The Application Value Of 3.0t T_1ρand T₂ Mapping Imaging In The Study Of Cervical Disc Generation In Patients

ObjectiveTo compare and evaluate the cervical intervertebral discs based on Pfirrmann grading standard with 3.0T magnetic resonance T_1ρand T₂ mapping quantitative imaging technique,and to analyze the correlation between the T_1ρ,T₂ mapping values and the subjects’age,sex,position,the Pfirrmann grading of cervical intervertebral discs,and to discuss the application of T_1ρ,T₂ mapping imaging in the evaluation of cervical intervertebral disc degeneration.Material and method56 cases of examinee who received a cervical MRI examination in our hospital from January to December,2017 were collected.GE Discovery MR 750 3.0T imaging examination system was used to conduct sagittal view T_1ρand T₂ mapping scan respect-ively.Three regions of interest,anterior margin of fibrous ring,posterior margin of fibrous ring and nucleus pulposus,were marked with the use of postprocessing work station software in order to measure the value of T_1ρand T₂ mapping at different segments of C2/3^C6/7 intervertebral discs and regions of interest.The independent sample T-test was used to analyze the difference in sensitivity of diagnosing cervical intervertebral disc degeneration by the value of T_1ρand T₂ mapping in each region of interest at each segment of cervical intervertebral disc.The analysis of variance（ANOVA）was used to analyze the difference in T_1ρvalue and T₂ mapping value between each segment of cervical intervertebral disc and each region of interest.The Spearman correlation test was used to analyze the correlation between T_1ρvalue and T₂ mapping value of each segment of cervical intervertebral disc and each region of interest and Pfirrmann grading as well as the correlation between Pfirrmann grading and age.The Spearman correlation test was used to transversely analyze the correlation between T_1ρvalue and T₂ mapping value at different positions of different cervical intervertebral discs and Pfirrmann grading of cervical intervertebral disc and the correl-ation between T_1ρvalue and T₂ mapping value in the region of interest at different positions of cervical intervertebral discs.Result1.According to analysis of variance,the difference in quantitative values of T_1ρand T₂ mapping between the Pfirrmann grading of AAF,NP and PAF was statistically significant（P was equally 0.000）.AAF was compared in pairs with Bonferroni method,as for T_1ρ,with the exception that there was no statistically significant difference between the level I and II（P=0.12）and level IV and V（P=0.658）,the differences between the other groups were all found to be statistically significant（P=0.000）;as for T₂ mapping,it was found that,there was a statistically significant difference between the level I and II（P=0.027）,the level II and III（P=0.000）,the level II and IV（P=0.000）.As for NP,the inter-group comparison showed that all differences were statistically significant（all P were0.000 except for P=0.018 between level IV and V）.It was shown by the inter-group comparison that,the difference in T₂ mapping between the level I and III-V(P_I-III=0.003,P_I-IV=0.000,P_I-V=0.049),the level II and III-V(P_II-III=0.000,P_II-IV=0.000,P_II-V=0.022)was equally statistically significant（P<0.05）;it was shown by PAF that,with the exception that there was no statistically significant difference between level IV and V（P=0.342）,the differences between the rest groups were all statistically significant;the difference in T₂mapping between the level II and III-IV(P_II-III=0.000,P_II-IV=0.000)was statistically significant.It was concluded by Spearman correlation analysis that,the T_1ρvalue was all significantly negatively correlated with Pfirrmann grading at the anterior margin of AF and the posterior margin of NP and AF（r=-0.648,r=-0.736,r=-0.738,P was equally 0.000）.It was concluded by Spearman correlation analysis that,the T₂ mapping value was all weakly negatively correlated with Pfirrmann grading in AAF,NP and PAF（r=-0.299,r=-0.450,r=-0.352,P was equally 0.000）.2.According to rank table chi-square analysis,the difference in the proportion of Pfirrmann grading of 280 intervertebral discs between all intervertebral discs was statistically significant（X²=30.23,P=0.003）.3.Based on the comparison of correlation between Pfirrmann grading and T_1ρand T₂mapping value,we found that,the coefficient of correlation（r=-0.648,P=0.000;r=-0.736,P=0.000;r=-0.738,P=0.000）between Pfirrmann grading and T_1ρvalue of NP,AAF and PAF was equally greater than that of correlation（r=-0.299,P=0.000;r=-0.450,P=0.000;r=-0.352,P=0.000）between Pfirrmann grading and T2 mapping of NP,AAF and PAF,suggesting that,T_1ρimaging technique was more sensitive to the grade of degeneration of intervertebral disc than T₂ mapping was.4.Through a pairwise comparison of ROC curve of T_1ρand T₂ mapping value at different positions of 5 pairs of cervical intervertebral disc,it was found that,the area under the curve of C2/3-C5/6 of T2 mapping in the area of nucleus pulposus was greater than that of T_1ρ,showing a high sensitivity-specificity,the resultant specificity critical value may have a greater ability to predict the risk of early degeneration of cervical intervertebral disc.Conclusion1.T_1ρand T₂ mapping value of NP and AF both drop as the Pfirrmann grading rises;T_1ρvalue can sensitively mirror the change in content of proteoglycan,T₂ mapping is sens-itive not only to the content of proteoglycan,but also to the completeness of collagen;the reduction of water content of intervertebral disc is associated with the decrease of content of nucleus pulposus protein.2.Comparing T_1ρvalue with T₂ mapping value,T_1ρis more sensitive to the judgment of Pfirrmann grading of intervertebral disc;and T_1ρimaging is more sensitive to the early degeneration of NP.3.It was shown by both T1ρand T2 mapping imaging that,age has a considerable influence on degeneration of cervical intervertebral disc.In general,T1ρand T2 mapping imaging techniques can be used to quantitatively detect changes in biochemical compon-ents in different degrees of cervical intervertebral disc degeneration,moreover,they can be used to make a prospective evaluation of early degeneration of the cervical intervertebral disc and the possible secondary injury,so as to allow for an early detection,early diagnosis and early treatment of possible early cervical intervertebral disc degenerat ion in patients.