title: Inter-observer and inter-examination variability of manual vertebral bone attenuation measurements on computed tomography.
abstract: OBJECTIVE
  To determine inter-observer and inter-examination variability of manual attenuation measurements of the vertebrae in low-dose unenhanced chest computed tomography (CT).
  
  
  METHODS
  Three hundred and sixty-seven lung cancer screening trial participants who underwent baseline and repeat unenhanced low-dose CT after 3 months because of an indeterminate lung nodule were included. The CT attenuation value of the first lumbar vertebrae (L1) was measured in all CTs by one observer to obtain inter-examination reliability. Six observers performed measurements in 100 randomly selected CTs to determine agreement with limits of agreement and Bland-Altman plots and reliability with intraclass correlation coefficients (ICCs). Reclassification analyses were performed using a threshold of 110 HU to define osteoporosis.
  
  
  RESULTS
  Inter-examination reliability was excellent with an ICC of 0.92 (p < 0.001). Inter-examination limits of agreement ranged from -26 to 28 HU with a mean difference of 1 ± 14 HU. Inter-observer reliability ICCs ranged from 0.70 to 0.91. Inter-examination variability led to 11.2 % reclassification of participants and inter-observer variability led to 22.1 % reclassification.
  
  
  CONCLUSIONS
  Vertebral attenuation values can be manually quantified with good to excellent inter-examination and inter-observer reliability on unenhanced low-dose chest CT. This information is valuable for early detection of osteoporosis on low-dose chest CT.
  
  
  CONCLUSIONS
  • Vertebral attenuation values can be manually quantified on low-dose unenhanced CT reliably. • Vertebral attenuation measurements may be helpful in detecting subclinical low bone density. • This could become of importance in the detection of osteoporosis.
authors.affiliation: Department of Pulmonology, University Medical Center Utrecht, P.O. Box 85500, 3508 GA, Utrecht, E.03.511, The Netherlands. e.pompe@umcutrecht.nl.
authors.forename: Esther
authors.initials: E
authors.lastname: Pompe
authors.affiliation: Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Pim A
authors.initials: PA
authors.lastname: de Jong
authors.affiliation: Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Werner U
authors.initials: WU
authors.lastname: de Jong
authors.affiliation: Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Richard A P
authors.initials: RA
authors.lastname: Takx
authors.affiliation: Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Anouk L M
authors.initials: AL
authors.lastname: Eikendal
authors.affiliation: Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Willemink
authors.affiliation: Department of Radiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Matthijs
authors.initials: M
authors.lastname: Oudkerk
authors.affiliation: Department of Radiology, Erasmus Medical Center, Rotterdam, The Netherlands.
authors.forename: Ricardo P J
authors.initials: RP
authors.lastname: Budde
authors.affiliation: Department of Pulmonology, University Medical Center Utrecht, P.O. Box 85500, 3508 GA, Utrecht, E.03.511, The Netherlands.
authors.forename: Jan-Willem J
authors.initials: JW
authors.lastname: Lammers
authors.affiliation: Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Firdaus A A
authors.initials: FA
authors.lastname: Mohamed Hoesein
mesh_terms: D000368:Aged; D055088:Early Detection of Cancer; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae / Q000502:physiology* / Q000528:radiation effects; D008175:Lung Neoplasms / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D010024:Osteoporosis / Q000000981:diagnostic imaging*; D011829:Radiation Dosage; D015203:Reproducibility of Results; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods
keywords: Bone mineral density; Computed tomography; Inter-observer variability; Intra-observer variability; Osteoporosis