Preliminary study on intravoxel incoherent motion imaging and diffusion kurtosis imaging based on magnetic resonance imaging of normal kidneys in children

BACKGROUND: Renal disease in children may lead to a continuous decline of renal function. Multimodal functional magnetic resonance imaging (fMRI) technology can provide quantitative evaluation of renal function information. We investigated the feasibility of intravoxel incoherent motion imaging (IVIM) and diffusion kurtosis imaging (DKI) based on 3.0T MRI for the assessment of normal renal function in children and then analyzed the changes in functional parameters during development. METHODS: A total of 132 children with normal function of both kidneys were grouped according to age: ≤1 year old, 1–≤2 years old, 2–≤3 years old, 3–≤10 years old, and 10–≤14 years old. All subjects received renal IVIM examinations to obtain the measured values of true diffusion coefficient (D), pseudo diffusion coefficient (Dp), perfusion fraction (f), and DKI examinations to obtain the mean diffusivity (MD) and mean kurtosis (MK) parameters of both kidneys. The differences of IVIM and DKI function indexes between the upper, middle and lower poles of the normal ipsilateral kidney, between the left and right kidneys, and between the renal cortex and medulla were compared. The correlations between the above parameters and age were analyzed. RESULTS: There was no significant difference in the IVIM and DKI parameters between the upper, middle and lower poles in the ipsilateral kidney. There was no significant difference between bilateral kidneys. The D, MD, and MK values of the renal cortex and medulla at the same age were statistically different. The D and MD values of the renal cortex were higher than those of the medulla; the MK value of the renal medulla was higher than that of the cortex. The Dp and f values of the renal cortex and medulla were not statistically different. Except for Dp, all functional parameters of the remaining renal cortex and medulla were related to age. CONCLUSIONS: IVIM and DKI functional imaging of children’s normal kidneys can reflect the physiological characteristics and differences in the renal cortex and medulla, and their functional parameters have particular regularity with growth and development, suggesting that this technique has potential application value in children’s kidney diseases.