Neuroimaging Flashcards
Diffusion restricting lesions
In the brain: cytotoxic edema/excitotoxic injury
– Infarct, hypoxic-ischemic encephalopathy
– Cerebritis, herpes encephalitis, CJD, PML
– Acute demyelination, Wallerian degeneration
– Diffuse axonal injury, shaken baby syndrome
– Status epilepticus, osmotic myelinolysis
In a cavity or cyst: pus or ?protein
– Abscess: distinguish from necrotic tumor
– Epidermoid cyst: distinguish from arachnoid cyst
MRI perfusion
MRI: Perfusion(PWI), ±contrast
– CBV: Cerebral blood volume (ml/100g)
– CBF: Cerebral blood flow (ml/min/100g)
– MTT: Mean transit time (sec)
•Acute stroke: ↑MTT ↓CBF ↓CBV
– ?Determine ischemic penumbra, “tissue at risk”
– Jury still out (DIAS, DEDAS, DEFUSE, EPITHET)
Tumor: ↑CBF ↑CBV in high-grade tumors
– Pre-operatively predict tumor grade
– Distinguish recurrent tumor v radiation necrosis
MRI spectroscopy
Metabolites resonate at specific frequencies
• 2.0 ppm: N-Acetyl Aspartate
– “NAA”, neuronal integrity
• 3.0 ppm: Creatine + PCr
– “Cr”, energy metabolite
• 3.2 ppm: Choline + PC
– “Cho”, membrane turnover
• ~1.3 ppm: Lipid/lactate
– “Lip/lac”, necrosis
• “Tumor signature”: ↑Cho, ↓NAA
• Canavan’s disease: ↑NAA due to enzyme deficiency (aspartoacylase)
Intra-axial brain tumors - imaging
Metastasis
Glioma
Astrocytoma, oligodendroglioma, ependymoma, CPP
Lymphoma
Abscess vs High grade Glioma
Double Rim sign w/abscess: On T2F & GRE: outer rim hypo-intense while inner rim hyper-intense (GBM both rims hypo-intense)
Homogenous enhancement (GBM heterogeneous enhancement)
Time course quicker onset of symptoms and growth rate for abscess
Extra-axial brain tumors - imaging
Meningioma
– Hemangiopericytoma
Nerve sheath tumor
Metastasis
– Lymphoma, sarcoid
Aneurysm
Cerebellopontine angle brain tumors
Schwannoma (75%)
Meningioma (10%)
Epidermoid (5%)
(Aneurysm)
CPP angle - schwannoma vs meningioma vs epidermoid cyst
Internal auditory canal - IAC
Suprasellar/sellar brain tumors
“SATCHMOE”:
– Sarcoid, suprasellar extension of adenoma
– Aneurysm, arachnoid cyst
– Teratoma/germinoma
– Craniopharyngioma, chordoma
– Hypothalamic glioma, hamartoma
– Metastatic disease, meningioma, mucocele – Optic nerve glioma
– Epidermoid/dermoid, Eosinophilic granuloma
Anterior to third ventricle
Pineal region tumors
Germ cell tumors
- Germinoma
- Teratoma
- Choriocarcinoma
- Yolk sac tumor
- Embryonal cell cancer
Pineal origin tumors
- Pineocytoma
- Pineoblastoma
“Other” tumors
- Meningioma
- Tectal glioma
- PNET
Posterior to third ventricle
Intramedullary spine tumors - imaging
Ependymoma
Astrocytoma
1st two comprise 90-95% of intramedullary tumors
Hemangioblastoma
Metastases
Intradural/extramedullary spine tumors - imaging
Nerve sheath tumor
Drop metastasis
Meningioma
90-95% of intradural tumors
Myxopapillary ependymoma at conus/filum
Drop/CSF metastases
Gliomas (esp. GBM, ependymoma)
Germ cell tumors
PNET
Lung, breast, melanoma, lymphoma, leukemia
Extradural, extra medullary spinal cord tumors
Vertebral/discogenic origin
Metastasis
Myeloma, lymphoma, leukemia
Other vertebral tumors
Posterior fossa tumors - children
Posterior fossa tumors - adults
Other intraventricular tumors
Calcified brain tumors
Hemorrhagic brain tumors
Hemorrhagic metastases
– Lung, breast, renal, thyroid, melanoma, choriocarcinoma
Gliomas, esp high-grades III and IV (GBM)
PNET, Rhabdoid tumor
Pituitary adenoma
Purely cystic brain tumors
Differential diagnosis: (purely) cystic brain tumors
- Arachnoid cyst
- Epidermoid cyst
- Dermoid cyst
- Colloid cyst
- Rathke cleft cyst
- Pineal cyst
- Choroid plexus cyst
Differential diagnosis - cystic/solid brain tumors
Metastasis (esp lung)
Glioma, esp oligo, JPA
Craniopharyngioma
Ganglion cell tumor
– ganglioglioma, gangliocytoma
Hemangioblastoma
Pleomorphic xanthoastrocytoma
Schwannoma > meningioma
Pituitary adenoma (post-radiation change)
Differential diagnosis - T1 hyperintense brain tumors
Hemorrhagic tumors
Craniopharyngioma
Lipoma
Epidermoid cyst
Melanoma
(Vascular lesions): cavernoma, aneurysm
Differential diagnosis: Hyperdense (CT) brain tumors
(Often, also T2- and/or ADC-hypointense)
Hemorrhagic, calcific, vascular lesions/tumors
Cellular tumors
– Lymphoma/leukemia
– Meningioma (depending on type)
– GBM, PNET, Rhabdoid, germ cell tumor
Ependymoma - spine
Intramedullary
Multisegmental expansion, may be centrally located
May hemorrhage – look at T2/T2* weighted images
Astrocytoma - spine
Hemangioblastoma - spine
Pial-based “cyst/mural nodule”
May be visible on angiography
Association with Von-Hippel Lindau
Intramedullary metastasis
Lung, breast, renal, gastric, melanoma
Lymphoma/leukemia
Aneurysm rupture
Aneurysm rupture
~85% of nontraumatic SAH, 30% also have parenchymal hemorrhage
Dx: CT→ (±LP) → angiogram (or CTA?)
– CT 95% sensitive to detect SAH in 12-24 hrs
– ISAT compared coils/clips (Lancet. 2002: 360: 1267-74)
Perimesencephalic nonaneurysmal hemorrhage
~10% of nontraumatic SAH
Localized to cisterns around midbrain, pons • ?bleeding from venous source
Clinically benign course
– Angiogram to exclude aneurysm, dissection
– Repeat angio?/Cervical spine MRI?/neck MRA?
AVM
Intracranial hemorrhage
– esp parenchymal, intraventricular, subarachnoid
– High hemorrhage risk (~2-4%/yr)
Arteriovenous shunting with nidus (on angio) – Enlarged arteries and veins
Treatments: surgery, radiation, embolization
dAVF
Enlarged dural arteries/veins near sinus
– Likely acquired, traumatic? prior thrombosis?
– AV shunting but no nidus
– SDH/SAH/IPH hemorrhage
Sxs: tinnitus, intracranial hypertension, sz, ocular sx
Moya-moya
Spinal dAVF
Spinal dAVF
Vasculitis
Vasculitis
RCVS
Carotid stenosis
Fibromuscular dysplasia
Arterial dissection
Spinal cord infarct
Venous thrombosis
Amyloid angiopathy
Global anoxic injury
Contusion
Axonal shear injury
Spontaneous intracranial hypotension
IIH
Spine fracture
Central cord syndrome
Wernicke’s encephalopathy
Subacute combined degeneration
Wilson’s disease
FIBGC
PKAN
Osmotic demyelination
Carbon monoxide toxicity
RPLS
MTS
ALS
Huntington’s disease
Olivopontocerebellar degeneration
DaT scan
NPH
MS
Acute traverse myelitis
Sarcoid
GBS
HSV I encephalitis
CJD
Meningitis - bacterial
Abscess
Subdural empyema
HIV encephalopathy
PML
Cysticercosis
Toxoplasmosis
Diskitis/osteomyelitis
Corpus callosum dysgenesis
Septic-optic dysplasia/holoprosencephaly
Schizencephaly
Porencephalic cyst
Heterotopia
Pachygyria
Dandy-Walker
Chiari malformations
Chiari II
