title: Investigation of the reproducibility and reliability of sagittal vertebral inclination measurements from MR images of the spine.
abstract: In this study, sagittal vertebral inclination (SVI) was systematically evaluated for 28 vertebrae (segments between T4 and L5) in magnetic resonance (MR) images of one normal and one scoliotic subject to compare the performance of manual and computerized measurements, and identify the most reproducible and reliable measurements. Manual measurements were performed by three observers, who identified on two occasions the distinctive anatomical landmarks required to evaluate SVI by six measurement methods, i.e. the superior tangents, inferior tangents, anterior tangents, posterior tangents, mid-endplate lines and mid-wall lines. Computerized measurements were performed by automatically evaluating SVI from the symmetry of vertebral anatomical structures in two-dimensional (2D) sagittal cross-sections and in three-dimensional (3D) volumetric images. The mid-wall lines and posterior tangents proved to be the manual measurements with the lowest intra-observer (standard deviation, SD, of 1.4° and 1.7°, respectively) and inter-observer variability (SD of 1.9° and 2.4°, respectively). The strongest inter-method agreement was found between the mid-wall lines and posterior tangents (SD of 2.0°). Computerized measurements in 2D and in 3D resulted in intra-observer (SD of 2.8° and 3.1°, respectively) and inter-observer variability (SD of 3.8° and 5.2°, respectively) that were comparable to those of the superior tangents (SD of 2.6° and 3.7°) and inferior tangents (SD of 3.2° and 4.5°), which represent standard Cobb angle measurements. It can be concluded that computerized measurements of SVI should be based on the inclination of vertebral body walls.
authors.affiliation: University of Ljubljana, Faculty of Electrical Engineering, Tržaška cesta 25, SI-1000 Ljubljana, Slovenia. Electronic address: tomaz.vrtovec@fe.uni-lj.si.
authors.forename: Tomaž
authors.initials: T
authors.lastname: Vrtovec
authors.affiliation: University of Ljubljana, Faculty of Electrical Engineering, Tržaška cesta 25, SI-1000 Ljubljana, Slovenia.
authors.forename: Franjo
authors.initials: F
authors.lastname: Pernuš
authors.affiliation: University of Ljubljana, Faculty of Electrical Engineering, Tržaška cesta 25, SI-1000 Ljubljana, Slovenia.
authors.forename: Boštjan
authors.initials: B
authors.lastname: Likar
mesh_terms: D000328:Adult; D000465:Algorithms; D016477:Artifacts; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D015588:Observer Variation; D056888:Patient Positioning / Q000379:methods*; D010363:Pattern Recognition, Automated / Q000379:methods*; D015203:Reproducibility of Results; D012600:Scoliosis / Q000473:pathology*; D012680:Sensitivity and Specificity
keywords: Computerized measurements; Magnetic resonance imaging; Manual measurements; Sagittal vertebral inclination