目的 应用二维灰阶血流成像技术（B⁃Flow）对儿童左肾静脉（LRV）及其周围血管显影， 评价 LRV 受压情况，探讨该技术在 LRV 检查中的应用价值。方法 收集南京医科大学附属儿童医院因 血尿、蛋白尿就诊并经 CT 检查后确诊为胡桃夹综合征（NCS）的青少年患儿 18 例为疾病组；收集同期 无相关临床症状、因非泌尿系情况行 CT 检查最终排除 NCS 的青少年儿童 17 例为对照组。采用超声 B⁃Flow 技术测量两组儿童肠系膜上动脉（SMA）与腹主动脉（AO）间的夹角（θ）、LRV 受压前扩张段 （a 段）内径（Φa）与受压段（b 段）内径（Φb）；应用脉冲多普勒测量 a 段血流峰值流速（Va）及 b 段血流峰 值流速（Vb）；计算比值Ⅰ=Φa/Φb、Ⅱ=Vb/Va。采用两独立样本 t 检验比较组间各指标的差异；绘制 ROC 曲线得到各指标单独及联合诊断 NCS 的最佳截断值、曲线下面积（AUC）、敏感性、特异性等，并比较各 指标的诊断效能。结果 疾病组 θ 角均值（26.79 ± 9.06）°明显小于对照组（52.23 ± 12.77）°；疾病组 b 段 受压及 a 段扩张普遍较对照组严重，其比值Ⅰ（4.82 ± 1.14）明显大于对照组（2.60 ± 0.52）；疾病组受压 b 段血流速度显著增快，其比值Ⅱ（8.98 ± 4.22）明显大于对照组（3.73 ± 1.30）。两组间 θ、Ⅰ、Ⅱ差异有统 计学意义（P < 0.001）。ROC 曲线显示 θ、Ⅰ、Ⅱ单独及联合诊断 NCS 的 AUC 均> 0.95，联合诊断效能大 于单指标诊断，但各诊断方法间差异无统计学意义（P > 0.05）。结论 B⁃Flow 技术对 NCS 有较好的诊 断价值，可作为儿童 LRV 超声检查的一种新的成像模式应用。

Objective Two dimensional gray scale blood flow imaging（B⁃Flow）was used to develop the left renal vein（LRV）and its surrounding vessels in children to evaluate the compression of LRV and to explore the application value of this technique in LRV. Methods A total of 18 children with nutcracker syndrome（NCS） diagnosed by CT in Children′s Hospital of Nanjing Medical University due to hematuria and proteinuria were enrolled as disease group and 17 children without related clinical symptoms and excluded NCS by CT examination due to non⁃urinary system conditions were enrolled as control group. The angle（θ）between the superior mesenteric artery （SMA）and the abdominal aorta（AO），the inner diameter of the dilated segment（a segment）before compression （Φa）and the inner diameter of the compressed segment（b segment）of the LRV（Φb）were measured by B⁃flow. Peak velocity（Va）of a segment and peak velocity（Vb）of b segment were measured by pulsed Doppler. The ratios Ⅰ=Φa/Φb and Ⅱ=Vb/Va were calculated.Two independent sample t test was used to compare the differences between the two groups. The ROC curve was drawn to obtain the best cut⁃off value，area under the curve（AUC）， sensitivity and specificity of each index alone and in combination in the diagnosis of NCS，and the diagnostic efficacy of each index was compared. P < 0.05 was considered statistically significant. Results The mean θ angle of the disease group（26.79 ± 9.06）° was significantly smaller than that of the control group（52.23 ± 12.77）°. The compression of segment b and the expansion of segment a in the disease group were generally more severe than those in the control group. The ratio Ⅰ（4.82 ± 1.14）was significantly higher than that in the control group（2.60 ±0.52）. The blood flow velocity of the compressed b segment in the disease group was significantly increased，and its ratio Ⅱ（8.98 ± 4.22）was significantly higher than that of the control group（3.73 ± 1.30）. The t test results of θ， Ⅰ and Ⅱ between the two groups all showed P < 0.001，and the difference was statistically significant. ROC curve showed that the AUC of θ，Ⅰ，Ⅱ alone and in combination for the diagnosis of NCS was greater than 0.95，and the combined diagnostic efficiency was greater than that of single index diagnosis，but the P values of the differences between the diagnostic methods were > 0.05，without statistical significance. Conclusion B⁃Flow proved to be a valuable diagnostic tool for NCS and could be used as a new ultrasound imaging for LRV in children.