The usefulness of MR angiography in evaluating arterio-venous shunt problems in patients on hemodialysis

Precise evaluation of the vasculature condition is the first step in the management of arterio-venous (AV) shunt problem. Shuntgraphy or digital subtraction angiography (DSA) using iodine contrast medium has been widely used for the diagnosis of AV shunt problems. Recently, Doppler ultrasonography (DUS) has been widely used for diagnosis because of its low invasiveness. Furthermore magnetic resonance angiography (MRA) with or without contrast medium, Gd-DTPA, has also started to be employed for this purpose in several institutions. In this study, we compared the findings of MRA to those of DUS and DSA in 12 patients (5 males and 7 females) with AV shunt problems such as stricture and venous hypertension. Most of these patients were treated by interventional radiology (IVR) such as percutaneous transluminal angioplasty (PTA), but some underwent surgery. The average period between AV shunting and problem onset was 8.3 years. Ten of 12 cases were native AV shunts and the remaining two were graft AV shunts. The diagnosis based on MRA findings was consistent with the diagnosis by DSA in 88.9% and with surgical findings in 100% of the cases. The overall conformity rate was 91.7%, but the conformity between MRA and DUS was only 58.3%. Although the issue of high cost remains and the method requires the use of a small amount of contrast medium (Gd-DTPA), MRA is minimally invasive without radiation exposure and is a useful tool providing accurate diagnoses in patients with AV shunt problem. (author)