title: Extremity cone-beam CT for evaluation of medial tibiofemoral osteoarthritis: Initial experience in imaging of the weight-bearing and non-weight-bearing knee.
abstract: OBJECTIVE
  To investigate differences in joint space width (JSW) and meniscal extrusion (ME) between non-weight bearing (NWB) and weight bearing (WB) examinations of knee joints with medial compartment osteoarthritis (OA) using a cone-beam CT (CBCT) extremity imaging system.
  
  
  METHODS
  In this IRB approved prospective study, informed consent was obtained for 17 patients symptomatic for OA (11 F,6 M; 31-78 years, mean 56 years) and 18 asymptomatic controls (0 F,18 M; 29-48 years, mean 38.5 years) enrolled for CBCT exams in NWB and WB positions. Three independent observers measured medial tibiofemoral JSW and ME. Measurements were compared between NWB and WB images using paired Wilcoxon signed-rank sum test.
  
  
  RESULTS
  OA subjects exhibited a statistically significant reduction in JSW between NWB and WB scans (average JSW(NWB)(OA)=2.1 mm and JSW(WB)(OA)=1.5 mm, p=0.016) and increase in ME (average ME(NWB)(OA)=6.9 mm and ME(WB)(OA)=8.2 mm, p=0.018)). For non-OA subjects, the change in JSW and ME between NWB and WB exams was reduced (average JSW(NWB)(nonOA)=3.7 mm and JSW(WB)(nonOA)=3.4 mm; average ME(NWB)(nonOA)=2.6 mm and ME(WB)(nonOA)=2.7 mm) and was not statistically significant. Inter-observer agreement was evaluated using Bland-Altman limits of agreement, with good agreement for all measurements (correlation coefficient 0.89-0.98).
  
  
  CONCLUSIONS
  The ability to conduct NWB and WB exams in CBCT with a dose profile that is favorable in comparison to multidetector CT (MDCT) and with image quality sufficient for morphological analysis of joint space narrowing and meniscal extrusion could provide a valuable tool for OA diagnosis and treatment assessment.
authors.affiliation: Johns Hopkins University, 601 N. Caroline Street, Baltimore, MD 21202, USA. Electronic address: gthawai1@jhmi.edu.
authors.forename: Gaurav K
authors.initials: GK
authors.lastname: Thawait
authors.affiliation: Johns Hopkins University, 601 N. Caroline Street, Baltimore, MD 21202, USA. Electronic address: sdemehr1@jhmi.edu.
authors.forename: Shadpour
authors.initials: S
authors.lastname: Demehri
authors.affiliation: Johns Hopkins University, 601 N. Caroline Street, Baltimore, MD 21202, USA. Electronic address: almuhit@gmail.com.
authors.forename: Abdullah
authors.initials: A
authors.lastname: AlMuhit
authors.affiliation: Johns Hopkins University, 601 N. Caroline Street, Baltimore, MD 21202, USA. Electronic address: wzbijewski@jhu.du.
authors.forename: Wojciech
authors.initials: W
authors.lastname: Zbijweski
authors.affiliation: Johns Hopkins University, 601 N. Caroline Street, Baltimore, MD 21202, USA. Electronic address: john.yorkston@carestream.com.
authors.forename: John
authors.initials: J
authors.lastname: Yorkston
authors.affiliation: Johns Hopkins University, 601 N. Caroline Street, Baltimore, MD 21202, USA. Electronic address: filippo.delgrande@gmail.com.
authors.forename: Filippo
authors.initials: F
authors.lastname: Del Grande
authors.affiliation: Johns Hopkins University, 601 N. Caroline Street, Baltimore, MD 21202, USA. Electronic address: bzikria2@jhmi.edu.
authors.forename: Bashir
authors.initials: B
authors.lastname: Zikria
authors.affiliation: Johns Hopkins University, 601 N. Caroline Street, Baltimore, MD 21202, USA. Electronic address: carrinoj@hss.edu.
authors.forename: John A
authors.initials: JA
authors.lastname: Carrino
authors.affiliation: Johns Hopkins University, 601 N. Caroline Street, Baltimore, MD 21202, USA. Electronic address: jeff.siewerdsen@jhu.edu.
authors.forename: Jeffrey H
authors.initials: JH
authors.lastname: Siewerdsen
mesh_terms: D000328:Adult; D000368:Aged; D054893:Cone-Beam Computed Tomography; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D011446:Prospective Studies; D016474:Weight-Bearing / Q000502:physiology*
keywords: Cone-beam CT; Extremity imaging; Functional imaging; Osteoarthritis; Weight bearing imaging