The authors reply: Letter on: "Pitfalls in the measurement of muscle mass: a need for a reference standard" by Clark et al.
Buckinx F., Landi F., Cesari M., Fieding RA., Visser M., Engelke K., Maggi S., Dennison E., Al-Daghri NM., Allepaerts S., Bauer J., Bautmans I., Brandi M-L., Bruyère O., Cederholm T., Cerreta F., Cherubini A., Cooper C., Cruz-Jentoft A., McCloskey E., Dawson-Hughes B., Kaufman J-M., Laslop A., Petermans J., Reginster J-Y., Rizzoli R., Robinson S., Rolland Y., Rueda R., Vellas B., Kanis JA.
However, semantics aside, we think that DXA can indeed serve as a reference standard for measuring muscle mass. Obviously, CT and MRI are advanced techniques that can and have been used to obtain important information such as muscle size/volume and more recently amount and distribution of intra- and intermuscular adipose tissue. Also individual muscles can be assessed separately. However, with respect to muscle mass, the comparison of DXA with CT/MRI is rather difficult because DXA and QCT/MRI measure different physical parameters.