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.
We investigated the value of supranormal function and renogram patterns on (99m)Tc-mercaptoacetyltriglycine ((99m)Tc-MAG3) scintigraphy in relation to the extent of hydronephrosis for predicting ureteropelvic junction (UPJ) obstruction in the newborn.


METHODS
We studied 48 patients with prenatally diagnosed unilateral hydronephrosis that was confirmed on postnatal ultrasonography. The anteroposterior pelvic diameter (APPD) and the Society for Fetal Urology (SFU) grade were measured on 1-mo ultrasonography to assess the extent of hydronephrosis. Neonates with an APPD of <or=10 mm or a differential renal function of <or=40% were excluded. Supranormal function (>or=55%) and renogram grades (1, not obstructive; 2, indeterminate; 3, obstructive; and 4, prolonged parenchymal transit) were determined on 1-mo (99m)Tc-MAG3 renography. Multivariate logistic regression analysis was performed to predict the presence of obstruction.


RESULTS
Of the 48 kidneys with hydronephrosis, 19 were diagnosed as having UPJ obstruction. Twenty-nine kidneys were classified as having nonobstructive hydronephrosis. The APPD of the 19 kidneys with obstruction (24.3 +/- 9.2 mm) was significantly larger than that of the 29 kidneys without obstruction (17.5 +/- 11.2 mm; P < 0.05). The SFU grades of UPJ obstruction (2 with grade 3, 17 with grade 4) were also significantly higher than those without UPJ obstruction (grades 1-4 in 1, 6, 10, and 12 kidneys, respectively; P < 0.01). Supranormal function was present in 4 kidneys with UPJ obstruction but in none without obstruction (P < 0.001). (99m)Tc-MAG3 renography of the 19 obstructions showed grades 2, 3, and 4 renograms in 4, 8, and 7 patients, respectively. The 29 without obstruction revealed significantly lower grades (grades 1-4 in 10, 13, 5, and 1 patient, respectively; P < 0.001). Multivariate logistic regression analysis revealed that the addition of supranormal function or renogram grade in the model significantly increased the likelihood ratio in comparison with that of the SFU grade only (chi(2) = 7.73 and 9.99, respectively; P < 0.01). Of the 29 neonates with SFU grade 4, supranormal function or renogram >or= grade 4 had a positive predictive value of 90% (9/10).


CONCLUSIONS
(99m)Tc-MAG3 renography at 1 mo after birth has a significant additive value in relation to the degree of hydronephrosis in predicting UPJ obstruction in patients with prenatally diagnosed unilateral hydronephrosis with normal function.
Department of Nuclear Medicine, Asan Medical Center, University of Ulsan College of Medicine, Songpa-gu, Seoul, Korea. dhmoon@amc.seoul.kr
Dae Hyuk
DH
Moon
Young Seo
YS
Park
Nu-Lee
NL
Jun
So Young
SY
Lee
Kun Suk
KS
Kim
Jin Hee
JH
Kim
Chong Hyun
CH
Yoon
Weechang
W
Kang
Hee Kyung
HK
Lee
D005189:False Positive Reactions; D005260:Female; D006801:Humans; D006869:Hydronephrosis / Q000000981:diagnostic imaging*; D007231:Infant, Newborn; D007668:Kidney / Q000000981:diagnostic imaging / Q000503:physiopathology*; D007682:Kidney Pelvis / Q000000981:diagnostic imaging*; D008297:Male; D015999:Multivariate Analysis; D011446:Prospective Studies; D011866:Radioisotope Renography; D019275:Radiopharmaceuticals; D017263:Technetium Tc 99m Mertiatide; D014517:Ureteral Obstruction / Q000000981:diagnostic imaging*
D019275:Radiopharmaceuticals; D017263:Technetium Tc 99m Mertiatide