目的：探讨双源CT虚拟平扫在小肠病变中的应用。方法：对35位患者在双源CT上行小肠造影检查，共三期扫描，即常规平扫、动脉期和静脉期对比增强双能量扫描（100 kV/140 kV），调入后处理软件中的Liver VNC选项卡，获得动、静脉期虚拟平扫图像，将其与真实平扫图像进行对比。对图像质量进行主观评分以及客观评分，主观评分由2名医生采用双盲法评分，客观评分在3个序列的图像上选择感兴趣区，分别记录下动、静脉期虚拟平扫及真实平扫的病灶、肝脏、肌肉、脂肪的平均CT值，以及由机器产生的噪声，病灶的信噪比（SNR）及对比信噪比（CNR）。同时记录下三期扫描的总辐射剂量及去除平扫剂量之后动、静脉增强两期扫描的总辐射剂量。采用单因素方差分析比较两组以上图像平均CT值、SNR、CNR。采用两个独立样本t检验分析辐射剂量。结果：35例患者，其中男16例，女19例，年龄27~83岁，未见明显异常16例，慢性结肠炎3例，粘连性肠梗阻4例，肿瘤切除术后2例，肠息肉3例，脂肪瘤2例，结肠恶性肿瘤3例，肠系膜纤维瘤1例，回盲部肿物1例。采用SPSS 21.0软件进行统计分析，病灶、脂肪、肌肉虚拟平扫的CT值小于真实平扫，差异有统计学意义，而肝脏虚拟平扫的CT值大于真实平扫，差异有统计学意义。虚拟平扫的标准差低于真实平扫，而SNR、CNR高于真实平扫，差异无统计学意义。3种图像主观评分均能满足诊断要求，虽然虚拟平扫的主观评分要低于真实平扫，但是其差异无统计学意义，优质图像率达71.8%。双能两期扫描辐射剂量低于常规三期扫描的24.8%。结论：在患者小肠造影的检查中， 双能CT的虚拟平扫图像可以用作基准的密度测量及传统平扫的替代，省去常规增强前扫描，大大降低患者接受的辐射剂量。

Objective: To explore the application of dual-source CT virtual scan in the small intestine. Methods: Thirty-five patients underwent small intestine radiography with dual source CT, a total of three scans, namely conventional unenhanced, arterial and venous phase. The virtual unenhanced images were obtained and compared with the real images in arterial and venous phase. The subjective score of image quality was evaluated by two doctors using double-blind method, the objective score of image quality was to select the region of interest in the images of three sequences, to record the average CT values of lesions, liver, muscle and fat of virtual unenhanced and real images in arterial and venous phase, and the noise generated by the machine, lesion-noise ratio(SNR) and contrast-noise ratio(CNR). At the same time, the total radiation dose of three phase scans and the total radiation dose of arterial and venous enhancement after the removal of the unenhanced dose were recorded. ANOVA was used to compare the average CT values of the images of two groups, SNR and CNR. Two independent samples t-test was used to analyze radiation dose. Results: In 35 patients, there were 16 males, and 19 females, aged 27~83 years old, which had no obvious abnormalities in 16 cases, chronic colitis in 3 cases, 4 cases of intestinal obstruction, 2 cases of tumor resection, intestinal polyp in 3 cases, 2 cases of lipoma, 3 cases of colon cancer, 1 case of mesenteric fibroma, ileocecal tumor in 1 case. Using SPSS 21.0 software for statistical analysis, the CT values of lesions, fat, muscle of virtrual non-contrasted(VNC) were less than the those of true non-contrasted(TNC), the difference was statistically significant, while the CT value of VNC of liver was greater than that of TNC, the difference was statistically significant. Virtual unenhanced SD was lower than the real plain, and SNR, CNR were higher than those of the real plain, the difference was not statistically significant. The subjective scores of the three images could meet the diagnostic requirements, although virtual unenhanced subjective rating was lower than that of real plain, but the difference was not statistically significant, high-quality image rate of 71.8%. The dual-energy two phases radiation dose was less than 24.8% of the conventional three phases radiation dose. Conclusions: In the examination of patients with small bowel radiography, the dual-energy CT VNC images can be used as a benchmark for the density measurement and an alternative for the traditional plain, eliminating the conventional pre-enhancement scan, greatly reducing the patient’s radiation dose.