Study On The Optimal Monochromatic Energy Level Of Coronary Stent After Coronary Stent Intervention

Purpose: To explore the optimal monochromatic level of coronary stent after coronary stent intervention by CT spectral imaging.Methods: 30 patients after coronary stent intervention 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 10keV)monochromatic energy level images,and the noise and contrast-to-noise ratio were calculated.The CT value of 5 points in the stent was measured,and the mean CT value of 5 points in the stent was taken as the CT value of intra-stent.The CT value of 5mm at the proximal of the stent and distal end of the stent were measured,their average was taken as the mean CT value outside the stent,and the difference of CT value between intra-stent and outside stent at each monochromatic level was calculated.Results: With the increase of monochromatic energy level,the image noise and CNR showed a decreasing trend(Noise:90keV-140keV:[(12.08±1.66)-(13.78±0.43)];40keV-80keV:[(14.05±0.03)-(28.81±1.54)]);(CNR:90keV-140keV:[(21.38±2.97)-(27.61±0.94)];40keV-80keV:[(33.32±0.30)-(49.90±2.62)]).With the increase of monochromatic energy level,the difference of CT value between intra-stent and outside stent also showed a decreasing trend(90keV-140keV:[(27.37±12.49)HU-(49.39±3.02)HU]);(40keV-80keV:[(62.24±0.13)HU-(233.13±0.21)HU]);The mean CT value of intra-stent and the CT value of ascending aorta root decreased with the increase of monochromatic energy level(40keV: [(1191.14±357.93)HU];[(1291.52±314.42)HU]);(80keV:[(340.08±100.95)]HU;[(324.82±74.70)HU]);(140keV:[(159.54±58.07)HU];[(116.76±24.48)HU]),and the mean CT value of intra-stent and the CT value of ascending aorta root was closest to 350 HU at 80 keV level.Conclusion: During cardiac CT energy spectrum scanning after PCI,the noise was relatively low,the CNR was relatively high,the difference of CT value of intra-stent and outside stent was relatively smaller,and the CT value is closest to the optimal vascular enhancement value at 80 keV monochromatic energy level.80 keV was the best monochromatic energy level for stent display.