The following is a summary of “MRI underestimates presence and size of knee osteophytes using CT as a reference standard,” published in the May 2023 issue of Osteoarthritis and Cartilage by Roemer et al.

This study aimed to investigate the diagnostic efficacy of standard MRI in the cross-sectional evaluation of osteophytes (OPs) in the knee’s three compartments, with computed tomography (CT) serving as the reference standard. The Strontium Ranelate Efficacy in Knee Osteoarthritis (SEKOIA) trial investigated the impact of administering strontium ranelate for 3 years on individuals with primary knee osteoarthritis. The patients underwent evaluation solely at the baseline visit, wherein they were assessed using a modified MRI Osteoarthritis Knee Score (MOAKS) scoring system. The scoring system evaluated the patellofemoral (PFJ), medial tibiofemoral (TFJ), and lateral TFJ regions. Size assessment was conducted on a scale of 0 to 3 in a total of 18 anatomical sites. 

Descriptive statistics delineated dissimilarities in ordinal grading amidst CT and MRI. Moreover, weighted-kappa statistics were utilized to evaluate the concordance between the two scoring techniques. The diagnostic performance was evaluated using CT as the reference standard, and measures such as sensitivity, specificity, positive predictive value, negative predictive value, and area under the curve (AUC) were utilized. A total of 74 patients were included in the study, with both MRI and CT data available. The mean age of the subjects was 62.9 ± 7.5 years. A total of 1,332 sites were assessed. The MRI findings for the patellofemoral joint revealed the detection of 141 out of 197 CT-defined osteochondral lesions, resulting in a weighted kappa value of 0.58 (95% CI [0.52-0.65]). 

The magnetic resonance imaging (MRI) results revealed the detection of 178 out of 219 computed tomography osteophytes (CT-OPs) in the medial tibiofemoral joint (TFJ), resulting in an 81% detection rate. The weighted kappa value was 0.58 (95% CI [0.51-0.64]). Regarding the lateral compartment, 84 out of 120 CT-OPs exhibited these figures, representing a percentage of 70%. The w-kappa value was 0.58 (95% CI [0.50–0.66]). The magnetic resonance imaging modality tends to underestimate the existence of osteophytes in the medial, lateral, and patellofemoral compartments of the knee joint. Therefore, computed tomography (CT) imaging may provide valuable assistance, especially in evaluating minor osteophytes, particularly in the early stages of the disease.

Source: https://www.sciencedirect.com/science/article/abs/pii/S1063458423005940