title: Microdose acquisition in adolescent leg length discrepancy using a low-dose biplane imaging system.
abstract: Background Children with leg length discrepancy often undergo repeat imaging. Therefore, every effort to reduce radiation dose is important. Using low dose preview images and noise reduction software rather than diagnostic images for length measurements might contribute to reducing dose. Purpose To compare leg length measurements performed on diagnostic images and low dose preview images both acquired using a low-dose bi-planar imaging system. Material and Methods Preview and diagnostic images from 22 patients were retrospectively collected (14 girls, 8 boys; mean age, 12.8 years; age range, 10-15 years). All images were anonymized and measured independently by two musculoskeletal radiologists. Three sets of measurements were performed on all images; the mechanical axis lines of the femur and the tibia as well as the anatomical line of the entire extremity. Statistical significance was tested with a paired t-test. Results No statistically significant difference was found between measurements performed on the preview and on the diagnostic image. The mean tibial length difference between the observers was -0.06 cm (95% confidence interval [CI], -0.12 to 0.01) and -0.08 cm (95% CI, -0.21 to 0.05), respectively; 0.10 cm (95% CI, 0.02-0.17) and 0.06 cm (95% CI, -0.02 to 0.14) for the femoral measurements and 0.12 cm (95% CI, -0.05 to 0.26) and 0.08 cm (95% CI, -0.02 to 0.19) for total leg length discrepancy. ICCs were >0.99 indicating excellent inter- and intra-rater reliability. Conclusion The data strongly imply that leg length measurements performed on preview images from a low-dose bi-planar imaging system are comparable to measurements performed on diagnostic images.
authors.affiliation: 1 Department of Radiology, Odense University Hospital, Odense, Denmark.
authors.forename: Janni
authors.initials: J
authors.lastname: Jensen
authors.affiliation: 1 Department of Radiology, Odense University Hospital, Odense, Denmark.|2 Institute of Clinical Research, University of Southern Denmark, Odense, Denmark.
authors.forename: Bo R
authors.initials: BR
authors.lastname: Mussmann
authors.affiliation: 1 Department of Radiology, Odense University Hospital, Odense, Denmark.|3 Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark.
authors.forename: John
authors.initials: J
authors.lastname: Hjarbæk
authors.affiliation: 1 Department of Radiology, Odense University Hospital, Odense, Denmark.
authors.forename: Zaid
authors.initials: Z
authors.lastname: Al-Aubaidi
authors.affiliation: 4 Department of Orthopedics, Odense University Hospital, Odense, Denmark.
authors.forename: Niels W
authors.initials: NW
authors.lastname: Pedersen
authors.affiliation: 5 Department of Nuclear Medicine, Odense University Hospital, Odense, Denmark.|6 Centre of Health Economics Research, University of Southern Denmark, Odense, Denmark.
authors.forename: Oke
authors.initials: O
authors.lastname: Gerke
authors.affiliation: 1 Department of Radiology, Odense University Hospital, Odense, Denmark.
authors.forename: Trine
authors.initials: T
authors.lastname: Torfing
mesh_terms: D000293:Adolescent; D002648:Child; D003952:Diagnostic Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007870:Leg Length Inequality / Q000000981:diagnostic imaging*; D008297:Male; D011829:Radiation Dosage; D012189:Retrospective Studies; D012984:Software
keywords: Leg length inequality; observer variation; pediatrics; radiology