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Background and Purpose: Brain perfusion is disturbed by cerebral arteriovenous malformations (AVMs). Our study was conducted to determine the radiosurgical effects on this disturbed perfusion., Methods: MR perfusion imaging with independent component analysis was performed in five healthy subjects and 19 patients with AVM before and after radiosurgery (every 6 months up to 2 years). Perfusion map relative cerebral blood volume (rCBV), cerebral blood flow (rCBF), and mean transient time (rMTT) were assessed. Regions of interest (ROIs) on AVM target sections were defined as follows: N, AVM nidus; H, the rest of the ipsilateral hemisphere; P, immediately posterior to the nidus; A, immediately anterior to the nidus; Ar, anterior remote; Pr, posterior remote. Similar ROIs in the contralateral hemisphere (N1, H1, P1, A1, Pr1, and Ar1) served as internal references. Perfusion ratios of ROI-ROI1 were defined. Nonparameteric Mann-Whitney U tests and generalized linear models were used for statistical analysis., Results: Before radiosurgery, patients' H/H1 rCBV and rCBF ratios were significantly higher than those of healthy subjects (P < .005), indicating AVM steal. Three types of perilesional perfusion disturbance were observed. From the first postradiosurgical follow-up at 6 months, N/N1 rCBV and rCBF ratios gradually decreased to 1.0 (both P < .001), whereas rMTT ratios gradually increased to 1.0 (P < .015); H/H1, A/A1, and P/P1 rCBV and rCBF ratios decreased after radiosurgery (P < .005), indicating reversal of steal toward normal perfusion., Conclusion: Initial high transnidal flow and perinidal perfusion disturbances were demonstrated. They gradually changed toward normal perfusion after radiosurgery. This explains, in part, the pathophysiologic factors of AVM and therapeutic effects.

Purpose: Radiosurgery is an effective treatment for cerebral arteriovenous malformations. We conducted the present study to investigate the feasibility and efficacy of gamma knife radiosurgery for dural arteriovenous fistulas (DAVFs) of the cavernous sinus., Methods: Eighteen patients (12 women and six men; 29-75 years old [mean age, 55 years]) with DAVFs of the cavernous sinus (Barrow's type B:1, C:7, and D:10) treated by gamma knife radiosurgery were enrolled in the study. DAVFs were bilateral in six patients and unilateral in 12. Stereotactic X-ray angiography and MR imaging were performed for targeting the radiosurgery. Areas of arteriovenous communication targeted for irradiation were first outlined on the X-ray angiograms. The target regions were then transferred to and displayed on the MR images. Dose planning was based on findings on the integrated images. Prescribed maximum target doses were 22 to 38 Gy (mean, 28 Gy). The targets were covered by 50% to 90% isodose levels. Radiation doses to the surrounding optic apparatus were kept to less than 8 Gy. The patients were followed up with color Doppler sonography and MR imaging. When noninvasive imaging suggested obliteration, X-ray angiography was performed to verify the results., Results: The DAVFs were totally obliterated in 12 (80%) of the 15 patients. In the other three, one was almost completely obliterated at 14 months and two were partially obliterated at 19 and 27 months, respectively, after radiosurgery. No complications or symptom worsening occurred during the follow-up period., Conclusion: Gamma knife radiosurgery is a feasible, effective, and safe treatment for DAVFs of the cavernous sinus. Integration of stereotactic X-ray angiography and MR imaging not only aids treatment efficacy but also protects the relevant vital structures, especially the optic apparatus, from the hazards of radiation.