Acoustic neuroma MRI: Difference between revisions

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{{CMG}}{{AE}}{{Simrat}}
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==Overview==
==Overview==
[[Gadolinium]]-enhanced [[MRI]] scan is diagnostic of acoutic neuroma. On brain MRI, acoustic neuroma characterized by hypointense mass on T1-weighted MRI, and hyperintense mass on T2-weighted MRI. <ref>{{Cite web | title =Wikipedia acoustic neuroma  diagnosis| url =https://en.wikipedia.org/wiki/Vestibular_schwannoma }}</ref>
[[Gadolinium]]-enhanced [[Magnetic resonance imaging|MRI scan]] is the definitive [[diagnostic test]] for acoustic neuroma and can identify [[tumors]] as small as 1-2 millimeter in [[diameter]]. On [[brain]] [[Magnetic resonance imaging|MRI]], acoustic neuroma characterized by hypointense mass on T1-weighted [[Magnetic resonance imaging|MRI]], and hyperintense mass on T2-weighted [[Magnetic resonance imaging|MRI]].
==MRI==
==MRI==
Magnetic resonance imaging (MRI) using [[gadolinium]] as an enhancing contrast material is the preferred diagnostic [[test]] for identifying acoustic neuromas. The image formed clearly defines an acoustic neuroma if it is present and this technique can identify [[tumors]] measuring only a few millimeters in diameter. Tumors as small as 1-2 mm in diameter can be demonstrated by well performed MRI scanning. Nonenhanced MRI can miss small tumors.<ref>{{Cite web | title =Wikipedia acoustic neuroma diagnosis| url =https://en.wikipedia.org/wiki/Vestibular_schwannoma }}</ref>
*[[Gadolinium]]-enhanced [[magnetic resonance imaging|magnetic resonance imaging (MRI)]] is the preferred [[diagnostic test]] for identifying acoustic neuromas and can identify [[tumors]] as small as 1-2 millimeter in [[diameter]].<ref>{{Cite journal
| author = [[E. P. Lin]] & [[B. T. Crane]]
| title = The Management and Imaging of Vestibular Schwannomas
| journal = [[AJNR. American journal of neuroradiology]]
| volume = 38
| issue = 11
| pages = 2034–2043
| year = 2017
| month = November
  | doi = 10.3174/ajnr.A5213
| pmid = 28546250
}}</ref><ref>{{Cite journal
| author = [[D. F. Wilson]], [[R. S. Hodgson]], [[M. F. Gustafson]], [[S. Hogue]] & [[L. Mills]]
| title = The sensitivity of auditory brainstem response testing in small acoustic neuromas
| journal = [[The Laryngoscope]]
| volume = 102
| issue = 9
| pages = 961–964
| year = 1992
| month = September
| doi = 10.1288/00005537-199209000-00001
| pmid = 1518359
}}</ref>


Most vestibular [[schwannomas]] have an intracanalicular component, and often result in widening of the porus acusticus resulting in the trumpeted IAM sign, which is present in up to 90% of cases. In a minority of cases (~20%) they are purely extracanalicular, only abutting the porus acousticus. Usually there is a small [[CSF]] cap between intracanalicular portion and the [[cochlea]]; occasionally, these tumors grow laterally through the cochlea (transmodiolar) or vestibule (transmacular) into the middle ear. Rarely they are small and confined to the vestibule (intravestibular) or to the cochlea (intracochlear) or both (vestibulocochlear). Extracanalicular extension into [[cerebellopontine]] angle (path of least resistance) can lead to "ice-cream-cone" appearance. Small tumors tend to be solid whereas [[cystic]] [[degeneration]] seen commonly in larger tumors. [[Haemorrhagic]] areas may also be seen. [[Calcification]] is typically not present.<ref>{{Cite web | title =Radiopedia acoustic neuroma radiographic features| url =http://radiopaedia.org/articles/acoustic-schwannoma }}</ref>
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! style="background: #4479BA; width: 200px;" | {{fontcolor|#FFF|MRI component}}
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:T1
:T1
| style="padding: 5px 5px; background: #F5F5F5;" |
| style="padding: 5px 5px; background: #F5F5F5;" |
*Slightly hypointense cf. adjacent brain (63%)
*Slightly hypointense to the adjacent [[brain]] (63%)
*Isointense cf. adjacent brain (37%)  
*Isointense to the adjacent [[brain]] (37%)  
*May contain hypointense cystic areas
*May contain hypointense [[Cyst|cystic]] areas
|-
|-
| style="padding: 5px 5px; background: #DCDCDC;font-weight: bold" |
| style="padding: 5px 5px; background: #DCDCDC;font-weight: bold" |
:T2
:T2
| style="padding: 5px 5px; background: #F5F5F5;" |
| style="padding: 5px 5px; background: #F5F5F5;" |
*Heterogeneously hyperintense cf. to adjacent brain
*[[Heterogeneous|Heterogeneously]] hyperintense to the adjacent [[brain]]
*Cystic areas fluid intensity
*[[Cyst|Cystic]] areas [[fluid]] intensity
*May have associated peritumoural arachnoid cysts  
*May have associated [[Tumor|peritumoral]] [[Arachnoid mater|arachnoid]] [[Cyst|cysts]]
|-
|-
| style="padding: 5px 5px; background: #DCDCDC;font-weight: bold" |
| style="padding: 5px 5px; background: #DCDCDC;font-weight: bold" |
:T1 C+ (Gd)
:T1 C+ (Gd)
| style="padding: 5px 5px; background: #F5F5F5;" |
| style="padding: 5px 5px; background: #F5F5F5;" |
*Contrast enhancement is vivid
*[[Contrast medium|Contrast]] enhancement is vivid
*But heterogeneous in larger tumors
*But [[heterogeneous]] in larger [[Tumor|tumors]]
|-
|-
|}
|}


Post-op MRI:Linear enhancement may not indicate tumor, but if there is nodular enhancement suspect tumor recurrence (needs follow up MRI).<ref>{{Cite web | title =Radiopedia acoustic neuroma  radiographic features| url =http://radiopaedia.org/articles/acoustic-schwannoma }}</ref>
Post-op [[Magnetic resonance imaging|MRI]]: Linear enhancement may not indicate [[tumor]]. But if there is [[Nodule (medicine)|nodular]] enhancement, suspect [[tumor]] recurrence which will necessitate follow-up [[Magnetic resonance imaging|MRI]]).<ref name="radio">Acoustic Schwannoma. Radiopedia(2015) http://radiopaedia.org/articles/acoustic-schwannoma Accessed on October 2 2015</ref>
 
[[File:Intracanalicular_acoustic_schwannoma.jpg|thumb|none|200px|[[Magnetic resonance imaging|MRI]] showing Intracanalicular acoustic neuroma<ref>Image courtesy of Dr Frank Gaillard. [http://www.radiopaedia.org Radiopaedia] (original file [http://radiopaedia.org/cases/intracanalicular-acoustic-schwannoma here]).[http://radiopaedia.org/licence Creative Commons BY-SA-NC</ref>]]
[[File:Intrameatal vestibularis schwannoma.jpg|thumb|none|200px|[[Magnetic resonance imaging|MRI]] showing [[Internal auditory meatus|Intrameatal]] vestibular schwannoma<ref>Image courtesy of Dr. Roberto Schubert [http://www.radiopaedia.org Radiopaedia] (original file [http://radiopaedia.org/cases/intrameatal-vestibularis-schwannoma here]).[http://radiopaedia.org/licence Creative Commons BY-SA-NC</ref>]]


[[File:Intracanalicular_acoustic_schwannoma.jpg|thumb|none|200px|MRI showing Intracanalicular acoustic neuroma<ref> Image courtesy of Dr Frank Gaillard. [http://www.radiopaedia.org Radiopaedia] (original file [http://radiopaedia.org/cases/intracanalicular-acoustic-schwannoma here]).[http://radiopaedia.org/licence Creative Commons BY-SA-NC</ref>]]
[[File:Intrameatal vestibularis schwannoma.jpg|thumb|none|200px|MRI showing Intrameatal vestibularis schwannoma<ref> Image courtesy of  Dr. Roberto Schubert [http://www.radiopaedia.org Radiopaedia] (original file [http://radiopaedia.org/cases/intrameatal-vestibularis-schwannoma here]).[http://radiopaedia.org/licence Creative Commons BY-SA-NC</ref>]]
==References==
==References==
{{reflist|2}}
{{reflist|2}}
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[[Category:PNS neoplasia]]
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[[Category:Types of cancer]]
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[[Category:Disease]]
[[Category:Up-To-Date]]
[[Category:Oncology]]
[[Category:Medicine]]
[[Category:Otolaryngology]]
[[Category:Neurology]]
[[Category:Neurosurgery]]

Latest revision as of 18:00, 26 April 2019

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Simrat Sarai, M.D. [2]

Overview

Gadolinium-enhanced MRI scan is the definitive diagnostic test for acoustic neuroma and can identify tumors as small as 1-2 millimeter in diameter. On brain MRI, acoustic neuroma characterized by hypointense mass on T1-weighted MRI, and hyperintense mass on T2-weighted MRI.

MRI
MRI component Features
T1
  • Slightly hypointense to the adjacent brain (63%)
  • Isointense to the adjacent brain (37%)
  • May contain hypointense cystic areas
T2
T1 C+ (Gd)

Post-op MRI: Linear enhancement may not indicate tumor. But if there is nodular enhancement, suspect tumor recurrence which will necessitate follow-up MRI).[3]

MRI showing Intracanalicular acoustic neuroma[4]
MRI showing Intrameatal vestibular schwannoma[5]

References

  1. ↑ E. P. Lin & B. T. Crane (2017). "The Management and Imaging of Vestibular Schwannomas". AJNR. American journal of neuroradiology. 38 (11): 2034–2043. doi:10.3174/ajnr.A5213. PMID 28546250. Unknown parameter |month= ignored (help)
  2. ↑ D. F. Wilson, R. S. Hodgson, M. F. Gustafson, S. Hogue & L. Mills (1992). "The sensitivity of auditory brainstem response testing in small acoustic neuromas". The Laryngoscope. 102 (9): 961–964. doi:10.1288/00005537-199209000-00001. PMID 1518359. Unknown parameter |month= ignored (help)
  3. ↑ Acoustic Schwannoma. Radiopedia(2015) http://radiopaedia.org/articles/acoustic-schwannoma Accessed on October 2 2015
  4. ↑ Image courtesy of Dr Frank Gaillard. Radiopaedia (original file here).[http://radiopaedia.org/licence Creative Commons BY-SA-NC
  5. ↑ Image courtesy of Dr. Roberto Schubert Radiopaedia (original file here).[http://radiopaedia.org/licence Creative Commons BY-SA-NC

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