The effects of local versus average baseline determination on spinal density.

We compared two approaches for determining soft tissue baseline with dual energy X-ray absorptiometry (DEXA) of the spine. An average baseline for the entire L2-L4 region resulted in overestimation of the L2 density by 2% and underestimation of L4 density by 2% in 122 subjects. The results for the L2-L4 region, and for L3, were comparable with both approaches and the precision error in vivo also was comparable (0.8%).