title: Evaluating Length: The Use of Low-dose Biplanar Radiography (EOS) and Tantalum Bead Implantation.
abstract: BACKGROUND
  Low-dose biplanar radiography (EOS) is an appealing imaging modality for use in children given its low radiation and ease of use. The goal of this study was to determine the accuracy and reliability of EOS compared with CT scanogram for measurement of leg length and to assess interrater and intrarater reliability of measured interbead distances for EOS and CT scanogram after insertion of tantalum beads into lamb femurs.
  
  
  METHODS
  Tantalum beads (0.8 mm) were inserted into the cortex on both the medial and lateral sides of 10 skeletally immature lamb femurs. CT scanogram and EOS imaging were obtained. Measurements of total length and distance between bead pairs were recorded on anteroposterior and lateral views by 2 orthopaedic surgeons on 2 separate occasions. Pearson correlations were performed for statistical comparisons.
  
  
  RESULTS
  EOS measurements showed near-perfect correlation to those of CT scanogram (r>0.96, P<0.001). Intrarater reliability was excellent for all measurements with EOS (r>0.98, P<0.001) and CT scanogram (r>0.99, P<0.001) as was interrater reliability for EOS (r>0.98, P<0.001) and CT scanogram (r>0.99, P<0.001).
  
  
  CONCLUSIONS
  EOS is comparable with CT scanogram in the assessment of limb length and the distance between 2 radiopaque markers. Reliability was excellent for all measurements. The combination of EOS imaging and tantalum bead implantation may be an effective way to evaluate physeal growth following procedures such as epiphysiodesis and physeal bar resection.
  
  
  METHODS
  Level II—diagnostic
authors.affiliation: *Hospital for Special Surgery †College of Physicians and Surgeons, Columbia University, New York, NY.
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Garner
authors.forename: Matthew
authors.initials: M
authors.lastname: Dow
authors.forename: Elise
authors.initials: E
authors.lastname: Bixby
authors.forename: Doug N
authors.initials: DN
authors.lastname: Mintz
authors.forename: Roger F
authors.initials: RF
authors.lastname: Widmann
authors.forename: Emily R
authors.initials: ER
authors.lastname: Dodwell
mesh_terms: D000818:Animals; D001852:Bone Lengthening / Q000379:methods*; D004195:Disease Models, Animal; D005269:Femur / Q000000981:diagnostic imaging* / Q000601:surgery; D007554:Isotopes; D007870:Leg Length Inequality / Q000000981:diagnostic imaging* / Q000601:surgery; D011829:Radiation Dosage; D015203:Reproducibility of Results; D012756:Sheep; D025321:Surgery, Computer-Assisted / Q000379:methods*; D013635:Tantalum; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D007554:Isotopes; D013635:Tantalum