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Background
Arteriovenous malformations (AVMs) are high flow vascular anomalies resulting from a congenital aberration in angiogenesis. Clinically, AVMs can manifest on a spectrum from being asymptomatic to contributing to chronic wounds, pain, hemorrhage, or high-output cardiac failure. Peripheral AVMs have a wide degree of complexity of angioarchitecture and pose a diagnostic and therapeutic dilemma. AVMs are felt to be the most complex subset of vascular anomalies to treat. Endovascular treatment of AVMs has emerged as a primary treatment paradigm. Transarterial, transvenous, and percutaneous embolization approaches have been described to treat AVMs. In spite of these varied approaches, successful treatment of AVMs remains challenging and there is a high rate of adverse events, such as treatment failure and nontarget embolization which have been reported to be as high as 30%. In spite of the procedural risk and clinical failure rate, AVMs can progress over time from asymptomatic to hemodynamically significant. For this reason, AVMS should be evaluated and treated even when asymptomatic. Classification schema have been developed to better categorize peripheral AVMs and to help guide treatment. Approaches to classify vascular anomalies by Hamburg and Mulliken have focused on embryological or histologic variation. Recently, the concept of anigoarchitecture has been employed to subclassify peripheral AVMs and recommend optimal treatment approaches. This approach was introduced by Cho, Do, et-al and expanded on by Yakes.

Educational Goals / Teaching Points
The goal of this educational exhibit will be to provide radiologists an updated review of the Cho-Do and Yakes AVM classification schema along with their similarities and differences, and their corresponding treatment strategies, and provide a pictorial review of this classification schema using angiographic and cross-sectional CT and MRA imaging correlates of cases and their respective treatment strategies.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
We aim to depict key angio-architectural components of AVMs that result in their specific stratification using the Cho-Do and Yakes classification systems with angiographic studies and their cross-sectional correlates.

Conclusion
Peripheral AVMs have been historically difficult to classify and treat due to their complex variety of angio-architectural manifestation. Complication and clinical failure of AVM treatment is relatively high. New categorization schema can help guide treatment of peripheral AVMs. Radiologists evaluating or treating AVMs should be aware of these newer classifications and relevant treatment recommendations.