Distribution characteristics and quantitative MRI of cartilage injury in knee osteoarthritis

Objective: To investigate the distribution characteristics as well as T₁-, T₂- and T₂^*-mapping MR quantitation of different grades of cartilage injury in knee osteoarthritis (OA). Methods: MRI of 73 knee joints with 213 cartilage lesions was retrospectively analyzed. The arthroscopic results were used as gold standard to compare the distribution and differences of T₁-, T₂-, and T₂^*-mapping values on MRI of different grades of cartilage lesions. Results: Grade I and II cartilage lesions were significantly more common in the patellofemoral joint surface than that in the medial and lateral femorotibial joint surfaces (P < 0.05). There was no difference in the distribution of lesion grades in the two cartilage subareas of the same articular surfaces (P > 0.05). The accuracy of T₂- and T₂^*-mapping was significantly higher than that of T₁-mapping (P < 0.05) for grade I-III lesions without significant difference in accuracy for grade IV lesions (P > 0.05). There was no significant difference between T₂- and T₂^*-mapping for the lesion grades (P > 0.05). The Kappa value of T₂^*-mapping was the highest (0.663). The values of T₁-, T₂- and T₂^*-mapping increased significantly from grade I to grade II lesions with less increase in grade III lesions. The changes of T₂^*-mapping value were more obvious than that of T₂-mapping. There was no significant difference in T₁-mapping values (P > 0.05) of different grade lesions whereas there was significant difference in T₂- and T₂^*-mapping values (P < 0.05). Conclusion: The distribution characteristics and MRI quantitative imaging have good diagnostic value for distinguishing different grades of cartilage lesions in knee OA. (authors)