Multimodality imaging evaluation of arteriovenous fistulas and grafts: a clinical practice review.

Arteriovenous fistulas (AVFs) and grafts (AVGs) are the preferred forms of vascular access for hemodialysis in patients with severe renal dysfunction. Multimodality imaging plays an important role in the pre-procedural evaluation of these patients. Ultrasound is often used for pre-procedural vascular mapping in preparation for the creation of an AVF or AVG. Pre-procedural mapping includes a comprehensive evaluation of the arterial and venous vasculature including evaluation of vessel diameter, stenosis, course, presence of collateral veins, wall thickness and wall abnormalities. Computed tomography (CT), magnetic resonance imaging (MRI) or catheter angiography are used when sonography is not available or when further characterization of sonographic abnormalities is required. Following the procedure, routine surveillance imaging is not recommended. If there are any clinical concerns or if physical examination is inconclusive, further evaluation with ultrasound is warranted. Ultrasound allows for assessment of vascular access site maturation by evaluating the time-averaged blood flow and helping characterize the outflow vein in the case of an AVF. CT and MRI can play a complementary role to ultrasound. Vascular access site complications include non-maturation, aneurysm, pseudoaneurysm, thrombosis, stenosis, steal phenomena or occlusion typically of the outflow vein, infection, bleeding and rarely angiosarcoma. In this article, we review the role of multimodality imaging in the pre- and post-procedural evaluation of patients with AVF and AVG. Additionally, novel technologies of vascular access site creation using endovascular techniques and upcoming non-invasive imaging techniques for evaluation of AVFs and AVGs are discussed.