Artifacts of vascular stents in 3D MR angiography: experimental studies.

Purpose: The purpose of this phantom study was to evaluate the visualizatio n of vascular stents by using contrast-enhanced (CE) 3D MR angiography (MRA ). Methods: The measurements were performed on a Magnetom Vision operating at 1.5 T with 25 mT/m gradients by using a head coil; a 3D FISP sequence (T R/TE/FA 4.6 ms/1.8 ms/30 degrees) was used. A phantom was designed with a l ength of 20 cm and consisted of a plastic cylinder filled with hydrogel. Tu bes were used to install 7 different stents (Strecker, Boston Scientific; C ragg, Mintec; Walt, Schneider; Memotherm, Angiomed; St-Come, Trigon-MTS; Si nus, Optimed: Palmaz, Johnson & Johnson) with different metal components. T he tubes were perfused with a solution of water and Gd-DTPA. Four radiologi sts evaluated the image quality. The measurements of the endoluminal stent diameters were compared with the findings obtained by digital subtraction a ngiography. The signal intensities were measured before (inflow), within (s tent) and after (outflow) the different stent types. Results: The endolumin al diameter of the Cragg stent and the strecker graft were easily detectabl e. The signal loss within the lumen of the Wall stent was approx. 10% in re lation to the inflow and outflow measurements. The result was an only sligh tly reduced image quality. The other grafts (St-Come, Sinus, Palmaz, Memoth erm) showed significant signal losses ranging From 65% to 96%. A correct di agnosis was not possible within these graft lumina. Conclusion: Contrast-en hanced MR angiography can be used to evaluate vascular stents. A prerequisi te is the application of particular commercially available grafts.