Friday, 1 June 2012

Cavernous Angioma of Brain

Axial T1 and T2 wt images of brain:
well defined predominantly T2 hypointense and T1 isointense lesion in anteromedial aspect of
left thalamus with few T2 hyper and T1 hypointense areas.Mild vasogenic edema noted
surrounding the lesion suggesting recent hemorrhagic complication.

Coronal T2 and Axial GRE images of Brain:
Mild dilatation of both lateral ventricles due to pressure effect of the lesion on 3rd ventricle.
There is blooming of the lesion on GRE sequence. 

Axial and coronal Contrast enhanced T1 wt images with fat supression:
There is intense homogenous enhancement of the lesion.
ReferenceHemangioma from Head to Toe: MR Imaging with Pathologic Correlation, March 2004 RadioGraphics, 24, 367-385.

·        Manifest in two different modes:
1.     Inherited (typically multiple and bilateral)
2.     Solitary and sporadic

·        Unlike AVMs, cavernous angiomas have no intervening brain tissue between vascular spaces - hence the descriptive term Blood Sponge.

·        MRI is far more sensitive than angiography in detecting these lesions.

·        Cavernous malformations typically have little or no mass effect, unless they are complicated by hemorrhage.

·        Similarly, surrounding vasogenic edema does not occur unless there are hemorrhagic complications.

·        Cavernous angiomas may have internal areas of thrombosis or hemorrhage.

·        These blood products are typically of various ages, representing hemorrhage in various states of degradation.

·        There may be conversion of hemoglobin to methemoglobin, which produces foci of hyperintensity on T1-weighted MR images.

·        Hemosiderin may be cleared from the central area of a cavernous angioma and deposited around the periphery. This peripheral hemosiderin causes significant T2 shortening, producing a black “halo” around the lesion.

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