“双低”在肝脏 CT 增强扫描中的可行性

目的：探讨降低辐射剂量方法结合运用低浓度对比剂进行肝脏CT动态增强扫描临床应用的可行性。 方法：180例受检者首先根据使用碘克沙醇剂量的不同随机分为I组(270 mgI/mL碘克沙醇)和II组(320 mgI/mL碘克沙 醇)，然后将A(120 kV/300 mA)，B(100 kV/400 mA)，C(100 kV/300 mA)3组不同的扫描条件随机分布于I组和II组各期 (动脉期、静脉期、延时期)的动态增强扫描中；记录、统计并比较各组有效辐射剂量(eff ective radiation dose，ED)、图 像CT值及反映图像质量的噪声值(image of noise，NI)、信噪比(signal to noise ratio，SNR)、对比 噪声比(contrast to noise ratio，CNR)、整体图像质量(overall image quality，OIQ)。结果：总体样本中C组的ED值比A组在3期动态增强扫描中分 别降低约38%，40%，41%，图像质量各值(NI，SNR，CNR，OIQ)两组间差异有统计学意义(P<0.05)；B组的ED值比A 组在3期动态增强扫描中分别降低约18%，20%，20%，而图像质量各值均无明显差异(P>0.05)。同扫描条件及时相下 I，II两组图像CT值存在明显差异(P<0.05)而图像质量各值无明显差异(P>0.05)；A-II组与B-I，C-I组图像CT值无明显差 异(P>0.05)；所得图像质量各值A-II组与B-I组无明显差异(P>0.05)，但A-II组与C-I组差异明显(P<0.05)。结论：通过降 低管电压适当提高管电流结合应用低浓度对比剂，肝脏CT动态增强扫描图像质量可满足诊断，同时降低了辐射剂量 及对比剂剂量。

Feasibility study on liver CT contrast-enhanced scan with low dose of radiation and contrast agent

Objective: To explore the feasibility for liver contrast-enhanced CT scan with low dose of radiation and contrast agent in clinical. Methods: A total of 180 cases were randomly divided into group I (low concentration of contrast agent, 270 mgI/mL of iodixanol) and group II (high concentration of contrast agent, 320 mgI/mL of iodixanol). Th ree scan conditions (A: 120 kV, 300 mA; B: 100 kV, 400 mA; and C: 100 kV, 300mA) were randomly distributed in 3 phases (arterial phase, venous phase and delay phase) for liver scans in each group. The effective radiation dose (ED), image CT values and quality of images (image of noise (NI), the image signal to noise ratio (SNR), contrast to noise ratio (CNR), and overall image quality (OIQ) scores were recorded and analyzed. Results: ED values for the group C in the total samples were decreased by 38%, 40% and 41%, respectively compared to the group A in contrast-enhanced scan for 3 phases. The image quality was significantly different (P<0.05); ED values in the group B were decreased by 18%, 20% and 20%, respectively compared to group A in contrast-enhanced scan for 3 phases, and there were no significant differences (P>0.05) in image quality. There were significant differences between the group I and the group II in CT values at the same scanning parameters and scanning phases (P<0.05), but the image quality was not obviously different; there was no significant difference between the group A-II and the group B-I as well as the group C-I in image CT values, and there was also no significant difference between the group A-II and the group B-I in image quality (P>0.05); however the differences in image quality were statistically significant between the group A-II and the group C-I (P<0.05). Conclusion: Reduction of the tube voltage (to improve the tube current) combined with the lowdose contrast agent can not only reduce the radiation dose and contrast agent dose but also meet the needs of double-low liver contrast-enhanced CT scan.