[Quantitative ultrasound for the assessment of bone in the preterm infant]. / Utilizzo dell'ultrasonografia quantitativa nella valutazione dello stato minerale osseo del neonato pretermine.

AIM: Preterm infants are at risk of osteopathy of prematurity (OP). The present study aims to assess quantitative ultrasound as a safe and non-invasive method in evaluating bone mineral status in the critically ill preterm infant. METHODS: Sixty preterm infants (27 females) have been evaluated in the Neonatal Intensive Care Unit of the University Hospital of Siena. Gestational age was between 22 and 36 weeks and birth weight ranged between 610 and 3240 g. A single operator did all the measurements on the second metacarpus by the DBM Sonic BP (IGEA). Ultrasound parameters were bone transmission time (BTT, micros) and speed of sound (SOS, m/s). RESULTS: BTT positively increased with birth gestational age (r=0.72, P<0.001, F-Ratio=62.4428), birth weight (r=0.7827, P<0.001, F-Ratio=91.7274) and birth length (r=0.7729, P<0.001, F-Ratio=86.0748). SOS was also related with gestational age (r=0.2937, P<0.023, F-Ratio=5.4768), birth weight (r=0.2634, P<0.042, F-Ratio=4.3250) and birth length (r=0.3252, P<0.011, F-Ratio=6.8596). Small infants for gestational age showed BTT values lower then infants with appropriate size for gestational age (P<0.03). There was no difference between male and female infants. CONCLUSION: Quantitative ultrasound is a non-invasive method, which is easy to perform in a Neonatal Intensive Unit, safe, harmless and gentle. This method detects subtle differences in bone mineral status, according to gestational age, weight and length. Quantitative ultrasound is a useful screening tool for early detection of bone status in newborns and a valid method for the longitudinal assessment of bone in growing children.