Value Of Conventional MRI And DTI In Evaluating Neurological Function And Predicting Surgical Outcome In Cervical Spondylotic Myelopathy

Objective:The aim of this study was to analyze conventional MRI(cMRI)and diffusion tensor imaging(DTI)characteristics of asymptomatic spondylotic cervical cord compression(A-SCCC)and cervical spondylotic myelopathy(CSM)and evaluate the capacity of cMRI and DTI parameters to discriminate between A-SCCC and CSM.To evaluate the efficacy of cMRI and DTI parameters in prediction of surgical outcome in CSM patients.The article also explored the association of postoperative cMRI and DTI parameters with the postoperative severity of myelopathy and surgical outcomes.Methods:The cMRI and DTI of the cervical spinal cord were performed within 97patients with spondylotic spinal cord compression on a 3.0-T MRI scanner from January 2018 to June 2018 in Tianjin Hospital.Based on the symptoms and signs of myelopathy,patients were divided into two groups:A-SCCC group and CSM group.Quantitative parameters obtained by cMRI included anteroposterior(AP)and laterolateral(LL)spinal cord diameter,compression ratio(CR)and transverse area(TA).DTI was evaluated for fractional anisotropy(FA)and apparent diffusion coefficient(ADC).The power of cMRI and DTI parameters required to discriminate between A-SCCC and CSM groups was analysed by receiver operating characteristic(ROC)analysis.Multivariate logistic regression analysis was used for analyzing the risk factors for the onset of myelopathic symptoms.In part two,one hundred and forty-two patients with CSM who underwent presurgical cMRI and DTI of the cervical spine were included.Quantitative parameters obtained by cMRI included maximum spinal cord compression(MSCC),CR,TA,and signal intensity ratio(SIR).DTI was evaluated for FA and ADC.A Japanese Orthopaedic Association(JOA)recovery rate<50%was defined as a poor surgical outcome.The relationship of surgical outcome with various imaging parameters was examined.ROC curves were used to measure the predictive ability.In part three,twenty-six patients with CSM who were treated with open-door laminoplasty were included.The alterations in cMRI and DTI parameters before and after laminoplasty surgery and the association of postoperative FA,ADC and SIR with the postoperative severity of myelopathy and surgical outcomes were investigated.Results:There were significant differences between the A-SCCC and CSM groups regarding the AP,CR,TA,FA and ADC.The largest area under the ROC curve(AUC)was observed for FA(0.739),followed by ADC(0.725),TA(0.690),CR(0.640),and AP(0.629).Multivariate logistic regression analyses revealed that FA≦0.585,ADC>1.182×10~-33 mm~2/s and TA≦68.25 mm~2 were significant factors to discriminate A-SCCC and symptomatic CSM patients.In part two,the largest AUC was for FA(0.750),followed by ADC(0.719),TA(0.716),SIR(0.673),MSCC(0.593)and CR(0.591).Multivariate logistic regression model revealed that JOA score≦8 points,TA≦46.02 mm~2,and FA≦0.390 were significantly associated with poor surgical outcome.In part three,there were significant differences compared between preoperative and postoperative conditions in FA,ADC and SIR.Postoperative FA and ADC values were significantly correlated with postoperative JOA scores(P<0.05),whereas postoperative SIR was not correlated with postoperative JOA score(P>0.05).Conclusions:The DTI parameters proved superior in this respect compared with the cMRI parameters used to detect or predict the presence of clinically symptomatic compression.Multivariate logistic regression analyses revealed that FA≦0.585,ADC>1.182×10~-33 mm~2/s and TA≦68.25 mm~2 were significant risk factors to detect or predict the presence of clinically symptomatic myelopathy.The DTI parameters showed higher discriminative ability in predicting surgical outcome in comparison with cMRI parameters.Multivariate analyses revealed that JOA score≦8 points,TA≦46.02 mm~2,and FA≦0.390 were independently associated with poor surgical outcome.Our study showed significant changes of DTI parameters in the spinal cord at compression level after laminoplasty in CSM patients,which could be associated with improvement of neurological function.Postoperative DTI analysis may be more valuable than postoperative cMRI analysis for prognosis evaluation in CSM patients.