Calcaneal ultrasound imaging in healthy children and adolescents: Relationof the ultrasound parameters BUA and SOS to age, body weight, height, footdimensions and pubertal stage

We investigated the quantitative ultrasound (QUS) parameters broadband ultr asound attenuation (BUA) and speed of sound (SOS) measured in the posterior part of the calcaneus at the region of interest (ROI) with the lowest atte nuation, using an ultrasound imaging device (UBIS 3000) in 491 healthy Cauc asian children and adolescents (262 girls, 229 boys) between 6 and 21 years old. The relation of age, body weight, height, foot dimensions and puberta l stage to BUA and SOS was assessed. BUA increased nonlinearly with age in boys and girls, r(2) being 0.44 (p<0.001) and 0.57 (p<0.001), respectively. SOS increased linearly with age in girls (r(2) = 0.04, p<0.001). There was no significant increase in SOS in boys (r(2) = 0.01, p>0.05). Heel width w as significantly con-elated with BUA (r = 0.20, p<0.005 in boys; r = 0.27, p<0.05 in girls) and with SOS (r = -0.19, p<0.005 in boys; r = -0.08, p<0.0 5 in girls). After downward adjustment of the ROI size according to foot le ngth quartiles, significantly lower BUA and SOS values were found compared with those with the standard ROI size of 14 mm. After correction for heel w idth and adjustment of the ROI size based on foot length, BUA and SOS were significantly associated with age in boys (r(2) = 0.36, p<0.001 and 0.06, p <0.05) and in girls (r(2) = 0.53 and 0.06, both p<0.001). Tanner stage was significantly correlated with BUA (u = 0.62,p<0.001 in boys; r = 0.73, p<0. 001 in girls) but not with SOS. BUA but not SOS increased significantly wit h the number of years since menarche (p<0.001). In a multiple stepwise regr ession analysis in boys, age, weight and foot length were independent predi ctors for BUA, and age and foot length for SOS. In girls, age and weight we re independent predictors for BUA and age was the only independent predicto r for SOS. After correction for age, pubertal stages and heel width were no longer determinants for QUS parameters in either boys or girls. In conclus ion, BUA increased significantly with age in both sexes. SOS increased with age in both boys and girls, but the increase was small and not statistical ly significant in boys. SOS, as measured with the UBIS 3000 device, may the refore not be appropriate to assess skeletal status in healthy children. Wh ether SOS and BUA are affected in children with skeletal disorders has yet to be determined. Tn boys, age, weight and foot length were independent pre dictors for BUA and age and foot length for SOS. In girls, age and weight w ere independent predictors for BUA and age was the only independent predict or for SOS. In our opinion, children with small feet should be measured wit h a smaller ROI diameter than those with larger feet.