Artifact quantification of venous stents in the MRI environment: Differences between braided and laser-cut designs

Purpose: To quantify B-0- and B-1-induced imaging artifacts of braided venous stents and to compare the artifacts to a set of laser-cut stents used in venous interventions. Methods: Three prototypes of braided venous stents with different geometries were tested in vitro. B-0 field distortion maps were measured via the frequency shift Delta f using multi-echo imaging. B-1 distortions were quantified using the double angle method. The relative amplitudes B-1(rel) were calculated to compare the intra-luminal alteration of B-1. Measurements were repeated with the stents in three different orientations: parallel, diagonal and orthogonal to B-0. Results: At 1.5 T, the braided stents induced a maximum frequency shift of vertical bar Delta f (x)vertical bar < 100Hz. Signal voids were limited to a distance of 2 mm to the stent walls at an echo time of 3 ms. No substantial difference in the B-0 field distortions was seen between laser-cut and braided venous stents. B-1(rel) maps showed strongly varying distortion patterns in the braided stents with the mean intraluminal B-1(rel) ranging from (63 +/- 18)% in prototype 1 to (98 +/- 38)% in prototype 2. Compared to laser-cut stents the braided stents showed a 5 to 9 times higher coefficient of variation of the intraluminal B-1(rel). Conclusion: Braided venous stent prototypes allow for MR imaging of the intraluminal area without substantial signal voids due to B-0-induced artifacts. Whereas B-1 is attenuated homogeneously in laser-cut stents, the B-1 distortion in braided stents is more inhomogeneous and shows areas with enhanced amplitude. This could potentially be used in braided stent designs for intraluminal signal amplification.

Automated summary

The study quantified and compared imaging artifacts induced by braided venous stents and laser-cut stents in MR imaging. Braided stents showed smaller frequency shifts and signal voids at 1.5 T compared to laser-cut stents, while differences in B-0 field distortions and B-1 distortions were observed between the two types of stents.