A Study to Assess Metabolic Bone Disease of Prematurity Using an Acoustic Method

National Institutes of Health (NIH), National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)

The goal of this project is to develop a new noninvasive ultrasound based technique, called vibro-acoustic analysis (VAA), for evaluation of infant bone health with particular application in assessment of bone health in premature infants who are at risk for bone disease.

With increased survival of very low birth weight and premature infants over recent decades, bone assessment has become especially vital with the recognition of metabolic bone disease (MBD) of prematurity. Bone assessment became especially vital during last decades with the growing emphasis on metabolic bone disease of prematurity and low-birth-weight infants. Statistics shows that up to 50% of low birth weight and preterm newborns are likely to develop metabolic bone disease. Currently, no screening test has been shown to provide both sensitive and specific evidence of developing MBD over the first several weeks of life in the premature infants. Therefore, there is a need for a non-invasive tool for evaluation of infant bone health. This study will be conducted on premature infants at risk for MBD at multiple time points during their growth, with full term infants as controls. vibro-acoustic analysis (VAA) measurements will be done on the tibia. VAA measurements for the premature infants will be compared to those of full term infants. Performance of VAA in identifying osteopenia and its ability to monitor the response to treatment will be evaluated. The investigators will use an ultrasound system that has been used in the pilot study and employ a transducer with a smaller footprint for pediatric application.

Bone Diseases, bone health, Fracture, infancy, Low Birth Weight Infant, mineralization, Neonatal, Pediatrics, Premature, ultrasound, Rickets

The study visits will be at ≥3 time points at ages: within the first 28 days after birth, 2 months, 3 months, and, if still hospitalized, at 4 months and at 6 months. The ultrasound machine to the nursery or neonatal intensive care unit at a scheduled time. The appropriate ultrasound probe will be placed on the infant's tibia and a miniature hydrophone near the probe. A series of ultrasound measurements will be obtained and the ultrasound data will be saved for offline processing. The Investigators will repeat the measurement in 3 locations of the infant's tibia. Each ultrasound measurement takes a few seconds. The complete ultrasound study will take about 15 minutes at each visit. All procedures will be conducted in the nursery or neonatal intensive care unit to ensure infant safety. The ultrasound measurement for full-term infants can be done in ultrasound lab.

The study will develop and validate a new ultrasonic method for assessment of infant bone by evaluating structural and mechanical characteristics of the infant tibia. This project will utilize a novel, non-invasive method, vibro-acoustic analysis (VAA), to evaluate infant bone properties in a wide frequency range while reducing the artifacts from soft tissue.

Specific Aim 1 - Optimize VAA method for quantitative. The goal is to optimize the VAA system for small size of preterm tibia bone.

Obtaining a pediatric ultrasound transducer with smaller footprint and shallower focus is the first step for optimization. Secondly, using smallest size hydrophone with a high receiver sensitivity complete the optimization. The investigators will consider hydrophone bandwidth as a measure for optimal sensitivity.

Specific Aim 2: Determine the efficacy of the VAA method for quantitative assessment of tibia bone in a pilot study of term and preterm infants. The goal is to measure the bone health of preterm newborn using our new ultrasound method.

Vibro-acoustic measurements for the age-adjusted premature infants will be compared to those of normal infants. Performance of vibro-acoustic in monitoring the treatment will be assessed by comparing to the measurement of previous visits.

Inclusion Criteria: Full term newborns, approximately equal number of male and female newborn, age <28 days. Preterm infants, approximately equal number of male and female preterm infants with gestational age at birth <37 weeks or birth weight <1500 grams. Exclusion Criteria: Infants currently requiring continuous cardiovascular medication infusions, including but not limited to, dopamine, epinephrine, milrinone, and dobutamine (may have received these medications in the past. Infants with major congenital anomalies that may affect bone health or structure. For full term infants, infants with a history of intrauterine growth restriction or who are small for gestational age (<10th percentile for weight) at birth.