summery about MRI method

1. Ghazale Boroumand
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6. 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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7. 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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9. T1-Weighted MRI
T2-Weighted MRI
PD(Proton Density)
FLAIR(Fluid Attenuated Inversion Recovery )
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11. 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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12. 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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13. Spin density–
weighted imaging
in which CSF has a
density similar to
brain tissue.
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14. Gradient echo
imaging, which has
the highest
sensitivity in
detecting early
hemorrhagic
changes.
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17. DWI in which the images reflect the
microscopic random motion of water
molecules.
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18. Trace(DWI) ADC map
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19. 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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20. Map of myelinated nerve patterns in pre-term
infants.
Distinguish between pathological and
traumatic fractures.
Assessment of bone bruises.
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21. Perfusion-weighted
imaging (PWI) in
which
hemodynamically
weighted MR
sequences are
based on passage
of MR contrast
through brain
tissue .
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22. 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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25. MRS creates a
graph or "spectrum"
arraying the types
and quantity of
chemicals in the
brain or other
organs.
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28. 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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30. 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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31. FMRI
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32. Blood-Oxygenation-
Level Dependent
contrast
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33. 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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35. Understanding Cognition.
Improving Clinical procedures.
Studying Brain Development.
Investigating Brain Physiology.
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36. 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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37. 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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38. 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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47. •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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