This document provides an overview of CT and MRI interpretation for various neurological structures and pathologies. It includes labeled images showing normal anatomy on different MRI sequences as well as examples of common conditions like infarction, hemorrhage, infection, tumors, trauma, dementia, multiple sclerosis, and epilepsy. The document is intended as an educational reference for medical students and residents to learn neuroradiology.
4. Coronal Section of the Brain at the level of IV Ventricle
Post Contrast Coronal T1 Weighted MRI
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Identify anatomical structures
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5. Coronal Section of the Brain at the level of IV Ventricle
Post Contrast Coronal T1 Weighted MRI
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1. Cerebellar tonsil
2. Cerebellar hemisphere
3. IV ventricle
4. Superior vermis
5. Tentorium
6. Posterior temporal lobe
7. Choroid plexus within lateral
ventricle
8. Posterior frontal lobe
6. Coronal Section of the Brain at the level of Pituitary gland
Post Contrast Coronal T1 Weighted MRI
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7. Coronal Section of the Brain at the level of Pituitary gland
Post Contrast Coronal T1 Weighted MRI
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1. Frontal lobe
2. Corpus callosum
3. Frontal horn
4. Caudate nucleus
5. III ventricle
6. Optic nerve
7. Pituitary stalk
8. Pituitary gland
9. Internal carotid artery
10. Cavernous sinus
11. Sphenoid sinus
12. Nasopharynx
8. Coronal Section of the Brain at the level of the orbits.
Post Contrast Coronal T1 Weighted MRI.
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Identify anatomical structures
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9. Coronal Section of the Brain at the level of the orbits.
Post Contrast Coronal T1 Weighted MRI.
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1. Frontal lobe
2. Orbital Fat
3. Globe
4. Nasal Cavity
5. Maxillary Sinus
10. Post Contrast Axial MR Image of
the brain
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Post Contrast sagittal T1
Weighted M.R.I.
Section at the level of Foramen
Magnum
Answers
1. Cisterna Magna
2. Cervical Cord
3. Nasopharynx
4. Mandible
5. Maxillary Sinus
11. Post Contrast Axial MR Image of the
brain
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Post Contrast sagittal T1
Wtd M.R.I.
Section at the level of
medulla
Answers
6. Medulla
7. Sigmoid Sinus
12. Post Contrast Axial MR Image of the brain
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Post Contrast sagittal T1 Wtd M.R.I.
Section at the level of Pons
Answers
8. Cerebellar
Hemisphere
9. Vermis
10. IV Ventricle
11. Pons
12. Basilar
Artery
13. Internal Carotid
Artery
14. Cavernous Sinus
15. Middle Cerebellar
Peduncle
16. Internal Auditory
Canal
17. Temporal Lobe
13. Post Contrast Axial MR Image of the brain
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Post Contrast sagittal T1 Wtd
M.R.I.
Section at the level of Mid
Brain
Answers
18. Aqueduct of Sylvius
19. Midbrain
20. Orbits
21. Posterior Cerebral
Artery
22. Middle Cerebral
Artery
14. Post Contrast Axial MR Image of the brain
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Post Contrast sagittal T1 Wtd M.R.I.
Section at the level of the
III Ventricle
Answers
23. Occipital Lobe
24. III Ventricle
25. Frontal Lobe
26. Temporal Lobe
27. Sylvian Fissure
15. Post Contrast Axial MR Image of the brain
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Post Contrast sagittal T1 Wtd M.R.I.
Section at the level of Thalamus
Answers
28. Superior Sagittal Sinus
29. Occipital Lobe
30. Choroid Plexus within
the occipital horn
31. Internal Cerebral Vein
32. Frontal Horn
33. Thalamus
34. Temporal
Lobe
35. Internal
Capsule
36. Putamen
37. Caudate
Nucleus
38. Frontal Lobe
16. Post Contrast Axial MR Image of the brain
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Post Contrast sagittal T1 Wtd
M.R.I.
Section at the level of Corpus
Callosum
Answers
39. Splenium of corpus callosum
40. Choroid plexus within the
body of lateral ventricle
41. Genu of corpus callosum
17. Post Contrast Axial MR
Image of the brain
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Post Contrast sagittal T1
Wtd M.R.I.
Section at the level of Body
of Corpus Callosum
Answers
42. Parietal Lobe
43. Body of the Corpus Callosum
44. Frontal Lobe
18. Post Contrast Axial MR Image of the brain
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Post Contrast sagittal T1 Wtd
M.R.I.
Section above the Corpus
Callosum
Answers
45. Parietal Lobe
46. Frontal Lobe
19. Brain Imaging: “The Big 10”
• Infarction
• Hemorrhage
• Infection
• Tumor
• Trauma
• Dementia
• MS
• Epilepsy
• Cranial neuropathy
• Orbits / Ophtho dx
21. CT Signs in Early MCA Ischemia
Hyperdense MCA Insular Ribbon Lentiform Nucleus
22. Pathophysiology of Ischemic Injury:
Duration and Degree of CBF
Normal neuronal function
Reversible injury
(penumbra)
Infarction
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0
CBF
ml /
100g /
min
Time (hrs)
1 2
23. Pipes Perfusion Parenchyma
MRA Perfusion MR Diffusion MR
“Penumbra”
MRI in Stroke Intervention
“The 4 P’s”
35. Subdural: Follows inner layer of dura
“Rounds the bend” to follow falx or tentorium
Not affected by sutures of skull
Tendency for crescentic shapes
More mass effect than expected for their size
Typical source of SDH: cortical vein
Epidural: Follows outer layer of dura (periosteum)
Crosses falx or tentorium
Limited by sutures of skull (typically)
Tendency for lentiform shapes
Typical source of EDH:
skull fracture with arterial or sinus laceration
Subdural vs. Epidural Hematoma
*
38. MRI of Hemorrhage
MR appearance of hematomas depends on image type.
Magnetic properties change over time (Hgb breakdown
products), allowing approximate dating
T1 T2 T2*
39. Brain Imaging: “The Big 10”
• Infarction
• Hemorrhage
• Infection
• Tumor
• Trauma
• Dementia
• MS
• Epilepsy
• Cranial neuropathy
• Orbits / Ophtho dx
61. Intra-axial Hemorrhage
Hemorrhagic contusions
Mechanism
Direct contact with skull
Shear-strain deformation
Lesion locations
Commonly located along inferior, lateral, and anterior
frontal and temporal lobes
Often above bony prominences (petrous pyramid,
sphenoid wing, orbital roof)
62. Intra-axial Hemorrhage
Hemorrhagic contusions
Appearance of cortical contusions
Overlying cortex, by definition, always involved (vs. DAI)
“Salt and pepper” appearance due to intermixed hemorrhage
and edema
Non-hemorrhagic contusions often not initially seen on CT scans
Lesions often more visible days after injury as edema and
hemorrhage increase
Acute lesions much more conspicuous on T2 or T2-FLAIR MRI
66. Diffuse Axonal (Shear) Injury (DAI)
• Tissues w/ differing elastic properties shear against each other,
tearing axons
• Caused by rapid deceleration/rotation of head
• Locations:
• Cerebral hemispheres near gray-white junction
• Basal ganglia
• Corpus callosum, especially splenium
• Dorsal brainstem
• High morbitity & mortality – common cause of post-traumatic
vegetative state
• Initial CT often normal despite poor GCS
• Lesions often non-hemorrhagic and seen only on MRI
67. Brain Imaging: “The Big 10”
• Infarction
• Hemorrhage
• Infection
• Tumor
• Trauma
• Dementia
• MS
• Epilepsy
• Cranial neuropathy
• Orbits / Ophtho dx
68. Dementia
• Primary role of imaging is to
exclude treatable causes, e.g.:
–Hydrocephalus
–Subdural hematoma
–Neoplasm
69. Dementia
Irreversible dementias (imaging non-
specific):
• Alzheimer’s disease
• Multi-infarct dementia
• Dementias associated with
Parkinson’s disease and similar
disorders
• AIDS dementia complex
71. Brain Imaging: “The Big 10”
• Infarction
• Hemorrhage
• Infection
• Tumor
• Trauma
• Dementia
• MS
• Epilepsy
• Cranial neuropathy
• Orbits / Ophtho dx
72. Multiple Sclerosis (MS) Imaging
• MRI is the imaging study of choice
• Help establish “dissemination of lesions in time
and space”
• Estimate disease burden
• Identify acute (inflammatory) vs. chronic lesions
(enhancement = active inflammation)
75. Brain Imaging: “The Big 10”
• Infarction
• Hemorrhage
• Infection
• Tumor
• Trauma
• Dementia
• MS
• Epilepsy
• Cranial neuropathy
• Orbits / Ophtho dx
76. Seizure Imaging
• MRI is the imaging study of choice
• Identify and localize offending lesion
• New onset vs. chronic epilepsy
• Younger vs. older patients
• Search may be guided by EEG / clinical sx
• Preoperative planning
e.g. language lateralization before temporal
lobectomy
79. Mesial Temporal Sclerosis
Most common pathology found in
medically refractory epilepsy patients
Rare under age 10 or with new seizures
Pathogenesis unknown
- Post ictal / kindling?
Pathology:
Hippocampal atrophy / gliosis
85. 30 y/o F
with 6wk
h/o blurred
vision
Craniopharyngioma
86. CT vs. MRI
Wide doughnut
Opening
10-20 minutes
Length
Adjust window
Technique
Aial
Plane
Bright
Bone
Long, narrow
30-60 min
T1, T2, Pd
3-D
Dark
Magnetic fld
X-ray beam
Obtained
MRI
CT
87. Advantages to CT
• Costs less than MRI
• Better access
• Shows up acute bleed
• A good quick screen
• Good visualization of bony structures
and calcified lesions
88. Disadvantages to CT
• Resolution
• Beam-hardening artifact
• Limited views of the posterior fossa and
poor visualization of white-matter
disease
89.
90. Advantages to MRI
• Good resolution—excellent view of brain
structure
• 3 dimensions
• Good gray-white differentiation
• Adjust settings based on characteristics of
the lesion
• Good view of the posterior fossa
91. Advantages to MRI
• No radiation exposure
• Gadolinium contrast is relatively nontoxic
• Capacity for quantitative imaging, 3-D
reconstruction, angiography, spectroscopy
92. Disadvantages of MRI
• Cost
• Some patients ineligible because
of pacemakers, other metal
• Claustrophobia
• Long exam
• Access
93. What Is Bright
on CT?
• Blood
• Contrast
• Bone
• Calcium
• Metal
What Is Dark
on CT?
•Air
•CSF/H20
98. Uses for SPECT and PET
• Acute stroke
• Identify a seizure focus-increased
flow during sz and decreased
interictal flow
• Dementia-frontal pattern in FTLD,
temporo-parietal pattern in AD
• Ligand imaging in PD, others
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100.
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103.
104. Landmarks
• Axial views
– Fourth ventricle
– Petrous bone and sphenoid ridge
– Aqueduct
– Third ventricle
– Lateral ventricles
– Frontal horns
– Calcifications in the choroid plexus, pineal,
basal ganglia and falx
– Caudate, putamen and globus pallidus
105. Landmarks (Cont.)
– Internal capsule—anterior and posterior limbs
– Thalami
– Sylvian fissures
• Sagittal views
– Severity of cortical atrophy
– Corpus callosum and cingulate gyrus
• Pituitary
– Coronal views
– Hippocampus and amygdala
111. Introduction to Scan Interpretation
• Is the scan
– Contrast or noncontrast?
– Good quality?
• Describe the abnormality
– Size—small, punctuate, medium, large
– Shape—round, well circumscribed, ovoid,
irregular, patchy
112. Introduction to Scan Interpretation
(Cont.)
• Signal intensity
– High signal,
hyperdense
– Low signal, hypodense
– Isointense, isodense
– Mixed signal
• Location
113. Vascular Dementia
Three types of vascular dementia
Multiple large
Vessel infarctions
Bilateral strategic
thalamic infarcts
Binswanger’s
Disease
114. Normal Pressure Hydrocephalus: NPH
• Cognitive Impairment
• Gait Disturbance
• Bladder Control
• May Have:
Behavior Problems
Parkinsonism
115. MRI findings
• Ventricular enlargement disproportionate to the
amount of atrophy
• Bowing of the corpus callosum
• Smooth rimming of high signal around the ventricles
due to transependymal flow of CSF
117. Types of fMRI
• BOLD-fMRI which measures regional differences in
oxygenated blood
• Diffusion-weighted fMRI which measures random
movement of water molecules. Diffusion tensor
imaging (DTI) measures diffusion of water in different
directions and is a good test for studying white
matter tracts.
• MRI spectroscopy which can measure certain
cerebral metabolites non-invasively
121. MR Spectroscopy
MR spectroscopy of N
acetyl aspartate
(NAA) showing
decline of NAA over
time in patients with
Alzheimer’s disease
(lower line)
compared to age-
matched controls.