Background: Until now, there have been few reports on the accuracy of in-stent restenosis (ISR) detection using high-definition computed tomography (HDCT). The purpose of this study was to assess ISR using HDCT with a new gemstone detector and to examine the diagnostic accuracy compared with invasive coronary angiography. Methods and Results: We evaluated 162 consecutive patients with 316 stents and the image quality (IQ) scores used to assess ISR, and analyzed whether stent strut thickness and diameter affected IQ score and assessability. In the 316 stents, 278 were diagnosed as assessable with HDCT (88.0%). IQ score for stent diameter ≥3 mm was significantly higher than that for stent diameter <3 mm, for stents with both thick struts ≥140 μm in thickness (mean IQ: 2.04±0.97 vs. 2.83±1.06, P<0.001) and thin struts <140 μm (mean IQ: 1.92±0.87 vs. 2.64±0.96, P=0.01). Assessability for stent diameter ≥3 mm was significantly higher than that for stent diameter <3 mm only for stents with thick struts (92.8% vs. 76.1%, P<0.001). Stent strut thickness, however, was not statistically significantly associated with either IQ score or assessability. Conclusions: In-stent lumens have high HDCT assessability, and HDCT is useful to evaluate thick-strut stents with diameter <3 mm.
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