| ObjectiveA steroid-induced Osteonecrosis of the Femoral Head(ONFH)model was established to dynamically observe the ultra-early changes in measured values of femoral heads such as Micro CT,T2 mapping,and T2*mapping,so as to analyze whether T2 mapping and T2*mapping could be used.to reflect the characteristics of the structure of bone.Materials and MethodsNew Zealand white rabbits 45(15 in blank control group,30 in experimental group)were randomly divided into five observation batches,including the 5d,7d,9d,11 d and13d,then the examination of Micro CT,MR T2 mapping and T2*mapping were underwent to analyze the changes of the microenvironment of the femoral bone in super-early stage ONFH comparised with histological findings,so as to discuss the change trends of the parameters and the correlation between the parameters from Micro CT,MR T2 mapping and T2*mapping.ResultsIn the experimental group,the T2 values and T2* values of the femoral head were lower than that of the control group at the time of the 5d,but gradually increased with the extension of the molding time,but was still lower than the control group at the 13d(P < 0.05).In the experimental group,the values of Tb.SP,Tb.N were gradually increased,and the values of BMD,Tb.Th,BV/TVwere gradually reduced with the extension of molding time.The significant differences(P < 0.05)of BMD,Tb.Th and Tb.N,Tb.Th between the control group and the experimental group were observed from the 7d and 9d,respectively.A statistically difference(P < 0.05)of the Tb.SP were occurred since the 5d In the experiment group.A statistically difference(P < 0.05)of the BV/TV were occurred since the 7d In the experiment group.Tb.Sp showed a significant positive correlation with T2 values and T2* values at most of the time,and Tb.Th showed a significantly negative correlation with T2 values and T2* values.In the experimental group,the rate of empty bone lacunae,the thinning or interruption of trabecular bone,the increase of adipocytes in number and volume,the intramedullaryhemorrhage and other pathological changes gradually increased with the time went on.Conclusion(1)Compared with the measurement of Micro CT,T2 mapping and T2*mapping might be more sensitive to detect the comprehensive changes in trabecular bone and bone marrow components.(2)The combination of Micro CT and MR T2 mapping,T2*mapping techniques were helpful for the comprehensive analysis of the pathological changes in ultra-early stage of ONFH.ObjectiveBased on the reference values of bone marrow T2* in different stress regions of normal femoral heads,MR T2*mapping observations on the lesions with different appearances were performed for the ONFH patients after routine MRI examination,so as to investigate the feasibility of T2*mapping for the quantitative analysis of ONFH lesions..Materials and Methods20 normal volunteers were recruited as the control group,aged from 24 to 50,with an average of 31.2±7.2 years old.A total of 20 ONFH patients admitted in our hospital from May 2017 to October 2017 were included in the experimental group.Coronal T2WI-FS,T1 WI,and T2*mapping sequences were underwent for them.The scanning parameters of T2*mapping sequences were TR 900 ms,TE 4.77,13.03,21.29,29.55,37.81,44.65,51.49 ms,thickness(ST)3.5 mm,and stratification(SS)0.7 mm,FOV160x160,NEX 2.Then the measurement and analysis of T2* values to necrotic regions(necrosis,osteosclerosis,necrotic repair zone)and non-necrotic regions(eema zone,non-necrotic and no edema zone)were performed.ResultsDifferent performances were all displayed on routine MRI and T2*mapping false color image in various stages of ONFH.The quality of the images collected in this experiment was high and the scoes were consistent(Kappa=0.669,P <0.001).(1)A total of 87 sequestrums were found in 20 ONFH patients,and the ratio of sequestrum in I-IV stage femoral necrosis group was 4.60%(4/87),13.79%(12/87),24.14%(21/87)and 57.47%(50/87),respectively.The T2* values of 87-bone sequestrum were all lower than that of the control group;the mean difference among the T2* values of the sequestrum of the I-IV stage and the control group was-0.43±0.22 ms,-2.69±0.75 ms,and-2.80± 1.26 ms,-2.18 ± 1.10 ms.Compared with the control group,there was no significate difference on the T2* values among the statistically-observable II,III and IV seizures with the control group(P>0.05).(2)The harden belt of the focus was not clear in 6 sick femoral heads.About57.69%(15/26)of the T2* values on the harden belts among the other 26 hips were lower than that in the control group.The mean differences of T2* values in the I-IV stage osteosclerosis band(experimental group-control group)were-1.47±1.26 ms,0.30±0.64 ms,-1.00±1.36 ms,and 0.21±0.89 ms,respectively.There was no significant difference in the T2* mean differences among the statistically-observable II,III,and IV stages(P >0.05).(3)The necrotic repair band was not clear in 3 sick femoral heads.On the other29 hips,the T2* values ??were all higher than that in the control group.The mean differences of the T2* values(test-control group)in the I-IV of the other 29 hips were6.93±3.47 ms,5.53±5.03 ms,12.08±4.88 ms,and 10.19±4.56 ms,respectively.Compared with the control group,significant difference(P ? 0.05)of T2* values in necrotic repair zones were only found in stage III ONFH with stage II ONFH.(4)In the 32 femoral heads of ONFH,26 edematous areas were found.The proportion of edema bands in the I-IV ONFH were 0%,26.92%(7/26),30.77%(8/26)and 42.31%(11/26),respectively.The T2* values were all higher than the control group.The average differences of T2* values between the stage II-IV edema zone with the control group were 1.23±1.31 ms,7.35±3.04 ms and 4.88±3.87 ms,respectively.There was a statistically significant difference in the T2* differences among the II,III and IV edema bands(P <0.05).A positive correlation of the T2* differences was found between the response zone and the edema region(r=0.633,P <0.05).(5)The mean values of T2* in stage I,II,III and IV non-edema areas were7.43±0.10 ms,7.44±0.26 ms,7.32±0.10 ms,7.23±0.10 ms,respectively.The mean values in the control group were 7.43±0.15 ms,7.42±0.19 ms,7.35±0.19 ms,7.33±0.25 ms.There was no significant difference in the D-values between the two groups of stage II and III(P > 0.05).Conclusion(1)In MRI examination,the incidence and degree of bone marrow edema are closely related to the stage and collapse of ONFH.Bone marrow edema can be used as an index to evaluate the progress or curative efficacy of ONFH.(2)T2*mapping can be used to measure the sebum,osteosclerosis,necrotic repair zone,and edema zone of ONFH.Among them,tbe T2* measurement in sequestrum,necrotic repair zone and edema zone showed a certain analytical values,but no regularity of D-value were found in hardened zones.There was no obvious abnormality in the mean value of T2* in the non-necrotic and no edema areas of ONFH.(3)Compared with the experimental studies,T2* values were more difficult to measure in the adult femoral head,because it was more complex in ONFH.The T2*quantitative technology need to be constant improved to avoid those influences,such as the thickness,clarity,volume effect and other factors. |
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