Dynamic Contrast-Enhanced MR Urography in the Evaluation of Pediatric Hydronephrosis: Part 1, Functional Assessment
Richard A. Jones1,2,
Kirk Easley3,
Stephen B. Little2,
Hal Scherz4,5,
Andrew J. Kirsch4,5 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 Biostatistics, Emory University, Atlanta, GA.
4 Department of Pediatric Urology, Emory University School of Medicine, Atlanta,
GA.
5 Department of Pediatric Urology, Children's Healthcare of Atlanta, Atlanta,
GA.
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Fig. 1A —Dynamic images of 3-month-old boy referred for mild bilateral
hydronephrosis. This patient had renal transit times of 1 min 37 sec on the
left and 3 min 30 sec on the right, with slight delay on right still being
within normal limits. Split renal function was calculated to be 49% on left
and 51% on right. Images A-C show maximum intensity projections derived
from volumes corresponding to three separate time points, whereas D-F
show same slice from each of the three data sets. A and D show
vascular or cortical phase. B and E were acquired 1 min 45 sec
after vascular phase and show homogeneous enhancement of cortex and medulla.
C and F were acquired 3 min 30 sec after vascular phase and show
enhancement of calyces and ureters of both kidneys.
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Fig. 1B —Dynamic images of 3-month-old boy referred for mild bilateral
hydronephrosis. This patient had renal transit times of 1 min 37 sec on the
left and 3 min 30 sec on the right, with slight delay on right still being
within normal limits. Split renal function was calculated to be 49% on left
and 51% on right. Images A-C show maximum intensity projections derived
from volumes corresponding to three separate time points, whereas D-F
show same slice from each of the three data sets. A and D show
vascular or cortical phase. B and E were acquired 1 min 45 sec
after vascular phase and show homogeneous enhancement of cortex and medulla.
C and F were acquired 3 min 30 sec after vascular phase and show
enhancement of calyces and ureters of both kidneys.
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Fig. 1C —Dynamic images of 3-month-old boy referred for mild bilateral
hydronephrosis. This patient had renal transit times of 1 min 37 sec on the
left and 3 min 30 sec on the right, with slight delay on right still being
within normal limits. Split renal function was calculated to be 49% on left
and 51% on right. Images A-C show maximum intensity projections derived
from volumes corresponding to three separate time points, whereas D-F
show same slice from each of the three data sets. A and D show
vascular or cortical phase. B and E were acquired 1 min 45 sec
after vascular phase and show homogeneous enhancement of cortex and medulla.
C and F were acquired 3 min 30 sec after vascular phase and show
enhancement of calyces and ureters of both kidneys.
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Fig. 1D —Dynamic images of 3-month-old boy referred for mild bilateral
hydronephrosis. This patient had renal transit times of 1 min 37 sec on the
left and 3 min 30 sec on the right, with slight delay on right still being
within normal limits. Split renal function was calculated to be 49% on left
and 51% on right. Images A-C show maximum intensity projections derived
from volumes corresponding to three separate time points, whereas D-F
show same slice from each of the three data sets. A and D show
vascular or cortical phase. B and E were acquired 1 min 45 sec
after vascular phase and show homogeneous enhancement of cortex and medulla.
C and F were acquired 3 min 30 sec after vascular phase and show
enhancement of calyces and ureters of both kidneys.
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Fig. 1E —Dynamic images of 3-month-old boy referred for mild bilateral
hydronephrosis. This patient had renal transit times of 1 min 37 sec on the
left and 3 min 30 sec on the right, with slight delay on right still being
within normal limits. Split renal function was calculated to be 49% on left
and 51% on right. Images A-C show maximum intensity projections derived
from volumes corresponding to three separate time points, whereas D-F
show same slice from each of the three data sets. A and D show
vascular or cortical phase. B and E were acquired 1 min 45 sec
after vascular phase and show homogeneous enhancement of cortex and medulla.
C and F were acquired 3 min 30 sec after vascular phase and show
enhancement of calyces and ureters of both kidneys.
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Fig. 1F —Dynamic images of 3-month-old boy referred for mild bilateral
hydronephrosis. This patient had renal transit times of 1 min 37 sec on the
left and 3 min 30 sec on the right, with slight delay on right still being
within normal limits. Split renal function was calculated to be 49% on left
and 51% on right. Images A-C show maximum intensity projections derived
from volumes corresponding to three separate time points, whereas D-F
show same slice from each of the three data sets. A and D show
vascular or cortical phase. B and E were acquired 1 min 45 sec
after vascular phase and show homogeneous enhancement of cortex and medulla.
C and F were acquired 3 min 30 sec after vascular phase and show
enhancement of calyces and ureters of both kidneys.
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Fig. 2A —Relative signal-versus-time curves for 3-month-old boy shown
in Figures 1A,
1B,
1C,
1D,
1E, and
1F. Graphs show signal from
calyces (A) and salient features of curves (B). Specifically,
note vascular peak in cortex (VASC), cortical distal convoluted tubular (DT)
peak, and peak caused by contrast material in loop of Henle (LH) in medulla.
Calyces show slight early signal enhancement, which is probably due to either
contrast material in vessels running over surface of calyces or partial volume
effects. Relative signals from cortex and medulla can be seen to fall in
linear range of phantom data shown in
Figure 3, whereas those from
calyces are in nonlinear range. Hence, relative signal levels in calyces are
somewhat underestimated and form of calyceal curves will be distorted.
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Fig. 2B —Relative signal-versus-time curves for 3-month-old boy shown
in Figures 1A,
1B,
1C,
1D,
1E, and
1F. Graphs show signal from
calyces (A) and salient features of curves (B). Specifically,
note vascular peak in cortex (VASC), cortical distal convoluted tubular (DT)
peak, and peak caused by contrast material in loop of Henle (LH) in medulla.
Calyces show slight early signal enhancement, which is probably due to either
contrast material in vessels running over surface of calyces or partial volume
effects. Relative signals from cortex and medulla can be seen to fall in
linear range of phantom data shown in
Figure 3, whereas those from
calyces are in nonlinear range. Hence, relative signal levels in calyces are
somewhat underestimated and form of calyceal curves will be distorted.
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Fig. 3 —Graph shows relative signal intensity from saline phantom.
Illustrated straight fit was calculated for gadopentetate dimeglumine
concentrations in range of 0-10 mmol/L. At higher concentrations, response
becomes nonlinear.
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Fig. 4 —Maximum intensity projection from delayed 3D volumes acquired
in same 3-month-old boy as shown in Figures
1A,
1B,
1C,
1D,
1E, and
1F. This delayed 3D volume was
acquired with high spatial resolution (0.8 x 0.8 x 1.0 mm) and was
obtained after dynamic volumes. Right kidney has an extrarenal pelvis and
persistent fetal folds of right ureter. Latter probably account for slightly
longer renal transit time observed on right side.
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Fig. 5 —Bland-Altman plot summarizes results of interobserver
position of distal convoluted tubule peak. Mean difference and limits of
agreement can be seen to be good, given temporal resolution of 15 sec used for
dynamic studies.
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Fig. 6A —Delayed contrast-enhanced maximum intensity projections
(MIPs). Infant boy who was studied at 3 months (A) and 9 months
(B) old. Renal transit times were 100 sec on left and 350 sec on right
in first study. In second study, corresponding times were 90 sec on left and
225 sec on right. MIPs show improvement in degree of hydroureteronephrosis,
with elongation and decreased tortuosity of ureter.
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Fig. 6B —Delayed contrast-enhanced maximum intensity projections
(MIPs). Infant boy who was studied at 3 months (A) and 9 months
(B) old. Renal transit times were 100 sec on left and 350 sec on right
in first study. In second study, corresponding times were 90 sec on left and
225 sec on right. MIPs show improvement in degree of hydroureteronephrosis,
with elongation and decreased tortuosity of ureter.
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Fig. 7A —Relative signal-versus-time curves for two studies from
patient shown in Figures 6A,
and 6B. Initial study when
infant was 3 months old (A) shows delayed crossover point. By time of
second study when infant was 9 months old (B), crossover point has
become symmetric, suggesting that intracortical pressure has returned to
normal. Distal cortical peak is preserved in both studies, as well as
concentration of contrast material in medulla and loop of Henle. Note mild
decrease in amplitude of cortex on right, indicating slight impairment in
ability of this kidney to extract and concentrate contrast material from
vasculature.
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Fig. 7B —Relative signal-versus-time curves for two studies from
patient shown in Figures 6A,
and 6B. Initial study when
infant was 3 months old (A) shows delayed crossover point. By time of
second study when infant was 9 months old (B), crossover point has
become symmetric, suggesting that intracortical pressure has returned to
normal. Distal cortical peak is preserved in both studies, as well as
concentration of contrast material in medulla and loop of Henle. Note mild
decrease in amplitude of cortex on right, indicating slight impairment in
ability of this kidney to extract and concentrate contrast material from
vasculature.
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Copyright © 2005 by the American Roentgen Ray Society.
