Usefulness of measuring coronary lumen density with multi-slice computed tomography to detect in-stent restenosis

Background A method to objectively detect in-stent restenosis (ISR) with multi-slice computed tomography (MSCT) has not been established yet. We aimed to evaluate the usefulness of measuring coronary lumen density with MSCT to detect ISR. Methods Forty-seven coronary stented lesions in 38 patients were evaluated with 16-slice CT (collimation thickness, 0.625 mm). In each assessable lesion, the stent lumen was visually evaluated, and reference CT density proximal to the stent (RCTD) and minimum CT density of the in-stent lumen (SCTD) were measured. ISR was defined as > 50% diameter stenosis measured by quantitative coronary angiography (QCA). Results Of 47 stented lesions, 35 (74%) were assessable, and there were 12 ISR (+) and 23 ISR (−) lesions. Mean ΔCTD (RCTD − SCTD) of the ISR (+) group was significantly greater than that of the ISR (−) group (196 ± 101 vs. 7 ± 30 HU, p < 0.001). Predictive accuracy of quantitative evaluation of ISR using our best cutoff value of ΔCTD was higher than that of visual evaluation (97% vs. 83%, p < 0.05). The ΔCTD showed a higher correlation with percent diameter stenosis (r = 0.85, p < 0.001) than with SCTD (r = − 0.73, p < 0.001). Conclusions Measuring differences of CT densities between reference vessel lumens and in-stent lumens using MSCT is a convenient and useful technique to detect ISR.