Validity of Radiograph-Based Infrapatellar Fat Pad Opacity Grading for Assessing Knee Synovitis: Correlation With
Seong Jong Yun1, Youngsik Lim2, Wook Jin2
11 Department of Medicine, Graduate School, Kyung Hee University, Seoul, Republic of Korea.
Objective:
The purpose of this study was to determine the validity of infrapatellar fat pad (IPFP) opacity grading based on lateral knee radiography for assessing knee synovitis using correlation with contrast-enhanced (CE) MRI.
Materials And Methods:
Retrospective reviews of radiographs and CE knee MR images from 79 patients were independently performed by two radiologists. They evaluated IPFP opacity alteration (IPFPCR) and joint effusion grades on lateral knee conventional radiographs, IPFP signal intensity alteration (IPFPMR) and joint effusion grades on CE MR images, and synovitis (SYNMR) grade in nine divided regions, three compartments (parapatellar, periligamentous, perimeniscal), and the whole knee on CE MR images. Correlations between radiographic grades and MRI assessments were evaluated using Spearman correlation tests, and the correlation coefficients (ρ) were compared. Interobserver agreement was evaluated using weighted kappa values.
Results:
The IPFPCR grade was very highly correlated with the IPFPMR grade (ρ = 0.906, p < 0.001) and highly correlated with SYNMR grades from four regions (suprapatellar, infrapatellar, intercondylar, lateral parapatellar recess), the parapatellar compartment, and the whole knee (ρ = 0.614-0.740, all p < 0.001). The IPFPCR grade was moderately correlated with the SYNMR grades of the remaining five regions and two compartments (ρ = 0.457-0.547, all p < 0.001). The differences between correlation coefficients for SYNMR grades and the IPFPCR and IPFPMR grades were not statistically significant (p = 0.290-1.0). Interobserver reliabilities were excellent or good for IPFPCR, IPFPMR, and SYNMR grades (κ = 0.661-1.000).
Conclusion:
IPFPCR grade assessment enables valid evaluation and reporting of knee synovitis, especially in the parapatellar compartment and the whole knee.
Insights
Infrapatellar fat pad (IPFP) opacity grading on knee X-rays is a valid method for assessing knee synovitis, correlating well with MRI findings. This radiographic assessment is particularly useful for evaluating the parapatellar compartment and the entire knee joint.
Area of Science:
- Orthopedics
- Radiology
- Medical Imaging
Background:
- Knee synovitis is a key indicator of joint inflammation.
- Accurate assessment of synovitis is crucial for effective treatment.
- Contrast-enhanced MRI is a gold standard for synovitis evaluation, but radiography offers a more accessible alternative.
Purpose of the Study:
- To validate the use of infrapatellar fat pad (IPFP) opacity grading on lateral knee radiography.
- To assess the correlation between radiographic IPFP opacity and synovitis detected by contrast-enhanced (CE) MRI.
- To determine the reliability of IPFP opacity grading for knee synovitis assessment.
Main Methods:
- Retrospective review of lateral knee radiographs and CE MRI scans from 79 patients.
- Independent evaluation of IPFP opacity (IPFPCR) and joint effusion on radiographs by two radiologists.
- Assessment of IPFP signal intensity (IPFPMR), joint effusion, and synovitis (SYNMR) in various knee regions and compartments on CE MRI.
- Statistical analysis using Spearman correlation and weighted kappa for interobserver agreement.
Main Results:
- IPFPCR grade showed very high correlation with IPFPMR grade (ρ = 0.906).
- IPFPCR grade demonstrated high correlation with SYNMR grades in four regions, the parapatellar compartment, and the whole knee (ρ = 0.614-0.740).
- Interobserver reliability for IPFPCR, IPFPMR, and SYNMR grading was excellent to good (κ = 0.661-1.000).
Conclusions:
- Infrapatellar fat pad (IPFP) opacity grading on lateral knee radiography is a valid method for evaluating knee synovitis.
- This radiographic assessment is particularly effective for the parapatellar compartment and the whole knee.
- IPFPCR grading offers a reliable and accessible approach for reporting knee synovitis.
Related Concept Videos
01:17Ultrasonography
During an ultrasonography procedure, a handheld device called...
01:30Radiological Investigation II: MRI and Ventilation Perfusion Scan
Magnetic Resonance Imaging (MRI) and Ventilation Perfusion Scans are two radiological investigations that offer detailed diagnostic images of the body, particularly lung structures.
MRI
MRI uses magnetic fields and radiofrequency signals to distinguish between normal and abnormal tissues. This technology provides a more detailed diagnostic image than CT scans, enabling it to characterize pulmonary nodules, stage bronchogenic carcinoma, and evaluate inflammatory activity in...