Pediatric emergency medicine trisk 4005 4005

architectural features include exact anatomic relationships of the nidus, feeding arteries, and draining veins as well as topographic relationships between AVM and adjacent brain MRI is sensitive in revealing subacute hemorrhage The AVM appears as a sponge-like structure with patchy signal loss, or flow voids, associated with feeding arteries or draining veins on T1-weighted sequences ( Fig 122.3 ) MRI and MRA in combination provide complementary information that facilitates understanding the threedimensional structure of the nidus, feeding arteries, and draining veins MRA currently cannot replace conventional cerebral angiography In the case of acute hemorrhage, the hematoma obscures all details of the AVM making MRA virtually useless This calls for direct use of cerebral angiography if the characteristics of the hematoma strongly suggest AVM as an etiology