Experimental And Clinical Studies On Diagnosis And Postoperative Functional Assessment Of Cervical Spondylotic Myelopathy Using CT And MR Imaging Techniques

Objective:To compare volume-occupying rate of cervical spinal canal between normal subjects and patients with cervical spondylotic myelopathy (CSM), and to investigate its clinical application of condition assessment and preoperative plan in CSM.Methods:Spiral computed tomography (CT) scan (from C4 to C6 segment) was performed in 20 normal subjects and 36 patients with CSM at a neutral position, and all images were transferred to the Advantage Workstation Version 4.2 for assessment. Measure bony cervical spinal canal area, fibrous cervical spinal canal area, sagittal diameters of cervical spinal canal and cervical spinal body on each cross-section. Then Torg ratio and effective cervical spinal canal ratio can be calculated. Volume-occupying rate of cervical spinal canal can be calculated using MATLAB. Japanese Orthopaedic Association score was used to assess cervical spinal cord function.Results:Volume-occupying rate of cervical spinal canal at a neutral position in patients with CSM was significantly higher than normal subjects(P<0.01). There was no correlation between Torg ratio and JOA score in patients with CSM, with a Pearson’s correlation coefficient of 0.171 (P>0.05). But sagittal diameter of secondary cervical spinal canal, effective cervical spinal canal ratio and volume-occupying rate of cervical spinal canal were significantly associated with JOA score which can reflect cervical spinal cord function, with Pearson’s coefficient correlations of 0.439 (P<0.05),0.491 (P<0.05) and-0.613 (P<0.05), respectively.Conclusions:Volume-occupying rate of cervical spinal canal is an objective indicator which can reflect compression of cervical spinal cord, and it is associated with cervical spinal cord function. These suggest that it may play a significant role in predicting the development of CSM.Objective:To compare DTI indexes of cervical spinal cord between normal subjects and patients with CSM, and to investigate its significance in the clinical diagnosis, surgical plan formulation and evaluation of postoperative curative effect.Methods:GE Signa HDxt 3.0T MRI machine scan was performed in 30 normal subjects and 50 patients with CSM using generic sequence and DTI respectively, and all images were transferred to the Advantage Workstation VolumeShare 5 workstations, using GE Functool 9.4.05 DTI data post-processing software, we can get diffusion tensor tractography images, cross section DTI images, ADC colormaps and FA colormaps of cervical spinal cord. ADC and FA values at C2-C3, C3-C4, C4-C5, C5-C6, C6-C7 cervical spinal cord levels were measured in normal subjects and patients with CSM. At the same time mJOA score and Nurick grade of the patients with CSM were recorded in pre-operation, post-operation 1 week, post-operation 1 month and post- operation 3 months respectively. Use SPSS 16.0 to analyse variation of DTI indexs in normal subjects and patients with CSM and its correlation with the spinal cord function scores.Results:1. DTI indexs of cervical spinal cord in normal subjects are not uniform constant, but from cranial level to caudal level ADC values increase but FA values decreased’ gradually (P< 0.05).2. DTI indexs of cervical spinal cord in normal subjects have age difference (P< 0.05), but there is no gender difference (P> 0.05). With increasing age, ADC value decreases and FA value increases gradually.3. Diffusion tensor tractography of cervical spinal cord in patients with CSM can intuitively reflect the site of spinal cord compression and spinal cord function status changes(DTI indexs). Cross section DTI images、ADC colormaps and FA colormaps of cervical spinal cord in patients with CSM not only can reflect the spinal cord compression from the form, but also ADC and FA colormaps can reflect spinal cord functional status changes(DTI indexs) through the intuitive color changes. With the exacerbation of cervical spinal cord compression, in ADC colormaps, ADC values increase gradually, show the colors:blue→ green; but in FA colormaps, FA values increase gradually, show the colors:red→yellow → green.4. There is significant difference of DTI indexs between CSM groups at maximal compression level and normal subjects at the same level(P< 0.01). The ADC values increase but FA values decreased at the compression level.5. FA value of maximal compression level in CSM groups linearly correlated with mJOA score, with a Pearson’s correlation coefficient of 0.58(P<0.01); but negative linearly correlated with Nurick grade, with a Pearson’s correlation coefficient of-0.39 (P<0.05).6. There is significant difference of DTI indexs of C2-C3 level between preoperative CSM groups and normal subjects(P< 0.05). The ADC values increase but FA values decreased in preoperative CSM groups.7. FA value of C2-C3 level in CSM groups at different times linearly correlated with mJOA score, with Pearson’s correlation coefficients of 0.63(P<0.01),0.61(P<0.05), 0.53(P<0.05) and 0.55(P<0.05), respectively; but negative linearly correlated with Nurick grade, with Pearson’s correlation coefficients of -0.44(P<0.01),-0.43(P<0.05),-0.39(P<0.05) and -0.46(P<0.05), respectively.Conclusions:1. DTI indexs of cervical spinal cord in normal subjects are not uniform constant, there is a significant age difference. That suggests DTI indexs is sensitive to degenerative diseases within spinal cord, but these lesions are hard to find in conventional MRI.2. DTI can find these lesions within spinal cord which is shown normal in T2 WI image. DTI can be used as indicators to reflect the damage of the spinal cord, which has better sensitivity and specificity compared with traditional MRI.3. Diffusion tensor tractography、cross section DTI images、ADC colormaps and FA colormaps of cervical spinal cord can reflect not only the spinal cord compression from the form, but also spinal cord functional status changes(DTI indexs) through the intuitive color changes.4. FA value of cervical spinal cord at the maximal compression level associated with better postoperative recovery of spinal cord function, which can be used as a valuable predictor of surgical outcome, so as to guide rational choice of surgical cases.5. DTI indexs at high level (C2-C3) above compression segment of cervical spinal cord is easier to measure, so it can be used as an ideal and sensitive imaging biomarker for early diagnosis and evaluation of spinal cord function in CSM.