Standardizing evaluation of pQCT image quality in the presence of subject movement: Qualitative versus quantitative assessment

Robert M. Blew, Vinson R. Lee, Joshua N. Farr, Daniel J. Schiferl, Scott B. Going

Research output: Contribution to journalArticlepeer-review

44 Scopus citations


Peripheral quantitative computed tomography (pQCT) is an essential tool for assessing bone parameters of the limbs, but subject movement and its impact on image quality remains a challenge to manage. The current approach to determine image viability is by visual inspection, but pQCT lacks a quantitative evaluation. Therefore, the aims of this study were to (1) examine the reliability of a qualitative visual inspection scale and (2) establish a quantitative motion assessment methodology. Scans were performed on 506 healthy girls (9-13 years) at diaphyseal regions of the femur and tibia. Scans were rated for movement independently by three technicians using a linear, nominal scale. Quantitatively, a ratio of movement to limb size (%Move) provided a measure of movement artifact. A repeat-scan subsample (n = 46) was examined to determine %Move's impact on bone parameters. Agreement between measurers was strong (intraclass correlation coefficient = 0.732 for tibia, 0.812 for femur), but greater variability was observed in scans rated 3 or 4, the delineation between repeat and no repeat. The quantitative approach found ≥95 % of subjects had %Move <25 %. Comparison of initial and repeat scans by groups above and below 25 % initial movement showed significant differences in the >25 % grouping. A pQCT visual inspection scale can be a reliable metric of image quality, but technicians may periodically mischaracterize subject motion. The presented quantitative methodology yields more consistent movement assessment and could unify procedure across laboratories. Data suggest a delineation of 25 % movement for determining whether a diaphyseal scan is viable or requires repeat.

Original languageEnglish (US)
Pages (from-to)202-211
Number of pages10
JournalCalcified Tissue International
Issue number2
StatePublished - Feb 2014


  • Image quality
  • Movement artifact
  • Peripheral quantitative computed tomography
  • Qualitative procedure
  • Quantitative procedure
  • Subject motion

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Orthopedics and Sports Medicine
  • Endocrinology


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