Comparison Of Prodigy Advance And Delphi A For Bone Mineral Density In Chinese Women

Comparison between two DXA Systems:Prodigy Advance and Delphi A,used for measuring spine and femurObjective To compare the differences of bone area(BA),bone mineral content(BMC)and bone mineral density(BMD)estimated with narrow fan beam(4.5°)X-ray densitometer(GE-Lunar Prodigy Advance) and fan beam(30°)X-ray densitometer(Hologic Delphi A),and to establish the transcalibrating equations between them.Methods BA,BMC and BMD of the lumber spine and proximal femur on 355 Chinese Women were measured with two types of dual X-ray absorptiometers(GE-Lunar Prodigy Advance and Hologic Delphi A).Results Comparisons on volunteers showed that measured lumbar spine BA was 11.5%lower,BMC 2.3%higher and BMD 15.7%higher with the Prodigy Advance compared with the Delphi A.Some regional differences were greater.The average Prodigy Advance values for BMD were 15.7%and 4.8%higher than those of Delphi A for the lumbar spine and femoral neck.Cross-calibration equations were derived for lumbar spine and proximal femur except Ward's triangle.Conversions of BMD values based on these regression equations are:(A)lumbar:Hologic=0.869×Lunar-0.003(r=0.988;p＜0.001);(B)femoral neck:Hologic=0.872×Lunar-0.025(r=0.988;p＜0.001);(C)trochanter:Hologic=0.801×Lunar+0.001(r=0.988;p＜0.001); (D)intertrochanter:Hologic=0.856×Lunar-0.003(r=0.988;p＜0.001);(E)total hip:Hologic=0.894×Lunar-0.008(r=0.988;p＜0.001).Conclusion The study demonstrates that there are appreciable differences ofBA,BMC and BMD values of the Lunar Prodigy Advance and Hologic Delphi A dual-energy X-ray absorptiometers,but they can be made compatible by use of cross-calibration equations and factors.