Dynamic Contrast-Enhanced MR Urography in the Evaluation of Pediatric Hydronephrosis: Part 2, Anatomic and Functional Assessment of Uteropelvic Junction Obstruction
Benjamin B. McDaniel1,
Richard A. Jones1,2,
Hal Scherz3,4,
Andrew J. Kirsch3,4,
Stephen B. Little2 and
J. Damien Grattan-Smith1,2
1 Department of Radiology, Emory University School of Medicine, Atlanta,
GA.
2 Department of Radiology, Children's Healthcare of Atlanta, 1001 Johnson Ferry
Rd., Atlanta, GA 30342.
3 Department of Pediatric Urology, Emory University School of Medicine, Atlanta,
GA.
4 Department of Pediatric Urology, Children's Healthcare of Atlanta, Atlanta,
GA.
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Fig. 1A —Atrophy of medullary pyramids in 9-year-old boy with left
ureteropelvic junction (UPJ) obstruction. Coronal T2-weighted image shows
caliectasis with thinning of medulla on left. T2-weighted images show loss of
high-signal-intensity pyramids.
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Fig. 1B —Atrophy of medullary pyramids in 9-year-old boy with left
ureteropelvic junction (UPJ) obstruction. Dynamic contrast-enhanced images
show preservation of renal cortex without evidence of scarring. Medulla is
thin and difficult to identify even after contrast administration.
Contralateral kidney shows normal anatomy.
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Fig. 1C —Atrophy of medullary pyramids in 9-year-old boy with left
ureteropelvic junction (UPJ) obstruction. Dynamic contrast-enhanced images
show preservation of renal cortex without evidence of scarring. Medulla is
thin and difficult to identify even after contrast administration.
Contralateral kidney shows normal anatomy.
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Fig. 2A —2-year-old boy with right-sided ureteropelvic junction
obstruction. Fluid levels in obstructed collecting system with a large
extrarenal pelvis. Delayed sagittal contrast-enhanced image shows fluid
levels, which are a good secondary sign of obstruction.
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Fig. 2B —2-year-old boy with right-sided ureteropelvic junction
obstruction. Swirling contrast medium in renal pelvis is best seen on dynamic
maximum intensity projection acquired 8 min after contrast injection.
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Fig. 2C —2-year-old boy with right-sided ureteropelvic junction
obstruction. Dynamic maximum intensity projection acquired 20 min after
injection of contrast material shows complete filling of extrarenal pelvis and
ureter.
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Fig. 3A —Fetal folds without obstruction in 6-week-old boy who was
evaluated for antenatal hydronephrosis. Coronal contrast-enhanced
maximum-intensity-projection image shows corkscrew appearance related to fetal
folds in proximal ureter. Hydronephrosis is minimal.
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Fig. 3B —Fetal folds without obstruction in 6-week-old boy who was
evaluated for antenatal hydronephrosis. Time-intensity curves show symmetry of
corticomedullary crossover points and comparable curves for the two kidneys.
Curves are annotated to show their main features: PME = peak medullary
enhancement, DTP = distal tubular peak, MEP = medullary excretory phase, XOP =
crossover point, CEP = cortical excretory phase.
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Fig. 4A —5-year-old boy with recurrent severe abdominal pain. Dynamic
series acquired during arterial phase (immediately after contrast medium
administration) shows aberrant lower pole artery (arrow) arising from
aorta and crossing mildly dilated renal pelvis.
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Fig. 4B —5-year-old boy with recurrent severe abdominal pain.
Contrast-enhanced maximum-intensity-projection image shows notching of
proximal left ureter and only mild hydronephrosis.
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Fig. 4C —5-year-old boy with recurrent severe abdominal pain. Frontal
radiograph from retrograde study shows extrinsic compression of proximal
ureter at ureteropelvic junction, consistent with a crossing vessel. After
surgery child became asymptomatic.
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Fig. 5A —7-week-old girl with left ureteropelvic junction (UPJ)
obstruction. Contrast-enhanced maximum-intensity-projection image shows UPJ
obstruction with renal transit time greater than 15 min. Differential renal
function was calculated at 37% on left kidney.
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Fig. 5B —7-week-old girl with left ureteropelvic junction (UPJ)
obstruction. Time-intensity curve shows delay in corticomedullary crossover
point, suggesting increased tubular pressure. Note also decreased amplitude of
medullary peak and loss of distal tubular peak in cortex, indicating impaired
concentrating ability in both cortex and medulla. These findings may indicate
that surgery to relieve increased tubular pressure might prevent further
functional deterioration in this kidney.
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Copyright © 2005 by the American Roentgen Ray Society.
