Cross-sectional reliability and concurrent validity of a quantitative 2-dimensional ultrasound image analysis of effusion and synovial hypertrophy in knee osteoarthritis

Robert Dima; Trevor B Birmingham; Holly T Philpott; Dianne Bryant; Aaron Fenster; C Thomas Appleton

doi:10.1016/j.ocarto.2023.100356

Cross-sectional reliability and concurrent validity of a quantitative 2-dimensional ultrasound image analysis of effusion and synovial hypertrophy in knee osteoarthritis

Osteoarthr Cartil Open. 2023 Mar 16;5(2):100356. doi: 10.1016/j.ocarto.2023.100356. eCollection 2023 Jun.

Authors

Robert Dima^{1

2}, Trevor B Birmingham^{1

2}, Holly T Philpott^{1

2}, Dianne Bryant^{1

2}, Aaron Fenster^{3

4}, C Thomas Appleton^{2

5

6}

Affiliations

¹ Faculty of Health Sciences, University of Western Ontario, London, ON, N6G 1H1, Canada.
² Bone and Joint Institute, University of Western Ontario, London Health Sciences Centre-University Hospital, London, ON, N6A 5B5, Canada.
³ Department of Medical Biophysics, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, N6A 5C1, Canada.
⁴ Centre for Medical Imaging, Robarts Research Institute, London, ON, N6A 5K8, Canada.
⁵ Department of Medicine, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, N6A 5C1, Canada.
⁶ Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, N6A 5C1, Canada.

Abstract

Objective: Effusion-synovitis is related to pain and progression in knee osteoarthritis (OA), but current gold standard ultrasound (US) measures are limited to semi-quantitative grading of joint distension or 1-dimensional thickness measures. A novel quantitative 2-dimensional image analysis methodology is applied to US images of effusion-synovitis; reliability and concurrent validity was assessed in patients with knee OA.

Methods: Cross sectional analysis of US images collected from 51 patients with symptomatic knee OA were processed in ImageJ and segmented in 3DSlicer to produce a binary mask of the supra-patellar synovitis region of interest (ROI). Area measures (mm²) of total synovitis, effusion and hypertrophy components were exported. Intra-rater reliability and test-retest reliability (1-14 days washout) were estimated with intra-class correlation coefficients (ICCs). Concurrent validity was measured by Spearman correlations between quantitative measures and gold standard OMERACT and caliper measurements of synovitis.

Results: Intra-rater reliability for hypertrophy area was estimated at 0.98, 0.99 for effusion area, and 0.99 for total synovitis area. The test-retest reliability for total synovitis area was 0.63 (SEM 87.8 mm²), 0.59 for hypertrophy area (SEM 21.0 mm²), and 0.64 for effusion area (SEM 73.8 mm²). Correlation between total synovitis area and OMERACT grade was 0.84, 0.81 between total synovitis area and effusion-synovitis calipers, and 0.81 between total effusion area and effusion calipers.

Conclusion: This new research tool for image analysis demonstrated excellent intra-rater reliability, good concurrent validity, and moderate test-retest reliability. Quantitative 2D US measures of effusion-synovitis and its individual components may enhance the study and management of knee OA.

Keywords: Measurement properties; Osteoarthritis; Reliability; Synovitis; Ultrasound; Validity.