MRA of hemodialysis access grafts and fistulae using selective contrast injection and flow interruption.

MR is a potentially attractive modality for evaluating hemodialysis access anatomy and function. However, the wide range of flow rates in the hemodialysis access complicates interpretation of phase contrast, time-of-flight, and even contrast-enhanced MR angiograms. At high flow rates, signal voids may easily arise at mild narrowings or sharp-angled anastomoses. A method is proposed which visualizes hemodialysis accesses without flow artifacts. Diluted Gd-DTPA is hand-injected directly into the access, while a cuff is used to reduce and subsequently interrupt access flow. Filling of the access is monitored using a fast projection technique with complex subtraction. When filling is satisfactory, a 3D acquisition is started. The feasibility of this selective contrast-enhanced MR angiography technique is demonstrated in four Cimino-fistulae and four PTFE grafts. Magn Reson Med 45:557-561, 2001. Copyright 2001 Wiley-Liss, Inc.