Thymus grows after birth, reaches maximal size after the first few years and involutes by puberty. Because of the postnatal developmental and involutional duration, we aimed toinvestigate normal stiffness values of mediastinal thymus by shear wave elastography (SWE) in different age groups of children and discuss imaging findings of thymus. We prospectively examined 146 children (90 girls, 56 boys) who underwent a thyroid or neck ultrasound examination. All subjects underwent ultrasound and SWE evaluation of mediastinal thymus by parasternal and suprasternal approach. We subdivided the subjects based on the ages as 0 to 2 months (group 1), >2 to 6 months (group 2); >6 months to 2 years (group 3), >2 to 5 years (group 4), >5 to 8 years (group 5), and greater than 8 years old (group 6).We investigated differences of mean shear wave elasticity (kPa) and shear wave velocity (m/sec) values among age groups and the association of SWE values with age, body mass index (BMI), height, and weight of the patients. Medians and ranges of age, height, weight, and BMI were 24 (2-84) months, 85 (55-120) cm, 12(4.55-22) kg, 15.37 (13.92-17.51) kg/m2, 11 (2.64-23.15) cc, respectively. Mean shear wave elasticity of thymus when all participants were included was 6.76±1.04 kPa. Differences of mean elasticity values among age groups and also gender groups were not statistically significant. There were highly significant negative correlations among age (r:0.3), height (r:0.26), weight (r:0.3) with elasticity and also velocity values (p<0.001). The thymus elasticity is negatively correlated with age. Quantitative evaluation of the thymus by SWE provides normative stiffness values based on age and gender groups. The thymus elasticity decreases with increased age, height and weight.

Objective: In the initial phases of parenchymal diseases, the only finding would be an increase in organ size. We aimed to provide percentile charts of solid intraabdominal organ sizes by age for Turkish children on contrast-enhanced computed tomography images and reveal relative size ratios. Materials and Methods: A total of 800 abdominal computed tomography examinations of otherwise healthy children (468 males, 332 females) were enrolled. The transverse diameter and lengths of both liver lobes, the thickness of the pancreas, width and length of the spleen, and anteroposterior diameters and lengths of both kidneys were measured. Differences in mean diameters among ages were compared with the analysis of variance test. Pearson’s correlation was assessed to depict the association of size with age and waist circumference. Results: Percentile charts for all measured size parameters that presented statistically significant positive correlations with age and waist circumference were provided. There were constant ratios of the right liver lobe to the left liver lobe (1.9 ± 0.37), right liver lobe to the right kidney (1.56 ± 0.26), left to the right kidney (1.03 ± 0.09), and spleen to the left kidney (1 ± 0.2) lengths in every age groups. Age (years)-dependant regression equation for waist circumference (mm) was depicted as “22 × age + 408.” Conclusion: Age-based percentile charts of solid intraabdominal organ diameters along with relative organ size ratios were provided. Cite this article as: Bayramoğlu Z, Ayyıldız H, Ersoy B. Reference ranges of age-based liver, spleen, pancreas, and kidney size in conjunction with waist circumference in children. Turk Arch Pediatr. 2022;57(2):175-185.

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