N806 and ct head

 CT radiology
 CT anatomy
 Glossary of terms
 Clinical indications
 Systematic interpretation
 Head trauma
 Stroke
 Tumor

 Brain mets/tumor
 Infection/abscess
 Nodes/masses
 Pulmonary embolism
 Abdomen/pelvis

Note how the subdural bleed (left side) has compressed the ipsilateral
ventricle resulting in a compensetory expansion of the contralateral
ventricle.

Used with permission by the CRASH Trials with credit to Mr. J. Wasserberg and Mr. B. Mitchell

 Terms beginning with A – M
 Terms beginning with N - Z

 Amnesia  Cistern(s)
 Corpus callosum
 Arachnoid granulations  Dorsum Sellae
 Arachnoid membrane  Dura mater
 Basal ganglia  Falx cerebri
 Basilar Artery  Globus pallidus (see basal
ganglia)
 Calvarium  Gyrus
 Caudate (see basal  Herniation
ganglia)  Insula/insullar ribbon
 Internal capsule
 Cerebellum  Lentiform nuclei (see basal
 Cerebral cortex ganglia)
 Choroid plexus  Medulla
 Midbrain
 Circle of Willis

 Process where by increased intracranial pressure
forces brain parenchyma through a fixed opening.
 Clinical scenarios:
 Transtentorial herniation (aka “uncal” herniation)
▪ Medial temporal lobes (uncus) and brainstem are forced through
the tentorium
▪ Symptoms include headache, decreased consciousness, pupillary
dilation and may progress to extensor posturing and death
 Cerebellar herniation (rare)
▪ Cerebellar tonsils are “pushed” into the foramen magnum
▪ Similar symptoms as transtentorial herniation

 The cerebrum is the largest part of the brain and is
responsible for thought and abstraction.
 The cerebrum is divided in four “lobes”. Some
authors include the insula as the fifth “lobe” of the
cerebrum
 The outer layer of the cerebrum (cortex) is gray
matter (lacks myelin)

 Anterograde amnesia = Loss of memory for an event
or events immediately following a head injury.

 Retrograde amnesia = Loss of memory for an event or
events preceeding a head injury.

 From the Greek Arachnoid granulations
arakhnoeid’s,
(cobweblike)
 Villous projects of
the pia-arachnoid
membrane whose
function is to
absorb CSF and
return it to the
venous circulation
via the superior
saggital sinus.

 A thin membrane
adherent to the dura
mater.
 The arachnoid
membrane is the middle
layer of the three
meningial layers (dura
mater, arachnoid
membrane, and pia
mater) that surround the
brain and spinal cord.

 The basasl ganglia consists of three gray matter
structures (caudate, putamen, and globus pallidus)
deep within cerebral hemispheres
 Lentiform nuclei = putamen and globus pallidus
 Functions as motor relay stations
 Pathology in the basal ganglia results in
purposeless movements (Parkinson’s disease)

 The basilar artery provides blood to the posterior
aspect of the Circle of Willis and is formed from the
paired vertebral arteries. Supplies blood to the
pons, cerebellum, and posterior cerebrum.

 The circle of Willis is a term used to describe
the arterial supply for the brain. The circle is
derived from the two internal carotid arteries
as well as the basilar artery, the latter being
the continuation of the two vertebral arteries.

 The bony
“roof” of the
skull; also know
as the “skull
cap”.

 The cerebellum is that portion of the brain that is
involved with coordination of voluntary movement,
balance, and muscle tone.

 Connects the brainstem with the forebrain and is
involved in the control of sensory processing

 Ventricluar tissue (ependyma) that produces
cerebral spinal fluid (CSF).

 From Latin (“box”).
 A well defined collection of CSF within the
subarachnoid space (located between the pia and
arachnoid membranes).
 Several cisterns are generally described and two
are of importance in the CT head:
 Suprasellar - (Star-shaped) Location of the Circle of Willis
 Quadrigeminal - W-shaped at top of midbrain

 The corpus callosum is the structure that
connects the left and right cerebral
hemispheres.

 The dorsum sellae is the square shaped part of
the sphenoid bone that forms the posterior
boundary of the pitutary fossa.

 Latin (“hard Dura Mater Epidural hematoma
Brain
mother”)
 The outer,
fibrous
portion of
the
meninges.

 A reflexion of the dura
mater located between
the cerebral
hemispheres. Function
is to provide support to
the cerebral
hemispheres.

 The rounded, elevated convolutions on the surfaces
of the cerebral hemispheres.

 The insula is one of the
five cerebral cortices
(frontal, parietal,
temporal, occipital,
insular) and is located
deep to the frontal,
parietal, and temporal
lobes. Function is to
integrate autonomic
functions.

 Collection of axons
that carry sensory
information to the
cortex and motor
information to the
cord.
 The internal
capsule is very
sensitive to stroke

 Aka “medulla oblongata”
 Located in the brain stem and sits below the
pons and in front of the cerebellum.
 Functions to help control autonomic function,
especially heart rate and breathing.

 Includes the midbrain, pons, and medulla.
Major function is survival (breathing,
digestion, heart rate, blood pressure) and for
arousal (being awake and alert).

 Occipital lobe  Septum pellucidum
 Parenchyma  Sulcus
 Parietal lobe  Suture(s)
 Pineal gland  Temporal lobe
 Pneumocephalus  Tentorium cerebelli
 Pons  Thalamus
 Posterior fossa  Uncus
 Putamen (see globus  Ventricle(s)
pallidus)
 Sagittal sinus

 Pneumocephalus (see
red arrow) is the
presence of air (or gas)
within the cranial
cavity and is usually
associated with a
basilar skull fracture

 The sutures are fibrous connections between
bones of the skull
 Sutures allow for some flexibility of the
cranium
 Fontanelles (aka “soft spots”) are unfused
areas where sutures meet
 Sutures ossify at various times throughout
life

 The pons sits between the brainstem and
medulla
 Controls rate and depth of breathing
 Relays impulse from medulla to cerebrum
 Clinical pathology results in:
 Bilateral, fixed, pinpoint pupils (comatose patient)
 Cheyne-Stokes breathing
▪ Hyperventialtion followed by apnea

 The uncus is the medial (innermost) portion
of the temporal lobe
 Under high intracranial pressure (ICP) the
uncus can be involved in a transtentorial
herniation syndrome
 ICP pushes the uncus through the tentorium
cerebelli which results in compression of the
brainstem

1. The brain squeezes under
the falx cerebri in
cingulate herniation
2. The brainstem herniates
caudally
3. The uncus and the
hippocampal gyrus
herniate into the tentorial
notch
4. The cerebellar tonsils
herniate through the
foramen magnum in
tonsillar herniation

 The ventricles are CSF-containing cavities
 Provides a protective cushion (buoys the
brain)
 CSF produced in roof of ventricles (choroid
plexes)
 Circulation of CSF through ventricles and
around the brain (subarachnoid space) and
cord (central canal) with reabsorption in
arachnoid villi

 The thalamus is the central relay station for
sensory fibers (except olfactory)
 Cerebral cortex communicates with thalamus
 Responsible for primitive emotional responses
 Fear
 Pleasant vs. unpleasant stimuli

 The temporal lobes are one of the five cortical
lobes
 The temporal lobes are responsible for hearing,
speech, and some emotional and memory
functions

 Lain – “groove” or “trench”
 Pleural – “sulci” (sul-sigh)
 The small cracks or dimples on the surface of the
brain

 The septum
pellucidum is a thin
midline structural
membrane
 The septum runs
vertically between the
lateral ventricles as
well as inferiorly from
the corpus callosum

 Aka “superior sagittal sinus”
 Large collection of venous blood above and behind the
brain
 Attached to the falx cerebri
 Receives CSF from the arachnoid granulations

 The posterior fossa is an area within the intracranial
cavity bound by the tentorium cerebelli above and
foramen magnum below
 The posterior fossa contains the cerebellum and
brainstem structures

 Aka “pineal body”
 The pineal glad is an endocrine gland that
produces melatonin and is important in sleep-wake
cycles

 The parietal lobe is the cortical lobe responsible for
sensation (cutaneous and muscular)
 Responsible for integration of thoughts and
feelings

 The functional tissue(s) (key elements) of an organ

 The occipital lobe is the cortical lobe responsible
for vision
 Integration areas for visual images with sensory
experiences.
 Dura matter (tentorium cerebelli) separates the
occipital lobe from the cerebellum

 The putamen is part of the basasl ganglia
 The basals ganglia consists of three gray matter
structures (caudate, putamen, and globus pallidus)
deep within cerebral hemispheres
 Lentiform nuclei = putamen and globus pallidus
 Functions as motor relay stations
 Pathology in the basal ganglia results in
purposeless movements (Parkinson’s disease)

 CT head is currently the procedure of choice for
evaluation of suspected stroke
 Stokes are either hemorrhagic (minority) or
nonhemorrhagic (vast majority of cases)
 Nonhemorrhagic strokes = “ischemic” strokes
 The latter, if diagnosed quickly, can (potentially) be
treated with thrombolytic agents
 The CT can reliably serve to rule out intracranial
hemorrhage
 The CT is examined for evidence of vascular
occlusion (clots), edema, and hemorrhage

 General considerations
 Stroke anatomy
 Hemorrhagic CVA
 Nonhemorrhagic (ischemic) CVA

 Cerebral vascular supply (Circle of Willis)
 The motor and sensory Homunculus
 Arterial supply and brain function

 CT findings

 CT scan of hemorrhagic CVAs
 Basal ganglia location
 Cerebellar location
 Gross pathology of cortical CVA

Hypertensive hemorrhage
in the basil ganglia

 Hemorrhagic strokes are due to rupture of a
cerebral blood vessel
 Bleeding can occur into or around the brain
 Blood may extend into the ventricular system
 Hemorrhagic strokes account for 16% of all
strokes
 Hypertensive hemorrhage accounts for
approximately 70-90% of non-traumatic primary
intracerebral hemorrhages

 Etiologies include thrombus, embolism, or
hypoperfusion
 Ischemic brain tissue becomes edematous
 Edematous tissue will appear hypodense on
noncontrast CT
 Hypodensity begins as early as 1h post-CVA
▪ Earliest sign of CVA is loss of gray-white differentiation (the "insular
ribbon" sign)
 Hypodensity is completely manifest by 12-24 hours post-
CVA

 Obscuration of the lentiform nuclei
 Hypoattenuation of the insular ribbon
 Sulcal effacement and cortical hypodensity
 Hyperdense vessel signs

 Lentiform nuclei =
globbus palladus and
putamen (parts of the
basal ganglia)
 Edema from ischemia
produces hypodenity of
basasl ganglia structures
within hours of event
 Red arrows denotes
hypodensity of the basal
ganglia structures
(compare to opposite
side)

 An occluded vessel
(thrombus) may
appear ”dark” on CT
 The red arrow
denotes a dense
basilar artery

 Red arrows point to
hypodensity and sulcal
effacement.
 Note the generalized
edematous appearance
of the tissues within
the middle cerebral
artery distribution

 Moderate - severe head trauma is an indication for a
CT head scan
 Some controversy exists as to when a CT should be
obtained for a “minor” head injury in adults:
 Canadian CT recommendations
 New Orleans Criteria
 For infants and children:
 Considerations
 General recommendations

 Things to Think About
 Interpretation Mnemonics
 Order of Evaluation (basic)
 Bone windows
 Blood (intracranial hemorrhage)
 Brain parenchyma
 Ventricles
 Cisterns

 Introduction
 CT considerations and clinical importance
 Diagrams
 Ventricular anatomy
 CSF circulation
 CT images
 Normal lateral ventricles
 Normal third ventricle
 Ventriculomegaly
 Ventricular compression and enlargement

 Brain parenchyma = brain “tissue”
 The brain parenchyma is symmetrical
 Gray and white matter should be well defined
 Edema results in poor delineation
 Midline structures (falx cerebri, third and fourth
ventricles) should not be deviated
 Deviated midline structures is evidence of mass effect =
edema, bleeding, tumor
 Check the parenchyma for evidence of blood

 CT images
 Normal midline structures
 Midline shift
 Cerebral edema

 Notice the
sharp
difference
between the
large
hypodense
edematous
(red arrows)
tissue and the
remaining
“normal”
cortical tissue

 Noncontrast study is standard
 A contrast study will be so designated on the CT images
 Most scanners are now “ultrafast” and can perform a
head CT in less than one minute
 Scan spans from the base of the occiput to the top of
the vertex in 5-mm increments
 Three sets of data are derived from the primary scan:
 Bone windows (fractures)
 Tissue windows (gray/white matter density)
 Subdural windows (brain bleed)

 Evaluation of head trauma
▪ Cerebral hemorrhages
▪ Skull fracture
 Suspected cerebrovascular accident (CVA)
 Suspected brain tumor
 Hydrocephalus

 Clinical syndromes
 CT indications versus MRI

 Progressive headaches associated with:
 Vomiting (especially early AM)
 Behavior changes

CT MRI
 Fast, easy, available, and  Slower and more expensive
relatively cheap  Soft tissue and joints
 Study of choice for  Spine and spinal cord
 Posterior fossa and orbits
suspected brain bleed
 Better for CNS
 Generally good for solid developmental
organs and bleeds applications
 Good study for chest,  Can’t be used with certain
abdomen, and pelvis pacemakers and (metal)
pathology implants
 Radiation exposure

 Relative Density (Attenuation)
 Radiation Exposure
 CT protocols
 Noncontrast (“standard”)
 With contrast (“enhanced”)

 IV contrast – general considerations
 Clinical indications
 Contraindications

 I.V. contrast is given to differentiate blood vessels
from soft tissue and organs
 Blood and falx appear white with contrast
 Original ionic contrast agents have largely been
replaced with nonionic agents (fewer reactions)
 Iodine reactions were actually responses to the carrier
molecule of the contrast rather than iodine
 Risk related to IV contrast:
 Anaphylaxis ~ 1:10,000
 Death ~ 1:40,000 – 100,000
 NPO X 4 hours before administration of IV
contrast
 Depends on urgency of exam

 Quick
 Easy
 Available
 Inexpensive (fairly)
 Standard of care for closed head injury
evaluation
 Shows bony calvarium well
▪ Bone windows can show fractures easily

“The five B’s” “Blood Can Be Very Bad”
 Blood  Blood = blood
 Brain  Can = cisterns
 Bone  Be = brain
 Balloons (ventricles)  Very = ventricles
 Boxes (cisterns)  Bad = bone

 Just like a standard X-ray, the CT shows
dense objects (bone) as white and less dense
objects (air) as black.
 The concept of relative density is known as
attenuation and is measured in Hounsfield
Units (HU)

Structure Hounsfield Units
 Bone + 1,000
 Blood + 50-100
 Gray matter + 32 - 46
 White matter + 22 - 36
 CSF + 4 - 10
 Water 0
 Air -1,000
Clincal caveat: The radioglogist can place the computer cursor
on any part of the CT image and determine the exact HU
density – a real time way to differentiate blood from abscess
from CSF, etc.

 The CT scan is a sophisticated x-ray that
literally takes a continuous x-ray as it moves
around the patient (tomogram)
 The X-ray source and detector unit are
situated opposite of each other
 360 degree movement around the patient
 Very thin x-ray beams are utilized
 The CT computer integrates the assembled x-
ray information and produces a “relative
density” map that we view as a gray-scale
image.

Type of Exposure Dosage (mSv)
 Background radiation 3 mSv/year
 CXR 0.1 mSv
 CT head 2 mSv
 CT chest 8 mSv
 CT abdomen and pelvis 20mSv

Caveat: A CT head is the equivalent of 20
CXRs, while a CT abdomen & pelvis equals
200 CXRs! Yikes!

 CT Description
 CT images
 Normal supracellar cistern
 Normal quadrigeminal cistern
 Compression of supracellar cistern (early)

Notice how the right uncus is pushing into the supracellar cistern.
Dx: Early uncal herniation from increased intracranial pressure

 From Latin (“box”)
 Collections of CSF within the subarachnoid space
(between the pia and arachnoid membranes)
 Cistern pathology is usually seen on CT as
compression or presence of blood
 Compression
▪ Increased intracranial pressure (herniation symndrome)
▪ Mass effect (tumor)

 Several cisterns are described but two are of
importance in the CT head:
 Supracellar cistern
▪ Star-shaped (“super star”)
▪ Location = Circle of Willis
 Quadrigeminal cistern
▪ W-shaped (looks like a baby’s bottom)
▪ Location = Level of tentorium cerebelli

A. Falx Cerebri
B. Frontal Lobe
C. Anterior Horn of Lateral Ventricle
D. Third Ventricle
E. Quadrigemina Cistern
F. Cerebellum

Can you visualize the
“baby’s bottom”?

 Notice how the
falx is deviated
(white arrow)
due to a space
filling lesion
(red outline)

 Developed from a series of patients ( > 16
years-of-age) presenting with minor head
injury (defined as GCS score of 13-15 after loss
of consciousness, definite amnesia, or
witnessed disorientation from trauma)
 Clinical criteria consist of five high-risk and
two moderate-risk factors.

Obtain CT Head if patient has > one the following
seven:
 GCS score lower than 15 two hours after injury
 Suspected open or depressed skull fracture
 Any sign of basal skull fracture
 Two or more episodes of vomiting
 Age 65 years or older
 Retrograde amnesia > 30 minutes
 Dangerous mechanism
 Motor vehicle involved
 Fall from a height of at least three ft or five stairs

 CT is needed if the patient > one of the following:
 Headache
 Vomiting
 Age older than 60 years
 Drug or alcohol intoxication
 Persistent anterograde amnesia (deficits in short-term memory)
 Visible trauma above the clavicle
 Seizure

*Applicable for adults with a normal Glasgow Coma Scale score of 15 and blunt
head trauma that occurred within the previous 24 hours that caused loss of
consciousness, definite amnesia, or witnessed disorientation.

 Evaluate the significance of the injury by physical
findings AND mechanism of injury
 Kids have heavy heads and weak necks
 Younger children are less likely to be symptomatic
 Signs of significant head injury can be subtle
(persistent irritability)
 Scalp hematomas in infants and toddlers suggest
significant injury

 All moderate and severe head trauma
 Any loss of consciousness
 Age under 3 months
 Skull fracture (intracranial injury in 15-30%)
 Scalp hematoma predicts fracture (>80% sensitivity)
 Depressed mental status
 Focal neurologic deficits
 Bulging fontanelle
 Persistent irritability after head injury
 Seizure following head injury
 Recurrent vomiting after injury

 Bone windows for fractures
 Brain tissue
 Hemorrhage or masses
 Symmetry
 Midline shift
 Edema
 Ventricles
 Compression, blood, or hydrocephalus
 Subarachnoid cistern compression

 The head contains four things (skull, brain,
blood, spinal fluid)
 The CT is reviewed to make sure all four are in the
right amount and location
 The brain is symmetrical; asymmetry is
abnormal
 The cerebral hemispheres are mirror image
structures - what is on the left should be on
the right

 Prior contrast reaction (“iodine allergy”)
 Poor renal function
 Creatinine > 2.0
 Lack of consent
 Suspend breast feedings for 24 hours
following I.V. contrast

Shellfish and/or Betadyne allergies
are not contraindications

A. Orbit
B. Sphenoid Sinus
C. Temporal Lobe
D. External Auditory Canal
A. Orbit E. E. Mastoid Air Cells
Mastoid Air Cells
B. Sphenoid Sinus F. F. Cerebellar Hemisphere
Cerebellar Hemisphere
C. Temporal Lobe
D. External Auditory Canal
Used with permission University of Virginia Health Sciences Center

A. Frontal Lobe
B. Frontal Bone
(Superior Surface of Orbit)
C. Dorsum Sellae
D. Basilar Artery
E. Temporal Lobe
F. Mastoid Air Cells
G. Cerebellar Hemisphere

A. Frontal Lobe
B. Sylvian Fissure
C. Temporal Lobe
D. Suprasellar Cistern
E. Midbrain
F. Fourth Ventricle
G. Cerebellar Hemisphere


A. Frontal Lobe
B. Falx Cerebri
C. Anterior Horn of Lateral
Ventricle
D. Third Ventricle
E. Quadrigeminal Plate
Cistern
F. Cerebellum

A. Anterior Horn of the Lateral Ventricle
B. Caudate Nucleus
C. Anterior Limb of the Internal Capsule
D. Putamen and Globus Pallidus
E. Posterior Limb of the Internal Capsule
F. Third Ventricle
G. Quadrigeminal Plate Cistern
H. Cerebellar Vermis
I. Occipital Lobe


A. Genu of the Corpus Callosum
B. Anterior Horn of the Lateral Ventricle
C. Internal Capsule
D. Thalamus
E. Pineal Gland
F. Choroid Plexus
G. Straight Sinus


A. Falx Cerebri
B. Frontal Lobe
C. Body of the Lateral Ventricle
D. Splenium of the Corpus Callosum
E. Parietal Lobe
F. Occipital Lobe
G. Superior Sagittal Sinus


A. Falx Cerebri
B. Sulcus
C. Gyrus
D. Superior Sagittal Sinus


Supracellar cisterrn
(can you visualize the “star” shape)

Fourth Ventricle
F = frontal lobes
U = uncus (medial temporal lobes)
Po = Pons

Dura (retracted)
Bridging vein(s)

1 - Anterior Fossa
2- Posterior Fossa
3- Frontal Sinus
4- Esphenoid Sinus
5- Tentorium Cerebelli

 Majority are due to aneurysms or
arterioventricular malformations (AVM)
 Bleeding is into the CSF space
 Ability to diagnose with CT decreases with
time:
▪ 95% positive at 12 hours
▪ 80% positive at 3 days
▪ 30% positive at two weeks

 Below the dura but above the arachnoid
 Usually venous in origin
 Commonly a ruptured bridging vein (dural drainage)
 Cresent or sickle shaped pattern on CT
 Can cross suture lines
 Common in elderly or anti-coagulated
 Density of blood determines the age of the bleed:
 Acute
 Chronic

 aka “intracerebral” hemorrhage
 Can follow hypertensive stroke
 Can follow deceleration (“contusion”) injuries
 Can extend into the ventricles (intracerebral
extension)

 Hemorrhage into the ventricular system
 Can be an extension of an intraparenchymal
or subarachnoid bleed
 Can be secondary to trauma (poor outcome)
 Not uncommon in extremely premature
infants
 Obstructive hydrocephalus can be a
complication

 Arterial blood
 Usually secondary to a linear skull fracture through an arterial
channel (like the middle meningeal artery)
 Biconvex shape (lens shaped)
 Bleeding may cross the midline
 Bleeding won’t cross suture lines
 A subdural and an epidural may occur together
 Epi vs. sub doesn’t matter – but volume does
 > 5 mm or > 10 mm in adults = surgical evacuation

Early ICP Findings Late ICP Findings
 Headache  Cushings triad
 Vomiting  Hypertension
 Vision distortion
 Bradycardia
 Decreased sensorium
 Papilledema possible
 Flexor/extensor
posturing
 Pupillary dysfunction

 Haydel MJ, Preston CA, Mills TJ, Luber S,
Blaudeau E, DeBlieux PM. Indications for
computed tomography in patients with minor
head injury. N Engl J Med. 2000;343:100-5.
 Stiell IG, et al. Comparison of the Canadian
CT Head Rule and the New Orleans Criteria in
patients with minor head injury. JAMA.
2005;294:1511-8.
 www.aafp.org/online/en/home/clinical/clinica
lrecs/headinjurychild.html

 Basic properties
 Skull fractures
 Suture lines versus fracture lines
 Basilar skull fracture
 Child abuse and skull fractures

 Fracture in any
location other than
parietal location
 Non-linear fracture
 Linear fracture length
exceeding 6 cm
 Fracture crossing
suture lines

 The bone windows information is part of the routine CT
head and is ideal for viewing fractures
 Sinuses can be seen well with bone windows
 The scout film of the CT scan is roughly the equivalent of
a lateral skull x-ray film – so look at it too
 Remember to look at the overlying soft tissue for
swelling as it may point to an underlying skull fracture

 Skull fractures may be classified as either linear or
comminuted
 Inwardly displaced comminuted = depressed skull fx
▪ A depressed skull fracture requires immediate neurosurgical
evaluation
 Cranial sutures can be confused with linear fractures

Suture Fracture
 Characteristic locations Usually
temperoparietal

 Symmetrical line on other side Asymmetrical

 Same size throughout Widest at the center/
narrow at the end

 Graceful curvy lines Straight lines with
angular turns

 A fracture of the orbital roof, sphenoid bone,
or mastoid portion of temporal bone
 Usually resolve on their own but can be:
 Displaced
 Cranial nerve damage (II, VII, VIII)
 CSF leak (otorhea or rhinorhea)
 “Classic” clinical findings may (or may not) be
present

 Hemotympanum
 Periorbital bruising ("raccoon eyes“)
 Cerebrospinal fluid otorrhea or rhinorrhea
 Battle's sign (Mastoid eccymoses)
 Pneumocephalus
 (Air and fluid/levels in sinuses)

 Superior to inferior
 Falx cerebri
 Body of lateral ventricles
 Internal capsule and thalamus
 Caudate and third ventricle
 3rd Ventricle and quadrigeminal cistern
 Supracellar cistern and 4th ventricle

Extra-axial hemorrhage Intra-axial hemorrhage
(outside the brain) (inside the brain)
 Subarachnoid (SAH)
 Epidural
 Below the arachnoid membrane
 Below the skull
 On the surface of the brain
 “above” the dura  Intraparenchymal (IPH)
 Subdural  Within the substance of the
 Below the dura brain
 Above the thin, spidery-like  Intraventricular (IVH)
arachnoid membrane  Within the ventricles

 CSF-filled balloons  CSF Direction of Flow:
 CSF is produced in the  Lateral ventricles
choroid plexes,  Foramen of Monroe
“circulates” through  Third ventricle
the ventricular system,  Cerebral aqueduct
percolates over the  Fourth ventricle
surface of the cord and  Foramen (Magendie and
brain, and is absorbed Lushka)
in the arachnoid  Subarachnoid space
granulations  Arachnoid granulations
 Venous circulation

 Size
 Large = too much fluid or brain atrophy
 Small = Compression (edema or mass)
 Symmetry
 Asymmetry = impingement from mass/edema, etc.
 Presence of blood
 IVH can lead to secondary hydrocephalus
 Anatomic landmarks
 Lateral and 3rd ventricle are supratentorial
▪ 3rd is located anterior to the pineal gland
▪ Looks like an exclamation point
 4th ventricle is infratentorial
▪ Looks like a pith helmet (roundish)

 Considerations
 Ventricular system
 CSF circulation
 CT images:
 Hydrocephalus
 Asymmetry (impingement from tumor)
 IVH

 A tough, fibrous structure separating the
cerebrum above and the cerebellum and
brain stem below
 Provides support for the cerebrum
 Structures above the tentorium are known as
supratentorial or anterior fossa
 Structures below the tentorium are known as
infratentorial or posterior fossa

Frontal Parietal Occipital Temporal

Note collection of blood above the dura mater

Dura mater

 Majority can be visualized without contrast
 Contrast is indicated if brain tumor is suspected and
not see on noncontrast study
 Appear as edematous, low density, poorly-
defined lesions
 Classified as intraaxial (within the brain tissue) or
extraaxial
 Adult tumors are usually supratentorial while
pediatric tumors are usually infratentorial
 Many metastatic tumors will be located at the
gray-white matter border(s)

 Brain tumors
 Meningioma
 Astrocytoma (pediatric)

 Cystic mass in the
midline of the
cerebellum (red
arrows)
 Note early
hydrocephalic
changes
secondary to
tumor
compression
(yellow arrows)

 Red arrow
points to a
large
cerebellar
hemorrhage


 Cocaine induced
hypertensive CVA
 Note the large
hemorrhagic lesion
in the left cortical
area as well as
multiple smaller
regions (redness)
near the
hippocampus and
other cortical
regions.

www.utsa.edu/tsi/assign/anat/neuropat.htm

 Loss of the gray-
white interface in
the lateral margins
of the insula
 The cortex of the left
insular ribbon is not
visualized (arrow).
 Right insular ribbon
is outlined in yellow

 Contrast enhanced CT
of meningioma (most
common extraxial
brain tumor)

A. Falx Cerebri
B. Frontal Lobe
C. Body of the Lateral
Ventricle
D. Splenium of the Corpus
Callosum
E. Parietal Lobe
F. Occipital Lobe
G. Superior Sagittal Sinus


Edema
 The darker gray
Edema
areas represent
Blood
Blood edema while the
white areas
represent the
intracerebral
contrusion
(“bruise”)


 Small red arrows point
to a biconvex epidural
hematoma secondary
to a skull fracture (large
red arrow)


 Red arrows denote
blood within the sulci
of the right cerebral
convexity


 The large red arrow
points to blood within
the ventricle while the
smaller red arrows
point to blood in the
sulci (subarachnoid
hemorrhage)


 Linear skull fracture
(parietal location)
found on bone
windows image

 The cortical areas of the
brain devoted to motor
(frontal motor strip) and
sensory (parietal sensory
strip) function can be
represented as an “upside”
down person.
 A disruption in cerebral
blood flow to these areas
will result in a
corresponding sensory
and/or motor deficit to the
corresponding region.

Artery Lobes Supplied Deficit

ACA Frontal Leg weakness

MCA Frontal Speech
Lateral Temporal Motor and sensory
Lateral Parietal to hand and arm

PCA Temporal Visual defects
Occipital

N806 and ct head

More Related Content

What's hot

Viewers also liked

Similar to N806 and ct head

Recently uploaded

N806 and ct head