Transcript Neuroradiology - University of Virginia School of Medicine

Neuroradiology for
Medical Students
By the end of this tutorial, you will be able
to recognize some of the common
radiologic problems most often seen by
physicians. Hopefully, you will also
become more aware of what tests to order
and when to order them. We also hope
that you will have a little fun in the
process!
CT Anatomy (you kind of need to
know this)
A = Frontal sinus
B = Orbit
C = Frontal lobe
D = Sphenoid sinus
E = Temporal lobe
F = External auditory canal
G = Mastoid air cells
H = Cerebellar tonsil
I = Foramen magnum
A
B
C
D
E
F
G
H
= Frontal lobe
= Sylvian fissure
= Temporal lobe
= Temporal horn of the
lateral ventricle
= Midbrain
= Ambient cistern
= Fourth ventricle
= Cerebellar hemisphere
A = Falx
B = Frontal horn of the lateral ventricle
C = Caudate nucleus
D = Internal capsule (anterior limb)
E = Sylvian fissure
F = Basal ganglia
G = Third ventricle
H = Quadrigeminal plate cistern
I = Cerebellum
A
B
C
D
E
F
G
H
=
=
=
=
=
=
=
=
Interhemispheric fissure
Genu of the corpus callosum
Frontal horn of the lateral ventricle
Internal capsule
Thalamus
Pineal gland (calcified)
Cerebellar vermis
Straight sinus
A
B
C
D
E
=
=
=
=
=
Falx cerebri
Frontal lobe
Parietal lobe
Body of the lateral ventricle
Occipital lobe
A
B
C
D
E
=
=
=
=
=
Falx cerebri
Sulcus
Gyrus
Central sulcus
Superior sagittal sinus
MRI Anatomy (this is kind of really
important too)
A
B
C
D
E
F
=
=
=
=
=
=
Internal carotid artery
Medulla
Cerebellar hemisphere
Maxillary sinus
Sigmoid sinus
External auditory canal
A
B
C
D
E
F
G
H
=
=
=
=
=
=
=
=
Sphenoid sinus
Internal carotid artery
Temporal lobe
Fourth ventricle
Basilar artery
Pons
Middle cerebellar peduncle
Cerebellum
A = Orbit
B = Optic chiasm
C = Hippocampal formation
D = Cerebral peduncle
E = Tegmentum (midbrain)
F = Cerebral aqueduct
G = Tectum (midbrain)
H = Quadrigeminal cistern
I = Occipital lobe
A = Caudate nucleus
B = Anterior limb of the internal capsule
C = Putamen
D = Fornix
E = Posterior limb of the internal capsule
F = Insula
G = Thalamus
H = Lateral ventricle (posterior horn)
I = Corpus callosum (splenium)
A
B
C
D
E
F
G
=
=
=
=
=
=
=
Lateral ventricle
Caudate nucleus
Septum pellucidum
Sylvian fissure
Corpus callosum (genu)
Gray matter
White matter
Coronal MRI Anatomy
A
B
C
D
E
F
G
=
=
=
=
=
=
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Intrahemispheric fissure
Corpus callosum
Lateral ventricle
Suprasellar cistern
Temporal lobe
Insular cortex
Sylvian fissure
A = Superior sagittal sinus
B = Corpus callosum
C = Septum pellucidum
D = Lateral ventricle
E = Caudate nucleus
F = Internal capsule
G = Interventricular foramen of Monro
H = Third ventricle
I = Insular cortex
A
B
C
D
E
F
G
=
=
=
=
=
=
=
Corpus callosum (splenium)
Choroid plexus of the lateral ventricle
Hippocampal formation
Quadrigeminal cistern
Fourth ventricle
Cerebellar hemisphere
Tentorium cerebelli
Sagittal MRI Anatomy
A = Corpus callosum
B = Fornix
C = Thalamus
D = Optic chiasm
E = Pituitary gland
F = Pons
G = Dens (C2 vertebra)
H = Spinal cord
I = Pineal gland
J = Tectum (midbrain)
K = Cerebral aqueduct
L = Tegmentum (midbrain)
M = Fourth ventricle
N = Medulla
Circle of Willis
A
B
C
D
E
F
G
H
=
=
=
=
=
=
=
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Basilar artery
Posterior cerebral artery
Thalamoperforators
Posterior communicating artery
Internal carotid artery
Middle cerebral artery
Anterior cerebral artery
Anterior communicating artery
Vascular Territories
A
B
C
D
=
=
=
=
Anterior cerebral artery
Middle cerebral artery
Posterior cerebral artery
Lenticulostriate arteries
A 82 y/o female presents with sudden
onset of right-sided weakness and garbled
speech for 3 hours. What, if any,
radiologic test would you order, and why?
Read about the following imaging
techniques to help you formulate an
answer:
Imaging
Techniques
CT vs. MRI: What to order?
CT
Acute neurological events:
– Stroke
– Trauma
– Worst HA of life
– Acute mental status change
– First seizure
– Neurosurgery immediate post-op
Follow up:
– Acute infarcts
– Hemorrhage
– Hydrocephalus
MRI
Acute (usually after CT):
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Stroke
Encephalitis
Subacute and chronic:
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Progressive, subacute, or chronic neurological
deficit
TIAs, h/o of stroke
Brain tumors
Metastatic disease
Dementia
Epilepsy
Chronic headaches
MS
Developmental delay
Pituitary disorders
Cranial nerve dysfunction
CT Head
For acute neurologic eventsCT of the head
without IV contrast
The most frequent reason that a CT head is
ordered is for the diagnosis of CVA’s and ICH
Does not exclude infarct in acute stage of a
stroke, but is useful to exclude a bleed (so
anticoagulant medication can be commenced)
IV contrast is not routinely used, but may be
useful for evaluating tumors, cerebral infections,
and sometimes for the evaluation of stroke
patients.
CT Head
CT can also be used to detect increases in
intracranial pressure, e.g. before lumbar
puncture or to evaluate the functioning of a VP
shunt.
CT is used in trauma for evaluating facial and
skull fractures.
In order to prevent unnecessary irradiation of the
orbits and especially the lenses, head CTs are
performed at an angle parallel to the base of the
skull, with the patient in the supine position.
Slice thickness generally is between 5 and 10
mm
MRI
MRI is also performed for possible brain
stem and posterior brain pathology, that is
not readily seen on CT
Currently, MRI with Diffusion Weighted
Imaging:
– Is superior to CT in detecting acute infarcts
– Is less sensitive than CT for SAH and hyperacute
parenchymal hemorrhage
- Has no exposure to radiation, but takes longer to get
study done
Imaging Techniques
Bone
Air
Fat
Water
Brain
CT
Bright
Dark
Dark
Dark
Intermed
MRI-T1
Dark
Dark
Bright
Dark
Gray=gray
White=white
MRI-T2
Dark
Dark
Bright
Bright
Intermed
Imaging Techniques
Normals
CT
vs.
MRI-T1
vs.
MRI-T2
Imaging Techniques
CT
MRI-T1
MRI-T2
Acute Bleed
Bright
Bright
Bright
Tumor
Dark
Bright
Dark
Infarct
Dark
Bright
Dark
Calcifications Bright
Bright
Dark
IV Contrast
Bright
Bright
Bright
CT Angiography (CTA)
Advantages:
– Noninvasive
– Faster than MRA or
Angiography
– Excellent for measuring lesions
– Easily demonstrates
intraluminal clots and
extravascular hematomas
Disadvantages:
– Radiation exposure
– Use of contrast material
– Can be diagnostic, but may
require invasive therapeutic
measures
Magnetic Resonance Angiography
(MRA)
•Advantages:
-Noninvasive
-Iodinated Contrast not needed
-Safe for patients with renal
insufficiency
-Images can be reconstructed in any
plain
-Does not require the use of radiation
-Depicts both anatomy and flow rate
•Disadvantages:
-Can not be used in patients with
pacemakers or certain hardware
-Long acquisition time
-Poor spatial relations
-Can be diagnostic but may require
invasive therapeutic measures
Angiogram
Advantages:
– Can be diagnostic and
theurapeutic
– Although invasive, if a clot or
aneurysm is seen, intervention
can be done at the time of the
procedure
Disadvantages:
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Invasive
Use of Contrast Material
Possible Kidney failure
Lengthy post-procedure
precautions for bleeding from
insertion site
A 82 y/o female presents with sudden onset of
right-sided weakness and garbled speech for 3
hours. What, if any, radiologic test would you
order, and why?
Answer: CT of head without IV contrast. Why, you
ask? As you can see from the above info, both
IV contrast and an acute bleed will show up
bright on CT. You must first rule out hemorrhage
in any acute stroke patient, so that appropriate
therapy can be started. You wouldn’t want to
start thrombolytic therapy on someone who is
actively bleeding!!!
Mini Quiz
Which of the following is NOT true concerning the
process of performing a head CT?
A. Head CTs are performed at an angle parallel to the
base of the skull.
B. Slice thickness is generally between 5 and 10 mm.
C. Intravenous contrast is routinely used.
D. The patient is placed in a supine position on the
table.
Stroke
68 y/o with left-sided weakness
and confusion
CT Head w/o Contrast
Ischemic Stroke
Ischemic strokes account for 84% of all strokes
Causes:
– Thrombosis
Blood clot forms in one of the cerebral arteries from
hypercoagulable state, rupture of atherosclerotic plaque,
or underlying stenosis
May be preceded by transient ischemic attack (TIA)
– Embolism
Detached clot from heart or large vessels such as
carotid
Afib is a common cause
– Hypoperfusion
Proximal stenosis of cerebral artery
Cardiac or respiratory failure
Sharply circumscribed hypodense edema
(arrowheads) in the right middle cerebral
artery territory
– Lacunar infarctions
walls of small arteries thicken and cause the occlusion
of the artery
involve the small perforating vessels of the brain and
result in lesions that are less than 1.5 cm in size.
Early CT findings in acute infarct
May be normal in first ~ 12
hours
Loss of gray-white matter
differentiation
– Loss of bright cortical ribbon
Subtle hypodensity (cytotoxic
edema)
– Loss of bright basal ganglia
Swelling/sulcal effacement
Hyperdense artery sign
CT showing acute infarct with loss of graywhite matter differentiation (arrows) and
sulcal effacement
– Artery must be brighter than other
Circle of Willis arteries
– Artery in question must fit clinical
picture
79 y/o female with HA and ataxia
CT Head w/o contrast
Hemorrhagic Stroke
Hemorrhagic strokes are due to
rupture of a cerebral blood vessel that
causes bleeding into or around the
brain.
2 Types (intracerebral and
subarachnoid)
Intracerebral
– Hypertensive hemorrhage (most
common cause)
Predilection for deep structures of the
brain, such as thalamus, pons,
cerebellum, and basal ganglia
Hemorrhage in the left posterior
parietal lobe (arrow)
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Amyloid angiopathy
Ruptured vascular malformation
Coagulopathy
Hemorrhage into a tumor
Drug Abuse
28 y/o female with “worst HA of
my life”
CT head w/o contrast
Subarachnoid Hemorrhage
Main causes:
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Trauma #1
Ruptured cerebral aneurysm
Other Causes:
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High density blood fills the third ventricle
and is in the sylvian fissure in this
subarachnoid hemorrhage.
AVM rupture
Coagulopathy
Vasculitis
Neoplasm
Pituitary apoplexy
Hypertension
Venous rupture/venous thrombosis
NONCONTRAST CT is the imaging of choice for
nontraumatic SAH
If CT is negative and there is still a strong clinical
suspicion→ LP may be used for the diagnosis
Detection of a subarachnoid hemorrhage is crucial
because the rehemorrhage rate of ruptured
aneurysms is high and rehemorrhage is often fatal.
On CT, a subarachnoid hemorrhage appears as
high density within sulci and cisterns.
After positive SAH on CT or
lumbar puncture:
Cerebral (catheter) angiography: “Gold
standard”
– Invasive
– Time and labor intensive
– Small risk of complications (stroke, contrast
reaction)
CTA—best first exam; replaces cerebral
angiography in many cases
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Minimally invasive (IV injection)
Very fast
Moderately labor intensive
May still need catheter angiography if CTA is
negative, or aneurysm not well delineated
– Iodinated contrast risk
25 y/o with new onset seizures
CT head w/o contrast
Arteriovenous Malformation with
Hemorrhage
Underlying AVM may or may not
be visible on CT scan
Prominent vessels adjacent to
the hematoma suggest an
underlying arteriovenous
malformation
Some arteriovenous
malformations contain dysplastic
areas of calcification and may be
visible as serpentine enhancing
structures after contrast
administration.
The CT on the top shows hemorrhage (arrow) due to underlying AVM
(arrowheads). The arteriogram on the left shows the tangle of vessels
(arrowheads) of the AVM. This lesion would be considered for intravascular
embolic therapy.
The most important issue to determine
when imaging a stroke patient is
whether a hemorrhagic or ischemic
event has occurred.
A. True
B. False
Which of the following is NOT true concerning stroke?
A. Hemorrhagic stroke is more common than ischemic
stroke.
B. An embolic stroke occurs when a detached clot flows
into and blocks a cerebral artery.
C. Global anoxia presents an ischemic challenge to the
brain and is classified as a hypoperfusion infarction.
D. The most common cause of non-traumatic
intracerebral hematoma is hypertensive
hemorrhage.
In which of the following locations is hypertensive
hemorrhage LEAST LIKELY to occur?
A. Thalamus
B. Cerebellum
C. Basal Ganglia
D. Pons
E. Occipital Lobe
Which of the following is NOT true concerning CT of a
stroke patient?
A. Patients who have a hypertensive hemorrhage may
have extension of blood into the ventricular system.
B. An acute infarct may be normal on CT for the first 12
hours.
C. The underlying arteriovenous malformation causing
stroke is almost always visible on CT scan.
D. On CT, prominent vessels adjacent to a hematoma
suggest an underlying arteriovenous malformation.
Which of the following is NOT a CT finding in
an acute infarct?
A. Loss of gray-white distinction
B. Subtle hypodensity due to cytotoxic edema
C. Hyperdensedense basilar or middle cerebral
artery corresponding to thrombus in the
affected vessel.
D. Dysplastic areas of calcification
E. Sulcal effacement
Which of the following is NOT true concerning
subarachnoid hemorrhage?
A. Appears as high density within sulci and
cisterns.
B. Noncontrast CT is the imaging of choice for
suspected SAH.
C. The rehemorrhage rate of a SAH is low.
D. Cerebral angiography is the “gold standard.”
E. Subarachnoid hemorrhage occurs most
commonly with trauma
Trauma
17 y/o status-post MVA
CT head w/o contrast
Skull Fracture
The bone windows must be examined carefully.
A skull fracture is most clinically significant if the
paranasal sinus or skull base is involved.
– Raccoon Eyes
– Battle’s Sign
Skull fractures are categorized as linear or
depressed
– Linear fractures are more common, resembling a
thin line w/o distortion or depression of bone
– Depressed fractures are breaks in bone with
depression of bone in towards brain
Linear skull fracture of the right parietal bone
(arrows).
Fractures must be distinguished from sutures that
occur in anatomical locations (sagittal, coronal,
lambdoidal) and venous channels.
– Sutures have undulating margins
– Both sutures and venous channels have sclerotic
margins.
– Venous channels have undulating sides
55 y/o male fell from roof
CT head w/o contrast
Traumatic Intraventricular
Hemorrhage
Intraventricular hemorrhage (arrow) found
in a trauma patient. Note the subarachnoid
hemorrhage in the sulci in the
subarachnoid space (arrowheads).
•Traumatic intraventricular hemorrhage is associated
with diffuse axonal injury, deep gray matter injury, and
brainstem contusion.
•An isolated intraventricular hemorrhage may be due to
rupture of subependymal veins.
•As you can see, this patient also has a SAH, which, if
you remember, is most commonly caused by TRAUMA!
-The ruptured vessel bleeds into the space between
the pia and arachnoid matter.
-The most common location of posttraumatic
subarachnoid hemorrhage is over the cerebral
convexity.
-This may be the only indication of cerebral injury.
47 y/o alcoholic “found down”
CT head w/o contrast
Subdural Hematoma
Deceleration and acceleration or rotational
forces that tear bridging veins can cause an
acute subdural hematoma.
The blood collects in the space between the
arachnoid matter and the dura matter.
Subacute
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Compressed lateral ventricle
Effaced sulci
White matter “buckling”
Thick cortical “mantle”
Acute
High density, crescent shaped hematoma
overlying the left cerebral hemisphere. Note the shift of
the normally midline septum pellucidum due to the mass
effect
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Crescent shaped, concave toward brain
Tapering edges
Crosses suture lines
May extend into interhemispheric fissure
Fracture may or may not be present
Hyperdense, may contain hypodense foci due to
serum, CSF or active bleeding
19 y/o post fist fight-5 hours later
has acute LOC
CT head w/o contrast
Epidural Hematoma
An epidural hematoma is usually
associated with a skull fracture.
The fractured bone lacerates a dural
artery or a venous sinus.
Most common artery involved is the
middle meningeal artery
The blood from the ruptured vessel
collects between the skull and dura.
Biconvex mixed hyperdense and hypodense
lesion overlying the left frontal cortex. Notice
that it does not cross suture lines.
– Hyperdense, lens shaped (lenticellular)
biconvex mass
– Abrupt edges
– Does not cross sutures
– Cannot extend into interhemispheric
fissure
47 y/o status-post car vs. tree
CT head w/o contrast
Diffuse Axonal Injury
Hemorrhage of the posterior limb of the internal capsule
(arrow) and hemorrhage of the thalamus (arrowhead).
Diffuse axonal injury is often referred to as "shear
injury“, caused by acceleration, deceleration, and
rotational forces
Portions of the brain with different densities move
relative to each other resulting in the deformation
and tearing of axons.
Immediate loss of consciousness is typical of these
injuries.
The CT of a patient with diffuse axonal injury may be
normal despite the patient's presentation with a
profound neurological deficit.
May appear as ill-defined areas of high density or
hemorrhage in characteristic locations, listed from
most likely location first followed by successively
less likely locations:
- Subcortical white matter
- Posterior limb internal capsule
- Corpus callosum
- Dorsolateral midbrain
92 y/o restrained driver in MVA
CT head w/o contrast
Cerebral Contusions
Multiple foci of high density corresponding to
hemorrhage (arrows) in an area of low
density (arrowheads) in the left frontal lobe
due to cerebral contusions.
Cerebral contusions are the most common primary
intra-axial injury, caused by coup/contrecoup injury
They often occur when the brain impacts an
osseous ridge or a dural fold. Multiple petechial
hemorrhage or edema are located along gyral
crests.
The following are common locations:
- Temporal lobe - anterior tip, inferior surface,
sylvian region
- Frontal lobe - anterior pole, inferior surface
- Dorsolateral midbrain
- Inferior cerebellum
On CT, cerebral contusion appears as an ill-defined
hypodense area mixed with foci of hemorrhage.
After 24-48 hours, hemorrhagic transformation or
coalescence of petechial hemorrhages into a
rounded hematoma is common.
Which of the following is NOT true concerning acute
subdural hematoma?
A. Tearing of bridging veins causes acute subdural
hematoma.
B. The hematoma is lenticellular in shape on CT.
C. The hematoma is crescent shaped on CT.
D. The hematoma may extend into hemispheric fissure
The most common cause of
subarachnoid hemorrhage is trauma.
A. True
B. False
Which of the following is NOT a characteristic of
subacute subdural hematoma?
A. Compression of the lateral ventricle on the side of the
hematoma.
B. Effaced sulci.
C. White matter buckling.
D. Thick cortical mantle.
E. Insular ribbon sign.
Which of the following is NOT true regarding a epidural
hematoma?
A.
B.
C.
D.
Caused by laceration of dural artery or venous sinus
Not usually associated with a skull fracture.
Blood collects between the skull and the dura
Blood does not cross suture lines
Which of the following is NOT true concerning
subacute subdural hematoma?
A. Contrast is often used to visualize the hematoma on CT.
B. It should be suspected when there is a midline shift of
structures without an obvious mass present.
C. On CT, the hemorrhage is hyperdense to normal
gray matter.
D. Blood collects in the space between the arachnoid
matter and the dura matter.
Tumor
65 y/o WM with mental status
changes and left sided weakness
CT head w/o contrast
CT head with contrast
Glioblastoma Multiforme
Glioblastoma Multiforme is the most
aggressive grade of astrocytoma.
On CT, GBM is characterized by necrosis
and irregular enhancement.
It is one of very few lesions that frequently
cross the corpus callosum.
Differentiating Intra-axial tumors:
An image post contrast administration in
the same patient reveals patchy
enhancement, a portion of which is
crossing the corpus callosum (arrow).
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Tumor completely surrounded by brain
Effaced CSF spaces
Gray–white junction not displaced inward
Cortical vessels not displaced inward
Bone normal
(rare: remodeling of inner table in cortical
tumors)
23 y/o with new onset seizures
T1 MRI
T2 MRI
Meningioma
Meningiomas are the most common
extra-axial neoplasm of the brain.
Twenty percent of meningiomas
calcify.
On CT, meningiomas are usually
isointense to gray matter.
Differentiating Extra-axial tumors
On this T2 weighted MRI this meningioma is extra-axial and
compressing adjacent brain structures, displacing the graywhite junction inward. Notice the “crinkling” of the displaced
brain.
– Tumor borders on CSF space
– Enlarged CSF spaces at edges of
mass
– Gray–white junction displaced inward
– Cortical vessels displaced inward
– Bone may have hyperostosis
(meningioma) or remodeling
53 y/o male with hx of melanoma,
with headache and gait disturbance
CT head w/o contrast
CT head with contrast
Metastatic Tumors
Metastatic tumors are the most
common intracranial tumors in adults.
Most common sites are from lung,
breasts, melanoma, renal, and colon.
Mets commonly occur at the
corticomedullary junction, and the
edema pattern is usually larger than
the tumor
Unenhanced and enhanced CT show
multiple high attenuation lesions without
contrast, with enhancement after contrast,
as well as surrounding edema
True or False
1. Lymphomas are the most common extra-axial neoplasm of the
brain.
A. True
B. False
2. On CT, meningiomas are usually isointense to gray matter.
A. True
B. False
3. MRI is more sensitive than CT for meningioma.
A. True
B. False
4. Like most tumors, glioblastoma multiforme does not cross the
corpus callosum.
A. True
B. False
5. On CT, glioblastoma multiforme is characterized by necrosis
and irregular enhancement.
A. True
B. False
Degenerative
74 y/o male with chronic memory loss
and impaired executive function
CT head w/o contrast
Alzheimer’s
In this CT, you can see enlarged
ventricles with atrophy of the cerebral
hemispheres without any other visible
causes of the dementia
Because of its low sensitivity and specificity for
the diagnosis of Alzheimer's disease, imaging
is typically not used to rule in Alzheimer's
disease but rather to rule out other causes of
dementia.
Nevertheless, in the right clinical context
Alzheimer's disease appears radiographically
as diffuse cerebral atrophy with enlarged
lateral ventricles and widened sulci on CT.
Large cortical neurons in the transentorhinal
region are the major types of neurons that
undergo this degeneration. This process
begins focally in the fronto/temporal lobes
(primarily the entorhinal cortex and
hippocampal regions) succeeded by the
parietal lobes and finally the occipital lobes.
The neuronal loss is severe resulting in
marked, diffuse atrophy that may be as much
as 10-30% of the total brain mass
95 y/o with dementia
CT head w/o contrast
Cerebral Atrophy
Cerebral atrophy refers to the wasting away
of brain tissue and cells that occurs as part
of normal aging
It is important to distinguish if atrohy is
“normal for patient age”
See widening of sulci and narrowing of the
gyri
Cerebral atrophy can also be secondary to
CT shows diffuse atrophy with
widened Sylvian cisterns
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Stroke
Alzheimer’s
Pick’s Disease
Infectious
Huntington’s
Cerebral palsy
Drugs
HIV
65 y/o male with resting tremor and
masked facies
T2-MRI
Parkinson’s Disease
The arrows indicate areas of decreased
width of the low signal intensity pars
compacta within the substantia nigra.
A clinical syndrome, Parkinson's disease is
clinically evident by its triad of bradykinesia
and hypokinesia, resting tremor, and
increased tonicity of voluntary musculature
and loss of postural reflexes.
There is a selective loss of neuromelanin
containing dopaminergic neurons within the
pars compacta of the substantia nigra, and
the disease manifests itself when 80% of
these neurons are lost.
Radiographically Parkinson’s disease
appears as nonspecific atrophy with enlarged
lateral ventricles and widened sulci on CT.
On MR, decreased width of the pars
compacta between the pars reticularis and
the red nucleus may be evident.
There is no cure for Parkinson's disease.
52 y/o male with spastic flailing of
extremities
CT head w/o contrast
Huntington’s Disease
The image on the left exhibits bilateral
caudate head atrophy (red arrowheads),
as seen by a decrease in the medial
convexities, & lateral ventricle dilatation.
Generalized atrophy evident as diffusely
widened sulci is also apparent in the image
on the left
Huntington’s disease is a progressive
neurodegenerative disorder characterized by
choreoathetoid movements, behavioral disturbances,
and progressive dementia.
Huntington's disease is a known genetically linked
disorder with autosomal dominant inheritance and
complete penetrance.
Huntington's disease is caused by a trinucleotide
repeat that is found within the huntingtin gene
located on chromosome 4.
Grossly changes are initially manifested by striatal
atrophy
Degeneration occurs most prominently in the
caudate tail followed by the body, head, and
eventually the putamen and nucleus accumbens.
By the time the disease reaches its terminal phases,
20-30% of the total brain mass may be reduced.
There is no cure for Huntington's disease, and it is
universally fatal.
72 y/o male preacher with
seductive behaviors, cussing, and
dementia
CT head w/o contrast
Pick’s Disease
Focal bifrontotemporal atrophy can be seen,
as exhibited by marked widening of the frontal and
temporal sulci, dilation of the lateral ventricles, and
the "knife-like" projections of the gyri.
Pick’s Disease is a neurodegenerative
disorder that is clinically evident as
behavioral and language disturbances
out of proportion to memory deficits.
Following Alzheimer’s disease and
diffuse Lewy body disease, Pick’s
disease is the third most common
neurodegenerative cortical dementia.
Due to severe neuronal loss and
gliosis, atrophy becomes readily
apparent in those regions of the cortex
most commonly affected, the frontal
and temporal lobes.
This atrophy may be asymmetric.
Currently there is no treatment.
Imaging is typically used to rule in the
diagnosis of Alzheimer's disease.
A. True
B. False
Huntington's disease is characterized by
the selective degeneration of neurons
within the striatum.
A. True
B. False
The process responsible for Alzheimer's disease
begins focally in the _______________.
A. parietal lobes
B. occipital lobes
C. fronto/temporal lobes
D. brainstem
On axial T2-weighted MRI, decreased
width of the pars compacta may be
evident in patients with Parkinson's
disease.
A. True
B. False
On CT, Huntington's disease appears as
_________________________________.
A. Decrease in the convexity of the caudate heads
bilaterally.
B. Decrease in the relative volume of the lateral
ventricles.
C. Both A and B.
D. Neither A nor B.
On CT in Pick's disease, one might observe which of
the following?
A. widening of the Sylvian fissure
B. atrophy of the inferior frontal and superior temporal
lobes
C. sulcal prominence
D. enlargement of the frontal horns of the lateral
ventricles
E. all of the above
Infections
5 month old with HA, neck stiffness,
and photophobia
Meningitis
Three subtypes of meningitis.
– Acute pyogenic meningitis is usually bacterial.
– Lymphocytic meningitis is usually viral, benign and
self-limited.
– Chronic meningitis is often seen in
immunocompromised hosts and may be fungal or
parasitic.
Imaging usually on done to look for complications
and assess for safety of LP
Imaging is usually normal, so it is not usually
performed for diagnosis
Diffuse leptomeningeal enhancement can
be seen overlying the cortex
Meningitis
Common complications of meningitis that can be seen using
imaging techniques:
–
–
–
–
–
–
Hydrocephalus
Ventriculitis/ Ependymitis
Subdural effusion
Subdural empyema
Cerebritis/ Abscess
Vasospasm
The development of cerebrovascular problems is the most common
complication of meningitis.
– Arterial infarction can occur which often affects the basal ganglia due to
the occlusion of small perforating vessels.
– Hemispheric infarction can also occur due to major vessel spasm.
– Venous infarctions are also common and can include cortical venous
occlusion or the involvement of the superior sagittal sinus.
23 y/o male with acute mental
status change
CT head w/o contrast
DWI-MR
Herpes Encephalitis
MRI with DWI highly sensitive
CT may be negative or misinterpreted as
infarct/tumor early in course
Anterior temporal lobes, basal frontal
lobes, cingulate cortex, insular cortex
(limbic system)
Spares basal ganglia
Bilateral ~ 50%
Hemorrhage or enhancement not until
subacute or chronic phase
As you can see, CT appears normal,
but on DWI MR, the right temporal lobe
lights up (arrow)
19 y/o male with hx of meningitis
with continued fever and confusion
CT head with contrast
Ventriculitis/Ependymitis
In this post contrast CT scan, note the ring
enhancing brain abscess (arrowheads) and
enhancement of the ependymal lining of the atrium
by the left lateral ventricle (arrow)
Ventriculitis is characterized by
inflammation and enlargement of the
ventricles.
Ependymitis shows hydrocephalus with
damage to the ependymal lining and
proliferation of subependymal glia.
A CT of patients with these conditions
reveals the presence of periventricular
edema and subependymal
enhancement.
Ventriculitis and Ependymitis affect
approximately 30% of the adult
patients and 90% of the pediatric
patients with meningitis.
35 y/o female with HA and fever
T1-MRI with Gad
Brain Abscess
Ring enhancing mass(es) with
edema
Location: anywhere, often gray-white
junction
Wall of abscess uniform width; may
be thinner at deep margin
– Ddx: Necrotic glioma, metastases
(irregularly thick, nodular walls)
CT & MR with contrast both highly
sensitive
– DWI: very bright in abscess
Notice the mass ring enhancing
mass (arrows) with surrounding
edema
Ddx: necrotic tumor
– MR spectroscopy accurate for abscess
vs. necrotic tumor
35 y/o AIDS patient with fever, HA,
and seizures
Toxoplasmosis
Caused by a single celled parasite
called Toxoplasma gondii
Typically seen in immunocompromised
or infants born to mothers with an
active infection during pregnancy
May infect the brain, lung, heart, eyes,
or liver
May appear as multiple ring enhancing
lesions
MRI is considered the best imaging
technique for toxoplasmic encephalitis
Multiple ring enhancing lesions seen at
many levels (arrows)
Ring-enhancing brain lesions
Lots of things can show up as ring-enhancing
lesions, so even though it sounded really cool in
medical school, it is really not very specific!
“MAGICAL DR”
–
–
–
–
–
–
–
–
–
Metastasis
Abscess
Glioblastoma/high grade glial neoplasm
Infarct (subacute; esp. in deep gray nuclei)
Contusion (subacute)
AIDS (Toxo)
Lymphoma (in immunocompromised)
Demyelinating lesion
Resolving hematoma (subacute)
Imaging studies of patients with
meningitis are frequently normal
despite the presence of the disease.
A. True
B. False
Typical findings on CT of patients with
ventriculitis or ependymitis are
periventricular edema and
subependymal enhancement.
A. True
B. False
Which of the following is NOT true concerning
cerebrovascular complications of meningitis?
A. The development of cerebrovascular problems is the
most common complication of meningitis.
B. Arterial infarction can occur and often affects the
basal ganglia.
C. Major vessel spasm can occur causing hemispheric
infarction.
D. Complications of meningitis can include cortical
venous occlusion.
E. Venous infarctions resulting from meningitis do not
involve the superior sagittal sinus.
A ring enhancing lesion is diagnostic of
toxoplasmosis
A. True
B. False
Other
67 y/o male with gait disturbance,
dementia, and urinary incontinence
CT head w/o contrast
Hydrocephalus
Abnormal buildup of CSF in the brain
Two types
– Communicating
Inadequate reabsorption of CSF
Nonobstructing
– Noncommunicating
Blockage of CSF
Can be associated with
CT shows enlargement of bilateral
lateral ventricles with shrinking of
adjacent brain matter
–
–
–
–
–
–
–
Tumors
Trauma
Meningitis
Arachnoid cysts
Congenital
SAH
Normal pressure hydrocephalus
38 y/o female with numbness in
LUE
T2 MRI
T2 MRI
Multiple Sclerosis
MRI: imaging study of choice
MS is due to myelin loss in multiple areas
leading to sclerosis
Small, discrete white matter lesions:
– Periventricular (esp. perpendicular to
ventricle)
– Peripheral brainstem
– Undersurface of corpus callosum
– Subcortical white matter
Variable enhancement; usually no edema
T2 weighted MRI showing “plaques”
(arrows) in both the brain and the
spinal cord
Final Quiz
(cross your fingers, because you’re
almost done!)
Question 1: Which of the following is NOT true
concerning epidural hematoma?
A. Epidural hematoma is caused by the laceration of a
dural artery or venous sinus by a fracture.
B. The hematoma may cross suture lines.
C. On CT, the hematoma forms a hyperdense, biconvex
mass.
D. On CT, the hematoma may contain hyperdense foci
due to active bleeding.
E. The hematoma may cross dural reflections.
Explanation: An epidural hematoma occurs when an artery ruptures and
blood collects between the dura and the skull. At suture lines, the dura
tightly adheres to the calvarium. Since an epidural hematoma does not
cross these tight junctions occur, it is not seen crossing suture lines.
Question 2: Which of the following is NOT true
concerning cerebral contusion?
A. Cerebral contusion often occurs when the brain
impacts an osseous ridge or dural fold.
B. On CT, cerebral contusions appear as ill-defined
hypodense areas.
C. On CT, cerebral contusions are often mixed with foci
of hemorrhage.
D. After 1 to 2 days, coalescence of petechial
hemorrhages into a rounded hematoma is common.
E. The occipital, temporal, and parietal lobes are the
most common locations of cerebral contusion.
Explanation: Cerebral contusions most commonly occur in the anterior
tip, the inferior surface and sylvian region of the temporal lobe, the
anterior pole and inferior surface of the frontal lobe, the dorsolateral
midbrain, and the inferior cerebellum.
Question 3: Which of the following is NOT true
concerning diffuse axonal injury?
A. Diffuse axonal injury can present with a normal head
CT.
B. Diffuse axonal injury is the most common cause of
morbidity in CNS trauma.
C. Diffuse axonal injury is often associated with
intraventricular hemorrhage.
D. On CT, diffuse axonal injury appears as ill-defined
areas of high density or hemorrhage.
E. Acceleration, deceleration, and rotational forces
cause diffuse axonal injury.
Explanation: On CT, diffuse axonal injury occurs as ill-defined areas of
low density. The often accompanying hemorrhage appears as bright
spots of high density.
Question 4: Given the following
CT, the most likely diagnosis
is:
A. Diffuse axonal injury.
B. Subarachnoid hemorrhage
over cerebral convexities.
C. Subdural hematoma.
D. Hypertensive hemorrhage
in the occipital lobe.
Explanation: The arrows in the image indicate the areas of high density
that correspond to hemorrhage over cerebral convexities.
Question 5: The CT on the top,
taken prior to contrast
administration and the CT on
the bottom, taken after
contrast administration, show:
A. Epidural hematoma.
B. Subarachnoid hemorrhage.
C. Glioblastoma multiforme
D. Subdural empyema.
Explanation: The gliobastoma in the right
frontal lobe is outlined by arrows in the
images here. Notice the enhancement of the
edges of the tumor upon contrast
administration (bottom), and how the tumor
crosses into the left hemisphere.
Question 6: Given the following
head CT, the most likely
diagnosis is:
A. Acute subdural hematoma.
B. Epidural hematoma.
C. Chronic subdural
hematoma.
D. Subarachnoid
hemorrhage.
Explanation: The arrowheads outline the high-density, crescent-shaped
hematoma overlying the right cerebral hemisphere. Note the hypodense
region (red arrow) within the high-density hematoma (blue arrows),
which may indicate active bleeding. The high density and active bleeding
are indicative of an acute subdural hematoma.
Question 7: Given the following
head CT, the most likely
diagnosis is:
A. Hypertensive hemorrhage
in the frontal lobe.
B. Subarachnoid
hemorrhage over
cerebral convexities.
C. Diffuse axonal injury.
D. Intracranial tumors.
Explanation: The arrows indicate the hemorrhage in the subcortical white
matter of the left frontal lobe. Such hemorrhage often accompanies
diffuse axonal injury, the direct evidence of which (ill-defined areas of low
density) is not always apparent on CT. (see question 3)
Question 8: Which of the
following is NOT shown
in this CT?
A. Intraventricular
hemorrhage
B. Subarachnoid
hemorrhage
C. Diffuse hypodensity
D. Diffuse axonal injury
Explanation: The intraventricular hemorrhage is clearly visible as the
high density blood in the left lateral ventricle. The area of high density in
the left cerebral hemisphere is the location of the subarachnoid
hemorrhage (red arrow). Areas of low density around the subarachnoid
hemorrhage are diffuse hypodensity as a result of edema (blue arrow).
Question 9: Which of the following is NOT an
advantage to performing a CT scan for stroke?
A. CT can be rapidly performed.
B. It is always possible to distinguish between old and
new infarcts.
C. CT allows easy exclusion of hemorrhage.
D. CT allows the assessment of parenchymal damage.
Explanation: It is not always easy to distinguish between old and new
infarcts. MR is a better in this regard. Other disadvantages of CT are its
current lack of functional information and limited ability to evaluate the
vertebrobasilar system.
Question 10: Which of the following is NOT true
concerning CT?
A. CT is the imaging modality of choice for the detectiing
of subarachnoid hemorrhage.
B. Small subarachnoid bleeds may be inapparent.
C. On CT, subarachnoid hemorrhage appears as high
density within sulci and CSF cisterns.
D. CT becomes more sensitive days to weeks after the
acute phase of a subarachnoid hemorrhage.
Explanation: Blood is reabsorbed from CSF days to weeks after the
acute phase of a subarachnoid hemorrhage. As this occurs, the
hemorrhage becomes isodense to the brain. Thus, CT becomes less
sensitive in detecting subarchnoid hemorrhage.