Enhance Your Understanding of Neuro-Imaging
Kelly A. Malloy, OD, FAAO, Diplomate, Neuro-Ophthalmic Disease
Course Description:This course highlights neuro-imaging studies ordered in neuro-ophthalmic
disease practice. CT/CTA, MRI/MRA/MRV, and Angiography are discussed in terms of
indications/contraindication/ordering protocol. Multiple images contrast normal and abnormal
studies. A case-based approach aids clinical application, and tests radiologic interpretation skills.
Course Learning Objectives:
1. To understand the indications of MRI/MRA/MRV/CT/CTA in clinical practice.
2. To understand the contraindications of MRI / CT.
3. To understand the indications/contraindications of contrast in neuro-imaging.
4. To review neuro-anatomy as it relates to neuro-radiology.
5. To understand the importance of proper neuro-radiology interpretation.
6. To become familiar with neuro-ophthalmic disease manifestations that warrant neuroimaging.
Course Outline:
Types Of Neuro-Imaging Studies
- Computed Axial Tomography (CAT / CT)
- Computed Axial Tomography Angiography (CTA)
- Magnetic Resonance Imaging (MRI)
- Magnetic Resonance Imaging Angiography (MRA)
- Magnetic Resonance Venography (MRV)
- Angiography
CT SCAN
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Good for looking at BONE and BLOOD - (trauma)
Good for meningiomas
Necessary to R/O fractures, sub-dural sub-arachnoid hemorrhage
Different window widths used ( Bone, soft tissue, etc.)
Available in the ER setting
Axial and coronal sections only
NO SAGITTAL sections possible
CT CONTRAST
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Iodine based
Metabolized in kidneys
CT CONTRAINDICATIONS
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Radiation exposure
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pregnant women
children
CONTRAST
o Abnormal kidney function (need to check BUN / creatinine levels)
o Allergy to iodine, shellfish, etc.
CT Angiography (CTA)
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Contrast IS necessary
View arteries of head (COW) and neck (carotids, vertebrals)
Can view as cross-section or in 3D
Look for aneurysms, A-V malformations, stenosis
MRI
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Magnetic Resonance Imaging
Magnetic field / hydrogen atom alignment
NO radiation exposure
Good for looking at ANATOMY / SOFT TISSUE
NOT normally available in the ER setting
MRI – Imaging Planes
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Axial, coronal and sagittal sections
Sagittal section useful to view:
• cervico-medullary junction
• pituitary gland
• pineal region
• corpus callosum
MRI - T1 Weighted Images
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Recovery time (TR) less than 1000
CSF, vitreous are DARK
Good for viewing ANATOMY
Used with CONTRAST media
Compare T1 with and without contrast (look for enhancement)
MRI - Diffusion Weighted Imaging (DWI)
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Very fast recovery time (seconds)
Used to diagnose ACUTE INFARCTS
MRI - FLAIR (Fluid-Attenuation Inversion Recovery)
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Recovery time is greater than 1000
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Like a T2, but the CSF, vitreous are DARK
Better view of pathology, especially in areas adjacent to CSF (ventricles,
etc.)
 Good for seeing MS plaques
MRI - GRADIENT ECHO
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Used to view BLOOD (Hemosiderin)
Not regularly done
Need to request this sequence if blood is expected
Blood appears black with this sequence
GADOLINIUM
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Contrast media for MRI (need to check kidney function on pt with DM,
HTN, etc before ordering contrast – BUN and creatinine)
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NOT iodine-based
Less potential for allergic reaction
Contrast needed if suspect a mass, abscess, inflammation, infiltration
Alters magnetic field (differing signals)
Abnormalities demonstrate areas of enhancement
ORBITAL STUDY
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Need to specify if orbital study is needed (MR/CT)
Obtain thinner cuts through the orbital region
If MRI – need to do fat-suppression
Unable to do fat-suppression in open gantry
Best done in a CLOSED gantry
MRA (head / neck)
- Contrast NOT necessary
- View arteries of head (COW) and neck
(carotids, vertebrals)
- Image is obtained by flow voids in vessels
- Vessels are normally dark due to movement of blood
- Series of acquisition images are used
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Look for aneurysms, A-V malformations, stenosis
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Cannot detect aneurysms smaller than 3 mm
MRV
• Similar to MRA
• Used to view venous sinuses
• Contrast is NOT necessary
• Look for venous sinus thrombosis (pts c papilledema / HA)
• Difficult to interpret - ? congenital dominance / hypoplasia
MR CONTRAINDICATIONS
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PACEMAKERS
COCHLEAR IMPLANTS
METALLIC FOREIGN BODY IN ORBITS
RECENT STENTS, METALLIC IMPLANTS (unless titanium is used)
Claustrophobia
Weight limitations (usually above 300lbs)
Previous Allergy to Contrast Medium
ANGIOGRAPHY
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Gold standard for looking at vasculature
Best for detecting even small aneurysms, and A-V malformations
ORDERING STUDIES
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Type of study, studies
Body part (Brain, orbits, c-spine, etc.)
Specific sequences requested
Areas to direct special attention
Clinical findings suggesting localization
Release films to patient
NEED TO KNOW ANATOMY
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Where do signs/symptoms localize anatomically
Need to know where to direct attention on the study
Should be able to determine where to focus the study, and what looking
for prior to ordering study
NEED TO REVIEW FILMS
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Only you have the clinical history, symptoms, and signs that lead to
localization
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Need to be sure that clinical picture can be explained by radiologic
findings….or else you need to look for something else
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Need to be able to review films yourself or take them for review with a
neuro-radiologist
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This course will compare and contrast normal and abnormal findings on various
types of neuro-imaging studies.
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Also, a case-based approach will be used to demonstrate when imaging studies
are warranted, and to help decide which type of study is most appropriate in
each situation. The cases will emphasize the importance of ordering the
appropriate study, using contrast when necessary, the value of clinical
correlation, and the need to have the films re-reviewed.
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Additionally, the audience will get a chance to test their radiologic interpretation
skills. They will be shown a series of images, asked to recognize an abnormality
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This course will help clinicians better understand when neuro-imaging studies are
warranted, and in turn, when additional referral is needed.