropsychological disorders◦ Understanding brain function may allow distinction among

subtypes.◦ Identifying markers for a disorder may help in treatment

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Aging◦ Which brain changes are associated with normal

aging?◦ Which changes are pathological?

Childhood Development◦ How does the human brain develop over the first

decades of life?◦ Can we improve educational or health policies

with a better understanding of the brain?

Longitudinal Studies

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•creates a graph

arraying the types

and quantity of

chemicals in body.

MRS

•Detection and

Diagnosis of lesions.

•Treatment Plan.

MRI•illustration of

functional brain

activity.

•Topographic map of

the brain.

FMRI

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