Hemodialysis access fistulas: MR angiography evaluation

Learning Objectives: 1) To provide MRA technique for evaluating permanent hemodialysis access fistulas of the forearm. 2) To explore the possibilities of MRA in the diagnosis and grading of hemodialysis fistula stenosis. Background: The patency of permanent hemodialysis access fistulas of the forearm is limited; with time, stenotic complications often compromise access function. Recognizing these complications is important to preserve the access. Evaluation of the vascular anatomy is fundamental for surgical or interventional treatment planning. Color Doppler ultrasound is usually the first step for diagnosis and treatment planning. It provides both morphological and functional information but DSA is still the gold standard. MRA has been proposed as a non-invasive alternative to DSA to evaluate the arterial and venous structures. We performed MRA in 23 patients with suspected haemodialysis forearm access dysfunction. The degree of stenosis was evaluated with a 3 point scale (1=mild; 3=severe); we compared MRA and ultrasound results. Procedure Details: We used a 1.5T unit (Philips Intera) and performed the examinations with the knee coil. We propose a protocol based on both 3D-PC technique (VENC 30 cm/sec) before and after iv GD injection, and 3D-FFE-T1 sequence during iv GD injection (CE-MRA). MIP reconstructions were always obtained. We observed a good correlation between MRA and ultrasound findings. MRA always showed the entire fistula with an excellent evaluation of the stenosis. In 2 cases MRA showed stenoses missed by ultrasound. CE-MRA proved more useful than PC-MRA. Conclusion: MRA is an effective tool to evaluate hemodialysis fistula complications, being a valid alternative to diagnostic DSA.