冠状动脉支架植入术后支架显示最佳单能量水平的研究

Study on the Optimal Monochromatic Energy Level of Coronary Stent After Percutaneous Coronary Stent Intervention

目的探讨CT能谱成像技术对冠状动脉支架植入术后支架显示的最佳单能量水平。方法连续搜集经皮冠状动脉介入治疗(PCI)术后患者30例,采用宝石CT能谱成像扫描,将扫描获得的原始图像采用40%自适应统计迭代重建40~140 keV(间隔10 keV)的单能量图像,计算噪声和对比噪声比;测量支架内5个点的CT值,取支架内5个点的平均值作为支架内平均CT值,测量支架外近端5 mm、支架外远端5 mm的CT值,计算支架外CT值的平均值,计算各单能量水平下支架内、外CT值的差值。结果噪声及对比噪声比随单能量水平的增加而降低[Noise:40~80 keV:(14.05±0.03)HU^(28.81±1.54)HU;90~140 keV:(12.08±1.66)HU^(13.78±0.43)HU。CNR:40~80 keV:33.32±0.30~49.90±2.62;90~140 keV:21.38±2.97~27.61±0.94],支架内平均CT值随单能量水平增加呈下降趋势[40 keV:(1191.14±357.93)HU;80 keV:(340.08±100.95)HU;140 keV:(159.54±58.07)HU];较高的单能量水平表现出较低的支架内、外CT值的差值[40~80 keV:(62.24±0.13)HU^(233.13±0.21)HU;90~140 keV:(27.37±12.49)HU^(49.39±3.02)HU]。结论PCI术后患者行心脏CT能谱扫描时在80 keV单能量水平下对比噪声比较高,支架内、外CT值差值较小并且支架内CT值最接近血管最佳强化值,80 keV是显示支架的最佳单能量水平。

Objective To explore the optimal monochromatic level of coronary stent after percutaneous coronary stent intervention by CT spectral imaging.Methods 30 patients post-PCI were continuously collected,all of them were scanned by dual-energy spectral CT mode.The original images obtained from the scan were iteratively reconstructed with 40%adaptive statistics(40-140)keV(interval 10 keV)monochromatic level images.Noise and CNR were calculated.The CT value of 5 points in the stent was measured,and the mean value of 5 points in the stent was taken as the CT value of in-stent.The CT value of 5 mm at the proximal and distal end of the stent were measured,and the mean CT value outside the stent was calculated,then the difference CT value of in-stent and outside the stent was calculated at each monochromatic level.Results With the increase of monochromatic levels,Noise and CNR showed a decreasing trend[Noise:40-80 keV:(14.05±0.03)HU-(28.81±1.54)HU,90-140 keV:(12.08±1.66)HU-(13.78±0.43)HU;CNR:40-80 keV:33.32±0.30-49.90±2.62,90-140 keV:21.38±2.97-27.61±0.94],the mean CT value of in-stent also showed a decreasing trend[40 keV:(1191.14±357.93)HU;80 keV:(340.08±100.95)HU;140 keV:(159.54±58.07)HU];The higher monochromatic level showed a lower difference in CT values of in-stent and outside the stent[40-80 keV:(62.24±0.13)HU-(233.13±0.21)HU,90-140 keV:(27.37±12.49)HU-(49.39±3.02)HU].Conclusion After PCI,the cardiac CT energy spectrum scanning showed that CNR was relatively higher at 80 keV monochromatic energy level,and at this level the difference in CT value of in-stent and outside the stent was relatively lower.The CT value of in-stent was closest to the optimal enhancement value.80 keV was the optimal monochromatic level to display the stent.