Quantitative SPECT of 99mTc-DMSA uptake in kidneys of infants with unilateral ureteropelvic junction obstruction: assessment of structural and functional abnormalities.
We evaluated individual renal function using quantitative SPECT of dimercaptosuccinic acid (DMSA) uptake by the kidneys (QDMSA) in infants with unilateral ureteropelvic junction (UPJ) obstruction and compared our findings with infants without obstruction.


METHODS
QDMSA was performed on 13 infants (mean age of 2.8 +/- 2.8 mo) with unilateral UPJ obstruction and on 15 age-matched controls without obstruction.


RESULTS
Control kidneys (n = 30) had a volume of 43.5 +/- 8.8 mL, a percentage injected dose (%ID)/mL 0.62 +/- 0.12 and uptake of 26.1% +/- 3.9%. Kidneys with UPJ obstruction (n = 13) had a volume of 61.2 +/- 19.3 mL, a %ID/mL of 0.42 +/- 0.11 and uptake of 25.4% +/- 8.2%. Contralateral kidneys (n = 13) had a volume of 44.0 +/- 11.9 mL, a %ID/mL of 0.57 +/- 0.16 and uptake of 24.2% +/- 4.6%. The uptake in obstructed kidneys was similar to that observed in contralateral and control kidneys (t = -0.77, P = 0.45; t = -0.37, P = 0.71; respectively). UPJ kidneys had a statistically significant increased volume and decreased %ID/mL, compared with contralateral kidneys (t = 3.35, P < 0.006 and t = 3.75, P < 0.003, respectively) and control kidneys (t = -4.2, P < 0.001 and t = 4.7, P < 0.001, respectively). There was no significant difference between contralateral kidneys and control kidneys regarding volume (t = -0.16, P = 0.87), %ID/mL (t = 0.98, P = 0.33) and uptake (t = -1.41, P = 0.16). Of 13 infants, 11 (85%) showed large kidneys with thinning of the renal cortex. In 1 infant, there was no difference between the obstructed and contralateral kidneys regarding volume, %ID/mL and uptake, and 1 infant showed significant decreased uptake in the UPJ kidney compared with the contralateral kidney.


CONCLUSIONS
Although the overall renal function of the obstructed kidneys remained unchanged, there was a statistically significant decrease in the %ID/mL of renal tissue in UPJ kidneys, which may represent renal dysfunction. Increased functional volume with a thin cortex may represent a compensatory mechanism of the obstructed kidney. Such changes may contribute to the understanding of pathophysiologic mechanisms and may be an early sign of obstruction in infants with hydronephrosis. Further longitudinal studies with an extended number of infants and serial measurements of kidney volumes and %ID/mL are warranted to assess the significance of QDMSA in the management of infants with asymptomatic unilateral renal pelvic dilatation.
Groshar
D
D
Department of Nuclear Medicine, Bnai Zion Medical Center, Faculty of Medicine, Technion-Israel Institute of Technology, Haifa.
Wald
M
M
Moskovitz
B
B
Issaq
E
E
Nativ
O
O
D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007223:Infant; D007668:Kidney / Q000000981:diagnostic imaging*; D007682:Kidney Pelvis / Q000000981:diagnostic imaging; D008297:Male; D011866:Radioisotope Renography; D019275:Radiopharmaceuticals; D019783:Technetium Tc 99m Dimercaptosuccinic Acid; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*; D014517:Ureteral Obstruction / Q000000981:diagnostic imaging*
D019275:Radiopharmaceuticals; D019783:Technetium Tc 99m Dimercaptosuccinic Acid