Neuroradiology Flashcards
Third ventricle recesses
Chiasmatic (Supra optic)
Infundibular
Suprapineal
Pineal
Massa intermedia
Gray and white matter
Passes 3rd ventricle
Connects bilateral thalami
Ventricles connection
Lateral—>3rd : Monro
3rd —> 4th: cerebral aqueduct
4th—> spinal canal: obex
4th —> subarachnoid and basal cisterns: Luschka and Magendie
Choroid plexus locations
Body and temporal horn of lateral
Roof of 3rd and 4th
CSF absorption
Arachnoid granulation (evaginations into dural venous sinuses)
Lymphatic
Cerebral veins
Cytotoxic vs vasogenic vs interstitial edema
Cytotoxic: involves both gray and white matter/ due to cell death(infarct)
Vasogenic: primarily in white matter ( neoplasm, infection)
Interstitial: obstructive hydrocephalus/ periventricular fluid ( transependymal flow of CSF)
Subfalcine herniation
Cingulate gyrus under the falx
Compression of ACA
Foremen of Monroe obstruction—> contra lateral hydro
Transtentorial(uncal) herniation
Downward: inferomedial uncus displacement—> ipsilateral CN 3(oculomotor) eye is down and out
Ipsilateral PCA: medial temporal/ occipital infarct
Duret hemorrhage
Contra lateral cerebral peduncle compression against Kernohan’s notch—> ipsilateral hemiparesis
Upward: superior tentorial of cerebellar vermis( posterior fossa mass effect) —> obstructive hydro
Cerebellar tonsillar herniation
Compression of medulla
Hydrocephalus types
Communicating:
Subarachnoid hemorrhage
Normal pressure hydrocephalus (lateral and 3rd)
Noncommunicating:
Obstruction
3rd colloid cyst
Posterior fossa mass
Basal or perimesencephalic cisterns
Suprasellar Prepontine Interpeduncular Ambient Quadrigeminal
Disc bulge vs herniation
Broad based bulge: >180 of disc circumference
Greater than 2mm
Herniation: <90 of disc circumference
Protrusion: neck>dome
Extrusion: neck
Nerve root exit site
Thoracic and lumbar: below
Cervical: above
C8 below C7 vertebral body
Position of herniation
Medial(Central, Paracentral):descending nerve root / L4-5 herniation—> Descending L5
Lateral(Foraminal, Far lateral):exiting nerve root/ L4-5–> exiting L4
Disc degeneration on imaging
Hypo on T2
Loss of height
Osteophytes
Schmorl’s node: superior or inferior disc herniation ( hyper on T2)
Modic changes
Modic 1: hyper T2 hypo T1/ inflammation/active back pain/ better surgery outcome
Modic 2: hyper on both/ fatty proliferation/ chronic ischemia/ no symptom
Modic 3: hypo on both/ sclerosis
Ligamentum flavum hypertrophy
Posterior of spinal canal
Infolding/ inward buckling
Stenosis
Facet Arthropathy
Medial to neural foramina
Can cause neural foraminal narrowing
Associated with synovial cyst ( hyper T2, variable T1)
Tarlov cyst
Perineural cyst in sacrum/ within nerve root sheath
High intensity zone
Hyper T2 in annulus fibrosus
Fissure or tear /can cause pain
Due to disc degeneration
Diffuse idiopathic skeletal hyperostosis
Anterior osteophytes extending at least four levels
Disc spaces are preserved
Spinal fx with small trauma (like AS)
Associated with OPLL
Ossification of Posterior Longitudinal Ligament
OPLL
Spinal canal stenosis
Compression on anterior cord
Low signal on MRI
Begins in cervical spine
Scar vs recurrent disc
Both hypo on T2
Scar enhances throughout
Disc enhances peripherally
Pyogenic disc it is/ osteomyelitis
Hematogenous source
Staph aureus
Adults: starts from subchondral bone then disc
Pets: starts from disc then end plates
Discitis/osteomyelitis on imaging
Marrow hypo on T1, both sides of abnormal disc which is hyper on T2
Loss of height
Loss of definition
Vertebral collapse
Adjacent soft tissue infection
Tuberculous osteomyelitis
Pot disease
Discs are spared
Wedge shaped compression anteriorly/ gibbus deformity
Gibbus deformity
Acutely angled kyphosis
Compression fracture
Achondroplasia
Mucopolysaccharidoses(Hunter and Hurler)
Dural AV fistula
Older males
Back pain and progressive myelopathy
Cognard type 5
MRI: flow voids surrounding the cord
Swollen cord
Myelogram: serpiginous filling defects in subarachnoid
Spinal cord infarction
Upper thoracic and thoracolumbar
Bowel bladder incontinency, loss of perineal sensation
Motor and sensory loss of legs
Blood supply to distal cord
Artery of Adamkiewicz
Risk factors for spinal cord infarction
Aortic surgery Aortic aneurysm Arthritis Sickle cell Vascular malformation Herniation
Spinal cord infarction on imaging
Hyper on T2
Enlarged cord
Restricted diffusion
Concomitant vertebral body infarction: sickle cell and steroid use
Tethered cord syndrome
Back and leg pain
Gait spasticity
Decreased lower sensation
Conus should end superior to inferior of L2
If below—> tethered
Thickened film or lipoma
Diastematomyelia
Congenital
Split spinal cord
Cause of scoliosis
Fatty film
Fat within film terminals
Associated with diastematomyelia, Tethered cord
Hyper on T1
Orbital cavity bones
Frontal Ethmoid Nasal Zygomatic Maxilla
Optic foremen
Optic nerve
Ophthalmic artery
Superior orbital fissure
CN III: superior, medial, inferior, inferior oblique
CN IV: superior oblique (SO4)
CN V1: sensory upper face
CN VI: lateral rectus (LR6)
Superior ophthalmic vein: valveless/ infection to brain
Inferior orbital fissure
CN V2: sensory inferior eyelid, upper lip, nose
Infraorbital artery
CN V2 course
Cavernous sinus—> foramen rotardum—>inferior orbital fissure
Orbits compartments
Septum : orbit margin—> Tarsus of eyelid
Presentable/postseptal: infection
Postseptal Extra conal: lacrimal gland, fat, bone Conal: extraocular muscles Intraconal: optic nerve-sheath complex, sensory motor of orbit, LNs, fat Globe
Optic nerve-sheath complex
Optic nerve
Surrounding CSF
Leptomeningeal and dural coverings
Extraocular muscles origin
Inferior oblique: medial floor
Rest: annulus of Zinn, apex of orbit at optic foramen and medial superior fissure
Orbital infection causes
Paranasal sinuses
Trauma
Foreign body
Odontogenic
Preseptal infection
Swelling and erythema of eyelid
Orbital cellulitis
Not yet organized or peripherally ring enhancing
Subperiosteal abscess
Organized at periosteum
Exophthalmos
Visual impairment
Surgical emergency
Orbital abscess
Severe form of subperiosteal
Ophthalmoplegia
Exophthalmous
Visual impairment
Cover outs sinus thrombosis
Multiple CN palsy
Orbital abscess
Orbital hemangioma
Cavernous: in adults, most common, progressive proptosis
Imaging: CT—>intraconal,ovoid, enhancing
MRI—>iso T1/ hyper T2, early patchy enhancement with progressive filling
Capillary: first year of life, rare
With port-wine stain and strawberry hemangioma
Enlarges first year then involuted
Orbital lymphoma
With systemic disease Lacrimal gland involvement—> painless downward proptosis CT: hyper dense MRI: hypo on T1 and T2 Mold the globe
DDx: pseudotumor/ painful
Orbital Lymphangioma
Hamartomatous In peds Extra conal Multilocular cystic mass, complex, fluid level Peripheral and septal enhancement
Orbital Schwannoma/ neurofibromas
Schwannoma more common
Sensory of V1–> superior orbit
MRI: hypo T1, hyper T2 with enhancement
Orbital metastasis
Breast, lung, thyroid, renal, melanoma
Metastatic breast cancer: no exo sometimes endophthalmous
Peds with Neuroblastoma: sunburst type Periosteal reaction
Lacrimal gland lesion
Epithelial salivary and lymphoid tissue
Epithelial: 50% benign poleomorphic adenoma
Malignant: adenoid cystic and mucoepidermoid carcinoma
Lymphoid: sarcoidosis, lymphoma, pseudotumor
Thyroid ophthalmopathy
Lymphocytes—> hyaluronic acid—> fibrosis of muscles
Increases fat—>extraocular muscle enlargement
Inferior rectus—> medial—>superior—>lateral
(I’M SLow)
Bilateral, spares the tendons
Orbital pseudotumor
Infiltrate of lymphocyte, plasma cell and macrophage
Painful proptosis
DDx: Wegener, sarcoidosis
Lacrimal gland
Imaging: fat stranding, increased ST, enlarged muscles
T2: steroid
Tolosa- Hunt syndrome
Same as orbital pseudotumor but involves cavernous sinus
Optic nerve glioma
Peds: low grade astrocytoma with indolent course
NF1/ bilateral
Imaging: fusiform, variable enhancement, cyst and nodule
Adults: anaplastic astrocytoma or GBM
Imaging: enhancing, involves chiasm, any part of optic tract
Optic nerve meningioma
Second most Arachnoid cells Middle age, female Slow progressive visual impairment Preserved central visual field
Imaging: circumferential thickening, uniform enhancement, tram-track sign
Optic neuritis
Painful subacute vision loss and reduced color perception
MS(most), viral, sarcoidosis, vasculitis, toxins
Imaging: optic enlargement, T2 prolongation, enhancement(active phase)
Chronic: atrophy
Devic syndrome
Neuromyelitis optica
Optic nerve and spinal cord, worse than MS
NMO-IgG—> Ab to aquaporin 4
Imaging: MS type lesions at optic tract s and spinal cord
Absence of brain lesions
Retinoblastoma
Most common in globe/ Under 5 years/Leukocoria
Sporadic: unilateral/ Familial: bilateral
Imaging: hyper, enhancing, calcification
Trilateral: bilateral retino with pineoblastoma
Quadrilateral: bilateral retino, pineoblastoma and suprasellar retinoblastoma
Coat disease
Vascular of retina
Boys
Lipoproteinaceous subretinal exudates—> retinal detachment
Normal size globe with subretinal soft tissue without enhancing
Retinopathy of prematurity
Prolonged oxygen therapy
Abnormal vascular, hemorrhage, retinal detachment
Bilat microphthalmia, hyper globe
End stage: phthisis bulbs, shrunken nonfunctional globes
Persistent hyper plastic primary vitreous
Embryonic vasculature within vitreous
Hemorrhage, cataract, detachment
Microphthalmia, hyper vitreous
No calcification
Coloboma
Incomplete fusion of embryonic intraocular fissure
Elongated globe
Trisomy 13, 18, CHARGE, VATER
IMAGING: cone shaped deformity
Optic nerve coloboma: Posterior out pouching
Iris coloboma: anterior
Uvea: microphthalmous and cyst
Sphenoid wing dysplasia
NF 1
CSF pulsating through defect , pulsation exophthalmos
Septo-optic dysplasia
Optic nerve hypoplasia
Agenesis of septum
Associated with Schizencephaly
T1 vs T2
T1–> longitudinal relaxation
T2–> transverse relaxation
T1 shortening—> hyper
Prolongation—> hypo
T2 shortening—> hypo
Prolongation—> hyper
Conventional spin echo T1
Most brain lesions hypo on T1
T1 hyper: Gadolinium, fat,proteinaceous Paramagnetic stages of blood(methemoglobin) Melanin Mineralization ( copper,iron,manganese) Slow flow blood Calcium
Conventional spin echo T2
Most brain lesions are hyper on T2
Water is bright/ edema
T2 hypo:
Paramagnetic stages of blood( except hyper acute,extracellular methemoglobin)
Calcification
Fibrous
Highly cellular ( lymphoma, medulloblastoma)
Vascular flow void
Mucin ( desiccated sinus secretion)
FLAIR—> fluid attenuation inversion recovery
T2 with suppression of water
T1: WM brighter than GM
FLAIR: WM darker than GM
Conventional spin echo proton density
Highest signal to noise ratio
MS, demyelination plaques in posterior fossa
DWI and ADC
DWI: signal loss by increased Brownian motion
T2 weighted, reduced diffusivity—> bright
ADC: without T2
reduced diffusivity—>dark
Higher b-value: more contrast, decreases signal to noise ratio
Anisotropic
Tendency of water to diffuse along white matter tract
Reduced diffusion DDx
Acute stroke Bacterial abscess Cellular tumor( lymphoma, medulloblastoma) Epidermis cyst Herpes encephalitis Creutzfeldt-Jakob disease
