Introduction to MRI

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Introduction to MRI

• Magnetic
• Resonance
• Imaging

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Bore 1.5-3.0 Tesla Super conductive Magnet, RF
coils
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Understanding and Reading MRIs
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How is this MRI Image produce?
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Numbers
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Transforming Radio Frequenciesinto Images?

• Lets step back, and look at a device that is
  familiar to all of usthe Radio

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Encoded RF 1060 on your dial
RF decoded
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X 1021 / 5mm slice of tissue
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Setting up the Machine
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Surface coil
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Reading the Images
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The emitted energy of the protonsonce the RF is
stopped is affected by in which tissue (the
lattice) it resides fat, muscle, ligament,
bone, brain, etc.
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RF Pulse sequence parameterswhich the technician
adjusts

• The three pulse sequence parameters are
• Repetition time (TR) measured in msec
• Echo time (TE) measured in msec
• Flip angle measured in degrees

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T1 and T2 relaxation times
Occur simultaneously and independently of each
other and form the basis of tissue contrast in
MR-reconstructed images
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• T1
• Low TR (400-700 msec)
• Low TE (20-40 msec)
• T2
• High TR (2,000-3,000 msec)
• High TE (40-70 msec)
• Proton density
• High TE (2,000-3,000msec)
• Low TE (20-40 msec)

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Basic Sequences

• T1 to view anatomy
• T2 to detect a pathologic process (edema,
  swelling)
• Proton Density (PD)
• great for ligamentous anatomy

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Basic Pulse Sequences for MRI Imaging
Image type Fat Water Advantage
T1 Bright Dark Anatomical detail
T2 Intermediate Bright edema
Fat Suppressed T2 Very Dark Very Bright edema
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Fat Suppression

• A very valuable tool to define whether a
  structure is composed of water (bright) such as
  blood or fat (bone marrow)

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TI
Fat
Water
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T2
Fat Water
Intermediate Bright
Fat
Water
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T2 Fat Suppressed
Fat
Water
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Proton Density Fat Suppressed (PD-S)
FAT
Water