低剂量CT扫描技术在右肾上腺静脉成像中的应用

目的 研究低剂量CT技术在右肾上腺静脉成像中的应用价值。方法 前瞻性收集天津医科大学第二医院2017年9月-2018年6月临床怀疑原发性醛固酮增多症需行肾上腺Ⅲ期增强CT检查的124例受检者，依排除标准排除4例，共计120例。按照随机数表法将受检者分为A、B、C 3组，每组40例。A组为常规剂量对照组，采用120 kV，自动毫安，按动脉期、静脉期、实质期又分为A₁、A₂、A₃组；B组为常规剂量试验组，采用120 kV，自动毫安，按动脉期、动脉晚期、静脉期分为B₁、B₂、B₃组；C组为低剂量试验组，第2期采用100 kV、150 mA，其余扫描参数及方法同B组，按动脉期、动脉晚期、静脉期分为C₁、C₂、C₃组。两名影像诊断医师分别对3组图像质量进行主观评分，测量不同扫描时期的右肾上腺静脉（RAV）、同层面临近右肾上腺（RAG）及前腹壁脂肪的CT值，记录剂量长度乘积（DLP），计算和比较图像信号噪声比（SNR）、对比噪声比（CNR）及有效剂量（E）。结果 两观察者图像质量主观评分一致性好（Kappa值=0.63）；A₂、B₂、C₂ 3组图像中B₂组图像的主观评分差异有统计学意义（H=7.18，P<0.05），组内比较仅B₂与A₂组主观评分差异有统计学意义（t=-18.03，P<0.05）；客观评价B₂组RAV的CT值、SNR、CNR均高于A₂组，差异有统计学意义（t=36.99、6.92、9.02，P<0.05）；C₁与C₂相比，E减少了45.52%，差异有统计学意义（t=12.19，P<0.05）。结论 使用100 kV 150 mA低管电压低管电流的对比增强多排螺旋CT（MDCT）扫描技术，在动脉晚期右肾上腺静脉检出率可达95%，并可在保证图像质量的基础上，降低约45.52%的有效剂量。

Application of low-dose CT scanning technique in right adrenal vein imaging

Objective To investgate the application value of low-dose CT scanning in right adrenal vein imaging. Methods A total of 124 patients were enrolled in the study who were suspected as primary aldosteronism and requiring a contrast enhanced CT examination on adrenal glands. Four patients were excluded according to the exclusion criteria, so that the rest 120 patients were divided equally into three groups. Group A was a control group with conventional radiation dose using tube voltage of 120 kV and automatic mA. It was divided into A₁, A₂ and A₃ groups according to arterial phase, portal venous phase and parenchymal phase. Group B was a experimental group with conventional tube voltage of 120 kV and automatic mA, which was divided into B₁, B₂ and B₃ groups according to arterial phase, late arterial phase and portal venous phase. Group C was a low-dose experimental group with a tube voltage of 100 kV and a tube current of 150 mA only in the second phase, the remaining scanning parameters and method were the same as that of group B. The subjective scores of the images of groups A, B and C were statistically analyzed, and the CT values of the right adrenal vein(RAV), the right adrenal gland(RAG), and the fat of anterior abdominal wall at different scan phases were measured. The dose length products (DLP) were recorded and the signal-to-noise ratios (SNR), contrast-to-noise ratios (CNR), effective doses (E) of the three groups were calculated and compared. Results The subjective scores of the two observers were consistent (Kappa value=0.63); the subjective scores of the B₂ images were statistically significant (H=7.18, P<0.05). Difference of subjective scores between B₂ and A₂ was statistically significant (t=-18.03, P<0.05).The CT values of RAV, SNR, and CNR of the B₂ group were higher than those of the A₂ group (t=36.99, 6.92, 9.02, P<0.05). The radiation dose comparison showed that the effective dose (E) was 45.52% lower in the low-dose group than the conventional dose group with the statistically significant difference(t=12.19, P<0.05). Conclusions Using MDCT scanning technique with lower tube voltage and lower tube current of 100 kV-150 mA, the detection rate of right adrenal vein can reach 95% in the late arterial phase, and the effective dose can be reduced about 45.52% on the basis of ensuring image quality.