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Diagnostic Radiology of Central Nervous System
Raphael B. Jiang, Section of Diagnostic Radiology
Sun Yat-Sen University First Affiliated Hospital
Outline
Normal Imaging Anatomy of Brain
Basic Features of Brain Lesions
Brain Tumor
Cerebrovascular Disease
Traumatic Brain Injury
Normal Imaging Anatomy of Brain Meninges
Dura mater Falx cerebri Tentorium cerebelli Venous sinuses
Arachnoid mater subdural space a potential space btw dura and arachnoid subarachnoid space interval btw arachnoid and pia Pia mater
Falx cerebriTentorium cerebelli
Normal Imaging Anatomy of Brain Meninges
Falx cerebri
Dura mater
Arachnoid
Subarachnoid space
Pia mater
Arachnoid granulationS. sagittal sinus
Normal Imaging Anatomy of Brain Meninges
Normal Imaging Anatomy of Brain Meninges
Falx and Tentorium
Iso-/-mildly hyperdense compared with cortex on CT
Hyperdense when calcified
Markedly enhanced after iodine contrast
Hypointense in T1WI and T2WI
Homogeneity in signal intensity
Markedly enhanced after Gadolinium
Normal Imaging Anatomy of Brain Cerebral Hemisphere
The layer of The layer of gray matter covers entire surface of cerebral hem. covers entire surface of cerebral hem.
Its deep layer is white matterIts deep layer is white matter and nucleus
Gray matter is slightly hyperattenuating than white matterwhite matter
White matter slightly hyperintense than gray matter on T1WI
Gray matter hyperintense than white matter on T2WI
T1WI T2WI
Normal Imaging Anatomy of Brain Cerebral Hemisphere
Frontal lobe Centrum semiovale Parietal lobe Longitudinal fissure Superior sagittal sinus
FL
CS
PL
LF
SSS
SECTION AT CENTRUM SEMIOVALE
Normal Imaging Anatomy of Brain
Normal Imaging Anatomy of Brain Basal Ganglia
Clusters of neurons, located deep in the brain
Caudate nucleus, putamen, globus pallidus, substantia nigra
CT and MR finding
Basal ganglia and Thalamus — gray matter density/intensity
Internal and External capsule— white matter density/intensity
Normal Imaging Anatomy of Brain
SECTION AT BASAL GANGLION
Caudate Nucleus Head Putamen Thalamus Internal Capsule External Capsule Falx Cerebri
CNH
PUEC
FC
TH
IC
Normal Imaging Anatomy of Brain
Caudate Nucleus Head Putamen Thalamus Internal Capsule External Capsule Falx Cerebri
SECTION AT BASAL GANGLION
CNH
PUEC
FC
TH
IC
Normal Imaging Anatomy of Brain
Normal Imaging Anatomy of Brain Brain Stem
Mid-brain, pons and medulla oblongata
CT appearance
Brain stem nuclei not identifiable
Surrounded by fluid-density cistern
MR finding
Brain stem nuclei
Mildly hypointense on T1WI, hyperintense on T2WI
White matter fiber—a slightly high intensity signal
Mildly hyperintense on T1WI, hypointense on T2WI
SECTION AT OPTICAL CHIASM Gyrus Rectus Sylvian Fissure Hippocampus Mid-
brain Aqueduct of Sylvius Optical Chiasm Occipital L S. Cerebellar Vermis
GR
OC
MB
OL
SF
HI
AS
SCV
Normal Imaging Anatomy of Brain
Normal Imaging Anatomy of Brain Cerebellum
CT appearance
Gray and white matter can be distinguished
Cerebellar tonsils and vermis slightly denser than other parts
MR finding
Signals of cortex, medulla and nuclei similar to those of brain
SECTION AT FOURTH VENTRICLE
Occipital Lobe Cerebellar Hemisphere Pons Temporal Lobe Trigeminal Nerve Fourth Ventricle
PO
CH
OL
TL
TN
FV
Normal Imaging Anatomy of Brain
Normal Imaging Anatomy of Brain
Th
AS
Ce
FV
CC
Mb
Po
MO
Corpus callosum Thalamus Aqueduct of SylviusFourth Ven. Mid-brain Pons Cerebellum Medulla oblongata
SECTION AT MID-SAGITTAL PLANE
Lateral Ven. Third Ven. Corpus Callosum Insula Temporal Lobe
LV
IN
TL
CC
TV
SECTION AT LATERAL & THIRD VEN.
Normal Imaging Anatomy of Brain Cerebral Vasculature
Internal Carotid ArteryInternal Carotid Artery
anterior cerebral artery and middle cerebral artery
Basilar Artery
posterior cerebral artery
Communicating Artery
anterior and posterior communicating arteries
Cerebral Vein
superior sagittal, transverse, straight, sigmoid sinuses
inferior sagittal sinus, Vein of Galen
Normal Imaging Anatomy of Brain
Internal Carotid Artery Anterior CA Middle CA Posterior CA Basilar A. Anterior&Posterior Com. A
ICA
MCA
PCA
BA
ACA
Normal Imaging Anatomy of Brain
Normal Imaging Anatomy of Brain
Transverse SinuseSigmoid Sinus
Superior Sagittal
Sinus
Straight Sinus
Confluence of sinusesInferior
SagittalSinus
Normal Imaging Anatomy of Brain
Normal Imaging Anatomy of Brain
Basic Features of Brain Lesions Hydrocephalus
The term hydrocephalus is derived from the Greek words "hydro" meaning water and "cephalus" meaning head
As the name implies, it is a condition in which the primary characteristic is excessive accumulation of fluid in the brain
The excessive accumulation of CSF results in an abnormal widening of spaces in the brain called ventricles
This widening creates potentially harmful pressure on the tissues of the brain
Normal CSF flow passage
Lateral V – (Foramina of Monro) – Third V – (Aqueduct of Sylvius) – Fourth V – (Median aperture & Luschka Foramina) – Subarachnoid Space – (Arachnoid Granulations) – Superior SS
Classification
Non-communicating
Communicating
Basic Features of Brain Lesions Hydrocephalus
Non-communicating Hydrocephalus Obstructive hydrocephalus CSF-flow obstruction ultimately preventing CSF from flowing
into subarachnoid space Secondary to congenital, infectious or tumor diseases Dilation of Ventricles above obstruction Ventricles normal below obstruction
Basic Features of Brain Lesions Hydrocephalus
Communicating Hydrocephalus Impaired CSF re-absorption in the absence of any CSF-flow
obstruction btw ventricles Secondary to subarachnoid inflammation, craniocerebral injury,
intracranial hemorrhage and brain tumors Ventricles and cisterns ubiquitously enlarged
Basic Features of Brain Lesions Hydrocephalus
Communicating Hydrocephalus
Reduction in brain tissue volume Secondary to expansion of the cranial CSF volume Caused by Normal Aging and diseases Diffused brain atrophy and localized brain atrophy
Basic Features of Brain Lesions Brain Atrophy
Lack of blood supply or interruption of blood flow
Tissue necrosis and liquefaction-cystic degeneration
Commonly found in tumor
Basic Features of Brain Lesions Necrosis and cystic degeneration
Physiological Calcification
Pineal calcification
Age-related basal ganglia calcificationPathological calcification
Calcification of craniopharyngioma
Calcification of gliomas
Calcification of meningioma
Basic Features of Brain Lesions Calcification
CHONDROMA MENINGIOMA
Structure departed from normal position due to intracranial lesion Commonly found in tumors, hematoma, infarction, abscess, etc
Basic Features of Brain Lesions
Mass effect
Signs of supratentorial space-occupying Displaced or compressed ventricle Narrowing or occlusion of ipsilateral cerebral sulcus and cistern Shift of midline structuresSigns of infratentorial space-occupying Deformation and shift of fourth ventricle and brainstem Ventricular dilatation caused by CSF pathway obstruction
Basic Features of Brain Lesions
Mass effect
Primary
Glioma 40 % ~50% 70 %— Astrocytoma
Angioma
Medulloblastoma
Lymphoma
Secondary
Metastatic
Brain TumorIntra-axial tumor
Astrocytoma The most common type of gliomas At any age, most commonly between the ages of 20- 40 Supratentorial predominantly for adult, infratentorial for children Present with seizures or focal neurological deficits,
headache and increased intracranial pressure Graded from I to IV based on histological differentiation
Brain TumorIntra-axial tumor
Astrocytoma Grade 1
Lower density on CT
Long T1 and long T2 intensity
Slight mass effect
Mild surrounding edema
Well-demarcated boundary
No post-contrast enhancement
Malignant astrocytoma
Heterogeneous density
Mixed signal intensity
Marked mass effect
Severe surrounding edema
Ill-demarcated boundary
Post-contrast enhancement
Brain TumorIntra-axial tumor
Astrocytoma Grade 1
Astrocytoma Grade 2
Astrocytoma Grade 2
Glioblastoma multiforme(Malignant)
Brain Metastases Via blood stream route Most commonly from lung cancer Imaging features Multiple nodules Necrosis-frequently seen Solitary nodule-rarely Lower density, hypointense on T1WI, hyperintense on T2WI Massive peri-nodular edema Substantial post-contrast enhancement
Brain TumorIntra-axial tumor
60Y/F
Lung Adenocarcinoma
Neoplasm, metastasis, renal cell primary
(1)MeningiomaThe most common tumor outside the brainOriginate from arachnoid villi cellsThe clinical symptomsare closely related to the exact site of the tumorSolid tumors most commonly. Adjacent skull is showed reactive
hyperplasia or bone destructionCT appearance Iso-density or slight low-density. Somtimes with calcificationMR finding
Isointense/slight hypointense on T1WI , slight hyperintense onT2WI High vascularized in or arround tumorsEnhancement significant
Brain TumorExtra-axial tumor
Meningioma The most common extracerebral tumor Originate from arachnoid villi cells Clinical symptoms closely related to site of tumor Most are solid texture Adjacent skull shown reactive hyperplasia or bone destruction
Brain TumorExtra-axial tumor
Acoustic neurinoma High incidence, lower than that of meningioma Located in the internal auditory canal Combined with hemorrhage and cystic degeneration No calcification, Iso-/ slight hyperdense on CT Iso-/hypointense on T1WI and hyperintense on T2WI
Enlarged internal auditory canal Post-contrast enhancement on both CT and MRI
Brain TumorExtra-axial tumor
Neoplasm, schwannoma, cerebellopontine angle
Hypertensive intracerebral hemorrhage (HIH)
Intracranial aneurysm
Brain infarction
Cerebrovascular Disease
Hypertensive intracerebral hemorrhage
Location: most frequently striatum and internal capsule
Etiology: chronic hypertension
Cerebrovascular DiseaseHIH
CT appearan A ellipse -shaped high-density mass Surrounding edema Hemorrhage breaking into ventricle Mass effect Cerebral hernia
Cerebrovascular DiseaseHIH
MR finding Signal intensity of intracerebral hemorrhage changes with the
evolution of hemoglobin Super-acute stage (within 6h)
Isointense or lower signal on T1WI, Hyperintense on T2WI
Acute stage (7h~3d)
Isointense or lower signal on T1WI, Hypointense on T2WI
Subacute stage (4d~4w)
Hyperintense on T1WI, Central isointensity or hypointensity
surrounded by hyperintensity on T2WI
Cerebrovascular DiseaseHIH
14 D later
2 days after first CT
Acute stage intracerebral hemorrhage
16 D later
2、 Intracranial aneurysm Congenital aneurysm
Associated with arterial fibro- muscular dysplasia or absence
Often occur in branches of the Circle of Willis , in particular at the arterial bifurcation
Acquired aneurysm
Traumatic
Infection
Atherosclerosis Easily mistaken for tumor to surgical resection
Cerebrovascular disease
Intracranial aneurysm Aneurysm rupture Severe headache is the most common symptom Depends on size, morphology and high blood pressure CT—subarachnoid hemorrhage, with intramural calcification Aneurysm
Flow void sign on T1WI and T2WI
MRA helps to find medium-size aneurysms Small aneurysms are confirmed by DSA
Cerebrovascular DiseaseIntracranial Aneurysm
Internal carotid artery aneurysm
Internal carotid-siphon aneurysm
Brain Infarction
Caused by arterial occlusion
Signs and symptoms vary with vessel involved and collateral
circulation available. Most commonly, sudden hemiplegia, aphasia
Neuronal eosinophilic degen.and nuclear pyknosis 4 h after attackNuclear necrosis starts within 15~24hPhagocytic cells emerge within 2~3dReactive astrocytosis and capillary hyperplasia 1w after onset
Cerebrovascular DiseaseBrain Infarction
CT appearance
The gray and white matter junctions vanish within 3h.
No positive-findings within 24h Direct-Signs:low-density
Indirect signs: gyri swelling, sulci disappearing,
ventricular compression Hemorrhage occurs due to reperfusion injury in infarction
Cerebrovascular DiseaseBrain Infarction
MR finding Long T1 and long T2 signal intensity
Diffusion Weighted Imaging (DWI) can identify cerebral infarction within 1 hour after onset
Acute stage: Enhancement of vessel
Subacute stage: Typical enhancement of gyri Perfusion MRI can display the ischemic core and penumbra MRA can demonstrate the corresponding arterial disorders
Cerebrovascular DiseaseBrain Infarction
Epidural hematoma
Subdural hematoma
Acute contusion and laceration
Traumatic Brain Injury
Epidural Hematoma Caused by rupture of blood vessels and dural arteryAccumulation of blood in space btw inner plate and dura materTemporo-parietal lobe the most commonly involvedNot cross suture lines, mostly unilateral Dura mater adheres skull so firmly that hematoma is confined
and shuttle-shapedAcompanied with fracture, but no intraparenchymal injury
Traumatic Brain InjuryEpidural Hematoma
CT appearance Confined shuttle-shaped or biconvex-shaped high density
beneath the inner plate Adjacent skull fracture, cerebral edema, midline deviation
Traumatic Brain InjuryEpidural Hematoma
MR finding Morphological alteration similar to CT Signal intensity depends on changes of hemoglobin over time
Acute stage(~3D): Isointense on T1WI, Hypointense on T2WI
Subacute stage(4D~3W): Hyperintense on T1WI and T2WI
Chronic stage(3W~): Hyperintense on T1WI and T2WI
Traumatic Brain InjuryEpidural Hematoma
Acute epidural hematoma, fusiform high density beneath Frontoparietal bone plate (white arrow) , liquid-plane (black arrow) Fracture in bone window ( white arrow)
MRI Acute stage epidural hematoma
Subdural Hematoma Caused by rupture of cortical A and V or bridging veins Accumulation of blood in space btw dura and arachnoid Typically, hematoma crescent-shaped Staging of subdural hematoma similar to that of epidural Hem.
Traumatic Brain InjurySubdural Hematoma
Acute stage Subacute stage Chronic stage
High-density High-/Isodensity Low-density
CT appearance Acute stage Crescent-shaped high density beneath inner skull plate Accompanied with cerebral contusion, subarachnoid hemorrhage, significant mass effect Subacute stage Crescent-shaped high density or isodensity Inward shift of the gray and white matter junctions on the affected side, sulci disappear, ventricle deformation Chronic stage Crescent-shaped low density
Traumatic Brain InjurySubdural Hematoma
Acute stage subdural hematoma , banded high density beneath the skull plate in left frontoparietal (black arrow)
MR finding
Staged signal intensity
stage T1WI T2WI
Acute stage Isointense
/Hyperintense
Hypointense
Subacute stage Hyperintense Hyperintense
Chronic stage Hyperintense Hyperintense surrounded by hypointense ring
Traumatic Brain InjurySubdural Hematoma
MRI Subacute stage subdural hematoma, cortical vein is stripped from the skull
CT vs MRI
Acute stage
CT
High desity
MRI
Isointense
CT
Advantage
Subacute stage
CT
Iso-density
MRI
Hyperintense
MRI
Advantage
Chronic stage
CT
Low density
Like CSF
MRI Hyperintense
MRI
Advantage
Traumatic Brain InjurySubdural Hematoma
Subacute stage subdural hematoma
CT :compression displacement of the right occipito-temporal sulcus
MRI : hyperintense
FLAIR :subarachnoid hemorrhage
MRI is superior to CT in display iso-density hematoma
Subdural hematoma (isodense to brain)1
1 M later
17 D later
3 、 Acute contusion and laceration of brain
Damage occurs at (and sometimes opposite) the point of
impact—the contact part of the gyri with the skull
Traumatic Brain InjuryContusion and Laceration
Acute contusion and laceration of brain
Pathology: regional cerebral edema, necrosis, liquefying,
bleeding foci
Clinical symptoms: headache, nausea, vomiting, disturbance
of consciousness
Traumatic Brain InjuryContusion and Laceration
CT appearance
Low density
edema with multiple scattered microhemorrhages
mass effect, subarachnoid hemorrhage, subdural hematoma
Mild cerebral contusion can be absorbed
Traumatic Brain InjuryContusion and Laceration
Acute cerebral contusion, there are low-density edema with flake high-density shadow(Asterisk), accompanied with subarachnoid hemorrhage in the suprasellar pool, sylvian cistern and around the right falx cerebri(black arrow). The gas in the suprasellar pool indicates basal skull fractures(black arrowhead).
MR finding
Acute and subacute cerebral contusion and laceration
multiple areas of mixed signal
Chronic cerebral contusion and laceration
edema and mass effect reduced, malacia, brain atrophy
Traumatic Brain InjuryContusion and Laceration
IR/T2WI , Oxyhaemoglobin in Hematoma
Isointense , Edema with mass effect
Acute cerebral contusion
Intracerebral hemorrhage and subarachnoid hemorrhage
MRI is superior to CT in showing subarachnoid hemorrhage
questions
Headache 4 months
No traumatic history
Acute onset of headache
Hypertension for 10 years
15 D later
Acute onset of left hand numbness
CT 1
MRI 2
Subacute hemorrhage