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Validation of accuracy and precision of dual energy X-ray absorptiometry for infants
W W Koo1, L R Massom, J Walters
1Department of Pediatrics, University of Tennessee-Memphis, USA.
Insights
Dual energy X-ray absorptiometry (DXA) bone mineral content (BMC) measurements reliably assess bone status in young pediatric subjects. This method is precise, though it proportionately underestimates ash weight.
Area of Science:
- Pediatric Bone Health
- Medical Imaging Technology
- Biomedical Engineering
Background:
- Limited data exists on dual energy X-ray absorptiometry (DXA) bone mineral content (BMC) validity in low-body-mass individuals.
- Accurate assessment of bone mineral status is crucial for pediatric populations.
Purpose of the Study:
- To evaluate the accuracy and precision of DXA BMC measurements in young subjects.
- To determine the reliability of DXA BMC in pediatric patients.
Main Methods:
- Stepwise multiple regression analysis to identify determinants of DXA BMC in piglets.
- In vivo replication of DXA BMC measurements in infants across a range of postnatal ages.
- Assessment of DXA BMC under various clinical conditions (blanket, diaper, positioning).
Main Results:
- Ash weight was the primary determinant of DXA BMC in piglets (adjusted r2 = 0.98).
- DXA BMC measurements were unaffected by cotton blankets, diapers, or positioning.
- High correlation (r2 = 0.99) and precision (CV = 2.8%) were observed for in vivo DXA BMC in infants.
Conclusions:
- DXA BMC is a highly precise method for assessing bone mineral status in young pediatric subjects.
- DXA BMC reliably but proportionately underestimates ash weight.
- DXA provides accurate bone mineral status assessment in infants and piglets.
Abstract:
There is limited information on the validity of bone mineral content measurement by dual energy X-ray absorptiometry (DXA BMC) for use in subjects with low body mass. We evaluated the accuracy and precision of DXA in piglets (body weight 886-5526 g, median 2096 g). Stepwise multiple regression analyses showed that ash weight is the major determinant of DXA BMC (adjusted r2 = 0.98, RMS residual = 3.61 g). The intercept was not significantly different from zero. DXA BMC measurements of other piglets under various clinical situations showed no significant effect from the use of cotton blanket, diaper, or positioning (prone, supine, lateral). In vivo replication of DXA BMC measurements of infants at a postnatal age of from 1-350 days showed a slope of 0.99 and high correlation coefficient (r2 = 0.99, RMS residual = 3.59 g). The intercept was not significantly different from zero, and the average coefficient of variation of duplicate DXA BMC in infants was 2.8%. We conclude that DXA BMC reliably but proportionately underestimates ash weight and is a highly precise method for measuring bone mineral status in young pediatric subjects.