BONE-DENSITY IN CHILDREN - A REVIEW OF THE AVAILABLE TECHNIQUES AND INDICATIONS

The recent development of methods for measuring bone mineral content i n children has markedly improved our ability to determine changes in b one mass during growth. Currently, the three most generally accepted t echniques for measuring the bones of children are dual-energy X-ray ab sorbtiometry (DXA), quantitative computed tomography (QCT) and quantit ative ultrasound (QUS). These techniques vary considerably in their ac quisition of data and comparisons between them are difficult and, more often than not, judgment regarding their value has been, at least par tially, subjective. DXA is, by far, the most widely used technique for bone measurements. It is low in cost, accessible, easy to use, and pr ovides an accurate and precise quantitation of bone mass in adults. Un fortunately, DXA is unable to account for the large changes in body an d skeletal size that occur during growth, limiting its use in longitud inal studies in children. QCT can asses both the volume and the densit y of bone in the axial and appendicular skeletons, without influence f rom body or skeletal size, giving it a major advantage over other moda lities for bone measurements in children. The cost and inaccessibility of CT scanners, however, has significantly limited its use for bone m easurements. Measuring the bones of children by QUS is appealing becau se ultrasound is low in cost, portable, easy to use and does not emit radiation. In adults, this technique is able to predict fracture risk independent of bone mass determinations in patients with osteoporosis and, therefore, its measurements must be related to certain aspects of bone strength. However, ultrasound values are dependent on so many;st ructural properties not yet fully understood, that it is difficult to use the information meaningfully in children. (C) 1998 Elsevier Scienc e Ireland Ltd.