Application Of Diffusion Tensor Imaging And Neurophysiological Monitoring In The Quantitative Evaluation Of Spinal Cord Function

Objective:The assessment of spinal cord status and function is a prerequisite for the diagnosis and treatment of spinal cord injury(SCI).Combined with diffusion tensor imaging(DTI)and neurophysiological monitoring(NM),spinal cord function can be quantitatively evaluated,and the relationship between lesions and spinal cord can be clarified to provide reference for clinical decision and future research of SCI patients.Methods:All patients underwent preoperative data acquisition,including medical history,physical signs examination,traditional MRI of spine and DTI.Supine position was used for examination.T1 and T2 weighted phase and DTI of spine were included in the examination sequence,and preoperative JOA scores were recorded.FA and ADC data of region of interest(ROI)and region without spinal cord compression on DTI images were obtained.Regular intraoperative neurophysiological monitoring(IOMN)was implemented,and the amplitudes of somatosensory evoked potential(SEP)(N20 or P40)were recorded.Patients were followed up 2 weeks after the operation.JOA scores were recorded,improvement rates were calculated,and prognoses were evaluated.Correlation analyses were performed to evaluate spinal cord function.Results:In the 12 patients,9 patients(75%)with intact spinal fiber bundles and 3 patients(25%)with disruptive spinal fiber bundles from preoperative DTI.The average value of ADC in the two regions of interest before operation was higher than that in the area without spinal cord compression,and the average value of FA was lower than that in the area without spinal cord compression;the difference of FA value between spinal cord compression area and non-compression area was more significant(P=0.018).IOMN indicated moderate to severe impairment in 5 patients(42%)and mild to no impairment in 7 patients(58%).The preoperative FA values significantly decreased in the fiber-interrupted group and the moderate-to-severe-damage group(P<0.05).The amplitudes of SEP before resection were positively correlated with the preoperative FA values(R=0.735,P=0.006).The pre-and postoperative neurological function scores(JOA score)and the improvement rates were positively correlated with preoperative FA values and amplitudes of SEP before lesion resection.In addition,in this study,the preoperative FA values of ROI of intramedullary tumors were significantly lower than that of extramedullary tumors.Conclusion:From a total of 12 patients who underwent surgical treatment in our hospital from 2018 to 2019 with stored DTI data,we found that FA value,SEP amplitude,neurological function score or improvement rate were correlated.DTI and NM could quantify spinal cord function and determine the prognosis of patients.That is,the lower the FA value and the smaller the amplitude of SEP,the worse the neurological function of the patient,the lower the improvement rate and the worse the prognosis.Therefore,we believe that the spinal cord function can be graded according to the JOA score,so as to find the corresponding FA value and SEP amplitude range;thus,by measuring the FA value and SEP amplitude of patient in the future,the spinal cord function,postoperative expected improvement and long-term prognosis can be evaluated reversely.At the same time,FA value can also help judge the pathological nature of lesions to some extent.The number of patients in this study is small,and a larger sample size is in need in the future to further refine the classification and corresponding interval.