Neurorad 2 Brain

8/8/2019 Neurorad 2 Brain

1/12

Introduction toIntroduction to

NeuroimagingNeuroimaging

Aaron S. Field, MD, PhDAaron S. Field, MD, PhD

NeuroradiologyNeuroradiology

University of WisconsinUniversity of WisconsinMadisonMadison

BRAINBRAIN

Updated 3/12/07

Brain Imaging:Brain Imaging: The Big 10The Big 10

InfarctionInfarction

HemorrhageHemorrhage

InfectionInfection

TumorTumor

TraumaTrauma

DementiaDementia

MSMS

EpilepsyEpilepsy

Cranial neuropathyCranial neuropathy

Orbits /Orbits / OphthoOphtho dxdx

Acute Ischemic Stroke ImagingAcute Ischemic Stroke Imaging

Confirm diagnosisConfirm diagnosis

Triage for therapy (risk / prognosis)Triage for therapy (risk / prognosis)

Rule outRule out hemorrhagehemorrhage

Assess damage: location, pattern, extentAssess damage: location, pattern, extent

Is there salvageable brain (Is there salvageable brain (penumbrapenumbra)?)?

Follow outcomeFollow outcome

VesselVessel patencypatency, ultimate infarct size,, ultimate infarct size,

hemorrhagic transformationhemorrhagic transformation

CT Signs in Early MCA IschemiaCT Signs in Early MCA Ischemia

HyperdenseHyperdense MCAMCA Insular RibbonInsular Ribbon LentiformLentiform NucleusNucleus

Pathophysiology of Ischemic Injury:Pathophysiology of Ischemic Injury:

Duration and Degree ofDuration and Degree of CBFCBFNormal neuronal function

Reversible injury(penumbra)

Infarction

25

20

15

10

5

0

CBF

ml /100g /min

Time (hrs)1 2

MRI in Stroke InterventionThe 4 Ps

Pipes Perfusion ParenchymaMRA Perfusion MR Diffusion MR

PenumbraRowley AJNR22(4); 599-601, 2001


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MCA InfarctMCA Infarct

MCA

PCA InfarctPCA Infarct

PCA

ACA InfarctACA Infarct ACA Brain Imaging:Brain Imaging: The Big 10The Big 10



InfectionInfection

TumorTumor

TraumaTrauma

DementiaDementia

MSMS

EpilepsyEpilepsy



Cerebral HemorrhageCerebral Hemorrhage

TraumaTrauma

Ruptured aneurysmRuptured aneurysm

HypertensiveHypertensive

Hemorrhagic transformation of ischemicHemorrhagic transformation of ischemicinfarction (esp. venous)infarction (esp. venous)

Venous infarctionVenous infarction

TumorTumor

Vascular malformationsVascular malformations

AngioinvasiveAngioinvasive infectioninfection

AmyloidAmyloid angiopathyangiopathyAcuteAcute intraparenchymalintraparenchymal hematomahematoma



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Hemorrhagic melanoma metastasesHemorrhagic melanoma metastases


Acute subarachnoid hemorrhageAcute subarachnoid hemorrhage

(and(and intraventricularintraventricular ))


SubduralSubdural vs. Epidural Hematomavs. Epidural Hematoma

AcuteAcute subduralsubdural hematomahematoma


Acute epidural hematomaAcute epidural hematoma

Cerebral HemorrhageCerebral HemorrhageSubdural Subdural :: Follows inner layer ofFollows inner layer ofduradura

Rounds the bendRounds the bend to followto follow falxfalx oror tentoriumtentorium

Not affected by sutures of skullNot affected by sutures of skull

Tendency forTendency for crescenticcrescentic shapesshapes

More mass effect than expected for their sizeMore mass effect than expected for their size

Typical source of SDH:Typical source of SDH: cortical veincortical vein

Epidural : Epidural : Follows outer layer ofFollows outer layer ofduradura ((periosteumperiosteum))

CrossesCrosses falxfalx oror tentoriumtentorium

Limited by sutures of skull (typically)Limited by sutures of skull (typically)

Tendency forTendency for lentiformlentiform shapesshapes

Typical source of EDH:Typical source of EDH:

skull fracture with arterial or sinus lacerationskull fracture with arterial or sinus laceration

SubduralSubdural vs. Epidural Hematomavs. Epidural Hematoma

*


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Mixed acute/ chronicMixed acute/ chronic subduralsubdural hematomahematoma


HematocritHematocrit level!level!


MRI of HemorrhageMRI of Hemorrhage

MR appearance ofMR appearance of hematomashematomas depends on image type.depends on image type.

Magnetic properties change over time (Magnetic properties change over time (HgbHgb breakdownbreakdownproducts), allowing approximate datingproducts), allowing approximate dating

T1 T2T1 T2 T2T2**




InfectionInfection

TumorTumor

TraumaTrauma

DementiaDementia

MSMS

EpilepsyEpilepsy



InfectionInfection

MeningitisMeningitis

EncephalitisEncephalitis

CerebritisCerebritis and parenchymal abscessand parenchymal abscess

EmpyemaEmpyema ((subduralsubdural/ epidural)/ epidural)

LeptoLeptomeningitismeningitis::piapia--arachnoidarachnoid

MeningitisMeningitis

PachyPachymeningitismeningitis:: duradura

Most common imaging findings in meningitis:Most common imaging findings in meningitis: NONENONE !!!!


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HerpesHerpes

EncephalitisEncephalitisCerebritisCerebritis w/ Bacterial Abscessw/ Bacterial Abscess

T1 +T1 + GdGd T2 DiffusiT2 Diffusionon

CerebritisCerebritis w/w/ SubduralSubdural EmpyemaEmpyema

T1 +T1 + GdGd T2 FLAIR DiffusionT2 FLAIR Diffusion




InfectionInfection

TumorTumor

TraumaTrauma

DementiaDementia

MSMS

EpilepsyEpilepsy



Brain Tumor ImagingBrain Tumor Imaging

DiagnosisDiagnosis Location: IntraLocation: Intra-- or Extraor Extra--axial, Supraaxial, Supra-- or Infraor Infra--

tentorialtentorial, Grey or white matter, etc., Grey or white matter, etc.

Single or multiple?Single or multiple?

Tumor or tumorTumor or tumor--like alternatives?like alternatives? Histology: Type and grade?Histology: Type and grade?

Treatment PlanningTreatment Planning Surgery, radiation, chemoSurgery, radiation, chemo txtx

Functional MRI for eloquent brain mappingFunctional MRI for eloquent brain mapping

3D scans to guide surgery, radiation3D scans to guide surgery, radiation

FollowFollow--upup Stable vs. recurrence / progressionStable vs. recurrence / progression

ComplicationsComplications

T1 +T1 + GdGd T2T2

IntraIntra-- or Extraor Extra--axial?axial?


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Intra- or Extra-axial? Tumor vs. Other MassesTumor vs. Other MassesArachnoid CystArachnoid Cyst

AbscessAbscess

HematomaHematoma

TumefactiveTumefactive MSMS

GBMGBM

Tumor vs. StrokeTumor vs. Stroke

CytotoxicCytotoxic EdemaEdema Vasogenic EdemaVasogenic EdemaCellular swellingCellular swelling

GrayGray--white margin lostwhite margin lostLeaky capillariesLeaky capillaries

Gray matter is sparedGray matter is spared

T1 T1 + Gd

T2T2 FLAIR

Tumor?Stroke?

Encephalitis?

3D Imaging for XRT

or Surgical Guidance Brain Imaging:Brain Imaging: The Big 10The Big 10



InfectionInfection

TumorTumor

TraumaTrauma

DementiaDementia

MSMS

EpilepsyEpilepsy




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Fractures: CT not MRI !Fractures: CT not MRI ! Traumatic Brain SwellingTraumatic Brain Swelling

CerebellopontineCerebellopontine

angleanglePontinePontineCerebellomedullaryCerebellomedullary

(Cisterna Magna)(Cisterna Magna)

Know your basal cisterns!Know your basal cisterns!

Traumatic Brain SwellingTraumatic Brain Swelling

Know your basal cisterns!Know your basal cisterns!

QuadrigeminalQuadrigeminalInterpeduncularInterpeduncular

SuprasellarSuprasellarAmbientAmbient

Effacement of basal cisternsEffacement of basal cisterns

Traumatic brain swelling w ithTraumatic brain swelling w ithdownwarddownward herniationherniation

Traumatic Brain SwellingTraumatic Brain Swelling

Traumatic brain swellingExtraExtra--axial Hemorrhageaxial Hemorrhage

SubduralSubdural EpiduralEpidural SubarachnoidSubarachnoid


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IntraIntra--axial Hemorrhageaxial Hemorrhage

Hemorrhagic contusionsHemorrhagic contusions

IntraIntra--axial Hemorrhageaxial Hemorrhage

Hemorrhagic contusionsHemorrhagic contusions

Mechanism

Direct contact with skull

Shear-strain deformation

Lesion locations

Commonly located along inferior, lateral, and anterior frontal and temporal lobes

Often above bony prominences (petrous pyramid, sphenoid wing, orbital roof)

Appearance of cortical contusions

Overlying cortex, by definition, always involved (vs. DAI)

Salt and pepper appearance due to intermixed hemorrhage and edema

Non-hemorrhagic contusions often not initially seen on CT scans

Lesions often more visible days after injury as edema and hemorrhage increase

Acute lesions much more conspicuous on T2 or T2-FLAIR MRI

Diffuse Axonal (Shear) Injury (DAI)

IntraIntra--axial Hemorrhageaxial Hemorrhage Diffuse Axonal (Shear) Injury (DAI)

T2: Reveals non-hemorrhagic lesions occult on CT

Diffuse Axonal (Shear) Injury (DAI)

T2*: Increased sensitivity to hemorrhage

DDiffuseiffuse AAxonal (Shear)xonal (Shear) IInjury (njury (DAIDAI))

Tissues w/ differing elastic properties shear against each other, tearing axons

Caused by rapid deceleration/rotation of head

Locations:

Cerebral hemispheres near gray-white junction Basal ganglia Corpus callosum, especially splenium Dorsal brainstem

High morbitity & mortality common cause of post-traumatic vegetative state

Initial CT often normal despite poor GCS Lesions often non-hemorrhagic and seen only on MRI


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InfectionInfection

TumorTumor

TraumaTrauma

DementiaDementia

MSMS

EpilepsyEpilepsy



DementiaDementia

Primary role of imaging is toPrimary role of imaging is to

exclude treatable causes, e.g.:exclude treatable causes, e.g.:

HydrocephalusHydrocephalus

SubduralSubdural hematomahematoma

NeoplasmNeoplasm

DementiaDementia

Irreversible dementias (imaging nonIrreversible dementias (imaging non--specific):specific):

AlzheimerAlzheimers diseases disease

MultiMulti--infarct dementiainfarct dementia

Dementias associated with ParkinsonDementias associated with Parkinsons disease and similar disorderss disease and similar disorders

AIDS dementia complexAIDS dementia complex

Alzheimers: Temporal-Parietal Lobe Atrophy (Late)




InfectionInfection

TumorTumor

TraumaTrauma

DementiaDementia

MSMS

EpilepsyEpilepsy



Multiple Sclerosis (MS) ImagingMultiple Sclerosis (MS) Imaging

MRI is the imaging study of choiceMRI is the imaging study of choice

Help establishHelp establish dissemination of lesions indissemination of lesions intime and spacetime and space

Estimate disease burdenEstimate disease burden

Identify acute (inflammatory) vs. chronicIdentify acute (inflammatory) vs. chroniclesions (enhancement = active inflammation)lesions (enhancement = active inflammation)


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MS Tumefactive MS




InfectionInfection

TumorTumor

TraumaTrauma

DementiaDementia

MSMS

EpilepsyEpilepsy



Seizure ImagingSeizure Imaging

MRI is the imaging study of choiceMRI is the imaging study of choice

Identify and localize offending lesionIdentify and localize offending lesion

-- New onset vs. chronic epilepsyNew onset vs. chronic epilepsy

-- Younger vs. older patientsYounger vs. older patients

-- Search may be guided by EEG / clinicalSearch may be guided by EEG / clinical sxsx

Preoperative planningPreoperative planning

e.g. language lateralization before temporale.g. language lateralization before temporal lobectomylobectomy

Congenital anomalies: Polymicrogyria Congenital anomalies: Schizencephaly


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MesialMesial Temporal SclerosisTemporal Sclerosis

Most common pathology found inMost common pathology found inmedically refractory epilepsy patientsmedically refractory epilepsy patients

Rare under age 10 or with new seizuresRare under age 10 or with new seizures

Pathogenesis unknownPathogenesis unknown-- PostPost ictalictal / kindling?/ kindling?

Pathology:Pathology:Hippocampal atrophy / gliosisHippocampal atrophy / gliosis

MesialTemporalSclerosis FLAIR

T1

T2

Atrophy Loss gray-white

T2 / FLAIR




InfectionInfection

TumorTumor

TraumaTrauma

DementiaDementia

MSMS

EpilepsyEpilepsy



Cranial Nerve ImagingCranial Nerve Imaging

FIESTAFIESTA

CN-5CN-8

CN-7

VestibularVestibular SchwannomaSchwannomaIntracochlearIntracochlear SchwannomaSchwannoma


12/12

30 y/o F with6wk h/o

blurred vision

CraniopharyngiomaCraniopharyngioma

Introduction toIntroduction to

NeuroimagingNeuroimaging

Aaron S. Field, MD, PhDAaron S. Field, MD, PhD

NeuroradiologyNeuroradiology

University of WisconsinUniversity of WisconsinMadisonMadison

BRAINBRAIN

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Neurorad 2 Brain