| Objective:(1)To summarize the characteristics and influencing factors of T1(MS),T2(MS)and Pd(PU)values of normal knee cartilage;(2)To explore the application value of SYMRI quantitative measurement in the grading of cartilage injury in patients with OA.Methods:(1)40 healthy volunteers with BMI between 18.5 kg/m~2and 24.0kg/m~2were scanned with Sy MRI MAGIC sequence of knee joint,three quantitative maps,T1 map,T2 map and PD map,were obtained after post-processing of the original scanned images,and compared the display of the three quantitative maps on cartilage.According to gender and age,the knee joint cartilage was divided into six regions:medial femoral cartilage,lateral femoral cartilage,trochlea femoral cartilage,medial tibia cartilage,lateral tibia cartilage and patellar cartilage,the thickness,T1,T2 and PD of the cartilage in each area were quantitatively measured.At the same time,the patellar cartilage and the trochlear cartilage of femur were divided into two layers to measure the T1 value,T2 value and PD value,and the statistical analysis was conducted.(2)60 patients with clinical diagnosis of OA were selected as the observation group,with an average age of(54.93±6.82)years old.Meanwhile,20 healthy volunteers were selected as the control group,with an average age of(50.0±6.5)years old.Sy MRI MAGIC sequence scan of knee joint was performed.The ICRS grading method was used as the evaluation standard to grade the damaged cartilage in each area,and the distribution of cartilage injury at different levels was observed.The T1,T2 and PD values of normal cartilage and different levels of injured cartilage were compared and statistically analyzed.Results:(1)The overall mean T1,T2 and PD values of the knee cartilage of normal volunteers were(836.89±79.22)ms,(47.12±2.60)ms and(59.20±7.10)pu,respectively.In the three pseudo-color images generated,T2 map and PD map showed better articular cartilage than T1 map.The differences in T1 and PD values of cartilage in different areas of knee joint were statistically significant(P<0.05),and there were no differences in the T2 value of cartilage in different regions(P>0.05);The values of T1,T2 and PD in the superficial layer of patellar cartilage and femoral trochlear cartilage were higher than those in the deep layer(P<0.01).(2)The T1 values of the lateral femoral cartilage,the medial tibia cartilage and the lateral tibia cartilage in males were higher than those in females(P<0.05),PD values of femoral trochlear cartilage and patellar cartilage were higher in males than in females(P<0.05),and there were no differences in the T2 values of cartilage in different parts of the sexes(P>0.05).(3)The T1 and PD values of medial tibial cartilage in different age groups showed statistically significant differences(P<0.05).The T2 values of medial femoral cartilage,trochlear femoral cartilage and patellar cartilage showed statistically significant differences among different ages(P<0.05);(4)The thickness of patellar cartilage,femoral trochlear cartilage and medial femoral cartilage in males was greater than that in females(P<0.05);There were no differences in cartilage thickness among different age groups(P>0.05).(5)In patients with OA,grade I to II cartilage injuries were mainly distributed in the patellofemoral joint surface(48.2%),grade III to IV cartilage injuries were mainly distributed in the internal side of knee joint(44.2%)and patellofemoral joint surface(38.5%);The T1 and T2 values of cartilage with different injury grades were higher than those of normal cartilage,and the differences were statistically significant(P<0.05),and the T1 and T2 values of Grade II damaged cartilage were higher than those of Grade I injured cartilage.Different cartilage injury grades were correlated with T1 and T2(P<0.05),and the correlation with T2 was greater than that with T1;there was no statistically significant difference in PD value among different injury grades(P>0.05).Conclusion:(1)Sy MRI has certain diagnostic and evaluation effects on knee cartilage,and the display effects of T2 map and PD map on cartilage are better than that of T1 map.(2)In normal volunteers,the biochemical quantitative values of knee cartilage were different among different genders and ages.In adults between the ages of 20 and 65,gender may be a factor influencing the differences in cartilage thickness,while age is less important.(3)In patients with knee OA,different levels of cartilage injuries have different distribution characteristics.Grade I to II injuries mainly distributed in the patellofemoral joint surface,and grade III to IV injuries mainly distributed in the medial side of knee joint and the patellofemoral joint surface.(4)T1 value and T2 value are helpful to evaluate different levels of cartilage injury in OA patients,and T2 value is more advantageous.The application value of PD value in evaluating the change of cartilage injury is limited. |
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