不同碘流率在腹部CT虚拟平扫图像的应用初探

发布时间：2019-01-19 11:23

【摘要】：目的:评估不同碘流率(IFR)及不同碘浓度对腹部双能量CT虚拟平扫(VUE)图像质量的影响。方法:94例患者使用双能CT行腹部平扫加三期增强,包含动脉期、门脉期和延迟期。根据注射碘流率的不同94例患者被随机分为4组。虚拟平扫图像在70 keV虚拟单能量图像条件下得到。测量、计算并记录每个患者腹主动脉、门静脉主干、肝脏实质、肝内病灶、胰腺实质、脾脏实质、双侧竖脊肌及腹膜后脂肪共8处感兴趣区的CT值、图像噪声、信噪比及对比噪声比。分别记录包括常规平扫及不包括常规平扫的剂量长度乘积及有效辐射剂量,用以计算潜在可降低的辐射剂量。两位有经验的放射科医师使用5分法分别对主观图像质量进行评分并记录。所得数据首先进行单样本正态性检验。组内数据符合正态分布,使用单因素方差分析CT值、图像质量、信噪比及对比噪声比值等客观指标;对于有数据不符合正态分布的情况,则使用非参数检验。由于进行了多组检验比较,统计学显著型水准校正为0.01(双侧)。结果:4个不同碘流率组各组间相同期相的虚拟平扫图像之间CT值比较没有统计学差异(P0.05)。同一碘流率组动脉期、静脉期及平衡期分别获得的虚拟平扫图像与常规平扫图像之间CT值比较没有统计学差异(P0.05)。虚拟平扫图像的信噪比值明显高于常规平扫图像(P0.01);虚拟平扫图像的对比噪声比值相等于或略高于常规平扫图像(P0.05)。虚拟平扫图像的主观评价得分相等于或略低于常规平扫图像(P0.05),可以满足临床诊断需要。使用虚拟平扫图像代替常规平扫图像可潜在降低辐射剂量约25%。结论:虚拟平扫图像可以部分代替常规平扫图像,且虚拟平扫的图像质量不会受到碘流率变化的影响。在不影响诊断的前提下使用虚拟平扫图像可潜在降低辐射剂量约25%。
[Abstract]:Aim: to evaluate the effect of different iodine flow rate (IFR) and different iodine concentration on the quality of abdominal dual energy CT virtual plain scan (VUE) images. Methods: 94 patients with dual energy CT were performed abdominal plain scan and three stages of enhancement, including arterial phase, portal phase and delayed phase. According to the different iodine flow rate, 94 patients were randomly divided into 4 groups. The virtual plain scan image is obtained under the condition of 70 keV virtual single energy image. To measure, calculate and record the CT value and image noise of 8 regions of interest in abdominal aorta, portal vein trunk, hepatic parenchyma, intrahepatic lesion, pancreatic parenchyma, splenic parenchyma, bilateral spinal muscle and retroperitoneal fat in each patient. SNR and contrast noise ratio. The dose length product and effective radiation dose, including conventional plain scan and non-conventional plain scan, were recorded respectively to calculate the potentially reduced radiation dose. Two experienced radiologists scored and recorded subjective image quality using a 5-point method. The obtained data are first tested by single sample normality test. The data in the group were in accordance with normal distribution, and the objective indexes such as CT value, image quality, signal-to-noise ratio and contrast noise ratio were used, and the non-parametric test was used for the cases where the data did not conform to the normal distribution. The statistical significant leveling correction was 0.01 (bilateral) as a result of multiple test comparisons. Results: there was no significant difference in CT between the four different iodine flow rate groups (P0.05). In the same iodine flow rate group, there was no significant difference in CT between the virtual plain scan images and the conventional plain scan images in arterial phase, venous phase and equilibrium phase (P0.05). The signal-to-noise ratio of the virtual plain scan image was significantly higher than that of the conventional plain scan image (P0.01); the contrast noise ratio of the virtual plain scan image was equal or slightly higher than that of the conventional plain scan image (P0.05). The subjective evaluation score of virtual plain scan image is equal to or slightly lower than that of conventional plain scan image (P0.05), which can meet the need of clinical diagnosis. Using virtual plain scan images instead of conventional plain scan images can potentially reduce radiation dose by about 25%. Conclusion: the virtual plain scan image can partly replace the conventional plain scan image, and the image quality of the virtual plain scan image is not affected by the change of iodine flow rate. Using virtual plain scan images without affecting diagnosis can potentially reduce radiation dose by about 25%.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：R816.5

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