Pencil-beam vs fan-beam dual-energy X-ray absorptiometry comparisons across four systems: body composition and bone mineral.
We compared bone mineral density (BMD) and body fat percentage (%fat) between two pencil-beam (Lunar DPX and DPX-L) and two fan-beam (Lunar Prodigy, Hologic Delphi A) dual-energy X-ray absorptiometry (DXA) systems. We examined these values in the total-body, spine, femur, and forearm scans in 78 healthy adults across these four DXA systems. BMD and %fat values were highly correlated among the four instruments. DPX-L gave the lowest mean %fat and Prodigy gave the highest mean %fat for both sexes. The means were system dependent for %fat estimates across the four DXA machines. There was a significant difference detected in BMD estimates across manufacturers, with the Delphi A providing systematically lower values than the Lunar systems in the whole body, spine, and femur sites but higher values than the Lunar systems in the forearm. The present study results show that both %fat and bone mineral estimates between pencil-beam and fan-beam systems are highly correlated, but vary by system. Significant differences exist between the instruments, especially between different manufacturers, and most of the comparisons are sex dependent. We conclude that longitudinal studies should always be evaluated on the same system when possible, and translation models should be used to assess cross-instrument differences.
Body Composition Unit and New York Obesity Research Center, St. Luke's-Roosevelt Hospital, Columbia University College of Physicians and Surgeons, New York, NY 10025, USA. jcp35@columbia.edu
Janet-Mae P
JM
Soriano
Elli
E
Ioannidou
Jack
J
Wang
John C
JC
Thornton
Mary N
MN
Horlick
Dympna
D
Gallagher
Steven B
SB
Heymsfield
Richard N
RN
Pierson
D015502:Absorptiometry, Photon / Q000295:instrumentation*; D000273:Adipose Tissue / Q000000981:diagnostic imaging*; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001823:Body Composition; D015519:Bone Density; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity