Cavernoma- Radiological Paradox

19 yr old male  with  headache shows on MRI, subtly enhancing, well defined ,regular, encapsulated, mixed signal intensity ,  popcorn shaped, lesion in pons (25mm)   blooming on SW  and  occult on DSA  is consistent with cavernoma.

Teaching points by Dr MGK Murthy

• In children consist of 2 to 18% of all vascular malformations(mean age 9-10 yrs) (M=F)
•  Congenital, developmental ,vascular malformations of vascular bed (prevalent 0.4 to 0.9%) and can grow  over time, hemorrhage more common in children (27 to 78%) versus Adults(8 to 37%)
•  Common in pons in children among posterior fossa  (20%  versus  supratentorial 80%) (neurological deficits high)
• Imaging shows 3 components  (a) peripheral pseudo capsule (gliotic with haemosiderin) (b) irregular intersecting connective tissue septae separating sinusoids (c) central vascular area of slow flow sinusoids. CT can show calcium (33%) 
• MRI blooming on Blood sensitive sequences  with mixed signals on others due to all stages of blood products due to repeated bleeding. TOF angio can show  flowing blood at times , due to methemoglobin, but phase contrast MR angio  with low velocity coding (10 to 20 cms/sec) is silent
• Occult on DSA due to slow flow  unless mixed variety (30%) , and can occasionally show  nonspecific capillary blush on  repeat injection.