双能量CT线性融合优化对比技术对肝脏增强图像质量的影响

Effect of Linear Blending Optimal Contrast Technique with Dual Energy CT on Liver Image Quality

目的探讨双能量CT线性融合优化对比技术对肝脏增强图像质量影响,获得线性融合方式在肝脏图像质量应用中最佳加权因子。方法收集50例肝脏双能量CT增强扫描患者线性融合图像数据进行分析测量,比较门静脉期加权因子0.1~0.9融合图像的噪声(SD)、信噪比(Signal to Noise Ratio,SNR)、对比噪声比(Contrast to Noise Ratio,CNR),并对各组图像质量进行主观评分。结果在加权因子为0.4~0.6的混合能量图像中图像SD较低。加权因子为0.5~0.7时图像的SNR较高,加权因子为0.6~0.8时图像的CNR较高,图像CT值在0.1~0.9加权因子中呈递增趋势。加权因子0.5与0.6、0.6与0.7组SD、SNR、CNR、CT值组间比较无统计学意义,0.5与0.7组组间比较CT值有统计学意义。加权因子0.5、0.6、0.7主观图像质量评价评分较高,0.7组最高,0.6组次之。结论双能肝脏增强扫描中加权因子为0.6、0.7时均可获取具有相对较低的SD和较高的SNR、CNR、CT值图像,对于观察肝脏乏血供病灶时选择加权因子0.7融合图像最佳,当在肝损害、脂肪肝背景下时,选用较低SD的加权因子0.6时图像观察较佳。

Objective The objective of this study was to evaluate the effect of linear blending optimal contrast technique using dual-energy CT(DECT)on contrast-enhanced liver images,and acquire an optimal weighting factor.Methods50patients undergoing dual energy contrast-enhanced CT of liver were enrolled.For each patient,datasets of linear blended images in the portal phase were generated with weighting factors of0.1～0.9.Noise(SD),signal to noise ratio(SNR),contrast to noise ratio(CNR),and subjective image quality score of fused images were obtained.Results The noise was lower in fused images with weighting factors of0.4～0.6.The SNR was higher in fused images with weighting factors of0.5～0.7.The CNR was higher in fused images with weighting factors of0.6～0.7.CT value presented an increased tendency with an increase of weighting factors.There were no significant differences in noise,SNR,CNR,or CT value between groups of weighting factors of0.5and0.6,and between groups of weighing factors of0.6and0.7.Noise,SNR,CNR,and CT value were significantly different between groups of weighing factors of0.5and0.7(P<0.05).Subjective image quality score was the highest in images with weighting factor of0.7,followed by images with weighting factor of0.6.Conclusion For linear blended images generated from liver dual energy contrast-enhanced CT scans,images with weighting factors of0.6and0.7had relatively low noise and high SNR,CNR,and CT value,and images with weighting factors of0.7were optimum for observing hypovascular liver lesions.Lower weighting factor of0.6was optimal for patients with liver injury or fatty liver.