9/23 Neuroimaging II Flashcards Preview

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Flashcards in 9/23 Neuroimaging II Deck (15):
1

planes

coronal: anterior/posterior

sagittal: left/right

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

2

recap: main use of FLAIR

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

3

T1W vs T2W vs FLAIR vs DWI

 

terminology

diffs/uses

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

4

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

5

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

6

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)

7

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

8

infiltrative oligodendroglioma

high signal in pons

infiltrative tumor of brainstem

9

optic chiasm glioma

suprasellar cistern looks huge

actually seeing a tumor of the optic chiasm

10

Chiari I malformation

hindbrain malformation

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

11

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

12

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

13

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

14

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

15

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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