Agreement between pQCT- and DXA-derived indices of bone geometry, density, and theoretical strength in females of varying age, maturity, and physical activity.

Measurement of bone mass, geometry, density, and strength are critical in bone research and clinical studies. For peripheral quantitative computed tomography (pQCT), single and repeated measurements are particularly adversely affected by movement and positional variation. Dual-energy X-ray absorptiometry (DXA)-derived indices may alleviate these problems and provide useful alternative assessments. To evaluate this hypothesis, distal radius DXA and pQCT indices were compared in 101 healthy females aged 8.0 to 22.8 years (prepuberty to adulthood), reflecting a broad range of body sizes, physical maturity, and activity exposures. At the diaphysis, correlations were ρ = +0.74 to +0.98, with strong intermethod agreement for most indices. At the metaphysis, correlations were ρ = +0.64 to +0.97; intermethod agreement improved with modifications to the simplified geometric formulas more closely reflecting metaphyseal bone geometry. Further improvements may be possible because skeletal size and maturity-related biases in agreement were detected. Overall, DXA-derived indices may provide a useful assessment of bone geometry, density, and theoretical strength contingent on appropriate consideration of their limitations.