Table 1.
The reference values of GFR for each age group.
The median, 2.5 percentile, and 97.5 percentile values were cited from a report by Uemura et al.[8] The mean and standard deviation values were not shown in their original report; however, in contacting them, we received these values and calculated the Z-scores.
Fig 1.
Longitudinal images of the right solitary kidneys with adjacent livers were captured in a 6-month-old female infant with an estimated glomerular filtration rate of 117.2 mL/min/1.73 m2 (A), (B) and in a 7-month-old male infant with an estimated glomerular filtration rate of 51.6 mL/min/1.73 m2 (C), (D).
In each picture, the region of interest was outlined around the entire kidneys (A), (C) and around the livers (B), (D) with ImageJ software, version 1.48v (National Institutes of Health, USA). Renal echogenicity was measured in 256-degree grayscale numerically from 0 to 255. The mean pixel density of the right kidney and liver were 70.3 and 67.3 respectively in the former patient with a right kidney-liver echogenicity ratio of 1.04, and 119.6 and 70.4 respectively in the latter patient with a ratio of 1.70.
Table 2.
Characteristics of 91 pediatric patients with solitary kidney.
Table 3.
Comparison of clinical parameters between the non-decreased and decreased glomerular filtration rate groups among 54 patients with right solitary kidney.
Fig 2.
Correlation analysis showed weak correlation between eGFR Z-scores for age and the right kidney-liver echogenicity ratio.
The Spearman correlation coefficient was –0.227 (p = 0.098).
Fig 3.
To analyze the change in echogenicity with age, Spearman correlation analysis was performed in the normal glomerular filtration rate group for each kidney.
(A) Among 46 patients with right solitary kidneys and a normal glomerular filtration rate, the age and right kidney-liver echogenicity ratio revealed a correlation coefficient of 0.361 with a p-value of 0.014. (B) In the analysis of the correlation between age and left kidney-spleen echogenicity ratio in 33 patients with left solitary kidneys and a normal glomerular filtration rate, the correlation coefficient was 0.015 with a p-value of 0.935.
Table 4.
Comparison of clinical parameters between patients with normal and decreased glomerular filtration rates among 37 patients with left solitary kidney.