Factors That Influence Measurements and Accurate Evaluation of Stent Apposition by Optical Coherence Tomography

Assessment Using a Phantom Model

Abstract

Background: Factors influencing measurements and accurate evaluation of stent apposition by optical coherence tomography (OCT) are not established. Methods and Results: Phantom models of known luminal sizes and lengths were evaluated by OCT under various conditions and measurements were compared with actual values. Stents implanted into phantom models were examined by OCT to validate the measurement point on the stent strut surface for accurate evaluation of stent apposition. Strut thickness was measured at 3 points (midpoint, inner and outer surfaces of the stent shadow). The precision of OCT measurements of lumen diameter and area was satisfactory when the image wire was positioned in the center, but the error and deviation were unsatisfactory when the image wire was positioned eccentrically using a low frame acquisition rate. Longitudinal OCT measurements were close to actual values under all conditions examined. Measurements from the midpoint of the stent shadow to the adjacent vessel wall surface coincided with actual stent thickness. Conclusions: Significant measurement error can occur if the image wire is positioned eccentrically with a lower frame acquisition rate than specified by the manufacturer. To accurately evaluate stent apposition, the stent surface should be measured from the center of the stent reflection. (Circ J 2009; 73: 1841-1847)