Multi-detector computed tomography to analyze in-stent restenoses at different heart rates

Purpose: This study was performed to evaluate the visualization of coronary in-stent restenosis by multi-detector Computed tomography (MDCT). Materials and Methods: A restenosis phantom with different stented stenoses was used. The phantom was placed into a dynamic heart phantom with heart rates from 40 to 120 bpm. MDCT was performed with two scan protocols: a standard and an ultra-high resolution scan protocol. Results: Using the ultra-high resolution protocol, artifacts occurred at 0.6 mm around the stent struts (p < 0.001). Artifacts compromised the discrimination between no stenosis and low-grade stenosis. Approximately 73% of the central lumen diameter was able to be assessed without limiting artifacts allowing the discrimination of no or low vs. moderate and high-grade stenoses (p < 0.05). Using the standard protocol in the dynamic phantom, the image quality and visibility of stenoses decreased with an increasing heart rate (p < 0.0002 and p < 0.004). This was able to be compensated by analysis in an appropriate RR-interval. At the optimal RR-interval, an assessment of the grade of stenoses > 30% was feasible up to 120 bpm. Conclusion: Multi-detector computed tomography ultra-high resolution scans allowed the assessment of a wide range of degrees of in-stent restenoses. In this experimental setup, standard protocols allowed a discrimination of low, moderate and high-grade stenoses even at heart rates above 100 bpm.