Magnetic resonance angiography of intravascular endoprostheses: investigation of three devices.

PURPOSE: To assess the value of magnetic resonance angiography (MRA) in the evaluation of vascular patency after intravascular endoprosthesis placement. METHODS: Three different metallic stents (Wallstent, Strecker, Palmaz) were studied in vitro, and in vivo in six patients with spin-echo (SE) and gradient-echo (GRE) MR imaging. Time-of-flight, two-dimensional (2D) gadolinium-enhanced MRA was performed with GRE and flow-compensation technique, and reconstructed with a maximum-intensity projection (MIP) algorithm. MRA was compared to digital angiograms. RESULTS: In vitro studies demonstrated that the signal intensity (SI) within the stent differed according to the device employed, the lowest SI being observed within the Palmaz stent (p = .001). There was no difference in SI or apparent diameter of the stent according to the sequence (SE vs GRE) or length of echo time (TE). In patients, the endoprostheses recorded as a well-defined area of signal void or drop-out (p = 0.004), whereas vessels above and below the stent displayed high signal intensities. CONCLUSION: MRA does not seem as yet to be well suited for evaluating vascular patency after endoprosthesis placement, even if the Strecker and Wallstent endoprostheses provide fewer artifacts than the Palmaz stent.