MSCT对左肾静脉走行规律的显示及对胡桃夹综合征诊断的启示

目的应用多层螺旋CT(MSCT)及后处理技术研究正常左肾静脉(left renal vein,LRV)、肠系膜上动脉(su-perior mesenteric artery,SMA)与腹主动脉(abdominal aorta,AA)夹角的解剖形态学规律,探讨MSCT诊断"胡桃夹"综合征(nutcracker syndrome,NCS)的临床应用价值。方法采用64层MSCT,前瞻性观察220例正常者的SMA与AA的夹角大小,LRV夹角处、近肾门段最宽处的内径(前后径)及相应水平的截面积,以明确LRV的走行特征及正常人SMA与AA夹角的大小对LRV形态的影响,并计算出正常人SMA与AA夹角的范围、LRV受压前后的内径、截面积的参考范围以及体重指数与夹角的关系。图像后处理技术包括MPR、MIP。另有3例临床已证实NCS的病例作为分析参考。结果 220例正常SMA与AA的夹角的大小为(56.67±18.27)°,肾门段LRV前后径(DD)为(9.91±2.23)mm,截面积(SAD)为(119.81±43.03)mm2;夹角段LRV前后径(DN)为(6.50±2.31)mm,截面积(SAN)为(86.47±41.27)mm2;并计算DD/DN,SAD/SAN。220例正常人中体重指数(body mass index,BMI,Kg/m2)与SMA与AA间的夹角不具有明显的相关性,但是有一定的正相关联系。结论正常人LRV于SMA夹角处呈所谓轻度受压征象(移行型或夹角小于50°)是一种普遍存在的正常现象。NCS是一个以临床症状为前提的综合诊断,不能单纯依靠CT表现确诊NCS,但CT表现可提示患NCS的可能性大小。当LRV呈未受压型或移行型,SMA夹角大于50°,截面积缩小在Ⅱ°以下,可排除NCS的可能;LRV呈漏斗型,夹角小于50°,截面积缩小达Ⅱ°以上者,高度可疑NCS,应结合临床症状进一步检查确诊。

Anatomic features of left renal vein depicted on MSCT and the tips in clinical diagnosis of nutcracker syndrome

Objective To depict the normal anatomic features of left renal vein （LRV）, mesenteric artery （SMA） with multi-slice spiral CT（MSCT）, to access its clinical value in diagnosis of nutcracker syndrome （NCS）. Methods 220 con- secutive patients were selected as a study group of normal population, who had undergone contrast MSC＇F examination on abdomen with some symptoms except that of related nutcracker syndrome （NCS）. The diameter and sectional area of LRV, the angle between AA and SMA （AMA） were measured and analyzed, as well as the body mass index （BMI）. The anatomic morphology of LRV on axial CT images were analyzed and classified into 3 types. The post-processing technique included muhi-planar reformation （MPR）, maximum intensity projection （MIP）. Another 3 cases ever confirmed NCS were selected as analyzing reference. Results The AMA was （56.67±18.27）°, the diameter of LRV on distened and nar- rowed portion were （9.91±2.23） mm, （6.50±2.31） mm respectively; the sectional area of LRV on distened and nar- rowed portion were （119, 81±43.03） mmz, （86.47±41. 27） mm^2 respectively. There was no obvious correlation be- tween BMI and AMA, but there was in some degree certain positive correlation. Conclusion It can be the normal common findings on MSCT that the LRV was shown some degree compressed in SMA portion. NCS was an comprehensive clinical diagnosis, not only based on imaging fidings, MSCT findings can recomend the possibility of NCS, or rule out the possi- bility of NCS.