 
Capillary hemangiomas
are the most common vascular lesion in infants and usually
present at birth with generally cutaneous components. They typically
grow during the first 6 months and then begin to involuate. Nowadays
angiography is unnecessary whereas MR is useful when the nature of the
lesion is not obvious, in case of deep hemangioma (fig. 27) or to
monitor the effect of therapy (steroïds or interferon)
Cavernous hemangiomas are the most
commun vascular lesion of adults of middle age with a predilection for
women. They are venous malformations with spongy architecture (ref. 15)
limited by a pseudo capsule. Generally unilateral, intra or extraconal
they can be multiple and extend intracranially (fig. 28). Presence of
septations, focal pooling of contrast inside the lesion and late
homogenous enhancement can help to the diagnosis on CT and MR.
Cavernous hemangiomas are isolated from systemic circulation and so,
angiography can be helpful if the diagnosis of hemangiopericytoma
(marked blush) is raised.
Orbital varices are venous dilatation
of one or more orbital veins with intermittent proptosis related to
increase venous pressure by Valsalva or positionning of the head. They
can present acutely due to thrombosis (fig. 29). They can be missed in
supine position unless Valsalva maneuver is maintained during the
acquisition of spiral CT or fast imaging MR (ref. 15).
Orbital lymphangiomas are non
encapsulated infiltrative lesions composed of dysplastic lymphatic and
venous channels (fig. 30). They are evident at birth or early childhood
and have a propensy to bleed. MR better than CT can delineate the
lesion and demonstrate the bleeding of different ages in the multiple
cystes of the process (ref. 15).
Carotid cavernous fistula can result
from trauma (fig. 31) or happen spontaneously. As orbital system is
without valves, if a shunt developped in the cavernous sinus,
transmission of arterial pressure is possible into the orbital venous
system. The consequences are pulsatile exophthalmos, papilledema and
ophthalmoplegia. | |
