Assessment Of Synovitis In Knee Osteoarthritis On Contrast-Enhanced MRI Using A Novel Comprehensive Semiquantitative Scoring System - The Most Study

Title:

Assessment Of Synovitis In Knee Osteoarthritis On Contrast-Enhanced MRI Using A Novel Comprehensive Semiquantitative Scoring System - The Most Study

Author(s):

Ali Guermazi1, Frank W. Roemer1, Michel D. Crema1, Jingbo Niu1, Yuqing Zhang1, Monica D. Marra1, John A. Lynch2, M. Kassim Javaid2, George Y. El-Khoury3, Kristin R. Baker1, Laura B. Hughes4, Michael C. Crema2, David T. Felson1. 1BUMC, Boston, MA; 2UCSF, San Francisco, CA; 3U of Iowa, Iowa City, IA; 4UAB, Birmingham, AL

Purpose: Synovitis is defined as inflammation of the synovial membrane and is characterized by thickening and enhancement after administration of i.v. contrast agent. To date, synovitis is assessed on non-contrast-enhanced (CE) MRI using a surrogate marker of signal changes in Hoffa’s fat pad which are a non-specific finding and do not reflect whole joint synovitis. Our aim is to introduce a detailed and reliable scoring system for the assessment of whole knee joint synovitis.

Methods: The MOST study is a longitudinal observational study of individuals who have or are at high risk for knee OA. Subjects are an unselected subset of the MOST who volunteered for CE MRI. Synovitis was assessed at 11 sites of the joint: the medial and lateral parapatellar recesses, suprapatellar, infrapatellar, intercondylar, medial and lateral perimeniscal, Baker cyst, adjacent to the PCL, ACL and loose bodies. Synovial thickness was scored semiquantitatively: grade 0 (<2 mm), grade 1 (2-4 mm) and grade 2 (>4 mm) at each site. Two musculoskeletal radiologists performed the readings. To assess whole-knee synovitis, we summed the scores for the 11 sites and categorized knees as follows: 0-4=normal synovium or equivocal synovitis, 5-8=mild synovitis, 9-12=moderate synovitis, ≥13=severe synovitis. Inter- and intra-reader reliability (rr) for each individual site was calculated using kappa statistics. In addition we assessed the association of the summed synovitis scores with the maximum value of 5 WOMAC knee pain items.

Results: 403 knees were included in the analysis (mean age 58.8 years ± 7.0, mean BMI 29.5 ± 4.9, 45.7% women). Intra-rr for the individual sites ranged from 0.70 and 1.00 for reader 1 and 0.60 to 1.00 for reader 2. Inter-rr ranged from 0.67 to 0.92. For the summed synovitis score of 11 sites, weighted-kappa for intra-rr was 0.99 for reader 1, 0.96 for reader 2 and weighted-kappa for inter-rr was 0.98 (Table 1). Moderate and severe synovitis showed a significant association with the maximum WOMAC pain score item (adjusted OR of 2.7 and 3.4 respectively, 95% CI 1.4-5.3 and 1.4-8.6 respectively).

Conclusions: We described a novel comprehensive semi-quantitative scoring system for the assessment of whole-knee synovitis. The proposed assessment is reliable and identifies knees with pain. The system provides a more comprehensive picture of whole-knee synovial changes in OA than previous methods do and could be applied in large epidemiological OA studies.

Inter- and intra-reader agreement for individual synovitis sites scores.

 

Feature

Intra-reader 1 weighted-kappa
(95% CI) 

Intra-reader 2 weighted-kappa
(95% CI)

 Inter-readers weighted-kappa (95% CI)
 Medial parapatellar recess 1.00 (1.00-1.00) 0.70 (0.48-0.92) 0.80 (0.62-0.98)
 Lateral parapatellar recess  0.80 (0.60-0.99) 0.93 (0.81-1.00) 0.81 (0.63-0.99)
 Suprapatellar 0.92 (0.81-1.00) 0.63 (0.41-0.86) 0.83 (0.69-0.97)
 Infrapatellar 0.83 (0.69-0.97) 0.81 (0.60-1.00)0.78 (0.62-0.93) 
 Intercondylar 0.80 (0.64-0.96)  1.00 (1.00-1.00) 0.67 (0.50-0.85)
 Adjacent to the PCL  0.83 (0.69-0.97) 0.60 (0.34-0.86) 0.70 (0.55-0.86)
 Adjacent to the ACL  0.76 (0.53-0.96) 0.95 (0.86-1.00)  0.69 (0.51-0.88)
 Medial perimeniscal  0.94 (0.84-1.00)  0.74 (0.57-0.91)  0.91 (0.79-1.00)
 Lateral perimeniscal  0.78 (0.61-0.94)  0.75 (0.53-0.96)  0.67 (0.49-0.85)
 Adjacent to loose bodies 0.67 (0.10-1.00) 0.00 (0.00-0.00)* 0.73 (0.31-1.00)
 Baker cyst  0.85 (0.56-1.00)  0.74 (0.26-1.00)  0.92 (0.77-1.00)
*Only few knees with loose bodies scored by reader 2

Disclosures:

A. Guermazi, Synarc Inc, 1; BICL LLC, 4; F.W. Roemer, None; M.D. Crema, None; J. Niu, None; Y. Zhang, None; M.D. Marra, None; J.A. Lynch, None; M.K. Javaid, None; G.Y. El-Khoury, None; K.R. Baker, None; L.B. Hughes, None; M.C. Crema, None; D.T. Felson, None.