双能量CT虚拟平扫对胰腺的显示:与真实平扫对比

目的 比较第二代双源双能量CT胰腺虚拟平扫（VNC）和真实平扫（TNC）的图像质量。方法 采用Siemens第二代双源双能量CT对21例怀疑胰腺病变的患者行腹部增强扫描，包括单能量TNC图像、胰腺实质期及门静脉期图像，后处理得到胰腺实质期及门脉期的虚拟平扫（VNCp、VNCv）图像。比较TNC、VNCp、VNCv图像的胰腺病灶、胰腺实质、肝脏、竖脊肌、腹主动脉及门静脉的CT值、噪声、CNR、主观评分。结果 TNC、VNCp、VNCv图像主观评分均满足诊断要求（P=0.150）。与TNC图像比较，VNC图像噪声明显减低（P<0.001）。胰腺实质的CT值在VNCv与TNC图像上差异无统计学意义（P=0.063）。胰腺囊性与实性病灶的CT值在VNCp、VNCv、TNC图像上差异均无统计学意义（P=0.277、0.799）。囊性病灶的CNR在VNCp最高。结论 第二代双源双能量CT对胰腺扫描的VNC图像质量接近TNC，并且可减少辐射剂量。

Virtual noncontrast-enhanced CT of pancreas with dual-energy CT: Comparison of true noncontrast-enhanced CT

Objective To compare the image quality of pancreas by virtual noncontrast-enhanced (VNC) images obtained with second-generation dual-source dual-energy CT (DECT) and true noncontrast-enhanced (TNC) images. Methods Twenty-one patients suspected of pancreatic mass underwent triphasic abdominal CT examination with Siemens DECT. The images of single-energy TNC, contrast enhanced dual-energy pancreatic parenchymal phase and portal venous phase were obtained. VNC images were generated from pancreatic parenchymal (VNCp) and portal venous (VNCv) phases. The CT value of pancreatic lesions, pancreatic parenchyma, liver, erector spinae,abdominal aorta and portal venous, image noise, CNR and image quality were measured and compared among TNC, VNCp and VNCv datasets. Results The subjective image evaluation of VNC images was as good as TNC images (P=0.150). Image noise was lower in VNC images than that in TNC images (P<0.001). There was no statistically significant difference of CT value for pancreatic parenchyma between VNCv and TNC images (P=0.063). The CT value of pancreatic cystic and solid lesions had no significant difference among VNCp, VNCv and TNC images (P=0.277, 0.799). CNR of cystic lesion was the highest in VNCp images. Conclusion VNC images of pancreas by dual-source DECT may close to the TNC and can reduce the radiation dose.