Veronika Janacova1, Pavol Szomolanyi1,2, Alexandra Kirner3, Siegfried Trattnig4,5,6,7, Vladimir Juras1. 1. High-Field MR Centre, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, BT32, Lazarettgasse 14, 1090, Vienna, Austria. 2. Institute of Measurement Science, Slovak Academy of Sciences, Bratislava, Slovakia. 3. TETEC Tissue Engineering Technologies AG, Aspenhaustraße 18, 72770, Reutlingen, Germany. 4. High-Field MR Centre, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, BT32, Lazarettgasse 14, 1090, Vienna, Austria. siegfried.trattnig@meduniwien.ac.at. 5. CD Laboratory for Clinical Molecular MR Imaging, Vienna, Austria. siegfried.trattnig@meduniwien.ac.at. 6. Austrian Cluster for Tissue Regeneration, Vienna, Austria. siegfried.trattnig@meduniwien.ac.at. 7. Institute for Clinical Molecular MRI in the Musculoskeletal System, Karl Landsteiner Society, Vienna, Austria. siegfried.trattnig@meduniwien.ac.at.
Abstract
OBJECTIVES: The aim of this study was to assess the texture of repair tissue and tissue adjacent to the repair site after matrix-associated chondrocyte transplantation (MACT) of the knee using gray-level co-occurrence matrix (GLCM) texture analysis of T2 quantitative maps. METHODS: Twenty patients derived from the MRI sub-study of multicenter, single-arm phase III study underwent examination on a 3 T MR scanner, including a T2 mapping sequence 12 and 24 months after MACT. Changes between the time points in mean T2 values and 20 GLCM features were assessed for repair tissue, adjacent tissue, and reference cartilage. Differences in T2 values and selected GLCM features between the three cartilage sites at two time points were analyzed using linear mixed-effect models. RESULTS: A significant decrease in T2 values after MACT, between time points, was observed only in repair cartilage (p < 0.001). Models showed significant differences in GLCM features between repair tissue and reference cartilage, namely, autocorrelation (p < 0.001), correlation (p = 0.015), homogeneity (p = 0.002), contrast (p < 0.001), and difference entropy (p = 0.047). The effect of time was significant in a majority of models with regard to GLCM features (except autocorrelation) (p ≤ 0.001). Values in repair and adjacent tissue became similar to reference tissue over time. CONCLUSIONS: GLCM is a useful add-on to T2 mapping in the evaluation of knee cartilage after MACT by increasing the sensitivity to changes in cartilage structure. The results suggest that cartilage tissue adjacent to the repair site heals along with the cartilage implant. KEY POINTS: • GLCM is a useful add-on to T2 mapping in the evaluation of knee cartilage after MACT by increasing the sensitivity to changes in cartilage structure. • Repair and adjacent tissue became similar to reference tissue over time. • The results suggest that cartilage tissue adjacent to the repair site heals along with the cartilage implant.
OBJECTIVES: The aim of this study was to assess the texture of repair tissue and tissue adjacent to the repair site after matrix-associated chondrocyte transplantation (MACT) of the knee using gray-level co-occurrence matrix (GLCM) texture analysis of T2 quantitative maps. METHODS: Twenty patients derived from the MRI sub-study of multicenter, single-arm phase III study underwent examination on a 3 T MR scanner, including a T2 mapping sequence 12 and 24 months after MACT. Changes between the time points in mean T2 values and 20 GLCM features were assessed for repair tissue, adjacent tissue, and reference cartilage. Differences in T2 values and selected GLCM features between the three cartilage sites at two time points were analyzed using linear mixed-effect models. RESULTS: A significant decrease in T2 values after MACT, between time points, was observed only in repair cartilage (p < 0.001). Models showed significant differences in GLCM features between repair tissue and reference cartilage, namely, autocorrelation (p < 0.001), correlation (p = 0.015), homogeneity (p = 0.002), contrast (p < 0.001), and difference entropy (p = 0.047). The effect of time was significant in a majority of models with regard to GLCM features (except autocorrelation) (p ≤ 0.001). Values in repair and adjacent tissue became similar to reference tissue over time. CONCLUSIONS: GLCM is a useful add-on to T2 mapping in the evaluation of knee cartilage after MACT by increasing the sensitivity to changes in cartilage structure. The results suggest that cartilage tissue adjacent to the repair site heals along with the cartilage implant. KEY POINTS: • GLCM is a useful add-on to T2 mapping in the evaluation of knee cartilage after MACT by increasing the sensitivity to changes in cartilage structure. • Repair and adjacent tissue became similar to reference tissue over time. • The results suggest that cartilage tissue adjacent to the repair site heals along with the cartilage implant.
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