Positioner and clothing artifact can affect one-third radius bone mineral density measurement.
This report identifies a radius dual-energy X-ray absorptiometry (DXA) confounder and technical approach to avoid this inaccuracy. Initially, a precision study revealed substantial differences (p<0.001) in radius bone mineral density (BMD) least significant change ranging from 0.038 to 0.073g/cm(2) between 3 technologists that each performed assessments in 30 men and 30 women. Subsequently, visual examination of all 360 forearm DXA images, including bone, soft tissue, neutral, and air point-typing was performed. Errors in automated "soft tissue" identification were observed; compared with the manufacturer's ideal depiction, suboptimal soft tissue point-typing was present in 30/360 scans (8.3%) involving 27 individuals. These point-typing deviations appeared to result from inclusion of forearm positioner slots at the scan field edges or clothing covering the forearm. Twenty-four individuals had a paired scan appropriately point-typed, thus allowing evaluation of the effect on BMD measurement. In those with incorrect point-typing associated with positioner slots, the mean one-third radius BMD was ∼7% higher. In conclusion, positioner slots at the edges of the distal scan field can lead to automated soft tissue identification inaccuracies and consequent erroneous one-third radius BMD measurement. DXA technologists should avoid slot inclusion in forearm scans and evaluate point-typing as part of routine analysis.
Osteoporosis Clinical Research Program, University of Wisconsin-Madison, WI 53705, USA. dckruege@wisc.edu
Diane
D
Krueger
Nellie
N
Vallarta-Ast
Jessie
J
Libber
Mary
M
Checovich
Ronald
R
Gangnon
Neil
N
Binkley
D015502:Absorptiometry, Photon; D000368:Aged; D016477:Artifacts; D015519:Bone Density; D003020:Clothing; D005260:Female; D006801:Humans; D008297:Male; D011884:Radius / Q000000981:diagnostic imaging / Q000502:physiology*