70kV低剂量CT血管成像在儿童胡桃夹综合征中的应用

目的：评价70 kV管电压CT血管成像在诊断儿童胡桃夹综合征中的应用价值。方法：27例临床疑似胡桃夹综合征的患者进行了新双源CT 70 kV CT动静脉混合期血管成像（70 kV组），另37例患者行120 kV腹部增强双期扫描（120 kV组）。测量患者左肾静脉、肠系膜上动脉、腹主动脉、腰大肌的CT值及皮下脂肪的标准差并计算图像的信噪比（SNR）和对比噪声比（CNR）。两名放射科医师对所有病例以四分法进行评分。计算有效剂量（ED）。比较两组间的图像质量及辐射剂量。结果：70 kV组左肾静脉的CT 值、SNR 及 CNR 明显高于120 kV 组，差别有统计学意义（P＜0．01），70 kV组肠系膜上动脉、腹主动脉的CT值、SNR及CNR与120 kV动脉期组比较差别无统计学意义（P＞0．05），与120 kV静脉期组比较明显提高，差别有统计学意义（P＜0．001）。70 kV组图像质量主观评分高于120 kV组，与120 kV动脉期组比较差别无统计学意义（P＝0．137），与120 kV 静脉期组比较差别有统计学意义（P＜0．001）。70 kV 组辐射剂量与120 kV组比较明显降低，有效辐射剂量降低了93．7％，差异有统计学意义（P＜0．001）。结论：临床疑似胡桃夹综合征的儿童70 kV动静脉混合期CT血管成像在保证图像质量满足诊断的同时大幅降低了辐射剂量。

The application of CT angiography at 70kV for diagnosis of nutcracker syndrome in children

Objective：To assess the diagnostic value of CT angiography at 70kV in children with nutcracker syndrome.Methods：27 subjects with clinically suspected nutcracker syndrome underwent CT scanning at 70kV （70kV group） and the other 37 subjects underwent CT dual-phase abdominal enhancement scanning at 120kV （120kV group）.The CT values of left renal vein,superior mesenteric artery,abdominal aorta,psoas muscle and the standard deviation of subcutane-ous fat were measured and the signal-to-noise ratio （SNR）and contrast-to-noise ratio （CNR）of the images were also calculated for each patient.Two radiologists evaluated the image quality using a 4-point scale and calculated each effective dose （ED）.The differences of radiation dose and image quality between two groups were compared.Results：The 70kV group showed higher CT values,SNR and CNR of left renal vein than the 120kV group （P〈0.01）,and the CT values,SNR and CNR of superior mesenteric artery and abdominal aorta in 70kV group were significantly higher than those in 120kV venous phase group （P〈0.001）,but there was no statistical difference between 70kV group and 120kV arterial phase group （P〉0.05）.The subjective score of image quality in 70kV group was higher than 120kV group,but there was no significant difference between 70kV group and 120kV arterial phase group （P= 0.137）,while there was significant difference between 70kV group and 120kV venous phase group （P〈0.001）.Compared with 120KV group,the radiation dose was significantly lower in 70kV group,and the effective radiation dose was reduced by 93.7% （P〈0.001）.Conclusion：70kV mixed phase CT angiography can effectively reduce the radiation dose while maintaining image quality in children with clinically suspected nutcracker syndrome.