| Objective The magnetic resonance T1-mapping test and the quantitative determination of proteoglycan in cartilage degeneration model of sheep knee joint at different stages were performed to explore the correlation between the T1-mappinp model of sheep knee osteoarthritis model and the content of proteoglycan in cartilage.Methods Fifteen healthy Mongolian sheep were selected and randomly divided into five groups: A,B,C,D,and E.Mongolian sheep left cartilage degeneration model was established by injecting papain solution into the left knee joint of sheep in groups B,C,D and E.Group A was not treated as a control group.B,C,D,E The group was modeled,and three injections(1.6 ml each)were performed on the first day,the fourth day,and the seventh day,respectively.MRI scan.The Siemens Skyra 3.0T magnetic resonance scanner was used to perform conventional magnetic resonance imaging(MRI)and T1-mapping scans of the knee control group and model of Mongolian sheep.The software was included in the syngo.via software provided by Siemens.Scan the two original T1-mapping images for image fusion,and perform cartilage editing and data measurement on the fusion image.The thickest part of the medial femoral condyle and medial tibial plateau cartilage was selected as the region of interest(ROI),the cartilage T1 value was measured,and the average was recorded three times.The T1 value of each group was analyzed statistically.Subsequently,knee cartilage specimens were stained with Alisin blue-periodate-Schiff staining(AB-PAS staining),the changes in proteoglycan content were observed with a microscope,and the integrated optical density(IOD)was used to evaluate cartilage The content of proteoglycan and the correlation between the content of proteoglycan and T1 value were statistically analyzed.It was statistically significant when P <0.05.Results(1)The T1 value of the knee cartilage of each model group increased compared with the control group.With the prolongation of the modeling time,the T1 value of the medial femoral condylar cartilage showed an upward trend.There was no significant difference between group B and group C(P> 0.05),and the differences between the other groups were statistically significant(P <0.05);T1 value of the medial cartilage of the tibial plateau showed an upward trend after testing.There was no significant difference between group C and group D.Significance(P> 0.05),and the differences between the other groups were statistically significant(P <0.05).(2)The evaluation values of proteoglycan content in femoral condyles and medial tibial plateau cartilage of each model were lower than those in the control group,and the evaluation values of proteoglycan content in cartilage of each model group were statistically different from the control group(P <0.05).With the prolongation of modeling time,the proteoglycan expression in the medial femoral condyle cartilage showed a downward trend.Except for the difference between group B and group C,which was not statistically significant(P> 0.05),the differences between the two groups were statistically significant(P <0.05);the expression of proteoglycan in the cartilage on the inner side of the tibial plateau showed a decreasing trend,and the differences between each group were statistically significant(P <0.05).(3)The T1 value of the medial femoral condylar cartilage has a linear correlation with the proteoglycan content.Pearson correlation analysis showed that as the T1 value increased,the expression of proteoglycan decreased,and the two showed a negative linear correlation(r =-0.570,P < 0.01).(4)The T1 value of the tibial plateau cartilage has a linear correlation with the proteoglycan content.Pearson correlation analysis showed that as the T1 value increased,the proteoglycan expression level decreased,and the two showed a negative linear correlation(r =-0.733,P <0.01).).Conclusions T1-mapping technology can quantitatively evaluate knee cartilage injury at different stages.At any time,the modeling time is prolonged,the degree of cartilage damage is increased,the T1 value is increased,and it can reflect the change of proteoglycan content in cartilage.T1 value may become a non-invasive imaging index reflecting the content ofproteoglycan in early articular cartilage degeneration.T1-mapping technology has high clinical application value. |
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