Changes in AVM angio-architecture and hemodynamics after stereotactic radiosurgery assessed by dynamic MRA and phase contrast flow assessments

Assessment of changes in the hemodynamics of Arteriovenous malformations (AVM) induced by radiosurgery by MR Phase contrast (PC) measurements of the internal carotid arteries (ICA). 65 patients shortly after or before stereotactic radiosurgery underwent MRI including morphological series, MR-Angiography (Time-of-flight, dynamic MRA) and bilateral ECG triggered MR phase contrast (PC) measurements of the ICA. Follow-up was performed in 34 patients. The observation period was up to 4 years. Over all subjects, a significant relationship between mean arterial blood flow in the ICA on the side of the lesion and AVM volume was revealed (p = 0,0002). In large (> 10 ccm) and medium-sized AVMs, (> 3, 5 a parts per thousand currency sign10 ccm) the blood flow was significantly increased on the side of the AVM (p = 0,0004; p = 0,047), whereas in lesions < 3, 5 ccm, no significant rise of the mean blood flow was detectable. At follow-up, the mean blood flow in the ipsilateral artery was not increased anymore compared to the contralateral ICA (p = 0,11). These changes correlated with a significant reduction of the average AVM volume (p = 0, 0026). The AVM angioarchitecture has significant impact on the blood flow in feeding arteries. A significant reduction of the shunt volume by successful radiotherapy leads to normalization of the hemodynamics.