Is Quantitative Ultrasound a Valid Technique for Assessing Bone Quality in Deceased Infants?

There is no quantitative method for evaluating infant bone quality that is non-invasive, portable, brief in scan duration, and does not use ionizing radiation. This study investigates the relationship between components of infant bone quality and a measure of quantitative ultrasound (QUS), speed of sound (SOS), to provide insight into the validity of QUS as a diagnostic tool for evaluating infant bone quality. The study sample was comprised of 78 infants between the age of 30 weeks estimated gestational age and 12 postnatal months receiving an autopsy at the Harris County Institute of Forensic Sciences and Texas Children’s Hospital. Bone SOS measurements, costochondral rib and iliac crest samples, and radiographs of the forearm and leg were prospectively collected over a 9-month period. Demographic information, medical history, autopsy findings, and investigator reports were collected and used to identify chronic illness. Qualitative radiographic evaluation, bone mineral density (BMD), and tibial measurements were obtained from radiographs.

Results indicated that SOS measures aspects of bone quality related to bone macrostructure. Prematurity and chronic illness were significantly associated in the current study sample and their detrimental effects could not be separated. Prematurity and, possibly, chronic illness significantly influenced SOS through their adverse effects on growth and bone health. BMD was not significantly associated with tibial or body size measurements, but this may have been due to the small area of bone used to estimate BMD. Although SOS and BMD were not significantly correlated, both showed a postnatal decline and subsequent increase at greater ages. Chronically ill infants had significantly lower BMD and greater qualitative radiographic evaluation scores than infants without chronic illness.

Assessing bone quality is complex due to the multitude of factors which compose it. QUS remains a highly promising technology for evaluating infant bone quality, but it cannot be definitively concluded that QUS is a valid technique for evaluating infant bone quality based on this research alone. Research comparing SOS to finer-grained measurements of aspects of bone quality are necessary before the validity of QUS as a diagnostic tool for evaluating infant bone quality and strength can be determined.