title: Severity mapping of the proximal femur: a new method for assessing hip osteoarthritis with computed tomography.
abstract: OBJECTIVE
  Plain radiography has been the mainstay of imaging assessment in osteoarthritis for over 50 years, but it does have limitations. Here we present the methodology and results of a new technique for identifying, grading, and mapping the severity and spatial distribution of osteoarthritic disease features at the hip in 3D with clinical computed tomography (CT).
  
  
  METHODS
  CT imaging of 456 hips from 230 adult female volunteers (mean age 66 ± 17 years) was reviewed using 3D multiplanar reformatting to identify bone-related radiological features of osteoarthritis, namely osteophytes, subchondral cysts and joint space narrowing. Scoresheets dividing up the femoral head, head-neck region and the joint space were used to register the location and severity of each feature (scored from 0 to 3). Novel 3D cumulative feature severity maps were then created to display where the most severe disease features from each individual were anatomically located across the cohort.
  
  
  RESULTS
  Feature severity maps showed a propensity for osteophytes at the inferoposterior and superolateral femoral head-neck junction. Subchondral cysts were a less common and less localised phenomenon. Joint space narrowing <1.5 mm was recorded in at least one sector of 83% of hips, but most frequently in the posterolateral joint space.
  
  
  CONCLUSIONS
  This is the first description of hip osteoarthritis using unenhanced clinical CT in which we describe the co-localisation of posterior osteophytes and joint space narrowing for the first time. We believe this technique can perform several important roles in future osteoarthritis research, including phenotyping and sensitive disease assessment in 3D.
authors.affiliation: Department of Engineering, University of Cambridge, Trumpington Street, Cambridge CB2 1PZ, UK; Department of Radiology, Box 218, Level 5, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0QQ, UK; Department of Medicine, Box 157, Level 5, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0QQ, UK. Electronic address: tom@diagnosticradiology.eu.
authors.forename: T D
authors.initials: TD
authors.lastname: Turmezei
authors.affiliation: Department of Radiology, Box 218, Level 5, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0QQ, UK.
authors.forename: D J
authors.initials: DJ
authors.lastname: Lomas
authors.affiliation: Department of Radiology, Box 218, Level 5, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0QQ, UK.
authors.forename: M A
authors.initials: MA
authors.lastname: Hopper
authors.affiliation: Department of Medicine, Box 157, Level 5, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0QQ, UK.
authors.forename: K E S
authors.initials: KE
authors.lastname: Poole
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001845:Bone Cysts / Q000000981:diagnostic imaging* / Q000209:etiology; D005260:Female; D005270:Femur Head / Q000000981:diagnostic imaging*; D005272:Femur Neck / Q000000981:diagnostic imaging*; D006621:Hip Joint / Q000000981:diagnostic imaging*; D006801:Humans; D021621:Imaging, Three-Dimensional; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000150:complications / Q000000981:diagnostic imaging*; D054850:Osteophyte / Q000000981:diagnostic imaging* / Q000209:etiology; D012720:Severity of Illness Index; D014057:Tomography, X-Ray Computed
keywords: Computed tomography; Hip joint; Osteoarthritis; Phenotyping