A preliminary evaluation of the lunar expert-XL for bone densitometry and vertebral morphometry

J Bone Miner Res. 1997 Jan;12(1):136-43. doi: 10.1359/jbmr.1997.12.1.136.


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.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Absorptiometry, Photon / instrumentation
  • Absorptiometry, Photon / methods*
  • Absorptiometry, Photon / standards
  • Adult
  • Aged
  • Aged, 80 and over
  • Bone Density / physiology*
  • Expert Systems
  • Female
  • Femur / diagnostic imaging
  • Femur / physiology*
  • Femur Neck / diagnostic imaging
  • Femur Neck / physiology*
  • Humans
  • Lumbar Vertebrae / diagnostic imaging
  • Lumbar Vertebrae / physiology*
  • Middle Aged
  • Models, Theoretical
  • Observer Variation
  • Osteoporosis, Postmenopausal / diagnosis
  • Osteoporosis, Postmenopausal / diagnostic imaging
  • Osteoporosis, Postmenopausal / physiopathology*
  • Phantoms, Imaging
  • Postmenopause / physiology
  • Reproducibility of Results