A novel method for assessing signal intensity within infrapatellar fat pad on MR images in patients with knee osteoarthritis

• Published in: Osteoarthritis and cartilage 2016-11, Vol.24 (11), p.1883-1889
• Main Authors: Lu, Ming, MD, Chen, Zhongshan, PhD, Han, Weiyu, PhD candidate, MD, Zhu, Zhaohua, PhD candidate, Jin, Xingzhong, PhD candidate, Hunter, David J., PhD, Ding, Changhai, MD
• Format: Article
• Language: English
• Subjects: Adipose Tissue; High signal intensity; Humans; Infrapatellar fat pad; Knee Joint; Magnetic Resonance Imaging; MR images; Osteoarthritis; Osteoarthritis, Knee; Reproducibility of Results; Rheumatology
• ISSN: 1063-4584; 1522-9653
• DOI: 10.1016/j.joca.2016.06.008

Summary Purpose To assess reliability and validity of a semi-automated quantitative method to measure infrapatellar fat pad (IPFP) signal intensity in patients with knee osteoarthritis (OA). Methods 100 patients with knee OA were selected. Sagittal planes of fat-saturated T2-weighted images obtained on 1.5-T MRI were utilized to assess IPFP signal intensity using MATLAB. Knee structural abnormalities including cartilage defects, bone marrow lesions and radiographic OA were evaluated. Clinical construct validity and concurrent validity were examined through describing associations of IPFP measurements with knee structural abnormalities and a semi-quantitative scoring method, respectively. The reliability was examined by calculating the intra- and inter-observer correlation coefficients. Results Significantly positive associations were found between standard deviation of IPFP intensity [sDev(IPFP)], clustering factor(H) and all knee structural abnormalities. The volume of high signal intensity regions [Volume(H)] and the ratio of Volume(H) to volume of whole IPFP [Percentage (H)] were positively associated with cartilage defects and radiographic OA, but not with bone marrow lesions. The median value [Median (H)] and upper quartile value [UQ(H)] of high signal intensity were only significantly associated with quartiles of cartilage defect score. Significant correlations were found between all quantitative measurements and semi-quantitative scores (All p0.90). Conclusions A novel and efficient method to segment IPFP and calculate its signal intensity on T2-weighted MRI images is documented. This method is reproducible, and has concurrent and clinical construct validity, but its predictive validity needs to be examined by future longitudinal studies.