MAGNETIC-RESONANCE ANGIOGRAPHY OF INTRAVASCULAR ENDOPROSTHESES - INVESTIGATION OF 3 DEVICES

Purpose: To assess the value of magnetic resonance angiography (MRA) i n the evaluation of vascular patency after intravascular endoprosthesi s placement. Methods: Three different metallic stents (Wallstent, Stre cker, 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 f low-compensation technique, and reconstructed with a maximum-intensity projection (MIP) algorithm. MRA was compared to digital angiograms. R esults: In vitro studies demonstrated that the signal intensity (SI) w ithin the stent differed according to the device employed, the lowest SI being observed within the Palmaz stent (p = .001). There was no dif ference in SI or apparent diameter of the stent according to the seque nce (SE vs GRE) or length of echo time (TE). In patients, the endopros theses recorded as a well-defined area of signal void or dropout (p = 0.004), whereas vessels above and below the stent displayed high signa l intensities. Conclusion: MRA does not seem as yet to be well suited for evaluating vascular patency after endoprosthesis placement, even i f the Strecker and Wallstent endoprostheses provide fewer artifacts th an the Palmaz stent.