title: In vivo precision of dual-energy X-ray absorptiometry-derived hip structural analysis in adults.
abstract: Precision is integral to the monitoring of bone mineral density (BMD) change using dual-energy X-ray absorptiometry (DXA). Hip structural analysis (HSA) is a relatively recent method of assessing cross-sectional geometrical strength from the 2-dimensional images produced by DXA scans. By performing serial scans, we evaluated the in vivo precision of DXA-derived HSA in adults using a GE Lunar iDXA absorptiometer (GE Medical Systems, Madison, WI) in males and females (n=42), mean age of 34.5 (standard deviation [SD]: 8.5; range: 19.3-52.6)yr with a heterogeneous sample. Two consecutive intelligent DXA (iDXA) scans with repositioning of both femurs were conducted for each participant. The coefficient of variation, root-mean-square (RMS) averages of SD, and hence the least significant change (95%) were calculated. We found a high level of precision for BMD measurements of both the total hip and femoral neck, with RMS-SD=0.006 and 0.010 g/cm(2) and percent coefficient of variation (%CV)=0.52% and 0.94%, respectively. We also found good precision for HSA-derived geometrical properties, including sectional modulus, cross-sectional moment of inertia, and cross-sectional area, with %CV (average of the left and right sides) at 4.48%, 3.78%, and 3.13%, respectively. Precision was poorer for buckling ratio and femoral strength index with %CV 28.5% and 9.25%, respectively. The iDXA provides high precision for BMD measurements and with varying levels of precision for HSA geometrical properties.
authors.affiliation: DXA Unit, Carnegie Research Institute, Leeds Metropolitan University, Headingley Campus, Leeds, UK. k.hind@leedsmet.ac.uk
authors.forename: Karen
authors.initials: K
authors.lastname: Hind
authors.forename: Brian
authors.initials: B
authors.lastname: Oldroyd
authors.forename: Anup
authors.initials: A
authors.lastname: Prajapati
authors.forename: Laura
authors.initials: L
authors.lastname: Rhodes
mesh_terms: D015502:Absorptiometry, Photon; D000328:Adult; D005260:Female; D006621:Hip Joint / Q000033:anatomy & histology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D055815:Young Adult