title: Characterization of 3D joint space morphology using an electrostatic model (with application to osteoarthritis).
abstract: Joint space morphology can be indicative of the risk, presence, progression, and/or treatment response of disease or trauma. We describe a novel methodology of characterizing joint space morphology in high-resolution 3D images (e.g. cone-beam CT (CBCT)) using a model based on elementary electrostatics that overcomes a variety of basic limitations of existing 2D and 3D methods. The method models each surface of a joint as a conductor at fixed electrostatic potential and characterizes the intra-articular space in terms of the electric field lines resulting from the solution of Gauss' Law and the Laplace equation. As a test case, the method was applied to discrimination of healthy and osteoarthritic subjects (N = 39) in 3D images of the knee acquired on an extremity CBCT system. The method demonstrated improved diagnostic performance (area under the receiver operating characteristic curve, AUC > 0.98) compared to simpler methods of quantitative measurement and qualitative image-based assessment by three expert musculoskeletal radiologists (AUC = 0.87, p-value = 0.007). The method is applicable to simple (e.g. the knee or elbow) or multi-axial joints (e.g. the wrist or ankle) and may provide a useful means of quantitatively assessing a variety of joint pathologies.
authors.affiliation: Department of Biomedical Engineering, Johns Hopkins University, Baltimore MD, USA.
authors.forename: Qian
authors.initials: Q
authors.lastname: Cao
authors.forename: Gaurav
authors.initials: G
authors.lastname: Thawait
authors.forename: Grace J
authors.initials: GJ
authors.lastname: Gang
authors.forename: Wojciech
authors.initials: W
authors.lastname: Zbijewski
authors.forename: Thomas
authors.initials: T
authors.lastname: Reigel
authors.forename: Tyler
authors.initials: T
authors.lastname: Brown
authors.forename: Brian
authors.initials: B
authors.lastname: Corner
authors.forename: Shadpour
authors.initials: S
authors.lastname: Demehri
authors.forename: Jeffrey H
authors.initials: JH
authors.lastname: Siewerdsen
mesh_terms: D000328:Adult; D000368:Aged; D003198:Computer Simulation; D054893:Cone-Beam Computed Tomography / Q000379:methods; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000473:pathology*; D055672:Static Electricity