3D TOF MR angiography of cerebral arteriovenous malformations after radiosurgery.

To investigate the potential of three-dimensional time-of-flight MR angiography (MRA) to complement SE imaging, 18 patients with intracerebral arteriovenous malformations were prospectively followed after undergoing radiosurgery. Vessel occlusion after stereotaxic single high dose radiotherapy develops slowly. The MRA detected signs of nidus obliteration earlier and with a higher sensitivity than did SE imaging. Six months after radiosurgery, MRA showed a reduction of the nidus flow signals in nine patients and after 1 year it showed reduction in 15 of the 18 patients. As shown by MRA, the loss of flow signals was related to a reduction of the nidus size in 4 patients after 6 months and in 11 after 1 year. The SE imaging revealed a reduction of the nidus size in only two patients after 6 months and in eight after 1 year. The signal intensity of the feeding arteries was reduced in nine patients and that of the draining veins was reduced in six. The T2-weighted images exhibited white matter lesions in eight patients after 1 year. For complete follow-up, SE imaging should be performed together with MRA.