Tibial quantitative ultrasound compared to dual-energy X-ray absorptiometry in preterm infants

OBJECTIVE: The gold standard for diagnosing metabolic bone disease in pediatrics is dual-energy x-ray absorptiometry (DXA). Bone quantitative ultrasound (QUS) has increasing applications. This study compared the relationship of DXA to QUS in preterm infants. DESIGN: Prospective observational study of preterm infants <= 32 weeks gestation or <= 1800 grams at birth. DXA scans measuring bone mineral content (BMC) and tibial QUS scans measuring bone speed of sound (SOS) were obtained near term gestation. RESULTS: 41 infants had bone scans at mean corrected gestation 37.7 +/- 2.1 weeks. BMC and SOS showed weak inverse correlation (R2 0.163, p < 0.01). BMC and SOS correlated with parameters at corrected gestational age at the time of the bone scans (p < 0.05-0.001). SOS correlated with birth gestational age (p < 0.001), not BMC. CONCLUSIONS: A statistically significant weak inverse correlation between DXA and QUS was observed. QUS may have advantages over DXA.