Soft-tissue fluid determination by dichromatic absorptiometry

W. H. Wolberg, R. M. Witt, J. A. Moylan and R. B. Mazess

Dichromatic absorptiometry (DA) in a noninvasive method for individually determining the amount of lipid, bone mineral, and protein and water present in a mixture by differential attenuation of radiation beams emitted from a dual photon source. The physics involved permit these components to be determined extremely accurately and precisely. The present study investigated the ability of DA limb scans to measure changes in total body water produced in dogs and in patients. Dichromatic absorptiometry was determined to be a valid method of measuring changes in total body water content as reflected by limb fluid content changes. Precision was limited by the accuracy in positioning the limb for repeated scanning. Dichromatic absorptiometry has the potential of becoming a clinically useful instrument for measuring fluid content changes in limbs produced either by changes in total body water content or by conditions causing limb edema.