腹部动脉能谱CT混合能量与单能量图像的比较研究

Comparative Study of Polychromatic and Monochromatic Images of Abdominal Artery with Spectral CT Imaging

目的通过比较腹部动脉能谱CT成像中混合能量重建模式图像与单能量重建模式图像的质量,筛选适宜观察腹部动脉的图像重建模式。方法 80例患者采用GE公司的宝石CT能谱成像技术,获得腹部动脉混合能量图像(140kVp)和40-140keV范围内的单能量图像。对混合能量图像和单能量图像进行感兴趣区CT值的测量,计算腹主动脉、肝动脉的SNR和CNR;各组图像由三名有经验的放射医师采用盲法进行图像质量主观评分。最后进行腹部动脉CT值、SNR、CNR和图像质量主观评分的综合比较。所获数据采用SPSS 19.0软件进行统计学分析。结果随着keV值的降低,腹部动脉CT值逐渐升高,图像噪声同时发生改变。根据腹部动脉图像质量的客观指标(CT值、SNR和CNR)和主观评分,对混合能量图像与各组单能量图像进行综合比较,结果显示50-60keV单能量组腹部动脉图像质量优于混合能量组,同时单能量成像对腹主动脉和肝动脉图像质量的影响存在差别。结论在腹部能谱CT常规增强扫描所获得的腹部动脉不同类型重建图像中,50-60keV单能量重建模式的图像质量优于混合能量重建模式,推荐其作为腹部动脉能谱CT扫描的常规重建模式。

Objective To evaluate the difference of polychromatic and monochromatic images reconstruction mode in abdominal artery with Spectral CT imaging, choose the appropriate reconstruction mode for the best displaying of abdominal artery. Methods Abdomen enhanced CT scans were applied with spectral imaging technique （Discovery CT750 HD, GE Healthcare） on eighty patients, and got the polychromatic images（140kVp） and monochromatic images ranged from 40 to 140 keV of abdominal artery. CT value measurements of ROIs were performed in the polychromatic and monochromatic images, then the SNR and CNR of abdominal aorta and hepatic artery were calculated. Three experienced radiologists evaluated subjective image quality of the images in all groups. The following variables of abdominal artery were compared together： CT value, SNR, CNR and subjective ratings. Statistical analysis of all data were accomplished with SPSS 19.0 soft package. Results The CT value of abdominal artery increased gradually with the decrease of keV, image noise changed at the same time. The image quality of 50-60 keV monochromatic images are better than polychromatic images by comparing all variables（CT value, SNR, CNR and subjective ratings） of them, there is something difference of monochromatic images between abdominal aorta and hepatic artery. Conclusion In abdominal spectral CT imaging with enhenced CT scan, 50-60 keV monochromatic reconstruction can provide better quality images, it was recommended as the conventional reconstruction mode of abdominal artery spectral CT scan.