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27 Cards in this Set
- Front
- Back
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What is corona radiata?
centrum semovale? |
white matter at the level of lateral ventricles
white matter superior to the lateral ventricles |
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4 steps for evaluating CT?
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1. Evaluate CSF spaces
2. Look for asymmetry, changes in light/dark 3. Contrast enhancement 4. If you see a lesion, characterize it's location, margination, density, contrast enhancement, and adjacent structures |
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Seen on CT -- dx?
Increased size of ventricles, small sulci and cisterns |
Hydrocephalus
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Seen on CT -- dx?
Increased size of ventricles, sulci, and cisterns |
volume loss due to atrophy
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Seen on CT -- dx?
Decreased size of ventricles, sulci, and cisterns |
Diffuse edema
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Focal attentuation of sulci or ventricle
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Focal mass or mass-like lesion
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Ipsilateral shift of midline
dx? |
volume loss, due to something like a chronic infarct
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Contralateral midline shift?
dx |
Volume increase due to mass
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5 structures with high density on CT
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Recent hemorrhage
Calcium Bone Contrast agent Inspissated mucoid material |
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4 things with low density on CT
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1. Edema (vasogenic or cytotoxic)
2. Encephalomalacia (atrophy of brain parenchyma) 3. Gliosis (fibrosis) 4. Chronic hematoma |
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2 types of edema and their causes
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vasogenic - white matter, associated with masses
cytotoxic - gray and white matter - associated with ischemia |
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5 things that enhance on IV contrast
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1. neoplasms-primary benign/malignant, metastases
2. Infection 3. Vascular lesions 4. Ischemia 5. Active demyelination |
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4 things that do not enhance with IV contrast
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chronic ischemia
low grade neoplasms quiescent demyelination PML |
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How should you describe a lesion if it is discovered on CT?
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1. location - parenchymal vs. extraparenchymal
2. margination well-cicumscribed = benign; infiltrative = malignant 3. Density 4. Contrast enhancement 5. effect on adjacent structures |
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CT--dx?
-shift midline contralaterally or focally attenuate adjacent CSF spaces -hyperdense, progresses to hypodense over weeks -zone of hypodense edema around hyperdense area |
Hematoma
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-High desnity fluid in basal cisterns (interpeduncular, lamina terminalis), fissures, sulci
-hydrocephalus pattern - large ventricles, small slci -No midline shift -no contrast enhancement dx? Most common causes? |
Subarachnoid hemorrhage
Trauma, aneurysms in circle of willis |
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How can you differentiate subdural from epidural hematoma?
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Both are hyperdense bleeds, but subdurals cross coronal suture, while epidural would not
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Crescentic mass with hyper and hypodense areas, not respecting coronal suture
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subdural hematoma
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-Hyperdense
-mass effect --> attentuation of sulci and ventricles on the side of the lesion -do not extend across coronal suture -midline shift contralateral -associated with skull fracture |
epidural hematoma
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-cytotoxic edema
-mass effect (less dense)--> atentuation of underlying sulci/ventricles -contralateral midline shift dx and mechanisms |
Acute infarct - thrombosis, embolism, hypoperfusion
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-hypodense mass with evidence of acute edema
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ischemic infarct
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how do you distinguish a subacute infarct?
chronic? |
subacute = enhancement seen 3 days to 3 weeks from event
chronic = marked hypodensity, volume loss --> shift ipsilaterally, enlargement of ipsilateral sulci and ventricles |
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-extraparenchymal mass
-peripheral -mass effect attenuates nearby sulci -moderately increased density -contrast enhancement |
meningioma
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-ring enhancing lesion
-mass effect, midline shift contralaterally -patchy areas of increased density and hypodesne edema (vasogenic) |
metastatic cancer
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Ring enhancing lesion
2 causes? How do you distinguish? |
Abscess or metastases
Abscess has a thicker wall on the peripheral side |
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What is the difference between a communicating and non communicating obstructive hydrocephalus
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communication = lesion is distal to 4th ventricular outlets, communicates with extra-ventricular spaces
Non-communicating = blockage proximal to fourth ventricular outlets |
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-large ventricles with invisible sulci
-cystic lesions throughout |
neurocysicerosis
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