目的：探讨能谱CT单能量成像与自适应统计迭代重建（ adaptive statistical reconstruction ， ASiR）心肌灌注的最佳扫描参数组合。方法对30例疑诊冠心病患者行心脏能谱扫描，对原始图像分别采用多组单能量联合不同权重ASiR技术以及传统混合能量模式重建并对特定心肌节段的噪声、信噪比（ signal－to－noise ratio ， SNR ）、对比噪声比（ con－trast－to－noise ratio， CNR）及线束硬化伪影（ beam－hardening artifacts ， BHA）进行单因素方差分析。结果与传统混合能量成像相比，较高单能量可降低图像噪声和BHA，40％及以上ASiR重建可增强降噪效果，对伪影改善并不显著；75keV对应的SNR（48％；P ＜0．001；联合80％ASiR）和CNR（35％；P ＜0．001；联合60％ASiR）有最大优化。结论与混合能量成像相比，70～75 keV单能量联合40％ASiR重建可显著降低心肌灌注图像噪声、改善伪影并提高SNR、CNR。%Objective To explore the optimum match of monochromatic energy level and adaptive statistical reconstruction (ASiR) for monochromatic reconstruction of myocardial CT perfusion (CTP) images with dual-energy CT.Methods Thirty sub-jects with suspected coronary artery disease ( CAD) were scanned on spectral CT , conventional polychromatic images and 10 sets of monochromatic images (60, 65, 70, 75, 80, 90, 100, 110, 120, and 130 kiloelectron volts ( keV); each with increasing contributions of ASiR , ie, 0%, 20%, 40%, 60%, 80%) was obtained from a single gemstone spectral imaging ( GSI) acquisi-tion.The background noise, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) and beam-hardening artifacts (BHA) of the specific myocardial segment in monochromatic images were assessed by ANOVA test and were compared with conventional pol -ychromatic groups .Results With the increase of monochromatic energy imaging noise , BHA decreased , reaching the noise ’ s nadir at 75keV level.Adding 40%or more ASiR contributed to the reduction of the noise , while for BHA, this seemed ambigu-ous.Compared with conventional polychromatic images , reconstructions with 75 keV showed the highest improvement in SNR (48%, P <0.001, combined with 80%ASiR) and CNR (35%, P <0.001, combined with 60%ASiR).Conclusion Mono-chromatic reconstruction at 70~75 keV combined with 40%ASiR can offer satisfactory reduction of noise and BHA , meanwhile , obtains superior SNR and CNR in this myocardial CTP scan with spectral CT .
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