FIG 5. Histopathologic and electron microscopic findings after embolization.

A, Photomicrograph of an RM obtained 15 h after embolization with 50% 2-P-HEMA shows that the vessels (arrow) of the embolized RM are mostly filled with precipitated 2-P-HEMA, which is dark because of the presence of tungsten. As many as 90% of the vessels were completely patched with the embolic agent; others were partially occluded and thrombosed (original magnification x25).

B, Photomicrograph obtained 6 mo after embolization with pure 2-P-HEMA shows that the tungsten has been replaced by amorphous material resembling a calcification (arrow) (original magnification x50).

C, Electron micrograph of an AVM embolized with 50% 2-P-HEMA shows homogeneous casting of the vessel lumen due to precipitated 2-P-HEMA.