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Radiology > Neuroradiology > Flashcards

Neuroradiology Flashcards

1
Q

Oligodendroglioma

A
  • Tumor of neuroglial origin
  • Young to Middle aged presenting w/seizures
  • Can be low to high aggression(can mimic GBM)
  • Third most common glioma
  • Imaging Findings
    • Calcifications in 20 - 90 %
    • Cystic degradation (occasional)
    • Hemorrhage (occasional)
    • Vasogenic edema - low amount
    • Low ADC (low extracellular hyaluronic acid)
  • OTHER DDX
    • Other primary CNS gliomas
    • Metastasis
    • Meningioma (very low)
      TYPICAL APPEARANCE - Calcifications, peripheral location, minimal vasogenic edema
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2
Q

Glioblastoma Multiforme (GBM)

A
  • Most common primary CNS neoplasm
  • WHO Grade IV
  • Glial origin
  • Aggressive spreads through white matter and subependymally
  • Age 40-70
  • Supratentorial in adults, Infratentorial in children
  • Arise de novo, no precursor lower grade lesion
  • Butterfly Tumor (crosses midline)
  • Imaging Findings
    • CT - Cortical based with necrotic and cystic foci
    • MRI - heterogeneously enhancing morphology, cystic/necrotic foci
    • nonehnacing T2/FLAIR hyper intensity.
    • MR Spectroscopy - Elevation choline (3.2ppm), Lactate peak (1.3ppm)
    • MR Perfusion - Elevated CBV (cerebral blood volume)
  • OTHER DDX
    • Metastasis
    • CNS Lymphoma
    • Demyelinating disease (esp if crosses midline)
    • Herpes Encephalitis
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3
Q

Von Hippel Landau

A
  • Pancreatic Neuroendocrine Tumors
  • Hemangioblastoma (brain)
  • Retinal Hemangioblastoma
  • Endolymphatic sac tumor
  • RCC
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4
Q

Hemangioblastoma

A
  • Benign slow growing tumor of vascular origin.
  • 2/3 sporadic 1/3 with VHL
  • Multiple - usually VHL or leptomeningeal hemnagioblastomatosis (rare)
  • Metastasis - rare
  • Most common - posterior fossa primary tumor (adult)
  • Morphology
    • 60% cystic with solid component
    • 30% Solid only
  • Imaging
    • CT - Cyst - Hypodense. Nodule - Isodense
    • MR - Cyst - T2 signal.
    • MR - Nodule- T2 hyper, T1 hypo
      • T1 w/ C+ - Avid enhancement - BLUSH
    • Surrounding vessels tortuous
    • Larger tumors - heterogenous enhancement
    • Cyst wall - no or minimal enhancement
  • Other DDX
    • Children - Pilocytic Astrocytoma - tend to calcify and walls enhance
    • Adults - Metastatic disease
    • RCC mets from VHL - hyper vascular
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5
Q

Meningioma

A
  • Meningeal
  • Extra-axial
  • Dural based tail
  • Can cause surrounding osseous hyperostosis
  • Imaging
  • MRI - Enhancing lesion
    • Restricted diffusion (Bright on DWI)
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6
Q

Epidermoid Lesion

A
  • Imaging
    • CT - CSF signal
    • MRI - typically follows CSF appearance
      • Restricted Diffusion (Bright on DWI)
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7
Q

Vestibular Schwannoma

A
  • Nerve sheath tumor
  • Most common mass in the CP angle
  • Benign slow growing trumor
  • Involves sensory fibers (CNVIII & trigeminal)
  • Involves the vestibular nerve (branch of CN VIII)
  • <20% with NF2
  • Presentation
    • Hearing Loss
    • Vertigo/Imbalance
  • Imaging
    • CT - Mass
    • MRI - contrast enhancing without restricted diffusion
  • Other DDX
    • Meningioma
    • Epidermoid
    • Metastasis
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8
Q

Ependymoma

A
  • Primary CNS neoplasm arises from the ependymal lining
  • WHO grade II
  • Neuroepithelial neoplasm
  • Younger - Posterior Fossa
  • Older - Supratentorial - can originate in the brain parenchyma vs third ventricle lining
  • Locations
    • All ventricles and spinal canal
    • Can go through foramen of Luschka and Magendie (toothpaste tumor)
    • Rarely extra ventricular
  • Imaging
    • CT - Calcification hemorrhage or cystic components
    • MR T2 hyperintense, T1 isointense, Avid contrast enhancement
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9
Q

Central Neurocytoma

A
  • WHO grade II
  • Young and Adolescent
  • Arises in the lateral ventricle and attached to the wall or septum pellucidum
  • Can be close to foramen of Monro and cause obstructive hydrocephalus
  • Can occur in spinal cord as primary intramedullary lesion
  • Imaging
    • Lobulated masses with cystic foci - bubbly appearance
    • 50% have calcifications
    • T1 - isointese
    • T1 w/ C+ - moderate to intense heterogenous enhancement
    • T2 - hyperintense. Periventricular hyperintensity and prominent flow voids
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10
Q

Brainstem Gliomas

A
  • Primarily in children
  • 10-20% of all intracranial tumors in children
  • Two Types
    • Focal
    • Diffuse infiltrating
  • NF1 association –> better prognosis
  • Midbrain gliomas
    • tectal or tegmental
    • Generally low grade (gangilioma or pilocytic astrocytoma) and indolent
    • obstructive hydrocephalus
    • Tx: Shunting and imaging, treat if growth only
  • Pons
    • Infiltrating fibrillary astrocytomas
    • Extend into medulla, midbrain, middle cerebellar peduncle and cerebellum
  • Focal Pons
    • Good prognosis
  • Medulla
    • Uncommon
    • Low grade
    • Exophytic growth
    • Obstructive hydrocephalus
  • Imaging
    • CT 1/3 - hypodense 1/3 isodense 1/3 mixed
    • MR T1 Hypointense T2/Flair Hyperintense
    • PONS - can have focal, patchy, ring enhancement or hemorrhage - worse prognosis
    • Focal and medullary - can enhance but not worrisome
    • Expanded brainstem, obliterate prepontine cistern, compressing fourth ventricle and envelop basilar artery = BSG
    • MRI Spectroscopy - Elevated Choline and Decreased n - acetylaspartate
  • DDX
    • Demyelinating disease
    • Infection - TB
    • Neuro- Behcet - Young adults (oral lesions, uveitis, genital lesions, and neurological symptoms
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11
Q

Tegmentum

A
  • Ventral part of the midbrain
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12
Q

Tectum

A
  • Dorsal part of the midbrain
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13
Q

Intracranial Epidermoids

A
  • Congenital Tumor- like inclusion cysts
  • Sequestration of ectodermal element within the neural tube during the 3rd and 5th week of embryonic development.
  • Well- marginated with irregular nodular surface
  • Wall made of stratified keratinized squamous epithelium with connective tissue.
  • Cyst content
    • desquamated epithelial cells
    • debris
    • keratin
    • water
    • cholesterol
  • Chemical meningitis if cyst contents leak
  • Locations
    • Cerebllopontine angle
    • fourth ventricle
    • sellar region
    • intraparenchymal, less likely
  • Imaging
    • Thinly marginated, irregular, insinuating in CSF space
    • calcification and hemorrhage are rare
    • CT - hypodense and well circumscribed
    • MRI T1 and T2 fluid signal
      • FLAIR incomplete signal suppression
      • DWI - restricted diffusion - BRIGHT
  • CAN BE HYPERDENSE AND T1 hyperintese secondary to hemorrhage or protein but DWI is still restricted.
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14
Q

Primary CNS Lymphoma

A
  • Extranodal non-Hodgkin lymphoma
  • Sites
    • Periventricular region and corpus callosum
    • Basal ganglia
    • Thalami
    • Posterior Fossa
  • Can be butterfly tumor (crosses midline)
  • Leptomeningeal involvement - 12%
  • Dural involvement is rare
  • Angiocentric growth (perivascular growth pattern)
  • Abut CSF (pia or ventricles)
  • Subependymal Spread
  • Solitary w/ less mass effect than expected
  • Imaging
    • Immunocompetent (age >60)
      • Solid uniformly enhancing lesion, high cellularity and perilesional edema
      • CT - Hyperdensity
      • T1 - iso/ mild hypo intensity
      • T2 - Hypointensity
      • DWI - Restricted (bright) (Very LOW ADC)
      • Can be infiltrative w/ hemorrhage, necrosis, no enhancement (rare)
    • Immunocompromised (age ~ 40)
      • higher incidence of necrosis, hemorrhage, heterogenous enhancement
  • Increased perfusion on cerebral blood volume
  • MR Spect - Tumor Signature (increased Lac and Cho with decreased NAA)
  • Other DDX
    • GBM - Hemorrhage, no CSF abutment
    • Mets - tend to be multiple vs Lymphoma(solitary)
    • Tumefactive Demyelination - Ring enhancement
    • Toxo - Eccentric target sign - NON FDG OR THALLIUM AVID
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15
Q

Dysembryoplastic Neuroepithelial Tumor

A
  • Benign grade I glial-neuronal neoplasm
  • Males, Second and Third decades of life
  • Intractable Seizures
  • Temporal and Frontal Lobes
    • Rare - deeper - basal ganglia, thalamus, pons, cerebellum
  • Located in the cortex with gyral expansion
  • Underlying white matter involvement
  • Clinicoradiologic Criteria
    • Seizures by age 20
    • no neuro deficits
    • cortical involvement
    • no peritumoral edema
    • no mass effect
  • Radiologic Features
    • cortex based, wedge shaped, toward ventricles, cortical dysplasia
    • internal septations
    • no contrast enhancement
    • scalloping of the surrounding bone
      CT - Hypo or isodense
      MRI - T2 hyperintesne T1 hypointense. Bubbly appearance . FLAIR - Thin rim surrounding. ADC - High. Nodular enhancement (1/3 of cases)
      Other DDX:
  • Ganglioma - Cystic with enhancing nodule. Calcifies, Contrast enhancement more common
  • Cortical dysplasia - Non-mass like. Cystic foci rare
  • Low grade astrocytoma - centered in white mater, no bony scalloping. ill defined.
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16
Q

Medulloblastoma

A
  • PNET
  • Most common malignant pediatric tumor
  • Small Blue Cell Origin
  • Usually seen in the first decade
  • Small percentage associated with genetic syndrome ( Gorlin, Turcot, Li-Fraumenia, Ataxia Talengectasia, Coffin-Siris syndrome)
  • Pediatric - Midline involving the vermis.
  • Young Adults - Cerebellar hemispheres
  • Inferior medullary velum - primary site of origin.
  • 1/3 have CSF dissemination at diagnosis - MRI + C for initial workup -
    • Leptomeningeal dissemination - Zuckerguss
  • Chemo and Rad therapy - develop other CA later
    Imaging
    • CT- Dense
    • MRI - T1 hyperintense T2 Hypo/isointense. DWI - Restricts (bright). 2/3 moderate to intense enhancement. 1/3 streaky enhancement.
    • MRI Spec - Elevated Choline, lactate and TAURINE
      Other DDX - Pilocytic astrocytoma - Cystic with nodule
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17
Q

Pilocytic Astrocytoma

A
  • Most common pediatric primary tumor
  • Grade I tumor - excellent prognosis in first two decades of life
  • Cerebellum, optic nerve chiasm, and hypothalamus
  • ADULTS - Cerebral
  • Optic and hypothalamus - NF1
  • Posterior Fossa - cystic lesion with solid enhancing portion
  • No surrounding edema
    Imaging
    • Nodule T1 - hypointense , t2 hyperintense, DWI - no restriction
    • Nodule CT - Hypodense
    • Cyst wall - enhancement 50%
    • Nodules can calcify
      Other Ddx
  • Posterior Fossa - medulloblastoma, Epndymoma, Hemangioblastoma
  • Hypothalamus - Pilomyxoid Astrocytoma
  • Hemisphere - Ganglioglioma, pleomorphic xanthroastroyctoma
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18
Q

Subependymal giant cell astrocytoma

A
  • Grade 1 localized tumor
  • Associated with Tuberous Scleorsis
  • Classic location - caudothalamic groove - Foramen of Monro
  • Can be asymptomatic or have obstructive hydrocephalus
  • Imaging
  • CT iso or hypodense
  • MRI T1 hypointense, T2 hyperintense, T1 +C - avid enhancement
  • GRE - shows calcifications
  • FLAIR shows other TSC nodules
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19
Q

Extra axial imaging characteristics

A
  • CSF cleft between the mass and the brain
  • superficial vessels between the mass and the brain
  • dura between the mass and the brain
  • changes in the overlying bone
  • dural tail sign
  • apparent brain displacement from the calvarium/dura
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20
Q

Choroid Plexus Papillomas/Carcinomas

A
  • Most common in the pediatric population
  • Most Common Sites (In order)
    • Lateral Ventricles
    • Fourth Ventricle
    • Third Ventricle
    • Multifocal
    • RARE - Extraventricular
  • Fourth Ventricle tumors can be found in adults <50
  • Usually males
  • Avidly enhancing, lobulated, cysts, hemorrhagic foci
  • CPC - greater parenchyma invasion and necrosis
  • MRI
    • GRE - foci of hypo intensity (hemorrhage)
    • T1 /T2 isointense
    • T1 +C - avidly enhancing
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21
Q

Small Blue Cell Tumor: Atypical teratoid/rhabdoid tumor

A
  • Pediatric tumors of embryonal origin - Primitive Neuroectodermal Tumors
  • Highly aggressive WHO grade IV
  • Associated with malignant rhabdoid tumor of the kidney
  • Predominantly in the posterior fossa
  • Supratentorial - rare - thick/wavy heterogeneously enhancing wall surrounding cystic parts of mass
  • Can have associated hemorrhage surrounding the tumor
  • Some tumors have predilection for CNIII
  • MRI
    • T1 - hypointense, T2 - hyperintense , T1 +C - enhances
    • DWI - bright ADC- Dark
    • GRE - associated hemorrhage
  • CT - hyperdense
    OTHER DDX
  • Lymphoma - No GRE signal until after TX
  • Schwannomas - involving CNIII but slow growing
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22
Q

Lhermite-Duclos/Dysplastic Gangliocytoma

A
  • Grade I dysplastic gangliocytoma of the cerebellum
  • Associated with Cowden syndrome
  • Ataxia, Nausea, Vomiting, and Hydrocephalus
  • MRI - T1 Hypointense, T2- Hyperintense, nonehancing expansile mass. Tigroid Pattern is very typical
  • May infiltrate the brainstem and cause mass effect on the fourth ventricle
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23
Q

Subependymoma

A
  • Slow growing WHO grade 1 neoplasm
  • Arises from subependymal lining under ependymal lining.
  • Ependymal origin; intraventricular in location.
  • Patients older than 15 y/o usually adults >40
  • Can cause CSF obstruction, usually asymptomatic
  • CT - iso and hypo-attenuating, well -circumscribed, with cystic component. Can be calcifications or hemorrhage
  • MRI T1 - iso-intense T1 C+ mild to no enhancement. T2 - Isointense
  • Other DDX
    • Ependymoma - contrast enhancement and calcifications, can invade surrounding parenchyma
  • Central Neurocytoma - speculated margin bully appearance moderate to intense enhancement
  • gliomas - none to minimal enhancement, but not microcytic
  • Medulloblastoma - increased diffusion and intense enhancement
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24
Q

Ganglioglioma

A
  • Most common neoplasm with intractable epilepsy
  • Superficial cortical location with solid/cystic mixed morphology.
  • Temporal lobes
  • Low peritumoral edema
  • Macrocalcifications
  • Skull scalloping
  • LOW ADC values
  • Other DDX
    • Pleomorphic Xanthoastrocytoma - DURAL THICKENING/ENHANCEMENT, No calc, No skull involvement
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25
Q

Pleomorphic xanthoastrocytoma

A
  • Grade II astrocytic tumor
  • Good prognosis
  • Children and young adults
  • Supratentorial and seen in temporal
  • MRI - Cystic, solid or mixed morphology with intense enhancement of the solid component
    • T1 C+ - Nodule and DURAL enhancement.
  • Low peritumoral edema
  • OTHER DDX
    • ganglioganglioma/ gangliocytoma
    • DNET - cortical dysplasia
    • pilocytic astrocytoma usually infratentorial
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26
Q

Balo Concentric Sclerosis

A
  • Rare demyelinating disease - variant of Multiple Sclerosis
  • Lamellar demyelination with concentric morphology.
  • Alternating rings of myelin preservation and loss
  • Demyelination starts centrally in the core and extend outward concentrically
  • Not always monophasic in course
  • Treat w/ steroids early
  • IMAGING
    • MRI - T2/FLAIR - hyper and hypointensities in a concentric ring like fashion
    • T1 w/ C - intense eccentric enhancement
  • Other DDX
    • Acute Disseminated Encephalomyelitis
    • MS
    • Abscess - Restricted Diffusion centrally (bright)
    • Neoplasm
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27
Q

Acute Disseminated Encephalomyelitis

A
  • Immune mediated multifocal inflammatory disorder preceded by viral infection. Vaccination can trigger (rare)
  • Molecular mimicry - cross reactivity of antibodies
  • Imaging - widespread bilateral and asymmetric lesion
    • Subcortical and deep white matter involvement
    • Peripheral cortical involvement - rarer
    • periventricular and callosal white matter - rarest
    • Deep gray matter - 50%
    • cerebellar, brainstem and spina cord 30-50%
    • Variable enhancement
    • variable size
    • CT - hypotenuse
    • MR - T2 - ill defined hyperintense lesions
  • Monophasic disease
  • Recurrent disease - recurrence of lesions in same location as original disease
  • Multiphasic - new lesions in new places not originally seen
  • Aggressive variants
    • acute hemorrhagic leukoencephalitis
    • acute hemorrhagic encephalomyelitis
    • acute necrohemorrhagic leukopencaphlitis
  • Other DDX
    • MS - smaller and better defined T1 - black hole, usually periventricular involvement
    • Vasculitis - older patients and have associated hemorrhage
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28
Q

Rasmussen Encephalitis

A
  • Progressive unilateral focal encephalitis of uncertain etiology
  • Atrophy in area of previous encephalitis
  • Patients between 1-15 y/o
  • Prodromal Stage: Low seizure hz, Imaging normal, Mild hemiplegia
  • Acute Stage:
    • Partial complex seizures
    • Progressive hemiparesis
    • Cognitive impairment
    • Imaging - Swelling of fronto-insular- temporal region
    • CT - Cortical and subcortical hypodensity
    • MRI T2/FLAIR - hyperintense - cortical and white matter
    • MAY see PIAL/CORTICAL enhancement.
  • Residual/Chronic - Stable neuro deficits and continued seizures.
    • Atrophy of involved areas seen on imaging
  • OTHER DDX
    • Sturge Weber - Port-Wine facial nevus and enhancement of the pial angioma.
    • Dyke-Davidoff-Masson - Unilateral brain atrophy with calvarial thickening and hyperaeration of the paranasal sinuses - Utero or perinatal hemispheric infarction.
    • Focal Cortical Dysplasia - Blurring of grey-white matter junction w/ subcortical WM signal abnormality, cortical thickening and signal change. Signal tapering from subcortical WM to the periventricular area
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29
Q

Autoimmune Paraneoplastic Limbic Encephalitis

A
  • Limbic encephalitis is the most common clinical paraneoplastic syndrome with SCLC
  • Associated antibodies include Anti-Hu, Anti Ri, Anti- Yu, VGKC, NMDAR, and AMPAR
  • Anti - Glutamic acid decarboxylase - associated with non-neoplastic cases
  • Imaging
    • CT - usually normal
    • MRI T1 - hypointense T2/FLARI hyperintense, DWI -normal , T1C patchy enhancement in the medial temporal; lobes, insular, cingulate gyrus, sub frontal cortex and inferior frontal white matter.
    • FDG-PET increased glucose avidity
  • Other paraneoplastic enchapilitis
    • brainstem - testicular germ cell tumors
    • paraneoplastic cerebellar degeneration - breast, ovarian, Hogkins - see cerebellar atrophy
  • OTHER DDX
    • Status Epilepticus - Unilateral - DWI and Enhancement
    • Low grade glioma - unilateral T2 hyperintese with midl mass effect. No enhancement
    • Herpes - DWI restriction, mass effect, enhancement, and hemorrhage. RAPID onset
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30
Q

Restricted Diffusion DDX

A
  • Acute Stroke
  • Abscess
  • Cellular Tumor (lymphoma/medulloblastoma/etc…)
  • Epidermoid Cyst
  • Herpes Encephalitis
  • Creutzfeldt-Jakob Disease
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31
Q

GRE/SWI - Multiple Dark Spot DDX

A
  • Hypertensive micro bleeds
  • Cerebral amyloid angiopathy
  • Familial cerebral cavernous malformations
  • Axonal Shear Injury
  • Multiple Hemorrhagic metastases
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32
Q

Canavan Disorder

A
  • Demyelinating disorder with elevated NAA on MR spectroscopy
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33
Q

Perfusion MR

A
  • Multiple boluses of gadolinium
  • GRE/SWI imaging is done in rapid sequence to evaluated perfusion
  • DECREASED INTENSITY IS NORMAL
  • Evaluates Stroke/Tumor
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34
Q

Areas of Brain that always Enhance w/ Contrast

A

These areas do not have a BBB

  • Choroid Plexus
  • Pituitary and Pineal
  • Tuber Cinereum
  • Area Postrema
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35
Q

Periventricular Enhancement DDX

A
  • Primary CNS Lymphoma
  • Infectious Ependymitis
  • Multiple Sclerosis
  • Primary Glial Tumor
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36
Q

Gyriform Enhancement DDX

A
  • Herpes Encephalitis
  • Subacute Infarct
  • Meningitis
  • PRES
37
Q

Nodular Subcortical enhancement DDX

A

Metastatic Disease

38
Q

Ring Enhancement DDX

A
  • MAGIC DR
  • Metastasis
  • Abscess - DWI restriction
  • Glioma - MR Perfusion/Spect
  • Infarct - Subacute basal ganglia (vs gyriform)
  • Contusion - Traumatic or NON - subacute /chronic
  • Demyelination - Incomplete C shape
  • Radiation - Looks like glioma use Perf/Spect
39
Q

Pachymeningeal Enhancement DDX

A

Dural Enhancement

  • Intracranial Hypotensions(usually see tonsillar sagging, pituiatary enlargement)
  • Post-op
  • Post Lumbar-Puncture
  • Meningeal neoplasm
  • Granulomatous Disease
  • Ig-G4 related hypertrophic pachymeningitis
40
Q

Leptomeningeal Enhancement DDX

A

Pai/Arachnoid Enhancement

  • Meningitis
    • Thick/Nodular - Fungal
    • Fine/Linear - Viral/Bacterial
  • Carcinomatosis (Medulloblastoma, Oligodendroglioma, Choroid Plexus, Germinoma, Glioblastoma, Ependymoma, Breast/lymphoma mets)
  • Viral Encephalitis - can have CN enhancement
  • Slow Vascular Flow - Hypercoagulable, MoyaMoya(ivy sign)
41
Q

FLAIR Intensity - Subarachnoid

A
  • Subarachnoid Hemorrhage
  • Slow Flow
  • Meningitis
  • Leptomeningeal Carcinomatosis
42
Q

Hemorrhagic Tumors

A 
Primary - Glioblastoma
Metastatic 
  - RCC
  - Thyroid
  - Melanoma 
  - Choriocarcinoma
  - Lung 
  - Breast
43
Q

T2 - Hypointense Tumors (abnormal) DDX

A
  • Metastatic disease containing desiccated Mucin
    • GI adenocarcinomas
  • Hypercellular Tumors
    • Lymphoma
    • Medulloblastoma
    • Germinomas
    • Glioblastomas
44
Q

T1 - Hyperintense Tumors (abnormal) DDX

A
  • Melanoma
  • Dermoid (fat)
  • Teratoma (fat)
  • Hemorrhagic metastasis
45
Q

Fibrillary Astrocytomas

A
  • Infiltrative Tumors that occur in brain/spine
  • Low grade astrocytoma
  • Anaplastic Astrocytoma
  • Glioblastoma
46
Q

Low-Grade Astroyctoma

A
  • Type of Fibrillary Astrocytoma
  • WHO Grade II
    • T2 hyperintense
    • No enhancement
47
Q

Anaplastic Astrocytoma

A
  • Type of Fibrillary Astrocytoma
  • WHO Grade III
    • Thickened Cortex
    • Can appear as irregularly enhancing mass
  • Natural progression to Glioblastoma Multiforme
48
Q

Gliomatosis Cerebri

A
  • Diffuse Infiltrative WHO Grade II or III ASTROCYTOMA that affects multiple lobes
  • Diagnostic Cx
    • > = 2 lobes
    • AND Extra-Cortical Involvement
      • Basal Ganglia, Corpus Callosum, brainstem or cerebellum.
  • Imaging
    • T2 Hyperintense diffusely
    • Mass Effects
    • NO enhancement
  • OTHER DDX
    • Immunocompromised Lymphoma
    • Progressive mutlifocal leukoencephalopathy
    • AIDS encephalopathy
49
Q

Progressive Multifocal Leukoencephalopathy

A
  • Rapidly progressive and potentially fatal CNS infection from reactivation of JC Virus
  • Severely immunocompromised patients
  • Extensive, confluent white matter disease
    • Restricts diffusion , and has punctuate/hazy enhancement
  • Immune reconstitution inflammatory syndrome - patient underlying immunocompromised state is treated and patients subsequently develop significant mass effect
  • Imaging Findings
    • PML
      • MRI
        • FLAIR Hyperintensities - involves white matter - from the ventricle to grey/white junction
        • T1C+ - No enhancement in this area
    • Immune reconstitution inflammatory syndrome
      • MRI
        • Increasing FLAIR hyperintensities with contrast enhancement
50
Q

Tumefactive Demyelination

A
  • Demyelinating lesions greater than 2 cm in size with mass effect and/or edema.
  • Focal/Supratentorial
  • Imaging Findings
    • CT - Hypodensity in the area of enhancement on MR
    • MR - T2 Hypointense rim, T1C+ enhancing rim, incomplete and open part points toward the grey matter. DWI - NO RESTRICTED DIFFUSION
    • FDG-PET - positive but not as much as with neoplasms (lymphoma)
  • Other DDX
    • Lymphoma - typically have central and not just peripheral enhancement
    • Abscess - Restricted diffusion within the lesion.
    • Low Grade Astrocytoma - NO ehancement at all vs peripheral ring.
  • TX - Steroids IV - short term . MR reimaging in 6-8 weeks
    • Patients can relapse into MS or NMO.
51
Q

Bells Palsy

A
  • Contrast enhancement of the geniculate ganglion and the proximal tympanic segment
  • Mild enhancement can be seen in the mastoid, labyrinthine, and meatal segments
  • CNS Lyme disease can show bilateral involvement
    OTHER DDX
  • Nodularity or enlargement of the nerve - mets, lymphoproliferative disorder, and perineurial spread of malignancy
52
Q

Neurosarcoidosis

A
  • Idiopathic systemic disorder with non-caseating granulomas
  • Elevated Serum ACE levels
    Imaging - Predilection for basilar pial enhancement
53
Q

Multiple Sclerosis

A
  • Chronic demyelinating illness of the central nervous system
  • Majority of demyelinating lesions are supratentorial
  • Typical location - periventricular with perivenular distribution
  • Parallel to the lateral ventricle - Dawsons fingers
  • Alternating linear iso and hyperintense on FLAIR imaging
  • Classic enhancement pattern of incomplete ring of enhancement - horseshoe shaped
  • small percent of lesions are diffusion restricted.
54
Q

Marburg Variant of MS

A
  • Rare variant of MS with extensive multifocal areas of tumefactive demyelination
  • Severe inflammation and edema with evidence of enhancement and mass effect
  • Other DDX
    • ADEM - Younger Patients
    • NMO - no brain involvement
    • Balo Centric Sclerosis - lamellate appearance
    • Susac syndrome - smaller lesion with central corpus callosal lesions.
55
Q

Marchiafava-Bignami Disease

A
  • rare necrotizing degeneration of the corpus callosum seen in chronic alcoholics
  • Lesions typically involve the body, extending into the genus and splenium
  • Acute presentation - disorientation, confusion, seizures
    Imaging
  • MRI - DWI - Restricted Dissusion. FLAIR - Hyperintensity
56
Q

Lupus

A
  • chronic systemic autoimmune disorder with multi system involvement
  • Neuropsych involvement include
    • Cerebrovascular, Cognitive dysfunction, seizures, psychosis and peripheral nervous system disorders
  • Positive serologic markers such as ANA and dsDNA.
  • Large vessel occlusive disease or stroke due to hyper coagulable state.
  • Imaging
    • FLAIR - Hyperintense cortical /subcortical lesions
    • enhancement on T1 C+
    • Pial enhancement
57
Q

Ig-G4 hypertrophic pachymeningitis

A
  • Ig-G4 related disease- immune mediated fibroinflammatory condition that can have multi systemic involvement
    • pancreatitis
    • sialdenitis
    • dacrocystitis
    • lymphadenopathy
    • thyroiditis
    • cholangitis
    • pulmonary disease
    • pachymeningeal or parenchymal
    • hypophysitis
    • orbital inflammatory pseudotumor
58
Q

Behcet Disease

A
  • Multisystem inflammatory disorder of unknown etiology
  • Most commonly involves the mesodiencephalic junction
  • Venous vasculitis
  • Predominantly non-hemorrhagic lesions - can hemorrhage rarely
  • Subcortical hemispheric lesions are rare
  • Other DDX
    • Brainstem astrocytoma, SLE, Vasculitis and sarcoidosis
59
Q

Susac Syndrome

A
  • AKA: SICRET - small infarctions of cochlear, retinal, and encephalic tissue
  • Microangiopathy
  • Women:Men 3:1
  • 2nd to 4th decade
  • immune mediated endotheliopathy
  • TRIAD
    • encephalopathy
    • Visual Field Abnormalities
    • hearing loss
  • Imaging Findings
    • Mimics MS - multifocal white matter lesions including corpus callosum, leptomeningeal enhancement, basal ganglia/thalamus involvement
    • As lesions resolve replaced by glial atrophy
    • FLAIR Signal abnormalities
  • Optho exam with fluorescein angiography - demonstrate peripheral retinal artery occlusion
  • OTHER DDX
    • MS
    • ADEM
    • Lyme
    • Age related microangiopathy
60
Q

Optic Neuritis

A
  • Inflammation of the optic nerve.
  • Optic nerve is an extension of the brain
  • Oligodendroglioma myelinate the nerve vs schwann cells in remaining cranial nerves
  • Classic Triad
    • Visual Loss
    • Periocular Pain
    • Dyschromatopsia(Deficiency in color vision)
  • Imaging
    • High T2/FLAIR signal in the optic nerve w/ or w/out enhancement
  • MS - unilateral, NMO - bilateral
  • Perineuritis - inflammation of the optic nerve sheath (tram-track appearance)
  • Other DDX
    • MS
    • NMO
    • Ischemia
    • Infection
    • optic nerve glioma
61
Q

Dermoid Cysts

A
  • Rare congenital inclusion cysts from inclusion of embryonic ectoderm into neural tube during 3rd to 5th weeks of embryonic life.
  • Midline, sellar, frontonasal, and posterior fossa
  • Contents include desquamated epithelium, sebaceous glad secretions, fat, and hair. Calcs and teeth rare
  • Unruptured lesions are asymptomatic
  • Rupture secondary to spontaneous, trauma, hormonal changes from aging
  • Present with headaches, seizures, focal neurologic defects, aseptic meningitis, hydrocephalus, vasospasm, and cerebral ischemia.
  • Imaging
    • CT - fat density
    • MRI T1 hyperintense T2- variable intensity. T1C+ no enhancement
    • W/ rupture fat intensity seen in subarachnoid spaces and within ventricular system.
    • Pial enhancement seen from chemical meningitis in cases of rupture
      Other DDX
    • Epidermoid Cyst - Cyst with CSF signal
    • Lipoma - Homogenous fat attenuation
62
Q

Colloid Cyst

A
  • Anterior Third Ventricular Lesions draped by the fornices
  • Cyst lined by simple to pseudo stratified epithelial lining with interspersed goblet cells and ciliated cells.
  • Cyst content is likely derived from secretions and breakdown products from the epithelium
  • Adults - 3rd and 5th decade of life
  • Imaging
    • CT - 2/3 hyper dense, 1/3 isodense
    • MRI - T1 - 1/2 hyperintense 1/2 - iso/hypointense
    • T2 hypointense
    • T1 C+ no or little enhancement
  • Concern for hydrocephalus especially if becomes lodged in foramen of Monro
63
Q

Idiopathic normal pressure hydrocephalus

A
  • Ventricular enlargement associated with the clinical Hakim - Adams triad
    • Urinary incontinence
    • dementia
    • gait abnormalities
  • NO obstructive cause - nonsobstructive impairment of CSF reabsorption
  • Widening of the sylvan fissure and medical hemispheric subarachnoid space with widening of the ventricle out of proportion to volume loss
  • Evans Index - Frontal Horn/skull diameter >.3 = abnormal
  • Phase contrast MRI with measuring of CSF acqueductal stroke volume,
  • High Volume LP 30-40ml
  • Nuclear cisternogram
  • Shunting most useful in patient with aqueduct stroke volume 2X given age.
64
Q

Dural Sinus thrombosis

A

An “empty delta” sign on contrast-enhanced CT or contrast-enhanced T1 MR is due to enhancement of the dura surrounding nonenhancing thrombus

65
Q

Intracranial Saccular Aneurysms

A
  • Intracranial saccular aneurysms (SAs) tend to arise from areas of maximum hemodynamic stress.
  • Almost 90% of SAs arise in the anterior circulation.
  • Approximately 1/3 of all SAs arise from the anterior communicating artery, and 1/3 arise from the junction of the internal carotid and posterior communicating arteries.
  • About 20% arise from the MCA bifurcation.
  • Only 10% arise in the posterior circulation. The majority of these originate at the basilar bifurcation.

-Of the listed possibilities, the least common site of origin is the posterior inferior cerebellar artery (PICA). PICA is the 2nd most common site for aneurysms arising in the vertebrobasilar system and represents between 2-3% of all aneurysms.

66
Q

MCA

A
  • The middle cerebral artery (MCA) supplies most of the lateral surfaces of the brain and many of its deep structures (including most of the basal ganglia).
  • It supplies the anterior pole of the temporal lobe, but the inferior surface is mostly supplied by the posterior cerebral artery (not the MCA).
  • True MCA anomalies (hypoplasia, aplasia, duplication) are rare
67
Q

Straight Sinus

A

the straight sinus, a single midline structure that extends posteroinferiorly from the vein of Galen to the sinus confluence (torcular Herophili).

68
Q

Hydrocephalus

A
  • Obstructive hydrocephalus can be intraventricular or extraventricular.
  • In intraventricular obstructive hydrocephalus (IVOH) the obstruction is proximal to the 4th ventricle outlet foramina, and in extraventricular obstructive hydrocephalus (EVOH) it is distal.
  • The presence of periventricular edema due to transependymal cerebrospinal fluid (CSF) flow from elevated intraventricular pressure favors the diagnosis of acute/subacute or progressive hydrocephalus and requires urgent surgical intervention.
  • Treatment includes CSF diversion procedures (shunt or endoscopic ventriculostomy) and surgery to alleviate the primary cause of obstruction.
69
Q

Middle Cerebellar Peduncles

A
  • The middle cerebellar peduncles (a.k.a. brachium pontis), the major white matter connections between the pons and the cerebellum.
  • They represent the continuation of the corticopontine tracts.
  • The flocculi of the cerebellum are the ovoid gray matter structures that lie posterolateral to the middle cerebellar peduncles and project into the cerebellopontine angle cistern.
70
Q

Internal Auditory Canal

A
  • The internal auditory canal is a funnel-shaped channel in the temporal bone that opens into the cerebellopontine angle cistern and contains cranial nerves 7 and 8 as well as the anterior inferior cerebellar artery.
71
Q

Circle of Willis

A
  • 10 components
  • 2 internal carotid arteries
  • 2 A1 horizontal (A1) anterior cerebral artery segments
  • the anterior communicating artery
  • 2 posterior communicating arteries
  • the distal basilar artery
  • 2 horizontal (P1) segments of the posterior cerebral arteries.
72
Q

Cerebral Artery Hyperdensity

A
  • Circulating blood in cerebral arteries (and veins/dural venous sinuses) is normally slightly hyperdense to brain parenchyma.
  • Anything that makes the brain parenchymal hypodense (e.g., diffuse cerebral edema) accentuates the difference in attenuation.
  • Do not mistake diffuse cerebral edema for thrombosis or subarachnoid hemorrhage.
  • Elevated hematocrit (polycythemia, physiologically increased hematocrit with high altitude, etc.) makes both the arteries and the veins appear denser than usual. A very high hematocrit level can actually make a NECT scan look like a CECT scan.
  • Subarachnoid hemorrhage does not cause a brain artery to appear dense relative to brain.
73
Q

Leptomeningeal Infectious Process

A
  • Imaging
    • The sag and ax T1WI C+ MR images demonstrate thick nodular enhancement on the cord surface due to a leptomeningeal infectious process.
    • This type of disease is intramurally but extra medullary.
74
Q

Hyperacute Infarction - MR Imaging

A
  • Around 95% of hyperacute infarcts (< 6 hours) show diffusion restriction on DWI, with hyperintensity on DWI and corresponding hypointensity on ADC maps(subtraction imaging).
  • The hyperintensity on DWI is due to cytotoxic edema.
75
Q

Odontoid Fractures

A

Type I: Avulsion fracture from tip of odontoid at insertion of alar ligament
Type II: Transverse fracture through base of odontoid
Type III: Oblique fracture extending from base of odontoid into body of C2

76
Q

Basilar Meningitis

A
  • The basilar cisterns are completely effaced and appear filled with ill-defined, mildly hyperdense material .
  • The right temporal horn is enlarged , suggesting early obstructive hydrocephalus. The substance that fills the basilar cisterns is not sufficiently hyperdense for blood.
  • Thick exudate and is most consistent with meningitis.
  • Tuberculosis and coccidiodomycosis are notorious for causing thick, dense exudates that preferentially involve the basilar cisterns.
77
Q

Post-Septal Orbital Cellulitis

A
  • The intraorbital soft tissues that are located posterior to the orbital septum. Additionally, postseptal cellulitis is usually related to paranasal sinus disease, whereas in this case the sinuses are clear.
  • Imaging
    • Poor definition of orbital planes
    • Inflammatory stranding in the intraconal fat
    • Intraconal or extraconal soft tissue mass
    • Edema of the extraocular muscles
    • Intraorbital abscess
    • Subperiosteal abscess
78
Q

Pre-Septal Orbital Cellulitis

A
  • Preseptal cellulitis in adults is most commonly the result of injury to the periorbital skin, such as penetrating trauma or insect bite. The orbital septum usually prevents ordinary cutaneous infections from spreading posteriorly into the orbit proper
  • Infiltrative soft tissue thickening in this case is limited to the preseptal cutaneous and subcutaneous tissues. In the absence of trauma, this is most likely due to localized cellulitis. Clinical examination would be expected to reveal typical signs of infection.
79
Q

Epidermoid Cyst

A
  • Epidermoid cyst microstructure of parallel-layered keratin filaments and flakes causes it to display restricted diffusion (high signal) when imaged with MR DWI.
  • When compared to arachnoid cyst the only way to differentiate between the two is the high DWI signal vs arachnoid cyst that has low DWI signal (does not restrict
80
Q

Intratonsillar Abscess

A
  • The vast majority of tonsillar abscesses occur in the palatine tonsil. Although the lingual (posterior tongue) and adenoidal (nasopharynx) tonsils may suppurate, this is a relatively rare occurrence. There is no tonsil in the hypopharynx.
81
Q

Fibrous Dysplasia

A
  • The appearance of expansile ground glass matrix involving multiple bones of the skull base in a younger patient is highly suggestive of fibrous dysplasia
  • Polyostotic fibrous dysplasia is more common in the skull base and face and is less likely to be syndromic than polyostotic disease in the appendicular skeleton.
82
Q

Contraindications to Lumbar Puncture

A
  • Contraindications to lumbar puncture include: Local skin infections over proposed puncture site (absolute contraindication), raised intracranial pressure (except in pseudotumor cerebri and cryptococcal meningitis), suspected spinal cord mass or intracranial mass lesion (based on lateralizing neurological findings or papilledema), uncontrolled bleeding diathesis(patient with bleeding conditions), and lack of patient cooperation.
83
Q

LeFort Fractures

A
  • Pterygomaxillary junction disjunction with fractures involving the superior medial and inferior lateral maxillary buttresses describe the LeFort type 2 of transfacial fracture. The fracture complex is also referred to as a “pyramidal fracture” as the midface is essentially separated from the skull by fracture planes that form a pyramid shape.

Similarly, type 1 fractures may be described as “floating palate,” and type 3 fractures may be described as “craniofacial dissociation.” In all 3 of the transfacial (Le Fort) type fractures, the pterygomaxillary junction is disrupted, there are fractures of the pterygoid plates/processes, and portions of the face become disjointed from the skull.

Zygomaticomaxillary complex fractures do not involve the pterygomaxillary junction and are not part of the LeFort classification scheme.

84
Q

Cervical Hyperflexion Injury

A
  • Hyperflexion injuries tend to occur in the mid or lower cervical spine. There is primary failure of the posterior column as demonstrated by the edema in the interspinous ligaments and widening of the interspinous distance. Bilateral locked/jumped facets indicate an unstable injury resulting from the rupture of the annulus fibrosis, the posterior longitudinal ligament, and the capsular and interspinous ligaments. This injury pattern is invariably associated with neurologic deficits.
85
Q

Acute Obstructive Hydrocephalus

A
  • The lateral ventricles are moderately severely and symmetrically enlarged . The 3rd ventricle is also moderately prominent . The margins of the lateral ventricles appear “blurred” and indistinct, surrounded by a hypodense periventricular “halo” . This appearance is caused by accumulation of interstitial fluid in the deep periventricular white matter.
86
Q

Masticator Space

A
  • The masticator space contains the muscles of mastication that are all innervated by the mandibular division of the trigeminal nerve (CNV3). A malignant tumor of the masticator space reaches the intracranial area via perineural spread along this nerve, through the FORAMEN OVALE.
87
Q

Lenticulostriate Arteries

A
  • Medial Lenticulostriate Arteries
    • The medial lenticulostriate arteries are seen here arising from the A1 segment of the anterior cerebral artery. Supply most of the medial basal ganglia.
  • Lateral Lenticulostriate Arteries
    • The lateral lenticulostriate arteries are penetrating branches that arise from the horizontal (M1) middle cerebral artery (MCA). They supply most of the lateral basal ganglia including the putamen and internal capsule. These penetrating branches are common sites for the 2 important pathologies: Hypertensive basal ganglionic hemorrhages and lacunar infarcts.
88
Q

Scheuermann Disease

A

-The diagnosis of Scheuermann disease depends upon 3 contiguous disc levels having the following abnormalities: (1) Mild anterior wedging (≥ 5 degrees), (2) endplate irregularity, (3) Schmorl nodes, and (4) kyphosis. Back pain is the typical symptomatic presentation, with many cases being incidental and asymptomatic.

Radiology (4 decks)

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