Evaluation of renal transit time [RTT] in children with MR urography

ABSTRACT

To evaluate use of dynamic contrast material-enhanced.magnetic resonance [MR] urdgraphy 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 RTT 490 seconds]. 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