Bone Abstracts

Background: The role of untrained observers in evaluating vertebrae height and therefore detection of vertebral fracture (VF) from spinal radiographs (SXR) and dual energy-absorptiometry (DXA) images in children with concerns about osteoporosis is currently unknown.

Objective: To assess intra-observer agreement of morphometric measurements of vertebra height by an untrained observer using SXR and DXA in boys with Duchenne Muscular Dystrophy (DMD).

Methods: Vertebral height from SXR and DXA were measured on two separate occasions using the 6-point quantitative method. Relative technical error of measurement (rTEM) and bland-altman analysis were performed to evaluate intra-observer agreement of vertebral height measurements. Weighted kappa scores (κ) were calculated to assess intra-observer agreement of VF grading based on measurements of vertebral height.

Results: Fourteen boys with no history of VF were selected from a prospective study of bone health in DMD, median age 9.5 years (range 7.1 to 14.9). Both SXR and DXA provided highly readable images for vertebral assessment with 97.1% and 96.4% of vertebrae readable in the L4-T5 region. Intra-observer error of vertebral height measurements (T5-L4) on SXR and DXA is low (SXR rTEM=2.5%, DXA rTEM=2.9%) and was comparable across vertebrae levels. Intra-observer error was lowest in lumbar spine using SXR (rTEM 1.9%) and highest in mid-thoracic region using DXA (rTEM 3.1%). Bland altman plots for vertebral height ratios were closely distributed around zero. Limits of agreement of anterior: posterior ratio 8.0 and 11.0% on SXR and DXA, whilst limits of agreement of middle:posterior height ratio 7.9 and 9.7% on SXR and DXA. Intra-observer agreement of VF grade from was substantial in both imaging modalities’ (iDXA, κ=0.61; SXR, κ=0.76).

Conclusion: This study showed for the first time that an untrained observer can precisely perform vertebral height measurements. However, the accuracy of VF detection may require confirmation by comparison with a trained radiologist.

Disclosure: The authors declared no competing interests.