Qualitative Analysis of Articular Cartilage of the Knee Joint on a 1.5 T MRI is Highly Sensitive and Correlates with Arthroscopic Assessments

The prevalence of osteoarthritis is increasing with aging and increasing rates of obesity. Currently, conventional methods of imaging provide accurate means to detect morphological deterioration of cartilage in the later stages of osteoarthritis, however these methods are not sensitive to the subtle changes during early disease stages. In osteoarthritis, assessment of degenerative cartilage disease is important for recommending adequate treatment. Using a representative sample of 10 patients, this case series investigated whether there is a correlation between MRI cartilage assessment and arthroscopy findings in patients with osteoarthritis of knee.

In a cross-sectional study as a part of the retrospective case-control study, 10 patients (mean age 53.1) with clinically suspected osteoarthritis underwent standardized MRI (Sag and Axial PD fatsat, Cor STIR, Cor T2* GRE, Sag T2 and T1, Cor and Axial T2 map) on a 1.5 T unit (GE Signa HDxt). The patients also underwent a diagnostic arthroscopy within 2 months of the MRI study to assess the grading of the articular cartilage.

The sensitivity and specificity in the detection of 23 cartilage lesions of all arthroscopic grades were 86.9% (20of 23 lesions) and 91.3% (21 of 23 lesions) for the MR imaging protocol with T2 maps. The addition of the T2 maps to the routine MR imaging protocol improved the sensitivity of detection among all grades of lesions. The MR imaging protocol with T2 maps had significantly higher sensitivity for detecting arthroscopic grade 1A (P <.001), arthroscopic grade 1B (P <.001), arthroscopic grade 2A (P =.004), arthroscopic grade 2B (P =.023), and all arthroscopic grades of cartilage lesions (P <.001) and significantly lower specificity for detecting all arthroscopic grades of cartilage lesions (P <.001). A tendency to underestimate the cartilage disorders on MRI images was not noticed.

According to our results there is a good correlation between MRI grading of articular cartilage and arthroscopic grading. However a diagnostic arthroscopy is of utmost importance when a crucial decision needs to be taken regarding therapeutic options in patients with osteoarthritis.