What is the nature of the original lesion causing these imaging findings?
Brain arteriovenous malformations are abnormal congenital connections between arteries and veins.
What imaging clue to the cause of this appearance is present in this case?
Tortuous signal voids representing AVM
What grading system is used to classify intracranial AVMs?
Spetzler-Martin AVM grading system
A rather rounded area of serpiginous, tortuous signal voids measuring 3 x 3 cm is seen in close proximity to the occipital horn of the right lateral ventricle and splenium of corpus callosum, consistent with an arteriovenous malformation (AVM). A large draining vein is seen draining into the straight venous sinus.
The aforementioned AVM is surrounded by an irregular area of subacute blood, measuring 2 x 7 cm, representing a subacute haematoma, closely related to, and compressing the body and occipital horn of the right lateral ventricle.
A significant blooming artefact can be clearly appreciated on axial gradient echo.
Levelling of subacute blood is seen in the frontal, temporal and occipital horns of the right lateral ventricle and the fourth ventricle.
A small amount of subacute subdural blood is seen in the right occipital parasagittal region.