Analysis The Changes Of DTI And Type-Ⅱ Collagens In Ovine Knee-osteoarthritis Model

Objective To investigate the relationship between DTI and Type-Ⅱ collagen fibers in OA degenerative cartilage by using MR-DTI examination of the ovine knee joint at different stages.Methods Fifteen healthy Mongolian sheep were randomly divided into groups A,B,C,D and E.The models of cartilage degeneration of Mongolian sheep in different stages were established by injecting papain solution into the left knee of sheep in groups B,C,D and E,and group A was used as the control group.Using GE 1.5T Magnetic resonance,the knee joints of control group and the model group were checked by routine MRI and DTI,and the images were reconstructed by using Functool 9.4.05 software on the AW4.6 workstation,and the DTI pseudo-color images(ADC,FA)were achieved.The thickest part of the patella cartilage was selected as the area of interest(region of interest,ROI)to measure the apparent dispersion coefficient(Apparent diffusion coefficient,ADC)values and partial anisotropy coefficient of patellar cartilage(fractional anisotropic,FA)values,and the ADC value and FA value of each group were analyzed statistically.The results were compared with Picro-sirius red staining and Type-Ⅱ collagen immunohistochemical staining ex-vivo,and the morphological changes of collagen fibers were observed by polarized light microscope,and the immunohistochemical positive sediments were semi-quantitatively analyzed by using integrated optical density(IOD),and the correlation between Type-Ⅱ collagens and ADC value and FA value were analyzed statistically.Results(1)The ADC values of patellar cartilage in each model group were increased compared with those in the control group,and the differences were statistically significant between each model group(P<0.05).The ADC values of patellar cartilage in the model groups showed a gradually increasing trend with the development of time.(2)The IOD value of patellar cartilage in each model group was decreased compared with that of the control group,and the difference between each model group was statistically significant(P<0.05),and the expression of Type-Ⅱ collagen in the model groups showed a decreasing trend with each time.(3)The FA value of patellar cartilage between the various models and the control group was a statistically significant difference(P<0.05).(4)There was a linear negative correlation between patellar cartilage ADC value and Type-Ⅱ collagen expression,and the ADC value was increased by Spearman correlation analysis,and the expression of Type-Ⅱ collagen decreased(r=-0.872,P<0.01).(5)There was a linear correlation between patellar cartilage FA value and Type-Ⅱ collagen expression,and the relationship between FA value and Type-Ⅱ collagen expression was positively correlate by Spearman correlation analysis(r=0.473,P<0.01).Conclusion(1)The ADC value can evaluate the severity of cartilage degeneration to a certain extent,and can reflect the change of Type-Ⅱ collagen content in cartilage.(2)Using FA value can distinguish normal cartilage and degenerative cartilage,and it can reflect the change of collagen structure to a certain extent.(3)DTI can be one of the effective means of early diagnosis and monitoring the occurrence and development of OA.