【摘要】 目的：探讨和线性融合图像相比，双能CT虚拟单能级成像提高胰周血管显示的能力。方法：对45例非胰腺病变患者行双能CT增强扫描（100kV/Sn150kV），并对动脉及门脉期图像进行单能级重建（40～100keV，间隔10keV）及权重因子M0.6的线性融合重建。测量并比较8组图像上腹腔干、肝总动脉、脾动脉、肠系膜上动脉、胃十二指肠动脉、门静脉、肠系膜上静脉和胰腺实质的CT值、信噪比（SNR）、对比噪声比（CNR）、信号强度比（SIR）及图像噪声，并以5分法对图像质量和胰周血管显影的能力进行主观评价。结果：各血管及胰腺实质的SNR、CNR及SIR随着能级的降低而逐渐增高，并在40keV单能级时达到最大值；图像噪声在40～50keV单能级图像上明显高于其他单能级和线性融合图像（P<0.001），线性融合图像噪声和60keV单能级图像相当（P=0.311）;40～60keV单能级图像胰周血管评分明显高于其他单能级及线性融合图像（P<0.001）,50～60keV时图像质量评分均高于其他单能级及线性融合图像（P<0.05）。结论：与线性融合图像相比，双能CT低keV单能级图像能获得更好的图像对比度及显示胰周血管，并在40keV单能级重建时显示血管效果最佳，50～60keV时显示图像质量最佳。更多还原

【Abstract】 Objective: To investigate the performance of virtual monoenergetic images of dual-energy CT in demonstration of peripancreatic vessels compared with conventional polyenergetic images. Methods: Forty-five patients with non-pancreatic lesions underwent contrast enhanced dual-energy CT scan using tube voltage of 100 k V and Sn150 k V. Then the arterial phase and portal phase images were postprocessed using virtual monoenergetic reconstruction and linear blending technique(M=0.6). One standard polyenergetic image(PEI) and seven virtual monoenergetic images(MEI[+]) ranging from 40 to 100 ke V at an interval of 10 ke V were generated. The CT values,signal-to-noise ratio(SNR), contrast-to-noise ratio(CNR), signal-to-intensity ratio(SIR) of pancreas parenchyma and seven peripancreatic vessels(celiac axis, common hepatic artery, splenic artery, superior mesenteric artery,gastroduodenal artery, portal vein and superior mesenteric vein) and image noise on the 8 sets of images were measured and compared. For subjective quality assessment, two readers independently assessed the images using a 5-point classification scale. Results: The SNR, CNR and SIR of each vessel and pancreatic parenchyma increased gradually with decreasing energy, and were maximized at 40 ke V MEI(+); image noise for 40-50 ke V MEI(+) were significantly higher than that for other MEI(+) and PEI(P<0.001), and the noise of 60 ke V MEI(+) was equivalent to PEI(P=0.311); the peripancreatic vessels scores of 40-60 ke V MEI(+) were significantly higher than that of other MEI(+) and PEI(P<0.001), and the subjective image qualities scores of 50-60 ke V MEI(+) were higher than that of other MEI(+) and PEI(P<0.05). Conclusion: Compared with the PEI, the dual energy CT low ke V MEI(+) can obtain better image contrast and improve visualization of peripancreatic vessels. The 40 ke V MEI(+) can provide best visualization of peripancreatic vessels, and the 50-60 ke V MEI(+) can provide best subjective and objective image quality.更多还原