title: Quantitative magnetic resonance imaging evidence of synovial proliferation is associated with radiographic severity of knee osteoarthritis.
abstract: OBJECTIVE
  To evaluate the relationships between both quantitative and semiquantitative assessments of the degree of knee synovitis on 3T magnetic resonance imaging (MRI) and the severity of knee osteoarthritis (OA) on radiography.
  
  
  METHODS
  Fifty-eight patients with knee OA underwent nonfluoroscopic fixed-flexion knee radiography. In addition, dynamic contrast-enhanced 3T MRI of the knees was performed, before and after gadolinium administration, to quantify synovial membrane volume (SV) as a measure of synovial proliferation (expressed as the quantitative SV), and semiquantitative measures of synovitis were also applied using both contrast-enhanced and unenhanced images. Two radiologists scored the knee radiographs using the Osteoarthritis Research Society International atlas; interreader agreement was assessed using kappa statistics and concordance correlation coefficients. Multiple linear and logistic regression analyses were used to assess associations among variables, while controlling for the effects of age, body mass index, sex, and meniscal extrusion. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated for measures of disease activity.
  
  
  RESULTS
  The Kellgren/Lawrence (K/L) grade of radiographic knee OA severity (β=0.78), the diseased compartment joint space width (dcJSW) (β=-0.22), and the diseased compartment joint space narrowing (dcJSN) score (β=0.53) were each significantly associated with the quantitative SV (P=0.0001, P=0.0003, and P=0.0001, respectively). Furthermore, the quantitative SV strongly correlated with the total volume of subchondral bone marrow lesions (BMLs) (β=0.22, P=0.0003). The K/L grade, dcJSW, and dcJSN score were each significantly associated with the semiquantitative Boston Leeds Osteoarthritis Knee Score (BLOKS) for the extent of infrapatellar synovitis (OR 9.05 [95% CI 1.94, 42.3] for K/L grade; OR 0.75 [95% CI 0.54, 1.03] for dcJSW; and OR 2.22 [95% CI 1.15, 4.31] for dcJSN score) and extent of joint effusion (OR 5.75 [95% CI 1.23, 26.8] for K/L grade; OR 0.70 [95% CI 0.50, 0.98] for dcJSW; and OR 1.96 [95% CI 1.02, 3.74] for dcJSN score). In addition, the semiquantitative synovitis grade on contrast-enhanced MRI was significantly associated with the K/L grade (β=0.036, P=0.0040) and dcJSN score (β=0.015, P=0.0266), and also significantly associated with the BLOKS synovitis score.
  
  
  CONCLUSIONS
  Synovitis is a characteristic feature of advancing knee OA and is significantly associated with the K/L grade, JSW, JSN score, and total volume of BMLs on radiographs. Furthermore, BLOKS scoring of synovitis on unenhanced MRI is associated with measurements of synovitis on contrast-enhanced MRI.
authors.affiliation: New York University Langone Medical Center and New York University Hospital for Joint Diseases, New York, New York 10003, USA. krasns01@nyumc.org
authors.forename: Svetlana
authors.initials: S
authors.lastname: Krasnokutsky
authors.forename: Ilana
authors.initials: I
authors.lastname: Belitskaya-Lévy
authors.forename: Jenny
authors.initials: J
authors.lastname: Bencardino
authors.forename: Jonathan
authors.initials: J
authors.lastname: Samuels
authors.forename: Mukundan
authors.initials: M
authors.lastname: Attur
authors.forename: Ravinder
authors.initials: R
authors.lastname: Regatte
authors.forename: Pamela
authors.initials: P
authors.lastname: Rosenthal
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Greenberg
authors.forename: Mark
authors.initials: M
authors.lastname: Schweitzer
authors.forename: Steven B
authors.initials: SB
authors.lastname: Abramson
authors.forename: Leon
authors.initials: L
authors.lastname: Rybak
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002358:Cartilage, Articular / Q000000981:diagnostic imaging / Q000473:pathology; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging* / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging* / Q000473:pathology; D010147:Pain Measurement; D011859:Radiography; D012720:Severity of Illness Index; D013583:Synovial Membrane / Q000000981:diagnostic imaging* / Q000473:pathology; D013585:Synovitis / Q000000981:diagnostic imaging* / Q000473:pathology