Jones Richard A, Perez-Brayfield Marcos R, Kirsch Andrew J, Grattan-Smith J Damien
Department of Radiology, Emory University School of Medicine, Atlanta, GA, USA.
Radiology. 2004 Oct;233(1):41-50. doi: 10.1148/radiol.2331031117. Epub 2004 Aug 18.
To prospectively evaluate use of dynamic contrast material-enhanced magnetic resonance (MR) urography for measurement of renal transit time (RTT) of a contrast agent through the kidney and collecting system so as to identify obstructive uropathy in children.
One hundred twenty-six children suspected of having hydronephrosis were hydrated prior to undergoing both conventional and dynamic contrast-enhanced MR urography of the kidneys and urinary tract. A three-dimensional sequence was used to track passage of contrast agent through the kidneys. Time between the appearance of contrast material in the kidney and its appearance in the ureter at or below the level of the lower pole of the kidney was defined as RTT. Bland-Altman plots were used to quantify intra- and interobserver performance. In 30 children, a nuclear medicine renogram was also obtained, and the half-life of renal signal decay after furosemide administration was derived and compared with the MR imaging RTT by using receiver operating characteristic curves.
On the basis of RTT, kidneys were classified as normal (RTT </= 245 seconds), equivocal (245 seconds > RTT </= 490 seconds), or obstructed (RTT > 490 seconds). Inter- and intraobserver agreement indicated that the technique is both robust and reproducible. Receiver operating characteristic analysis for comparison of results of MR imaging and diuretic renal scintigraphy showed good agreement between the modalities, with a mean area under the curve of 0.90.
When used in conjunction with morphologic images obtained in the same examination, RTT generally allowed normal kidneys to be differentiated from obstructed and partially obstructed kidneys.
前瞻性评估动态对比剂增强磁共振（MR）尿路造影在测量对比剂通过肾脏及集合系统的肾转运时间（RTT）方面的应用，以识别儿童梗阻性尿路病。
126例疑似肾积水的儿童在接受肾脏和尿路的传统及动态对比增强MR尿路造影检查前进行水化处理。采用三维序列追踪对比剂通过肾脏的过程。对比剂在肾脏出现至其在肾下极水平或以下输尿管出现的时间定义为RTT。采用Bland-Altman图量化观察者间和观察者内的表现。对30例儿童还进行了核医学肾图检查，得出呋塞米给药后肾信号衰减的半衰期，并通过绘制受试者工作特征曲线将其与MR成像的RTT进行比较。
根据RTT，将肾脏分为正常（RTT≤245秒）、可疑（245秒＜RTT≤490秒）或梗阻（RTT＞490秒）。观察者间和观察者内的一致性表明该技术可靠且可重复。对MR成像和利尿肾闪烁显像结果进行比较的受试者工作特征分析显示，两种检查方法结果具有良好的一致性，曲线下平均面积为0.90。
当与同一检查中获得的形态学图像联合使用时，RTT通常能够区分正常肾脏与梗阻及部分梗阻的肾脏。
