laren3, W
the discrepancy in inherent in the 2-dimensional dexa measurement. With a dexa score, the actual bmd would be higher in a small bone than it would be in a large bone because dexa doesn't register volume of the bone.
The numbers generated through dexa and QCT can't be directly compared.
Because I have an older spine, the concern was that dexa might be giving me a better T score by including bone spurs. With a lower score, I might have chosen a different medication (Tymlos instead of Forteo).
QCT measures trabecular bone the more delicate inner portion of the vertebrae and femoral neck. Dexa measures both cortical and trabecular bone