Microwave spectrometry for non-invasive stent monitoring using near-field probes

Abstract

The aim of this work has been to characterize the capabilities of different probes to detect structural and enviromental changes in a stent through microwave spectrometry. We begin comparing the stent detection capabilities of four near-field probes (named as Brass, Half-MoonG, Origin and Magnetic probes) by distancing and misalingning a stent sunken in distilled water. The two probes which perform better (Origin and Magnetic probes) are used to conduct a more indepth study of their detection capabilities in open-air conditions. Stent detection at large distances (1.5cm) is only achieved by Magnetic probe. Tolerance to stent misalignments is also greater with Magnetic probe. Subsequently, we analyse the capacity of these two probes to detect changes in the stent length (fractures) in open-air conditions. Three stents are used to perform fractures at three different points of their total length; three types of fracture are analysed in each stent. Both probes discern each fracture type, regardless the point where it is performed, and exhibit results in agreement with theoretical predictions. Similarly, we analyse the capacity of these two probes to detect changes in the stent vicinity (restenosis). Artery segments of different lengths are inserted to mimic restenosis into a stent wrapped inside another artery of larger diameter. The results obtained have been compromised by changes in the water content of the arteries.