Three-dimensional rotational angiographic detection of in-stent stenosis in wide-necked aneurysms treated with a self-expanding intracranial stent.

OBJECTIVE: To determine the effect of Neuroform stent (Boston Scientific/Target, Fremont, CA) deployment on parent vessel lumen and detect in-stent changes in patients harboring wide-necked intracranial aneurysms treated with the stent-coil technique. METHODS: Parent vessel dimensions were quantified before and after the procedure and at intermediate follow-up examinations by use of high-resolution three-dimensional rotational angiography. By use of shaded surface segmentation of the acquired volume, measurements of the parent vessel proximal to the stent (Point A), at three points within the stented vascular segment (Points B, C, and D), and distal to the stent (Point E) at each study time were compared by use of paired t tests. Correlation between degree of in-stent stenosis and reported ischemic events was estimated by use of a linear regression model. RESULTS: Stent and coil deployment had no immediate effect on parent vessel dimensions. At angiographic follow-up, there was no significant change in vessel size proximal to the stent. Within the stent and distal to it, however, there was a statistically significant 0.31- to 0.41-mm reduction in average diameter (P < 0.001, P < 0.011, P < 0.003, and P < 0.014 for Points B, C, D, and E, respectively). The highest degree of stenosis occurred at Point B, with an average decrease in cross sectional surface area of 2.4 mm 2 (P < 0.001), corresponding to a 19% stenosis and 52% estimated increase in focal hemodynamic resistance by Poiseuille's law. No clinical correlation was noted with the degree of in-stent stenosis. CONCLUSION: Intracranial stenting using a soft self-expanding stent without angioplasty induced a statistically, but not clinically, significant decrease in cross sectional area. Further research and longer-term follow-up are needed to elucidate the mechanism and clinical importance of this response.