Renal Transit Time with MR Urography in Children
Renal Transit Time with MR Urography in Children
PURPOSE: 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.
MATERIALS AND METHODS: 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.
RESULTS: 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.
CONCLUSION: 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.
Radiology 2004;233:41-50
PURPOSE: 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.
MATERIALS AND METHODS: 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.
RESULTS: 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.
CONCLUSION: 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.
Radiology 2004;233:41-50
Renal Transit Time with MR Urography in Children
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Reviewed by Sumer Sethi
on
Sunday, October 10, 2004
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Sumer Sethi
Unique blend of academic excellence and entrepreneurship, heading leading firms in India- Teleradiology Providers, pioneering company providing teleradiology services and DAMS (Delhi Academy of Medical Sciences) Premier test preparation institute in India for MD/MS/MCI preparation. He has also been an invited faculty member at various conferences, including Teleradiology in IRIA 2008 and 2011, Hospital Build Middle East, Congress of the Brain Tumor Radiology in Neuro-oncology Society. Dr. Sethi is Editor-in-Chief of Internet Journal of Radiology. He has a keen interest in Web 2.0 technologies and in maintaining his famous radiology blog, which has been featured in multiple international journals.
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