Introduction to MRI Head Imaging

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Introduction to MRI Head Imaging

• Ryan Hakimi, DO, MS
• Director, Critical Care Neurology
• Assistant Professor
• Department of Neurology
• The University of Oklahoma Health Sciences Center
• January 16, 2015

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DISCLOSURES

• FINANCIAL DISCLOSURE
• Nothing to disclose
• UNLABELED/UNAPPROVED USES DISCLOSURE
• Nothing to disclose

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Objectives

• Describe the pros and cons of MRI versus CT when
  imaging the head
• Discuss some common MRI sequences
• Illustrate the appearance of acute ischemic
  stroke on various MRI head sequences
• Present MRI head imaging of other common
  neurological diagnoses

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Principles of Magnetic Resonance Imaging

• Uses a magnet and radio waves to create an image
  based on changes in alignment of protons in the
  tissue
• Terminology
• Hyperintense (bright, white)
• Hypointense (dark, black)

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Advantages of MRI over CT Head

• No radiation
• Can image in multiple planes (axial, sagital,
  coronal, oblique)
• Superior soft tissue imaging
• Can image some vessels without contrast (MRA
  head)
• Many different sequences allow for specialized
  imaging
• Can image the brainstem and cerebellum

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Disadvantages of MRI vs CT Head

• Inferior bone imaging
• Cost
• Longer study time
• Images degraded by motion
• Can not image patient with pacemaker,
  claustrophobia, metallic foreign bodies (bullet)

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Axial T1

• T1 looks like a CT
• CSF is black
• (hypointense)

orbit
pons
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Sagital T1

• atrophy
• corpus collosum
• pons
• cerebellum

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Coronal with contrast (gadolinium)

• With contrast can see
• hyperintensity of the blood
• vessels
• Good for visualization of
• hyppocampi

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Axial T2

• T2 has white
• (hyperintense)CSF
• lateral ventricles
• frontal horn
• occipital horn

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DWI brainstem

• Breakdown of blood brain barrier
• acute ischemic stroke
• acute demyelination
• acute trauma

Right pontine ischemic infarction
T2 shine through
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T2 acute ICH

• (gradient echo)
• Blood will appear black
• (hypointense)

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Acute Ischemic StrokeDWI T1
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Acute Ischemic Stroke T2 FLAIR
(fluid-attenuated inversion recovery)
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Acute Ischemic StrokeT2

• petechial hemorrhages within the ischemic tissue

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MRA (LMCA patent)

• Image can be rotated, left is not always on the
  right side of the screen, must look at labels

anterior cerebral artery
middle cerebral artery
L
R
internal corotid artery
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Normal Pressure Hydrocephalus

• Central atrophy (large
• ventricles) out of proportion to
• peripheral atrophy (minimal
• atrophy)

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Meningioma

• Extraaxial brain tumor
• (outside of the brain) displacing
• The brain)
• Enhances with gadolinium
• Has a dural tail

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Multiple Sclerosis
Periventricular white matter hyperintensities,
some of which enhance, from National MS Center
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GAD with NSF

• Puts patients at risk for nephrogenic systemic
  fibrosis
• Fibrosis of skin, eyes, organs
• Gadolinium can not be administered in patients
• Glomerular filtration rate (GFR) of 30 or less
• On dialysis

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Questions

• Thank you