Is T2 mapping reliable in evaluation of native and repair cartilage tissue of the knee?

Abstract

Purpose To evaluate the effect of imaging plane and experience of observers on the reliability of T2 mapping of native and repair cartilage tissue of the knee. Methods Fifteen consecutive patients from two randomised controlled trials (RCTs) were included in this cross-sectional study. Patients with an isolated knee cartilage lesion were randomised to receive either debridement or microfracture (RCT 1) or debridement or autologous chondrocyte implantation (RCT 2). T2 mapping was performed in coronal and sagittal planes two years postoperatively. A musculoskeletal radiologist, a resident of radiology and two orthopaedic surgeons measured the T2 values independently. Intraclass Correlation Coefficient (ICC) with 95% Confidence Intervals was used to calculate the inter- and intraobserver agreement. Results Mean age for the patients was 36.8 ± 11 years, 8 (53%) were men. The overall interobserver agreement varied from poor to good with ICCs in the range of 0.27– 0.76 for native cartilage and 0.00 – 0.90 for repair tissue. The lowest agreement was achieved for evaluations of repair cartilage tissue. The estimated ICCs suggested higher inter- and intraobserver agreement for radiologists. On medial femoral condyles, T2 values were higher for native cartilage on coronal images (p < 0.001) and for repair tissue on sagittal images (p < 0.001). Conclusions The reliability of T2 mapping of articular cartilage is influenced by the imaging plane and the experience of the observers. This influence may be more profound for repair cartilage tissue. This is important to consider when using T2 mapping to measure outcomes after cartilage repair surgery. Trial registration ClinicalTrials.gov, NCT02637505 and NCT02636881, registered December 2015. Level of evidence II, based on prospective data from two RCTs.

Editorial for “Effects of T1p Characteristics of Load‐Bearing Hip Cartilage on Bilateral Knee Patellar Cartilage Subregions: Subjects with None to Moderate Radiographic Hip Osteoarthritis”

“…Initial cartilage degradation starts with loss of proteoglycan content, 3 increase in water content, 4 and disruption of the collagen network. 5 These changes over time can lead to broader extents of irreversible morphological cartilage damage and narrowing of joint spaces. 6 Quantitative magnetic resonance imaging (MRI), specifically T1p and T2 mapping 7 have been quite well established as compositional imaging biomarkers to depict such microscopic extents of early cartilage changes, even in asymptomatic populations.…”

“…Initial cartilage degradation starts with loss of proteoglycan content, 3 increase in water content, 4 and disruption of the collagen network 5 . These changes over time can lead to broader extents of irreversible morphological cartilage damage and narrowing of joint spaces 6 .…”