Contrast-Enhanced MR Angiography of Failing Hemodialysis Arteriovenous Fistulas and Grafts: A Preliminary Experience

ABSTRACT

PURPOSE: The purpose of this report is to evaluate the vascular stenosis for failing hemodialysis arteriovenous fistulas and grafts using contrast-enhanced MR imaging (CE-MRI) and to compare the results with digital subtraction angiography (DSA). MATERIALS AND METHODS: Nine patients (27 segmental vessels) with symptoms and signs of AVF stenosis or occlusion who presented to our medical department were recruited into this prospective comparative study. All of the patients with Brescia-Cimino arteriovenous fistula (AVF) or synthetic polytetrafluoroethylene (PTFE, Goretex(R)) loop graft underwent MRA and DSA of the fistula. MRA was performed with a 1.5-T system using VIBE sequence TR/TE=3.5/1.5 msec, flip angle 20-25degrees, matrix 115x256, FOV 350x350, interpolated slice thickness 2.0 mm, fat suppression, scan time 13-18 sec and total time of 5 min. DSA was used as the reference standard for assessing the accuracy of MRA, and MRA was analyzed for the presence of stenosis or occlusion, a grading of stenosis, and the presence of collateral vessels. Two radiologists prospectively analyzed the MRAs by working in consensus. RESULTS: Regarding the stenotic grade, CE-MRA corresponded with the DSA in six patients (66.7%) and it overestimated the stenoses in three patients (33.3%). For the stenotic site, MRA had a sensitivity of 86.4%, a specificity of 40%, a positive predictive value of 32.1%, and a negative predictive value of 66.7%. CONCLUSION:Multiphase CE-MRA of the AVF noninvasively provided information comparable to that provided by DSA for the vascular stenosis regarding failing hemodialysis arteriovenous fistula.