The purpose of this study is to investigate the role of multimodal CT in evaluating and predicting different clinical outcomes in patients with unruptured brain arteriovenous malformations with medical management alone. This study will be undertaken in the following aspects: 1. Morphological, structural and imaging histological signal analysis based on multimodal CT to explore the relationship between imaging features and different clinical outcomes of bAVMs. 2. Hemodynamic and flow pattern analysis of local and peripheral bAVMs based on multimodal CT to explore the association between blood flow features and different clinical outcomes. 3. Based on multimodal CT and deep learning algorithms to create an automated segmentation model for bAVMs and a prediction model for distinct clinical outcomes. The obtained patient information includes: Baseline information, CT, MRI, DSA (Optional), and follow-up information. Follow-up will be undertaken at 6 months, 12 months, 24 months and 36 months after enrollment with the following primary observation. Main observation endpoints: 1. Hemorrhage events associated with bAVMs 2. New epilepsy symptoms or exacerbations 3. New neurological dysfunction(including motor dysfunction, cognitive dysfunction, etc).