低剂量扫描在多层螺旋CT下肢动脉成像中的临床研究

The clinical research of low dose scanning protocol for aorto-iliac and lower extremity arteries CT angiography

目的探讨多层螺旋CT（MSCT）下肢动脉成像中应用低管电压（kVp，100kV）设置和管电流调制减低辐射剂量的可行性。方法连续选取需行下肢动脉造影的患者61例，按随机数表随机分为A组（120kV）、B组（100kV）、c组（100kV＋管电流调制）。比较3组患者的图像客观评价指标、图像质量主观评分以及辐射剂量。c组进-步按体重指数（BMI）分为c1组（BMI〈24．9kg／m2）及c2组（BMI≥24．9kg／m2），比较2组患者间的辐射剂量。结果3组患者的主．髂部轴位、容积再现（VR）、最大强度投影（MIP）图像的主观质量评分均在良好以上，且3组图像的信噪比、对比噪声比差异无统计学意义（P〉0．05）。A、B、c3组的有效吸收剂量分别为8．20、5．36和7．48mSv；B组较A组有效吸收剂量减低约34．6％，C组较B组有效吸收剂量增加约39．5％，且与A组比较差异无统计学意义（P〉0．05）。c1组和c2组有效吸收剂量为7．11和9．69mSv，两组比较差异有统计学意义（t=-3．163，P〈0．05），c1组较c2组有效剂量减低约26．6％。C1组较A组有效剂量减低13．3％（Z=-2．822，P〈0．05），但较B组有效剂量增加了32．6％（Z=-3．900，P〈0．05）；C2组较A组有效吸收剂量增加18．2％（P〉0．05），较B组有效剂量增加了80．8％（Z=-3．426，P〈0．05）。结论下肢动脉MSCTA运用低kVp设置（100kV）能在保证图像质量的同时降低辐射剂量，其应用是可行有效的；低kVp设置（100kV）结合管电流调制技术仅对特定人群（体重指数〈24．9kg／m2）具有减低辐射剂量的价值。

Objective To study the feasibility of reducing radiation dose in aorto-iliac and lower extremity arteries CT angiography （CTA） with low tube voltage （100 kV） and automatic tube current modulation（ATCM）. Methods Totally 61 patients requiring aorto-iliac and lower extremity arteries CTA for clinical reasons were prospectively enrolled in study. The patients were randomly assigned to 3 groups： Group A（ 120 kV）, Group B（ 100 kV） and Group C（ 100 kV with automatic tube current modulation）. Both quantitative and qualitative analysis were included in this research. Group C was divided into obese group（BMI≥ 24. 9 kg/m2 ） and normal group （ BMI 〈 24.9 kg/m2 ）. The radiation doses were analyzed respectively among two groups. Results The subjective evaluations of image quality for axial, MIP and VR were good. There were no significant differences among group A, B and C in SNR and CNR （P 〉 0. 05）. The effective dose of group A, B and C was 8.20 mSv, 5.36 mSv, and was 7.48 mSv, respectively Group B was 34.6% less than group A. Group C was 39.5% more than group B, and there was no significant differences between group A and C （P 〉 0. 05 ）. The effective dose of group C1 was 7.11 mSv, group C2 was 9.69 mSv, the E with group C1 were significantly less than group C2 （ t = - 3. 163 ,P 〈 0.05）, the effective dose of group C1 was 13.3% less than group A（Z = -2.822,P 〈0.05）, but the group C2 was more than group A（P 〉 0. 05） and group B （Z = - 3. 426,P 〈 0.05 ）. Conclusions Low-kilovohage （100 kV） CT scanning protocol is feasible in multi-detector CT angiography for aortoiliac and lower extremity arteries. Automatic low tube voltage （ 100 kV） with automatic tube current modulation （ATCM） scanning protocol can be used for someone with BMI less than 24.9 kg/m2.