Thursday, November 29, 2012

80 - Tiger eye sign (Eye of the tiger sign)

- Lets begin from the basics and go on to the main stuff ....

*At birth, the central nervous system does not contain any iron in it.

*As the child grows into an adult there is (physiologically normal) gradual deposition of iron in the central nervous system.

*The part of the central nervous system where this iron deposition is most significant is the globus pallidus.

*Given below is an axial MRI image (T1 weighted) of the brain showing the exact location of the globus pallidus.

*Now this excessive iron deposition in the globus pallidus bilaterally with a central area of gliosis and edema changes gives the appearance of tigers eyes because of the different shape of globus pallidus.

*The peripheral iron appears hypointense (black on MRI) and the central gliosis and edema changes appear hyperintense (white on MRI) giving the appearance described above.

*One of the conditions in which this occurs is Hallervorden-Spatz syndrome.

*The exact image of the tiger eye sign cannot be posted here due to copyright issues, but you can see the image here ----> click here 

No comments:

Subscribe Now: Feed

You are visitor number

Visitors currently online