Contrast enhanced MR angiography after metallic stent placement : experimental study

The purpose of this study was to evaluate the efficacy of contrast-enhanced MR angiography for follow-up examinations after metallic stent placement and to examine the effects of change of imaging parameters used for contrast-enhanced MR angiography. After four metallic stents (Passager, Ninitol, Wallstent, and Memotherm) were placed in an abdominal aorta shaped vascular phantom, efGRE (enhanced fast gradient recalled echo) 3-D MR angiography was performed, using a 1.5T unit. The four metallic stents were graded 1-3 according to the width and length of their high signal intensity. Variations in the degree of high signal intensity were evaluated according to imaging parameters. The width and length of high signal intensity with the Passager stent and Ninitol stent were greater than with the Wallstent and Memotherm. The larger the field of view, the smaller the matrix number, the larger the flip angle, the greater the width and length of high signal intensity in the metallic stent. Contrast-enhanced MR angiography may be a useful follow-up procedure after the placement of Passager and Ninitol metallic stents. The signal intensity of stent lumen varies according to imaging parameters, and the selection of optimal parameters is therefore important. (author)