9/23 Neuroimaging II Flashcards

1
Q

planes

A

coronal: anterior/posterior
sagittal: left/right

transverse/axial/horizontal: superior/inferior or cranial caudal

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2
Q

recap: main use of FLAIR

A

similar to T2W BUT CSF is hypointense → good for viewing demyelination around ventricles in multiple sclerosis

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3
Q

T1W vs T2W vs FLAIR vs DWI

terminology

diffs/uses

A

hyper/iso/hypoINTENSITY

T1W:

water/csf (hypo) < edema < gray matter (iso) < white matter (myelin = fat) (hyper)

T2W:

white matter (hypo) < gray matter (iso) < edema < water/csf (hyper)

FLAIR: fluid attenuation inversion recovery → pathology (MS)

similar to T2W except csf is hypointense

  • good for eval of white matter adj to ventricles!

DWI: diffusion weighted image

primary seq for detection of acute/subacute infarcts up to 14d old → STROKES

  • hyperintense signal = abnormal
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4
Q

blood products on CT

  • hyperacute
  • acute
  • early subacute
  • late subacute
  • chronic

why change in signals?

A

stage → CT signal → time

hyperacute → high → under 6hr

acute → high → 8-72hr

early subacute → high → 3d-1wk

late subacute → isodense → 1wk-1mo

chronic → low → 1mo+

changes in density due to changes in Hb and types

summary: blood on CT starts off bright, then becomes darker

  • changes start around 3d point
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5
Q

why might you see mixed types of blood in subdural hematoma?

A

subdural hematoma: usually due to tearing of bridging veins

  • blood oozes out slowly
  • older blood will show up isodense
  • newer blood will show up hyperdense
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6
Q

characteristics of epidural hematoma

A

usually lens shaped, hyperdense (bc brain cant accomodate it the same way it might in gyri/sulci so sx become apparent/debilitating sooner)

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7
Q

characteristics of subarachnoid hematoma

A

“worst headache of life” presentation

  • want to do a LP just in case you miss blood on CT

often from trauma or aneurysm

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8
Q

infiltrative oligodendroglioma

A

high signal in pons

infiltrative tumor of brainstem

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9
Q

optic chiasm glioma

A

suprasellar cistern looks huge

actually seeing a tumor of the optic chiasm

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10
Q

Chiari I malformation

A

hindbrain malformation

  • cerebellar tonsillar herniation through foramen magnum
    • blocks csf flow → syrinx in cervical cord → headaches in young patients
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11
Q

neurofibromatosis spots in globus pallidi

A

skin lesions and brain lesions simultaneously

  • cafe au lait spots & multiple neurofibromas

prone to tumors (esp intracranial)

globus pallidus preferentially affected

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12
Q

pineal gland germinoma

A

tumor of pineal gland → pushes down on tectum (roof of 4th ventricle) → blocks flow of CSF, causing hydrocephalus

can also extend into thalamus and 3rd ventricle

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13
Q

pericallosal lipoma

A

curvilinear fatty structure above corpus callosum

present with devpt delay, incoordination, vague symptoms bc can inhibit formation of corpus callosum

can see dark fluid where body/splenium should be bc devpt of corpus callosum was inhibited

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14
Q

Alexander’s disease

A
  • inborn error of metabolism
  • dismyelinating disease
  • present with enlarged heads, seizure, spasticity, incoordination

MRI shows tons of abnormal white matter

  • disease preferentially affects white matter
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15
Q

vestibular Schwannoma

A

occurs in internal auditory canal (CN VIII)

  • potential deformation of fourth ventricle

present with hearing loss

want to get an MRI!!! bc cant see with CT

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