Accuracy and reproducibility of stent-strut thickness determined by optical coherence tomography

Optical coherence tomography (OCT) has been increasingly used to evaluate stent apposition following implantation. Since stent struts are visualized as linear structures with strong surface reflection and typical dorsal shadowing, apposition of struts is evaluated by measuring the distance between the strut surface reflection and adjacent vessel surface in consideration of strut thickness. However, there are no data available to validate the measurements of strut thickness by OCT. The aim of this in vitro study is to validate the accuracy of OCT measurement of stent-strut thickness of different commercially available stents in evaluating stent apposition.

We performed the in vitro study after implantation of 5 commonly used stents in a phantom model artery. Stent-strut thickness was measured by a commercially available OCT system and was compared to the manufacturers' nominal strut-thickness data for each stent. Intra- and interobserver variability were also assessed.

A total of 239 stent struts were evaluated. The differences in stent-strut measurements as compared to the manufacturers' nominal strut thickness data were low. The intra- and interobserver measurement differences were low (6 +/- 7 microm, and 6 +/- 7 microm, respectively), with high correlation coefficients (r = 0.957 and r = 0.957, respectively; p < 0.0001).

This in vitro study demonstrates that OCT analysis measuring stent-strut thickness provides accurate data with high reproducibility, suggesting that assessment of stent-strut apposition using OCT is feasible.