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目的:评价能谱CT单能量重建技术结合ASIR重建算法对冠脉优化显示的作用;方法:前瞻性收集能谱冠状动脉CT检查20例,患者均采用能谱扫描模式、单源瞬时(0.5 ms)管电压(140、80 k Vp)切换技术行心脏能谱CT检查。将扫描获得的原始图像采用40%自适应统计迭代重组技术重组为轴位单能量图像(60、70、80、90、100、110、120、130、140 ke V),并常规重组轴位混合能量图像。在不同重建模式下,分别测量主动脉根部、左主干、前降支中段、右冠状动脉根部、右冠状动脉中段血管腔内的噪声,信噪比、对比噪声比。将9个单能量水平的上述测量指标分别与混合能量的对应指标进行统计学分析比较,统计学比较方法均采用随机区组设计的方差分析。结果:1噪声:混合能量水平主动脉根部、左主干、右冠状动脉根部、前降支中段、右冠状动脉中段血管腔内的噪声分别为(24.32±5.84)HU、(25.65±10.83)HU、(33.27±11.95)HU、(42.16±15.52)HU、(35.58±13.21)HU,随着ke V上升噪声逐渐下降,与混合能量相比,所测冠脉噪声均在90~140ke V水平得到了改善(P均<0.05),其中除主动脉根部血管腔内噪声在130ke V达到最低水平(10.85±2.49)HU外,余各测量位置血管腔内的噪声均在140ke V水平达到最低水平,分别为左主干(10.65±6.55)HU、右冠状动脉根部(13.07±5.06)HU、前降支中段(21.94±8.31)HU、右冠中段(16.83±6.05)HU;2信噪比:混合能量水平主动脉根部、左主干、右冠状动脉根部、前降支中段、右冠状动脉中段血管腔内的信噪比分别11.47±1.97、15.23±7.51、10.19±3.98、6.94±2.85、7.60±3.28,与混合能量相比,上述测量点信噪比分别在60~90ke V、60~80ke V、60~70ke V、60ke V、60~70ke V水平得到明显改善(P均<0.05),且均在60ke V水平得到最佳改善,分别为22.20±5.74、23.82±11.19、16.61±8.15、8.78±3.67、8.91±4.12;3、对比噪声比:混合能量水平主动脉根部、左主干、右冠状动脉根部、前降支中段、右冠状动脉中段血管腔内的对比噪声比分别18.68±6.90、18.74±7.12、17.58±6.56、12.29±2.40、17.88±7.16,与混合能量相比,上述测量点对比噪声比分别在60~80ke V、60~80ke V、60~80ke V、60~70ke V、60~70ke V水平得到明显改善(P均<0.05),其中前降支中段的对比噪声比在60ke V得到了最佳改善,为17.82±5.40,余各测量点的对比噪声比均在70ke V水平得到了最佳改善,分别为主动脉根部29.73±8.46、左主干28.69±7.65、右冠状动脉根部25.70±7.59、右冠状动脉中段21.62±10.23;结论:冠状动脉能谱CT成像的单能量图像结合迭代重建算法,能够有效降低冠脉的噪声,提高冠脉信噪比及对比噪声比,从而达到优化冠脉显示的目的。
Objective: To evaluate the effect of single-energy CT reconstruction combined with ASIR reconstruction algorithm on coronary artery stenosis.Methods: 20 cases of coronary artery CT were prospectively collected by energy spectrum scanning, single-source transient (0.5 ms ) Tube Voltage (140,80 k Vp) Switching Technique Cardiac Spectrum CT Examination. The original images obtained by scanning were reconstructed into single axial energy images (60, 70, 80, 90, 100, 110, 120, 130 and 140 keV) by using 40% adaptive statistical iterative recombination technique, Energy image. Under different reconstruction modes, the noise, signal-to-noise ratio and contrast-to-noise ratio of the aortic root, left main trunk, middle part of the anterior descending artery, root of right coronary artery and middle coronary artery were measured respectively. The above nine single energy level measurement indicators were respectively mixed energy corresponding indicators for statistical analysis and comparison, statistical methods were used randomized block design analysis of variance. Results: (1) Noises: The noise in the aortic root, left main trunk, right coronary artery, middle part of the left anterior descending artery and middle right coronary artery were (24.32 ± 5.84) HU and (25.65 ± 10.83) HU, (33.27 ± 11.95) HU, (42.16 ± 15.52) HU and (35.58 ± 13.21) HU, respectively. As the rising noise of ke V decreased gradually, compared with the mixed energy, the measured coronary noise was obtained at the level of 90 ~ 140 keV (P <0.05). The noise in the vascular lumen reached the lowest level at 140ke V except for the lowest level of vascular endothelium at 130ke V (10.85 ± 2.49) HU (10.65 ± 6.55) HU, right coronary artery (13.07 ± 5.06) HU, middle anterior descending artery (21.94 ± 8.31) HU and middle right coronary artery (16.83 ± 6.05) HU; 2 Signal to noise ratio: The signal-to-noise ratios in the aortic root, left main trunk, right coronary artery, middle segment of the left anterior descending artery and middle coronary artery were 11.47 ± 1.97,15.23 ± 7.51,10.19 ± 3.98,6.94 ± 2.85,7.60 ± 3.28, Compared with the mixed energy, the signal-to-noise ratio of the above measurement points is respectively 60-90keV, 60-80keV, 60-70keV, 60keV, 60-70ke V levels were significantly improved (P <0.05), and were best at 60ke V levels were improved, respectively, 22.20 ± 5.74,23.82 ± 11.19,16.61 ± 8.15,8.78 ± 3.67,8.91 ± 4.12; 3, the contrast ratio : The contrast noise ratios in the aortic root, left main trunk, right coronary artery, middle part of left anterior descending artery and middle right coronary artery in mixed energy level were 18.68 ± 6.90, 18.74 ± 7.12, 17.58 ± 6.56, 12.29 ± 2.40, 17.88 ± 7.16, compared with the mixed energy, the contrast ratio of the above measurement points were significantly improved in the 60 ~ 80ke V, 60 ~ 80ke V, 60 ~ 80ke V, 60 ~ 70ke V, 60 ~ 70ke V (P <0.05 ), Of which the contrast ratio of the middle part of the anterior descending artery was best improved at 60ke V, which was 17.82 ± 5.40, and the contrast noise ratios at all measuring points were all improved at the level of 70ke V, which were 29.73 ± 8.46, the left main trunk was 28.69 ± 7.65, the right coronary artery was 25.70 ± 7.59, the middle right coronary artery was 21.62 ± 10.23. Conclusion: The single energy image of coronary artery imaging CT combined with iterative reconstruction algorithm can effectively reduce the coronary artery noise, Improve coronary signal to noise ratio and contrast ratio, so as to achieve optimization The purpose of the clock display.