Arachnoid cyst MRI: Difference between revisions

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{{Arachnoid cyst}}
{{Arachnoid cyst}}
{{CMG}}
{{CMG}} {{AE}} {{Jose}}


==Overview==
==Overview==
Diagnosis is principally by [[Magnetic resonance imaging|MRI]].  Frequently, arachnoid cysts are incidental findings on MRI scans performed for other clinical reasons.  In practice, diagnosis of symptomatic arachnoid cysts requires symptoms to be present, and many with the disorder never develop symptoms.   
On [[brain]]/[[spine]] MRI, [[arachnoid cysts]] are characterized by cystic images with similar density to [[CSF]] and non-enhancing borders, mostly found in the [[middle cranial fossa]] while they only rarely occur in the [[spinal cord]]. [[Magnetic resonance imaging|MRIs]] are more adequate than [[CT scans]] for evaluating [[Arachnoid cyst|arachnoid cysts]].   


==MRI==
==MRI==
MRI can demonstrate the exact location, extent, and relationship of the cyst, as well as differentiate arachnoid from epidermoid cysts. CSF signal is seen within the well-defined cyst on all sequences. Epidermoids also may have a signal identical or very similar to that of arachnoid cyst on T1-weighted and T2-weighted images. To differentiate this from arachnoid cysts FLAIR as well as diffusion weighted sequences are used. On the FLAIR sequence, , an arachnoid cysts follow the CSF signal, so no signal seen, while there is a higher signal with FLAIR in epidermoid cysts. With DWI, diffusion is reduced within epidermoids, which then appear brighter than CSF, but for arachnoid cysts the signal intensity is low. In some instances though, arachnoid cysts may contain proteinaceous fluid or blood, and signal loss on DWIs may not be marked, which can cause diagnostic confusion. Plain radiographic findings are nonspecific and are not valuable offer in the diagnosis of arachnoid cysts, except for changes in skull contour due to large cysts. Large arachnoid cysts should be considered for serial scans because they may show progressive enlargement, and patients may become candidates for surgical consideration. Indications for surgical intervention include hydrocephalus and increased intracranial pressure. Surgery for asymptomatic cysts is controversial.


*[[Magnetic resonance imaging|MRIs]] are better to diagnose and evaluate the extent of the [[arachnoid cyst]] than the [[CT Scan]];
*Most cysts (50-60%) are found in the floor of the [[middle cranial fossa]], while 1/4 to 1/3 of occur in the [[Posterior cranial fossa|posterior foss]]<nowiki/>a, particularly in the [[retrocerebellar]], [[cerebellopontine]], and [[quadrigeminal plate]] [[cisterns]]. Rarely, they may be found in the [[spinal cord]].<ref>Robertson, S. J., S. M. Wolpert, and V. M. Runge. "MR imaging of middle cranial fossa arachnoid cysts: temporal lobe agenesis syndrome revisited." ''American journal of neuroradiology'' 10.5 (1989): 1007-1010.</ref><ref>{{Cite web|url=https://emedicine.medscape.com/article/336489-overview|title=Arachnoid Cysts - Imaging|last=|first=|date=06/26/2020|website=Medscape|archive-url=|archive-date=|dead-url=|access-date=}}</ref>
* Demonstrate the exact location, extent, and relationship of the cyst;
* Can differentiate arachnoid from [[epidermoid cysts]] (arachnoid cysts are identical to [[CSF]], while epidermoid present a higher signal with [[FLAIR]] and reduced diffusion with [[DWI]], making them appear brighter than [[CSF]]).
*[[CSF]] signal is seen within the cyst;
* Eventually, arachnoid cysts may contain [[proteinaceous]] fluid or blood, which can cause diagnostic confusion.<ref>{{Cite web|url=https://medpix.nlm.nih.gov/case?id=9c946ba2-4e56-458a-a20b-bd3092a4704e|title=Arachnoid Cysts|last=|first=|date=06/26/2020|website=MedPix|archive-url=|archive-date=|dead-url=|access-date=}}</ref>
=== Differential Diagnosis ===
{| class="wikitable"
|+Arachnoid cysts differential diagnosis<ref>Cincu, Rafael, Amit Agrawal, and Jose Eiras. "Intracranial arachnoid cysts: current concepts and treatment alternatives." ''Clinical neurology and neurosurgery'' 109.10 (2007): 837-843.</ref>
|'''Intraventricularly:'''
|[[Colloid cysts]]
|-
|'''Intraparenchymally:'''
|[[Parasitic infections]], [[cystic metastases]]
|-
|[[Porencephalic cysts]]
|
|-
|[[Craniopharyngiomas]]
|
|-
|[[Holoprosencephaly|Holoprosencephalies]]
|
|-
|[[Agenesis of the corpus callosum|Agenesis of corpus callosum]]
|
|-
|Defect in the hemispheral cleavage
|
|-
|[[Dandy-Walker complex]] (posterior fossa cysts)
|}
As differential diagnosis, the following hypothesis must be considered:


==MRI Images==
#Enlarged [[CSF]] space;
#[[Epidermoid cyst]];
#[[Subdural hygroma]]/[[Subdural hematoma|chronic subdural hemorrhage]];
#Cystic tumors;
#[[Pilocytic astrocytoma]];
#[[Hemangioblastoma]];
#[[Neurenteric cyst]];
#[[Neuroglial cyst]];
#[[Porencephalic cyst]];
#[[Neurocysticercosis]].<ref>{{Cite web|url=https://radiopaedia.org/articles/arachnoid-cyst?lang=us|title=Arachnoid Cysts - Radiopaedia|last=|first=|date=06/26/2020|website=Radiopaedia|archive-url=|archive-date=|dead-url=|access-date=}}</ref>
 
==References==
 
{{Reflist|2}}
 
==MRI Examples of Arachnoid Cysts==


([http://www.radswiki.net Images courtesy of RadsWiki])
([http://www.radswiki.net Images courtesy of RadsWiki])
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</gallery>
</gallery>


==References==
{{Reflist|2}}
[[Category:Central nervous system]]
[[Category:Central nervous system]]
[[Category:Congenital disorders]]
[[Category:Congenital disorders]]

Latest revision as of 02:19, 30 June 2020

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: José Eduardo Riceto Loyola Junior, M.D.[2]

Overview

On brain/spine MRI, arachnoid cysts are characterized by cystic images with similar density to CSF and non-enhancing borders, mostly found in the middle cranial fossa while they only rarely occur in the spinal cord. MRIs are more adequate than CT scans for evaluating arachnoid cysts.

MRI

Differential Diagnosis

Arachnoid cysts differential diagnosis[4]
Intraventricularly: Colloid cysts
Intraparenchymally: Parasitic infections, cystic metastases
Porencephalic cysts
Craniopharyngiomas
Holoprosencephalies
Agenesis of corpus callosum
Defect in the hemispheral cleavage
Dandy-Walker complex (posterior fossa cysts)

As differential diagnosis, the following hypothesis must be considered:

  1. Enlarged CSF space;
  2. Epidermoid cyst;
  3. Subdural hygroma/chronic subdural hemorrhage;
  4. Cystic tumors;
  5. Pilocytic astrocytoma;
  6. Hemangioblastoma;
  7. Neurenteric cyst;
  8. Neuroglial cyst;
  9. Porencephalic cyst;
  10. Neurocysticercosis.[5]

References

  1. ↑ Robertson, S. J., S. M. Wolpert, and V. M. Runge. "MR imaging of middle cranial fossa arachnoid cysts: temporal lobe agenesis syndrome revisited." American journal of neuroradiology 10.5 (1989): 1007-1010.
  2. ↑ "Arachnoid Cysts - Imaging". Medscape. 06/26/2020. Check date values in: |date= (help)
  3. ↑ "Arachnoid Cysts". MedPix. 06/26/2020. Check date values in: |date= (help)
  4. ↑ Cincu, Rafael, Amit Agrawal, and Jose Eiras. "Intracranial arachnoid cysts: current concepts and treatment alternatives." Clinical neurology and neurosurgery 109.10 (2007): 837-843.
  5. ↑ "Arachnoid Cysts - Radiopaedia". Radiopaedia. 06/26/2020. Check date values in: |date= (help)

MRI Examples of Arachnoid Cysts

(Images courtesy of RadsWiki)

Patient #1: Left middle cranial fossa arachnoid cyst

  • Cor T2

    Cor T2

  • Sag T1

    Sag T1

  • Axial T1 FLAIR

    Axial T1 FLAIR

  • Axial T2

    Axial T2

Patient #2: CT and MR images demonstrate a hemorrhagic arachnoid cyst

  • CT

    CT

  • Sag T1

    Sag T1

  • Ax T1

    Ax T1

  • Ax FLAIR

    Ax FLAIR

  • Ax T2

    Ax T2

  • Ax T1 with GAD

    Ax T1 with GAD

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