Diagnostic imaging of angiographically occult vascular malformations.

Occult vascular malformations of the central nervous system include cavernous malformations, capillary telangiectasis, and developmental venous anomalies (DVAs). Cavernous malformations are prone to multiple small hemorrhages and may enlarge with time. They have a heterogeneous appearance on CT and MR imaging with areas of hemorrhage in various states of evolution and sometimes calcifications. Developmental venous anomalies and capillary telangiectasis are usually incidental findings on imaging studies. They usually are not the cause of pathology by themselves, although DVAs can be associated with cavernous malformations in 8% to 33% of cases.