Research On Magnetic Resonance Imaging Quantitative T1ho/T2mapping And Biomechanics In Knee Osteoarthritis

Background:Nano-indentation technology,histopathological diagnosis and standardized MRI T1rho/T2mapping sequence images were compared to identify the relationship between the analysis results and the micro-biomechanical changes of articular cartilage in different stages of degeneration.Early quantitative diagnosis method for cartilage degeneration was established to provide accurate analyses for the early diagnosis and early intervention of clinical OA.Methods:General clinical data,X-ray,MRI Tlrho/T2mapping sequence and routine sequence scanning were performed on 20 knee OA patients preoperatively.Medial distal femoral condyle,lateral distal femoral condyle,medial and lateral posterior femoral condyles were region of interest.The histopathological grading results were achieved and the biomechanical examination were acquired by applying nano-indentation technology.Histopathological scales,MRI semi-quantitative results,including cartilage volume scores,cartilage defect scores and subchondral bone marrow lesion scores,T1rho/T2mapping values and mechanical test results of different parts were compared by ANOVA analyzing.Regression analysis was used to evaluate the correlation between histopathological grade,biomechanical results and MRI.Result:(1)The cartilage defect of the medial knee joint is more severe than that of lateral knee joint.The mean cartilage defect score of lateral tibial plateau is the lowest.The mean cartilage defect score of medial femoral condyle is the highest.MRI cartilage defect scoring system can only distinguish the difference between the histopathological grade 2 and grade 3.Mean bone marrow lesion score of subchondral bone of the medial femoral condyles is the highest.Mean scores of medial tibial plateaus,lateral tibial plateaus,medial femoral condyles and lateral femoral condyles increased orderly.(2)T1rho/T2mapping mean values of the medial distal condyles were higher than those of the other three parts(lateral distal condyles,medial posterior condyles and lateral posterior condyles).The mean value of T1rho/T2mapping between different histopathological grades increased orderly.Except for between grade 1 and grade 2 or between grade 4 and grade 5,there were significant differences of Tlrho values between each histopathological grade.There were statistical differences of T2mapping values among grade 2 to grade 6.T2mapping image can reflect the severity of histopathology directly by its different color scales.The correlation between T1rho/T2mapping and histopathological grade(grade 2 to grade 6)was confirmed.T1rho value 30 and 120 as well as T2mapping value 35 and 125 can be used as the criteria to diagnose the severity of cartilage preoperatively.(3)The modulus and hardness of medial distal condyle were higher than those of the other three parts.Modulus of cartilage of all four parts could be positively correlated with histopathological scores.Modulus of the cartilage was positively correlated with T1rho/T2mapping values.We can use the correlation formula to calculate biomechanical and histopathological fitting results of the cartilage with T2mapping value preoperatively.So we can diagnose the degeneration of articular cartilage of early stage.Conclusion:MRI T1rho/T2mapping can be used to diagnose the cartilage degeneration of different stages(histopathology grade 2-6).Quantitative cartilage imaging is an effective method to reflect the changes of extracellular matrix in OA knees.MRI T1rho/T2mapping is useful for the diagnosis of early osteoarthritis,so early treatment can be applied to avoid the progression.