9/23 Neuroimaging II Flashcards Preview

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Flashcards in 9/23 Neuroimaging II Deck (15)


coronal: anterior/posterior

sagittal: left/right

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


recap: main use of FLAIR

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


T1W vs T2W vs FLAIR vs DWI







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


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


blood products on CT


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


why change in signals?

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


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

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


characteristics of epidural hematoma

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


characteristics of subarachnoid hematoma

"worst headache of life" presentation

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

often from trauma or aneurysm


infiltrative oligodendroglioma

high signal in pons

infiltrative tumor of brainstem


optic chiasm glioma

suprasellar cistern looks huge

actually seeing a tumor of the optic chiasm


Chiari I malformation

hindbrain malformation

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


neurofibromatosis spots in globus pallidi

skin lesions and brain lesions simultaneously

  • cafe au lait spots & multiple neurofibromas

prone to tumors (esp intracranial)


globus pallidus preferentially affected


pineal gland germinoma

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


pericallosal lipoma

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


Alexander's disease

  • 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


vestibular Schwannoma

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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