title: Navel jewelry artifacts and intravertebral variation in spine bone densitometry in adolescents and young women.
abstract: Non-removable navel jewelry can increase the measured bone density of the underlying vertebra. We measured lumbar spine bone mineral density (BMD) by dual-energy X-ray absorptiometry (DXA) in an observational study of 727 adolescents and young women aged 14-30 yr. We evaluated several methods of correcting BMD: manually erasing a small area, eliminating 1 or 2 vertebrae, estimating the BMD from 1 or 2 vertebrae using data from remaining vertebrae, and estimating the BMD using T-scores of the remaining vertebrae. Ten percent (n=71) of the subjects were wearing navel jewelry. The areal BMD by DXA of L1 and L2 was similar in those with jewels as in controls without jewels, but L3-L4 showed higher bone density in those with jewelry, and the spine BMD of L1-L4 was significantly higher in the bejeweled women (1.043+/-0.011 vs 1.006+/-0.004 g/cm2, p=0.01). The estimated errors in accuracy (g/cm2) were 0.034 due to the jewels; 0.005 from erasing a small area; 0.019 from eliminating L4; 0.044 from eliminating both L3 and L4; 0.016 from predicting BMD using L1-L3; and 0.028 using L1-L2. The T-scores using the Hologic database were progressively lower in the caudal vertebrae, even in 96 local women aged 30-35 yr, whose average T-score was 0.35 at L1 but -0.26 at L4. Thus, we found significant errors due to intravertebral variability. We suggest the optimal method of correcting for small artifacts is to erase the area under the artifact.
authors.affiliation: Department of Medicine, School of Medicine, University of Washington, Seattle, WA 98195-6426, USA. smott@u.washington.edu
authors.forename: Susan M
authors.initials: SM
authors.lastname: Ott
authors.forename: Laura E
authors.initials: LE
authors.lastname: Ichikawa
authors.forename: Andrea Z
authors.initials: AZ
authors.lastname: LaCroix
authors.forename: Delia
authors.initials: D
authors.lastname: Scholes
mesh_terms: D015502:Absorptiometry, Photon; D000293:Adolescent; D016477:Artifacts; D046288:Body Piercing; D015519:Bone Density; D005260:Female; D005547:Foreign Bodies / Q000000981:diagnostic imaging; D006801:Humans; D055498:Jewelry; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging* / Q000502:physiology*; D055815:Young Adult