The Use Of Ultrasonic Backscatter Signals In Assessing Cancellous Bone Status In Newborn Infants

Objective: At present, the number of extremely premature infants surviving is still increasing. Thus, the incidence of metabolic bone disease is increasing too. The purpose of this thesis is to evaluate the potential role of ultrasonic backscatter signals and its backscatter coefficient (BSC) in assessing cancellous bone status in newborn infants by analyzing the relationship between the BSC and gestational age, birth weight, length, head circumference, age and serum biochemical markers.Methods: One hundred and twenty two infants (93 preterm infants and 39 term infants) who were admitted to the Division of Neonatology, Children's Hospital of Fudan University from February 1st to March 31st 2008 within 48 hours after birth were enrolled in the study. The infants with congenital anomalies, congenital metabolic disease, intestinal malformation or known bone diseases were excluded. The BSC was measured at the neonatal calcaneus by using the ultrasound at < 48 hours, at 7 days, 14 days and 28 days of age under different frequencies.Results: (1) In all newborns, significant correlations were found between BSC and gestational age (r=0.242, P<0.01; r=0.19, P<0.05; r=0.466, P<0.001; r=0.362, PO.001) and birth weight (r=0.244, P<0.01; r=0.241, P<0.05; r=0.465, P<0.0001; r=0.345, P<0.0001) under different frequencies (2.25MHz,3.5MHz,5MHz and 7.5MHz). Significant correlations were also found between BSC and length (r=0.187, P<0.05; r=0.427, P<0.001; r=0.278, P<0.01) under the three different frequencies (3.5MHz,5MHz and 7.5MHz). (2) BSC decreased initially and then increased gradually after birth. Correlation was still found between BSC with gestational age at different postnatal age. (3) For measuring BSC, higher frequencies are suitable for the preterm infants and lower frequencies are suitable for the term infants.Conclusions: This study suggests that BSC are closely correlated with gestational age, birth weight and length at birth. BSC also shows regular change at different postnatal age. Ultrasonic backscatter signals and its BSC might be a good indicator for assessing neonatal cancellous bone status and following skeletal development and maturation after birth.