Radiology and imaging for cavernous malformations.

Cavernous malformations are low-flow vascular malformations that are histologically characterized by the lack of mural elements of mature vascular structures and intervening parenchymal neural tissue. They are often clinically quiescent, and may grow, bleed, and regress, but can also manifest clinically as neurologic deficits or seizures in the setting of an acute hemorrhage. The low-flow nature of cavernous malformations renders them inherently occult on cerebral angiography. Magnetic resonance imaging has become the mainstay imaging modality in evaluating cavernous malformations, producing characteristic imaging features that usually provide a straightforward diagnosis. Features on magnetic resonance imaging include a reticulated pattern of mixed hyper- and hypointensity on T1- and T2-weighted imaging, with a characteristic hypointense rim best appreciated on T2-weighted imaging or gradient-echo sequences. Contrast enhancement is useful for revealing coexisting developmental venous anomalies that are frequently associated with sporadic cavernous malformations, and may further support the diagnosis. Susceptibility-weighted imaging is highly sensitive for cavernous malformations and accompanying developmental venous anomalies, and is superior to gradient-echo sequences in screening for multifocal, familial cavernous malformations.