For spine, the mean BMD differences between Apex and Prodigy were reduced from 16% to 4.1% for L1-L4 sBMD spine and from 15.6% to 3.3% for L2-L4 sBMD spine. The femoral neck sBMD values for Apex and Prodigy were not significantly different. There was 1.0% difference for the left femur total sBMD values, or 0.009 ± 0.027 g/cm2 (P < 0.05), but no differences were found for the right total sBMD values. Significant trends in the sBMD differences in the spine as a function of the magnitude of the BMD (r = 0.31, P < 0.05) were found CHIR-99021 ic50 (see Table 3). The difference between the spine sBMD measures increased as the sBMD increased (Fig. 1).

In contrast to the spine, the femoral total and neck sBMD did not show significant AZD8055 concentration differences or trends between

the differences and means (See Figs. 2, 3, 4, and 5). The cross-calibration equations derived from this study data are shown in Table 4. The cross-calibration equations for L1-L4 and L2-L4 spine BMD had significantly different slopes and intercepts. The total femur and femoral neck BMD cross-calibration equations were also unique. However, the femur equations did not differ significantly between the left and right sides. Table 3 Bland–Altman analysis results Region of Interest Before standardization After standardization Intercept Slope SEE Intercept Slope SEE L1-L4 spine BMD −0.039 −0.127** 0.06 −0.003 −0.039 0.06 L2-L4 spine BMD 0.019 −0.175** 0.05 0.057 −0.088* 0.05 Left total hip BMD −0.019 −0.060* 0.03 0.018 −0.031 0.03 Right total hip BMD −0.007 −0.070* 0.03 0.029 −0.040 0.03 Left neck BMD −0.086* −0.099* 0.04 −0.049 0.052 0.04 Right neck BMD −0.086* −0.089* 0.04 0.048 0.061 0.04 The difference was defined as (Hologic Apex BMD − GE-Lunar Prodigy BMD) *P < 0.05 **P < 0.001 Fig. 1 Bland–Altman plot of lumbar spine L1-L4 (a) and L2-L4 (b) sBMD of Hologic Apex and GE-Lunar Prodigy. The dotted Cytidine deaminase lines are the 95% confidence

intervals around the best-fit line Fig. 2 Bland–Altman plot of left total femur sBMD of Hologic Apex and GE-Lunar Prodigy. The dotted lines are the 95% confidence intervals around the best-fit line Fig. 3 Bland−Altman plot of right total femur sBMD of Hologic Apex and GE-Lunar Prodigy. The dotted lines are the 95% confidence intervals around the best-fit line Fig. 4 Bland−Altman plot of left femur neck sBMD of Hologic Apex and GE-Lunar Prodigy. The dotted lines are the 95% confidence intervals around the best-fit line Fig. 5 Bland−Altman plot of right femur neck sBMD of Hologic Apex and GE-Lunar Prodigy. The dotted lines are the 95% confidence intervals around the best-fit line Table 4 Conversion equations for GE-Lunar Prodigy and Hologic Apex systems Variables From Hologic to GE-Lunar From GE-Lunar to Hologic L1-L4 spine BMD GE-Lunar = 1.140 × Hologic + 0.037 Hologic = 0.877 × GE-Lunar − 0.033 L2-L4 spine BMD GE-Lunar = 1.195 × Hologic − 0.023 Hologic = 0.837 × GE-Lunar + 0.021 Left total hip BMD GE-Lunar = 1.