Value of Supranormal Function and Renogram Patterns on 99mTc-Mercaptoacetyltriglycine Scintigraphy in Relation to the Extent of Hydronephrosis for Predicting Ureteropelvic Junction Obstruction in the Newborn

Dae Hyuk Moon; Young Seo Park; Nu-Lee Jun; So Young Lee; Kun Suk Kim; Jin Hee Kim; Chong Hyun Yoon; Weechang Kang; Hee Kyung Lee

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FIGURE 1.
Posterior 2-min-interval images of ^99mTc-MAG3 scan are displayed. (A) Basal renal scan (38 d after birth) of boy with SFU grade 4 hydronephrosis of left kidney demonstrates evidence of delayed parenchymal transit (persistent renal parenchymal activity and delayed appearance of pelvocalyceal radiotracer). Differential renal function of left kidney was 43%. (B) Diuretic scan shows deterioration of clearance from left renal pelvis (t_1/2 > 20 min). Postoperatively, improved hydronephrosis and drainage (t_1/2 = 8 min) were observed on ultrasonography and diuretic ^99mTc-MAG3 scan at 6 mo.

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TABLE 1

Baseline Clinical, Ultrasonographic, and ^99mTc-MAG3 Diuretic Renographic Results in Patients with Unilateral Hydronephrosis and Normal Differential Renal Function

Variable	Mean ± SD or number (%)
Sex
Male	41 (85.4)
Female	7 (14.6)
Site of unilateral hydronephrosis
Left	38 (79.2)
Right	10 (20.8)
Ultrasonography
APPD (mm)	20.2 ± 10.9
SFU system
Grade 1	2 (4.2)
Grade 2	5 (10.4)
Grade 3	12 (25.0)
Grade 4	29 (60.4)
^99mTc-MAG3 diuretic renography
Differential renal function (%)	50.5 ± 3.9
Supranormal function
No (<55%)	44 (91.7)
Yes (≥55%)	4 (8.3)
Renogram*
Grade 1	10 (20.8)
Grade 2	17 (35.4)
Grade 3	13 (27.1)
Grade 4	8 (16.7)

↵* Grade 1, obstructive basal and nonobstructive diuretic renograms; 2, obstructive basal and indeterminate diuretic renograms; 3, both obstructive renograms; 4, both obstructive renograms with delayed parenchymal transit.

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TABLE 2

Univariate Analysis of Variables that Predict UPJ Obstruction in Neonates with Unilateral Hydronephrosis

Variable	No UPJ obstruction (n = 29)	UPJ obstruction (n = 19)	P value
Sex (male/female)	25/4	16/3	NS
Site of hydronephrosis (left/right)	21/8	17/2	NS
APPD* (mm)	17.5 ± 11.2	24.3 ± 9.2	<0.05
SFU
Grade 1 or grade 2	7	0	<0.01
Grade 3	10	2
Grade 4	12	17
Differential function* (%)	50.0 ± 2.7	51.4 ± 5.3	NS
Differential function ≥ 55% (no/yes)	29/0	15/4	<0.05
Renogram^†
Grade 1	10	0	<0.001
Grade 2	13	4
Grade 3	5	8
Grade 4	1	7

↵* Mean ± SD.
↵^† Grade 1, obstructive basal and nonobstructive diuretic renograms; 2, obstructive basal and indeterminate diuretic renograms; 3, both obstructive renograms; 4, both obstructive renograms with delayed parenchymal transit.
NS = not significant.

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TABLE 3

Multivariate Logistic Regression Analysis Showing Increased Likelihood Ratio for Prediction of UPJ Obstruction by Addition of ^99mTc-MAG3 Variables

Model	χ²	Degree of freedom	P value
APPD (mm)	4.760	1	<0.05
SFU grade	14.042	1	<0.001
SFU grade + function ≥ 55%	7.728*	1*	<0.01
SFU grade + renogram	9.989*	1*	<0.01
SFU grade + function ≥ 55% + renogram	14.352*	2*	<0.001

↵* Increased χ² and degree of freedom in comparison with those of SFU grade only.

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TABLE 4
Summary of SFU Grade, Supranormal Function, and ^99mTc-MAG3 Renogram Findings in Neonates with Unilateral Hydronephrosis
SFU grade Function ≥ 55% Renogram grade % UPJ obstruction
1 or 2 No 1 or 2 0 (0/7)
3 or 4 No 1 0 (0/7)
3 No 2 or 3 20 (1/5)
Supranormal 2 or 3 50 (1/2)
4 No 2 38 (3/8)
No 3 56 (5/9)
No 4 86 (6/7)
Supranormal 3 or 4 100 (3/3)