title: A preliminary evaluation of the lunar expert-XL for bone densitometry and vertebral morphometry.
abstract: We have evaluated the Lunar Expert-XL for standard bone mineral densitometry (BMD) and for morphometric imaging of the spine in the lateral projection. The short-term precision in vitro of the Expert-XL for BMD measurements was 0.7% for the Hologic and European spine phantoms, and the long-term stability (15-month) measurements had a 1.1% coefficient of variation. The precision in vivo for three operators examining a group of 10 premenopausal women was 0.9-1.5% for lumbar spine (L2-L4), 1.7-2.2% for the femoral neck, and 0.9% for the total hip region of interest. For a group of nine postmenopausal women, the lumbar spine, femoral neck, and total femur precision ranges were 2.0-2.4, 1.2-2.9, and 1.6-1.7% respectively. For L2-L4, BMD comparison between the Expert-XL and DPX-L yielded a correlation coefficient of r = 0.98, a slope of 0.86, and an intercept of 0.139 g/cm2. The femoral neck results were r = 0.92, slope = 1.00, and intercept = 0.03 g/cm2. In an evaluation of the Expert-XL for lateral morphometry, we employed a group of 16 postmenopausal women. Comparison of vertebral dimensions between the Expert-XL and radiographic morphometry showed strong agreement (r = 0.97), but the interobserver variability for vertebral height was higher for the Expert-XL than for radiographs (3-5% vs. 1-2%). In a subset of four women who had repeat scans, the interscan precision for measuring vertebral dimensions was 1.9, 4.1, and 43% for the L1-L4, T12-T8, and T7-T5 levels respectively. In the Expert-XL images, it was possible to identify clearly L4-T4 in 10 of 16 patients and L4-T6 in 15 of 16, indicating potential utility for vertebral fracture prescreening.
authors.affiliation: Osteoporosis Research Group, Department of Radiology, University of California-San Francisco, 94143-1250, U.S.A.
authors.forename: T
authors.initials: T
authors.lastname: Lang
authors.forename: M
authors.initials: M
authors.lastname: Takada
authors.forename: R
authors.initials: R
authors.lastname: Gee
authors.forename: C
authors.initials: C
authors.lastname: Wu
authors.forename: J
authors.initials: J
authors.lastname: Li
authors.forename: C
authors.initials: C
authors.lastname: Hayashi-Clark
authors.forename: S
authors.initials: S
authors.lastname: Schoen
authors.forename: V
authors.initials: V
authors.lastname: March
authors.forename: H K
authors.initials: HK
authors.lastname: Genant
mesh_terms: D015502:Absorptiometry, Photon / Q000295:instrumentation / Q000379:methods* / Q000592:standards; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015519:Bone Density / Q000502:physiology*; D005103:Expert Systems; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging / Q000502:physiology*; D005272:Femur Neck / Q000000981:diagnostic imaging / Q000502:physiology*; D006801:Humans; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000502:physiology*; D008875:Middle Aged; D008962:Models, Theoretical; D015588:Observer Variation; D015663:Osteoporosis, Postmenopausal / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000503:physiopathology*; D019047:Phantoms, Imaging; D017698:Postmenopause / Q000502:physiology; D015203:Reproducibility of Results