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New approaches for interpreting projected bone densitometry data
Author(s) -
Carter Dennis R.,
Bouxsein Mary L.,
Marcus Robert
Publication year - 1992
Publication title -
journal of bone and mineral research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.882
H-Index - 241
eISSN - 1523-4681
pISSN - 0884-0431
DOI - 10.1002/jbmr.5650070204
Subject(s) - densitometry , bone mineral , bone density , dual energy , dual energy x ray absorptiometry , population , osteoporosis , confounding , nuclear medicine , medicine , mathematics , statistics , environmental health
Bone densitometry using dual‐photon absorptiometry (DPA) or dual‐energy x‐ray absorptiometry (DXA) has become a standard method for assessing bone mineral content in the spine and other skeletal regions. A projected areal density, referred to as bone mineral density (BMD,g/cm 2 ), is normally calculated to assess regional bone density and strength. We demonstrate that this measure can be misleading when used to compare bones of different sizes due to inherent biases caused by bone thickness differences. For example, assuming that volumetric bone density remains constant and bony linear dimensions are proportional to height, a 20% increase in height would result in a 20% increase in both the thickness and the BMD of any bone. We describe new analysis methods to reduce the confounding effect of bone size, and we introduce a parameter, bone mineral apparent density (BMAD, g/cm 3 ), that better reflects bone apparent density. Using this parameter, we calculate a quantity that serves as an index of bone strength (IBS, g 2 /cm 4 ) for whole vertebral bodies. These analyses were applied to lumbar spine (L2–4) DXA measurements in a population of women 17–40 years old and appear to offer advantages to conventional techniques.