To evaluate the value of apparent diffusion coefficient(ADC) value of renal magnetic resonance imaging in evaluating the function of molecular diffusion in the kidney of children under 6 years old.

Eighty children under 6 years old were selected as the study subjects, all the children had unilateral congenital hydronephrosis, magnetic resonance examination was performed in 40 children with normal renal function, the children were first, divided into two groups according to the age: less than 1 year old group and 1-6 years old group. The children were divided into normal, light-moderate hydronephrosis, severe hydronephrosis and huge hydronephrosis supgroup in different age groups, and then to examine whether there were differences in ADC values among the different degrees of unilateral hydronephrosis supgroups in different age groups.

There was significant difference in the ADC value of severe, huge hydronephrosis and the ADC of the normal kidney in less than 1 year old children; ADC was significantly different between severe and huge hydronephrosis in 1-6 years old children(P<0.05); There were significant differences in ADC values between the two hydronephrosis groups and the normal control group, and the ADC value increased with the degree of hydronephrosis accumulation. There was no significant difference in the ADC value of contralateral kidney and the ADC value of the normal kidney among different degree of hydronephrosis(P>0.05).

The magnetic resonance imaging of the kidney is DWI, by calculating the ADC value of the kidney, can clear the change of the molecular diffusion function of the kidney in children with congenital hydronephrosis, to provide guidance for the quantitative diagnosis and treatment of unilateral congenital renal hydrocephalus in infants and preschool children.

Congenital hydronephrosis; Ureteropelvic junction obstruction; Diffusion weighted imaging; Apparent diffusion coefficient