Preliminary Exploration Of The Quantitative Evaluation Value Of SyMRI And T2 Mapping In Discoid Meniscus And Its Injury

Objective:To evaluate the microscopic composition of the DM using SyMRI and T2 mapping.To analyze the differences of tear modes and quantitative parameters in different surgical methods combined with conventional MRI,T2 mapping and SyMRI,and investigate the preoperative predictive value of different quantitative parameters on the surgical methods of DM injury,so as to lay the foundation for the individualized treatment of DM injury.Part Ⅰ:Quantitative assessment of the internal heterogeneity of the discoid meniscus by SyMRI and T2 mapping Methods:20 cases of patients with undamaged DM diagnosed by MRI in the second hospital of Shanxi Medical University from June 2020 to February 2021 were collected,and another 20 cases of gender and age-matched normal meniscus were selected as the control group.All participants were scanned with conventional MRI,T2 mapping and SyMRI,and the pseudo color images were generated after post-processing to obtain the parameters of T2(mapping),T2(SyMRI),T1 and PD.The differences between DM and normal meniscus were analyzed by independent sample t test or Mann Whitney U test,and the differences between the internal regions of DM were analyzed by one-way ANOVA.All T2 values measured by T2 mapping and SyMRI were evaluated by Pearson correlation analysis,and the two techniques were compared and analyzed.Results:(1)The T2(mapping)and T2(SyMRI)values of the anterior horn and posterior horn of the DM were higher than those of the normal meniscus(P < 0.001),T1(P = 0.946,0.57)and PD(P = 0.13,0.062)were not significantly different.(2)The T2(mapping)and T2(SyMRI)values of DM from large to small were body > posterior horn > anterior horn(P <0.001).There was no significant difference between T1 and PD values(P > 0.05).(3)T2values obtained from SyMRI and T2 mapping exhibited highly positive correlation(r =0.909,P < 0.001).Part Ⅱ:Preliminary Study on the Preoperative Prediction Value of SyMRI and T2 mapping for Discoid Meniscus Injury Methods:43 patients with DM injury diagnosed by MRI in the second hospital of Shanxi Medical University from June 2020 to February 2021 were collected and divided into partial resection group(n = 24)and total resection group(n = 19)according to the operation method under arthroscope.All participants were scanned with conventional MRI,T2 mapping and SyMRI,and the pseudo color images were generated after post-processing to obtain the parameters of T2(mapping),T2(SyMRI),T1 and PD.The differences of each factor in conventional MRI between the two groups were analyzed by fisher exact test.The differences of quantitative parameters between the two groups were analyzed by independent sample t test or Mann Whitney U test.All T2 values measured by T2 mapping and SyMRI were evaluated by Pearson correlation analysis.The sensitivity and specificity of different quantitative values for the prediction of surgical methods were evaluated by ROC curve,and the best cut-off values were found.Results:(1)There were statistical differences in tear pattern(P=0.015),tear region(P=0.005),tear length(P=0.010)and tear width(P=0.012)between the the two groups.(2)The values of T2(Mapping),T2(SyMRI)and PD in the anterior and posterior horn of the DM in the total resection group were higher than those in the partial resection group(P <0.001).There was no significant difference in T1 value of anterior and posterior horn of DM and all quantitative parameters of body between total resection group and partial resection group(P >0.05).(3)T2 values obtained from SyMRI and T2 mapping exhibited highly positive correlation(r = 0.840,P < 0.001).(4)The AUC of T2(mapping),T2(SyMRI)and PD values were significantly different(P < 0.05),among which T2(mapping)had the best predictive effect on the surgical method of discoid meniscus injury.The AUC of the anterior horn was0.894,with a sensitivity of 84.2% and specificity of 83.3%,and a critical value of 26.51 ms.The AUC of the posterior horn was 0.912,with a sensitivity of 89.5% a specificity of83.3%,and a critical value of 27.71 ms.Conclusion:(1)T2 mapping and SyMRI can effectively evaluate the internal components of DM,and can directly reflect the heterogeneity of internal components of DM,and the changes of micro components after DM injury through the changes of pseudo color image and quantitative parameters.(2)The quantitative values of T2 and PD have certain value for predicting the surgical method of DM injury,and T2 mapping has the best prediction efficiency.(3)On conventional MRI,DM tear pattern,tear region and tear scope are the influencing factors for the choice of surgical methods of DM injury,which can guide the clinical routine MRI evaluation before operation.(4)This study verified the feasibility of quantitative assessment of knee meniscus by SyMRI,but the current version of SyMRI technology still has some limitations in meniscus assessment.