Noninvasive assessment of coronary stents in patients by 16-slice computed tomography

Background The usefulness of thin-slice multi-detector computed tomography (MDCT) has been highly expected to assess the lumens of coronary artery stents. We evaluated the usefulness of 16-slice MDCT to assess the in-stent lumen after coronary artery stenting. Methods In 42 consecutive patients after coronary artery stenting, retrospective ECG-gated CT-angiography using 16-slice MDCT (0.5-s rotation time, 16 × 0.625-mm detector collimation) was performed. The qualitative assessability of the lumens of 61 coronary stents (14 different types) by MDCT and the reasons for non-assessability were investigated. Furthermore, the evaluation of in-stent restenosis in 21 assessable stents of 16 patients, inluding quantitative density analysis by MDCT, was performed and the results were compared with those of conventional coronary angiography (CAG). Results Of 61 stents, 42 (68.9%) were assessable. The assessability of diameter ≥ 3.5-mm stents made of stainless steel or cobalt was high (88.6%, 31/35), that of 3.0-mm stents was low (57.9%, 11/19) and all 2.5-mm stents were non-assessable due to partial volume effects and metal artifacts of stents. The lumens of stents made of tantalum were totally obscured and the metal artifacts of Bestent2 (gold markers) and S670 were severer than others. All non-assessable stents due to banding artifact and calcification were implanted in segment #1–3 and #6, respectively. In comparison to CAG, MDCT correctly detected the 5 in-stent restenoses and identified absence of restenoses was influenced strongly by the stent strut. Conclusion Despite some limitations, 16-slice MSCT is sufficiently useful for assessment of various coronary stents in patients and can detect in-stent restenoses of assessable stents with high accuracy in comparison to CAG.