Brain CT & MRI

Brain CT & MRI
6/12/2017 jalili.dr@gmail.com 1
E .brahim Jalili M.D - MPH
Assistant Professor of Emergency Medicine
Hamedan University of Medical Sciences

A. Orbit
B. Sphenoid Sinus
C. Temporal Lobe
D. External Auditory
Canal
E. Mastoid Air Cells
F. Cerebellar Hemisphere

A. Frontal Lobe
B. Frontal Bone (Superior
Surface of Orbital Part)
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. Falx Cerebri
B. Frontal Lobe
C. Anterior Horn of Lateral
Ventricle
D. Third Ventricle
E. Quadrigeminal Plate
Cistern
F. Cerebellu

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 Sinus6/12/2017 jalili.dr@gmail.com 9

Skull Fractures
• Skull fractures are categorized as linear or depressed, depending on
whether the fracture fragments are depressed below the surface of
the skull. Linear fractures are more common.
• The bone windows must be examined carefully.
• A skull fracture is most clinically significant if the paranasal sinus or
skull base is involved.
• 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.
• Depressed fractures are characterized by inward displacement of
fracture fragments.

• Linear skull fracture of the right parietal bone (arrows).

Subarachnoid Hemorrhage
• A subarachnoid hemorrhage occurs with injury of small arteries or veins on the surface
of the brain. The ruptured vessel bleeds into the space between the pia and arachnoid
matter.
• The most common cause of subarachnoid hemorrhage is trauma.
• In the absence of significant trauma, the most common cause of subarachnoid
hemorrhage is the rupture of a cerebral aneurysm.
• When traumatic, subarachnoid hemorrhage occurs most commonly over the cerebral
convexities or adjacent to otherwise injured brain (i.e. adjacent to a cerebral
contusion).
• If there is a large amount of subarachnoid hemorrhage, particularly in the basilar
cisterns, the physician should consider whether a ruptured aneurysm led to the
subsequent trauma.
• Cerebral angiography may be needed for further evaluation.
• On CT, subarachnoid hemorrhage appears as focal high density in sulci and fissures or
linear hyperdensity in the cerebral sulci.
• Again, the most common location of posttraumatic subarachnoid hemorrhage is over
the cerebral convexity. This may be the only indication of cerebral injury.

High density blood (arrowheads) fills the sulci over the
right cerebral convexity in this subarachnoid hemorrhage6/12/2017 jalili.dr@gmail.com 13

Acute 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.
• The hematoma on CT has the following
characteristics:
- Crescent shaped
- Hyperdense, may contain hypodense foci due to
serum, CSF or active bleeding
- Does not cross dural reflections

• High density, crescent shaped hematoma (arrowheads)
overlying the right cerebral hemisphere. Note the shift of the
normally midline septum pellucidum due to the mass effect arrow.6/12/2017 jalili.dr@gmail.com 15

• The hypodense region (arrow) within the high density
hematoma (arrowheads) may indicate active bleeding.6/12/2017 jalili.dr@gmail.com 16

Subacute Subdural Hematoma
• Subacute SDH may be difficult to visualize by CT because as the hemorrhage
is reabsorbed it becomes isodense to normal gray matter.
• A subacute SDH should be suspected when you identify shift of midline
structures without an obvious mass.
• Giving contrast may help in difficult cases because the interface between the
hematoma and the adjacent brain usually becomes more obvious due to
enhancement of the dura and adjacent vascular structures.
• Some of the notable characteristics of subacute SDH are:
- Compressed lateral ventricle
- Effaced sulci
- White matter "buckling"
- Thick cortical "mantle"

• Subacute subdural hematoma (arrowheads). Note the compression of
gray and white matter in the left hemisphere due to the mass effect.

Chronic Subdural Hematoma
• Chronic SDH becomes low density as the
hemorrhage is further reabsorbed.
• It is usually uniformly low density but may be
loculated.
• Rebleeding often occurs and causes mixed
density and fluid levels.

• Crescent shaped chronic subdural hematoma (arrowheads). Notice
the low attenuation due to reabsorbtion of the hemorrhage over
time.

• This chronic subdural hematoma (arrowheads) shows
the septations and loculations that often occur over time.6/12/2017 jalili.dr@gmail.com 21

Epidural Hematoma
• An epidural hematoma is usually associated with a skull fracture.
• It often occurs when an impact fractures the calvarium.
• The fractured bone lacerates a dural artery or a venous sinus.
• The blood from the ruptured vessel collects between the skull and
dura.
• On CT, the hematoma forms a hyperdense biconvex mass.
• It is usually uniformly high density but may contain hypodense foci
due to active bleeding.
• Since an epidural hematoma is extradural it can cross the dural
reflections unlike a subdural hematoma.
• However an epidural hematoma usually does not cross suture lines
where the dura tightly adheres to the adjacent skull.

• Biconvex (lenticellular) epidural hematoma (arrowheads),
deep to the parietal skull fracture (arrow).

Diffuse Axonal Injury
• Diffuse axonal injury is often referred to as "shear injury".
• It is the most common cause of significant morbidity in CNS trauma.
• Fifty percent of all primary intra-axial injuries are diffuse axonal injuries.
• Acceleration, deceleration and rotational forces cause portions of the brain
with different densities to 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.
• With CT, diffuse axonal injury may appear as ill-defined areas of high density
or hemorrhage in characteristic locations.
• The injury occurs in a sequential pattern of locations based on the severity of
the trauma.
• The following list of diffuse axonal injury locations is ordered with the most
likely location listed first followed by successively less likely locations:
- Subcortical white matter
- Posterior limb internal capsule
- Corpus callosum
- Dorsolateral midbrain

• Hemorrhage of the posterior limb of the internal capsule
(arrow) and hemorrhage of the thalamus (arrowhead).

• Hemorrhage in the corpus callosum (arrow).

Cerebral Contusion
• Cerebral contusions are the most common primary intra-axial injury.
• They often occur when the brain impacts an osseous ridge or a dural
fold.
• The foci of punctate 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.
• Adjacent subarachnoid hemorrhage is common.
• After 24-48 hours, hemorrhagic transformation or coalescence of
petechial hemorrhages into a rounded hematoma is common.

• Multiple foci of high density corresponding to hemorrhage (arrows)
in an area of low density(arrowheads) in the left frontal lobe due to
cerebral contusion.6/12/2017 jalili.dr@gmail.com 28

Intraventricular Hemorrhage
• 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.

• Intraventricular hemorrhage (arrow) found in a trauma patient.
Note the subarachnoid hemorrhage in the sulci in the subarachnoid
space (arrowheads).6/12/2017 jalili.dr@gmail.com 30

Hemorrhagic Stroke
• Hemorrhagic strokes account for 16% of all
strokes.
• There are two major categories of hemorrhagic
stroke.
• Intracerebral hemorrhage is the most
common, accounting for 10% of all strokes.
• Subarachnoid hemorrhage, due to rupture of a
cerebral aneurysm, accounts for 6% of strokes
overall.

• Hemorrhage in the cerebellum (arrow).

Intracerebral Hemorrhage
• The most common cause of non-traumatic
intracerebral hematoma is hypertensive
hemorrhage.
• Other causes include amyloid angiopathy, a
ruptured vascular malformation,coagulopathy,
hemorrhage into a tumor, venous infarction,
and drug abuse.

• Thalamic hemorrhage (arrow) extending into
the left lateral ventricle (arrowheads).6/12/2017 jalili.dr@gmail.com 34

Hypertensive Hemorrhage
• Hypertensive hemorrhage accounts for approximately 70-
90% of non-traumatic primary intracerebral hemorrhages.
• It is commonly due to vasculopathy involving deep
penetrating arteries of the brain.
• Hypertensive hemorrhage has a predilection for deep
structures including the thalamus, pons, cerebellum, and
basal ganglia, particularly the putamen and external
capsule.
• Thus, it often appears as a high-density hemorrhage in the
region of the basal ganglia.
• Blood may extend into the ventricular system.
• Intraventricular extension of the hematoma is associated
with a poor prognosis.

• Hypertensive hemorrhage in the basil ganglia.

Coagulopathy Related Intracerebral Hemorrhage
• Coagulopathy related intracerebral hemorrhage
can be due to drugs such as coumadin or a
systemic abnormality such as thrombocytopenia.
• On imaging, this hemorrhage often has a
heterogeneous appearance due to incompletely
clotted blood.
• A fluid level within a hematoma suggest
coagulopathy as an underlying mechanism.

• Notice the fluid level within the hematoma(arrow).

Hemorrhage Due to Arteriovenous Malformation
• An underlying arteriovenous malformation (AVM) may
or may not be visible on a CT scan.
• However, prominent vessels adjacent to the hematoma
suggest an underlying arteriovenous malformation.
• In addition, some arteriovenous malformations contain
dysplastic areas of calcification and may be visible as
serpentine enhancing structures after contrast
administration.

• The CT on the left shows hemorrhage (arrow) due to underlying
AVM (arrowheads). The arteriogram on the right shows the
tangle of vessels (arrowheads) of the AVM. This lesion would be
considered for intravascular embolic therapy6/12/2017 jalili.dr@gmail.com 40

Subarachnoid Hemorrhage
• In the absence of trauma, the most common cause of subarachnoid hemorrhage is
a ruptured cerebral aneurysm.
• Cerebral aneurysms tend to occur at branch points of intracranial vessels and thus
are frequently located around the Circle of Willis.
• Common aneurysm locations include the anterior and posterior communicating
arteries, the middle cerebral artery bifurcation and the tip of the basilar artery.
• Subarachnoid hemorrhage typically presents as the "worst headache of life" for
the patient.
• Detection of a subarachnoid hemorrhage is crucial because the rehemorrhage
rate of ruptured aneurysms is high and rehemorrhage is often fatal.
• CT is currently the imaging modality of choice because of its high sensitivity for the
detection of subarachnoid hemorrhage.
• CT is most sensitive for acute subarachnoid hemorrhage. After a period of days to
weeks CT becomes much less sensitive as blood is resorbed from the CSF.
• If there is a strong clinical indication, LP may be warranted despite a negative CT
since small bleeds can be unapparent on imaging.
• On CT, a subarachnoid hemorrhage appears as high density within sulci and
cisterns.
• The insular regions and basilar cisterns should be carefully scrutinized for subtle
signs of subarachnoid hemorrhage.
• Subarachnoid hemorrhage may have associated intraventricular hemorrhage and
hydrocephalus.

• High density blood fills the cisterns (arrowheads) in this patient
with hemorrhage from the left middle cerebral

Ischemic stroke
• Ischemic strokes are caused by thrombosis, embolism of thrombosis, hypoperfusion and lacunar
infarctions.
• A thrombotic stroke occurs when a blood clot forms in situ within a cerebral artery and blocks or
reduces the flow of blood through the artery.
• This may be due to an underlying stenosis, rupture of an atherosclerotic plaque, hemorrhage
within the wall of the blood vessel, or an underlying hypercoagulable state.
• This may be preceded by a transient ischemic attack and often occurs at night or in the morning
when blood pressure is low.
• Thrombotic ischemic strokes account for 53% of all strokes.
• An embolic stroke occurs when a detached clot flows into and blocks a cerebral artery.
• The detached clot often originates from the heart or from the walls of large vessels such as the
carotid arteries.
• Atrial fibrillation is also a common cause.
• Embolic strokes account for 30% of all strokes.
• A lacunar infarction occurs when the walls of small arteries thicken and cause the occlusion of the
artery.
• These typically involve the small perforating vessels of the brain and result in lesions that are less
than 1.5 cm in size.
• Hypoperfusion infarctions occur under two circumstances.
• Global anoxia may occur from cardiac or respiratory failure and presents an ischemic challenge
to the brain.
• Tissue downstream from a severe proximal stenosis of a cerebral artery may undergo a localized
hypoperfusion infarction.
• Lacunar and hypoperfusion strokes, account for the remaining 1% of strokes of the ischemic
type.

• Sharply circumscribed hypodense edema (arrowheads) in the right middle
cerebral artery territory.6/12/2017 jalili.dr@gmail.com 44

CT Findings of Stroke
• When analyzing the CT of a potential stroke victim, one of
the first findings to look for is the presence or absence of
hemorrhage.
• Another common finding in stroke patients is a dense
middle cerebral artery or a dense basilar artery, which
corresponds to thrombus in the affected vessel.
• There are also more subtle changes of acute ischemia due
to edema which include the following:
- Obscuration of the lentiform nuclei
- Loss of insular ribbon
- Loss of gray/white distinction
- Sulcal effacement

• Dense basilar artery (arrow).

Hyperdense Vessel Sign
• A hyperdense vessel is defined as a vessel denser
than its counterpart and denser than any non-
calcified vessel of similar size.
• This is seen in 25% of stroke patients.
• In patients presenting with clinical deficit
referable to the middle cerebral artery territory,
the hyperdense vessel sign is present 35-50% of
the time.
• This sign indicates poor outcome and poor
response to IV-TPA therapy.

• High density in the right middle cerebral artery (arrowheads).
Compare it with the normal left middle cerebral artery (arrow).

Basilar Thrombosis
• Thrombosis of the basilar artery is a common
finding in stroke patients.
• CT findings include a dense basilar artery
without contrast injection.

• Dense basilar artery (arrow). Compare this to
the normal internal carotid artery (arrowhead).

Lentiform Nucleus Obscuration
• Lentiform nucleus obscuration is due to
cytotoxic edema in the basal ganglia.
• This sign indicates proximal middle cerebral
artery occlusion, which results in limited flow
to lenticulostriate arteries.
• Lentiform nucleus obscuration can be seen as
early as one hour post onset of stroke.

• Hypodensity in the left hemisphere (arrows) involving the
caudate nucleus and lentiform nuclei (globus pallidus and
putamen).6/12/2017 jalili.dr@gmail.com 52

Insular Ribbon Sign
• The insular ribbon sign is the loss of the gray-
white interface in the lateral margins of the
insula.
• This area is supplied by the insular segment of
the middle cerebral artery and is particularly
susceptible to ischemia because it is the most
distal region from either anterior or posterior
collaterals.
• The insular ribbon sign may involve only the
anterior or the posterior insula.

• The cortex of the left insular ribbon is not visualized (arrow).

Diffuse Hypodensity and Sulcal Effacement
• Diffuse hypodensity and sulcal effacement is the most
consistent sign of infarction.
• Extensive parenchymal hypodensity is associated with
poor outcome.
• If this sign is present in greater than 50% of the
middle cerebral artery territory there is, on average,
an 85% mortality rate.
• Hypodensity in greater than one-third of the middle
cerebral artery territory is generally considered to be a
contra-indication to thrombolytic therapy.

• Hypodensity and sulcal effacement (arrowheads) in the right
middle cerebral artery distribution

CT of Subacute Infarction
• The CT of a subactue infarction has the following findings
in 1 -3 days:
- Increasing mass effect
- Wedge shaped low density
- Hemorrhagic transformation
• After 4 - 7 days the CT is characterized by:
- Gyral enhancement
- Persistent mass effect
• In 1-8 weeks:
- Mass effect resolves
- Enhancement may persist

• This image was taken 4 hours after the infarction.

• This image, from the same patient, was taken
2 days after the infaction.

Enhancement in Infarctions
• Ninety percent of infarcts enhance on CT
examinations with intravenous contrast at 1 week
after the infarct. Approximately 35% enhance by
3 days. Faint enhancement begins near the pial
surface or near the infarct margins. The
enhancement is initially smaller than the area of
infarction. It subsequently becomes gyriform.
Enhancement is due to breakdown of the blood
brain barrier, neovascularity, and reperfusion of
damaged brain tissue.

Post contrast CT scan demonstrating gyriform enhancement
of subacute right frontal lobe infarct (arrow).

Meningitis
• There are 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 in suspected meningitis patients is performed to
look for complications and assess safety of lumbar
puncture.
• Imaging is not usually performed to diagnose meningitis
because imaging studies are frequently normal despite
the presence of the disease.

Hydrocephalus
• Hydrocephalus, a problem with the ratio of
production of CSF to its reabsorbtion, is most
frequent in children.
• Communicating hydrocephalus is the most
common and is due to arachnoid villi and
subarachnoid space obstruction.
• Obstructive hydrocephalus is less common but
may occur as a result of the following:
- Aqueductal stenosis or occlusion
- Trapped fourth ventricle
- Ependymitis

In these sections from the same patient notice the enlagement of the
ventricles and cisterns that occurs with hydrocephalus.

Ventriculitis / Ependymitis
• Inflammation and enlargement of the ventricles
characterizes ventriculitis.
• 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 affec approximately 30%
of the adult patients and 90% of the pediatric patients
with meningitis.

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).

The image on the left shows thrombosis of the superior sagittal sinus (arrow)
prior to the administration of contrast. The image on the right shows the
thrombosis in the same patient after contrast administration.

Extra-axial CNS Infection
• Extra-axial CNS infections can involve epidural abscess or
subdural empyema.
• Extra-axial CNS infections account for 20-30% of CNS
infections.
• Fifty percent of extra-axial infections are associated with
sinusitis, usually frontal sinusitis.
• The infection occurs by direct extension or septic
thrombophlebitis.
• Thirty percent of extra-axial infections occur post-
craniotomy.
• Finally, 10-15% of extra-axial CNS infections are related to
meningitis.
• CT findings include a focal fluid collection usually with an
enhancing margin in a subdural or epidural location.

Epidural Abscess
• On CT, an epidural abscess appears as a focal
low-density epidural mass.
• Dural enhancement may be present as well.
• The mass may extend into the subgaleal space.
• It also may cross the midline but usually does
not cross suture lines.

• In the left image notice the rim enhancing epdural fluid collection
(arrowheads).
• In the right image, notice the opacification of the left frontal sinus due to
acute sinusitis (arrow).

Subdural Empyema
• Subdural empyema is usually due to meningitis,
sinusitis, trauma or prior surgery.
• It is a neurosurgical emergency.
• Subdural empyema leads to rapid clinical
deterioration, especially if it is due to sinusitis.
• On CT it appears as an isodense or hypodense extra-
axial mass. It has a lentiform or crescentic shape.
• The margin of collection often enhances with contrast
material administration due to the presence of
granulation tissue or subjacent cortical inflammation.

In the same patient, post contrast
administration,
notice the patchy enhancement of the fluid
collection.
• Notice the heterogeneous
subdural fluid collection

Intracranial Tumors
• Intracranial tumors generally present with a
focal neurological deficit, seizure, or headache.
Multiple enhancing masses located at the grey-white junction zones.6/12/2017 jalili.dr@gmail.com 74

Glioblastoma Multiforme
• Glioblastoma Multiforme is the most aggressive grade
of astrocytoma.
• The two-year survival rate of patients diagnosed with
Glioblastoma Multiforme is 10-15%.
• On CT, GBM is characterized by necrosis and irregular
enhancement.
• It is one of very few lesions that frequently cross the
corpus callosum.

An image post contrast administration in
the same patient reveals patchy
enhancement, a portion of which is
crossing the corpus callosum (arrow).
• Notice the ill-defined low density in
the right frontal region.

Meningioma
• Meningiomas are the most common extra-
axial neoplasm of the brain.
• Middle-aged women are most frequently
affected.
• Twenty percent of meningiomas calcify.
• On CT, meningiomas are usually isointense to
gray matter.

Axial, post contrast CT
demonstrating broad based
enhancing extra-axial mass.
• Bone windows confirm
calcification within the
mass.

‫تشکر‬ ‫با‬

MR
► Faster
► Less expensive
► Less sensitive to patient
movements
► Easier in claustrophobics
► Acute haemorrhage
► Calcification
► Bone details
► Foreign body
► No ionising radiation
► Greater details, hence
more sensitive and more
specific
► Any plane scanning
► Contrast less allergic
► No beam hardening
artefact
CT

Indications (almost everything)
► Anatomy
► Congenital anomalies
► Hereditary and
metabolic diseases
► Infections
► Demyelination
► Vascular event
► Tumours
► Trauma
► Dementia
► Hydrocephalus
► Cranial nerves
► Arteriograms
► Venograms
► Skull base
► Pituitary gland

But why we can’t act like
magnets?
► The protons (i.e.
Hydrogen ions) in
body are spinning in a
hap hazard fashion,
and cancel all the
magnetism. That is our
natural state!
► We need to discipline
them first, how?

Proton alignment
► Compass aligns with
the earth
► In a similar fashion,
► Our body protons
(hydrogen) align with
this external magnetic
field.
► Now, we are
disciplined (spinning
in line with each
other!), what next?

Copyright ©Radiological Society of North America, 2005
Pooley, R. A. Radiographics 2005;25:1087-1099
T1-weighted contrast

‫تصاویر‬ ‫مشخصات‬T1
►‫تصاویر‬T1:
‫عالی‬‫است‬‫ر‬‫کنت‬(‫شن‬‫و‬‫ر‬ ‫چربی‬ ‫و‬‫تیره‬‫بسیار‬ ‫مایعات‬)
‫آناتومی‬ ‫اسکن‬ ‫نام‬ ‫به‬(‫مشخص‬ ‫ها‬ ‫بافت‬‫ز‬‫مر‬)
‫چه‬ ‫هر‬TR‫بیشتر‬‫است‬‫ر‬‫کنت‬ ،‫تر‬ ‫کوتاه‬
6/12/2017 85jalili.dr@gmail.com

Copyright ©Radiological Society of North America, 2005
Pooley, R. A. Radiographics 2005;25:1087-1099
T2-weighted contrast

‫تصاویر‬ ‫مشخصات‬T2
►‫تصاویر‬T2‫به‬ ،TR‫و‬TE‫تر‬‫طوالنی‬
‫طوال‬ ‫اسکن‬ ‫مان‬‫ز‬ ‫این‬‫ر‬‫بناب‬ ،‫د‬‫ر‬‫دا‬ ‫نیاز‬‫نی‬
‫از‬ ‫تر‬T1
‫ها‬ ‫ی‬‫ژ‬‫پاتولو‬‫اسکن‬
‫چه‬ ‫هر‬TE‫تصاویر‬ ،‫تر‬ ‫طوالنی‬T2‫با‬
‫بیشتر‬‫است‬‫ر‬‫کنت‬
►‫اگر‬TE‫تصویر‬،‫شود‬‫کوتاه‬‫خیلی‬PD

What kind of images?
► T1WI
► T2WI
► PDWI
► DWI
► ADC
► GE
► Perfusion images
► fMRI
► BOLD images
► MRA
► MRV
► Post-Gd images
► Volumetric images
► MR arthrograms
► FLAIR
► STIR
► Etc etc etc

Ischemic CVA; MRI

Hemorrhagic CVA; MRI

Hyperacute and Acute Hemorrhage

Early and Late Subacute H.

Chronic Hemorrhage

SAH

SDH

Diffusion-Weighted Imaging
•‫تغیی‬ ‫و‬‫آب‬ ‫های‬ ‫ل‬‫مولکو‬ ‫حرکت‬ ‫به‬‫ر‬
‫است‬ ‫وابسته‬ ‫ی‬‫بیمار‬ ‫هنگام‬ ‫در‬ ‫آن‬
–،‫ن‬‫ژ‬‫دیفیو‬ ‫ن‬‫بدو‬High Signal
–‫کم‬ ‫سیگنال‬ ،‫بیشتر‬ ‫ن‬‫ژ‬‫دیفیو‬ ‫با‬‫تر‬

Diffusion-Weighted MR
–‫ها‬ ‫ی‬‫بیمار‬‫سایر‬ ‫از‬‫آن‬ ‫تفکیک‬ ‫و‬‫ی‬‫مغز‬ ‫حاد‬ ‫انفارکتوس‬‫تشخیص‬ ‫ای‬‫ر‬‫ب‬
•‫شود‬ ‫می‬ ‫حاصل‬‫داخل‬ ‫به‬ ‫ل‬‫سلو‬‫خارج‬‫از‬‫آب‬ ‫ن‬‫ژ‬‫دیفیو‬ ‫در‬ ‫شدید‬ ‫محدودیت‬ ‫دقیقه‬ ‫چند‬ ‫طی‬‫در‬
•‫طی‬‫در‬30‫ت‬‫ر‬‫صو‬ ‫به‬‫دقیقه‬Hyperintensity‫شناسایی‬ ‫قابل‬
•‫از‬ ‫ترکیبی‬ ‫ت‬‫ر‬‫صو‬ ‫به‬ ‫تصویر‬T2 – weighted‫و‬DWI‫شود‬ ‫می‬‫داده‬ ‫نشان‬
–Masses:‫ها‬‫ر‬‫تومو‬ ‫موئید‬‫ر‬‫اپید‬(Hyperintense)
–Abscess:Hyperintense
–،‫ی‬‫خونریز‬ ،‫ما‬‫و‬‫تر‬MS

Acute Ischemic Stroke

Acute and Chronic Ischemic Stroke

Epidermoid tumor
T1 Weighted T2 Weighted DWI

Brain Abscess
T2 weighted Gadolinium-T1 weighted DWI

Herpes Encephalitis
DWI

Acute infarct best shown on DWI

Head Trauma; Diffuse Axonal Injury

Fluid attenuated inversion recovery
(FLAIR)
•‫تصویر‬T2-weighted‫با‬T1
‫طوالنی‬(T1‫تقریبا‬ms2000)‫به‬
‫مایعات‬ ‫اثر‬ ‫بردن‬ ‫بین‬ ‫از‬ ‫ر‬‫منظو‬
(CSF)‫بهتر‬‫و‬ ‫حاصل‬ ‫تصویر‬ ‫از‬
‫بطن؛‬ ‫اف‬‫ر‬‫اط‬ ‫ضایعات‬ ‫دیدن‬MS.

Lacunar Infarction

Cerebral Venous Thrombosis
• Acute stage (0–5 days) (10 – 30%):
– Isointense on T1-weighted and hypointense on T2-
weighted images

• Subacute stage (6–15 days) (50 - 55%):
– Hyperintense on both T1-weighted images and T2-weighted images
because of methemoglobin in the thrombus

• Chronic thrombosis (>15 days) (≈15%):
– Isointense or hyperintense on T2-weighted images and isointense on
T1-weighted images; however

Brain CT & MRI

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