The usefulness of quantitative ultrasound (QUS) measurements in the evaluation of skeletal status in newborns and in children

This study aimed to evaluate both the feasibility and usefulness of QUS in newborns and children and the factors influencing QUS parameters. In 50 consecutive healthy full-term newborns (23 males and 27 females; gestational age: 39,22,0 weeks) QUS parameters were assessed within three days of birth at distal diaphysis of humerus using Bone Profiler (IGEA, Italy), after an appropriate modification of calliper and software, and after 4 years of life by the standard technique used in the children and adults. In all subjects we evaluated: AD-SoS (m/s), the characterizing graphic trace parameters (SDy, FWA and BTT), SoS (m/s), that is the speed of sound calculated on the first peak and hBTT, that is the interval time between the first peak of the ultrasound and when this reaches the speed of 1570 m/s, that is the velocity of ultrasound in the soft tissue. This latter parameter allows to measure bone tissue independently of soft tissue. QUS were also performed at phalanges on all mothers, who also self-reported a questionnaire on their obstetric history, smoking and dietary habits and family history of osteoporosis. At birth all QUS parameters were slightly higher in male than in female newborns but the difference was not significant. BTT and hBTT of newborns showed a significant relationship with weight at birth and with the cranial circumference. In newborns none of the QUS parameters was significantly influenced by maternal QUS or by maternal smoking and calcium intake. By using a model of multiple regression analysis the cranial circumference was the only parameter entered into the model, explaining about 15% of hBTT value. At the fourth year of life BTT and ADSoS showed a significant increase with respect to basal values. BTT was positively correlated with the weight (r=0.53; p<0.01). BTT values at birth, expressed as percentile, showed a significant concordance with BTT in percentile at the fourth year of life. In addition, a multiple regression analysis showed that both BTT at birth and weight at the fourth year of life were predictive of BTT after 4 years of life (R²: 0.11; p<0.05 and 0.30, p<0.01 respectively). The present study demonstrates that the assessment of BTT at birth seems to be partially predictive of skeletal status after 4 years of life. In addition, BTT appears to be the best parameter for both evaluation of skeletal status at birth and monitoring of bone growth in the first years of life.