Finding the Nidus: Detection and Workup of Non-Central Nervous System Arteriovenous Malformations.

Vascular anomalies are a diverse group of pathologic conditions. They have different manifestations, natural histories, and treatments. Compared with other vascular malformations, arteriovenous malformations (AVMs) are considered the most symptomatic and difficult to manage. AVMs inherently progress and have a high rate of recurrence after treatment. Imaging helps provide an accurate and early diagnosis, which can then be used to direct appropriate management, with embolization evolving as the primary therapy. Thus, radiology plays a crucial role in the detection, workup, and management of AVMs. Ultrasonography (US) is a useful initial imaging modality, particularly when AVMs involve the extremities or a superficial or accessible location. Limitations include poor identification of soft-tissue and bone components, as well as suboptimal evaluation of deep or complex AVMs. Magnetic resonance (MR) angiography is the preferred imaging modality for AVMs and should be considered in any symptomatic patient or in the initial evaluation of vascular anomalies that are equivocal at US. Computed tomographic angiography should be reserved for those patients who are unable to undergo MR angiography or for evaluation of acute symptoms, such as bleeding or airway compromise. Conventional catheter-based angiography is useful for real-time depiction and evaluation of AVMs, particularly in the planning and execution of endovascular treatment and in the diagnosis of an AVM when findings from noninvasive imaging are equivocal for a high-flow component. As with the diagnostic workup, MR angiography is the preferred posttreatment modality. (©)RSNA, 2016.