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UnlabelledThe standardized bone mineral density (sBMD) values, derived using universal standardized equations, were shown to be equivalent within 1.0% for hip but significantly different for spine for state-of-art fan-beam dual X-ray absorptiometry (DXA) Hologic and GE-Lunar systems. Spine L1-L4 and L2-L4 sBMD mean differences between the two systems were 0.042 g/cm(2) (4.1%) and 0.035 g/cm(2) (3.2%), respectively.IntroductionThe objective of this study is to validate the 1994 pencil-beam DXA "universal standardization equations" for state-of-the-art fan-beam DXA systems.MethodsThe spine and bilateral femurs of 87 postmenopausal women were scanned on both Hologic Delphi and GE-Lunar Prodigy DXA systems at three different clinical centers. The scans were analyzed using Hologic Apex and GE-Lunar EnCore software. The BMD results were converted to sBMD using the equations previously developed. Linear regression analysis was used to describe the relationship of the two systems' BMD results. Bland-Altman analysis was used to assess the differences in measures.ResultsThe Apex and Prodigy sBMD values were highly correlated (r ranged from 0.92 to 0.98). Spine L1-L4 and L2-L4 sBMD values had significant intercepts and slopes for Bland-Altman regression, with mean differences of 0.042 g/cm(2) (4.1%) and 0.035 g/cm(2) (3.2%), respectively. The total hip and neck sBMD showed no significant intercept and slope, except left total sBMD had a significant difference between the two systems of 0.009 g/cm(2) (1.0%).ConclusionsThe sBMD values were shown to be equivalent within 1.0% for hip but were significantly different for spine on the two systems. Biases may persist in pooled sBMD data from different manufacturers, and further study is necessary to determine the cause.

Background: Femoral shaft fracture incidence increases in older adults and is associated with low-energy trauma. Apart from bone density, the distribution and size of bone contributes to its strength. Aim: To examine if bone geometry and density of the femoral mid-shaft in older adults differs by sex and race, we studied 197 White women, 225 Black women, 242 White men, and 148 Black men aged 70-79 years participating in the Health, Aging, and Body Composition study; a prospective cohort study in the USA. A secondary purpose of the study was to examine the association of site-specific muscle and fat to bone geometry and density. Subjects and methods: Subjects were community-dwelling and reported no difficulty walking one-quarter of a mile or climbing stairs. Mid-femoral volumetric bone mineral density (vBMD, mg cm[SUP-3]), total area (TA), cortical area (CA), medullary area (MA), cross-sectional moments of inertia (CSMI: I[SUBx],I[SUBy],J), and muscle and fat areas (cm[SUP2]) were determined by computed tomography (CT; GE CT-9800, 10 mm slice thickness). Results: vBMD was greater in men than women with no difference by race (p < 0:001). Bone areas and area moments of inertia were also greater in men than women (p < 0:001), with Black women having higher values than White women for TA and CA. Standardizing geometric parameters for body size differences by dividing by powers of femur length did not negate the sex difference for TA and MA. Significant differences (p < 0:05) among the four groups also remained for I[SUBx] and J. Mid-thigh muscle area was an independent contributor to TA in all groups (Std β = 0:181-0.351, p < 0:05) as well as CA in women (Std β = 0:246-0.254, p < 0:01) and CSMI in White women (Std β = 0:175-0.185, p < 0:05). Further, muscle area was a significant contributor to vBMD in Black women. Conclusion: These results indicate that bone geometry and density of the femoral diaphysis differs primarily by sex,... [ABSTRACT FROM AUTHOR]

The article presents a letter to the editor commenting on an article by Hausler et al. that examined the relationship between static histomorphometry and ultrasound in the human calcaneus. The advent of quantitative ultrasound (QUS) in medical diagnosis has resulted in a desire to link QUS variables and the measured bone mineral density (BMD) from axial sites because it is thought that QUS gives information about structures. The authors propose that the weak association of QUS and BMD can be explained by other factors.