Diffusion Tensor Imaging And Fiber Tracking In Cervical Spondylotic Myelopathy

PART I The manifestation of diffusion tensor imaging and fiber tracking maps, quantitative analysis and age relevant research for normal cervical cordObjective To study the manifestation of diffusion tensor imaging (DTI) for normal cervical cord, to quantify and compare the parameter values among the different age groups and segments, to study on the correlaton of the parameter values with age, to perform fiber tracting(FT) on cervical cord and nervi spinales, to provide evidence for further research of the cervical cord disease. Methods Conventional MRI and DTI examination were performed with a3.0T MR scanner on30cases of healthy subjects.The subjects were divided into different groups based on the ages and the segments of interverbral discs respectively. Study the manifestation of DTI and FT maps, measure the values of FA、ADC、E1、E2and E3, calculate the values of MD, E⊥and2E1/E2+E3, compare the parameter values among the different age groups and segments, to study on the correlaton of the parameter values with age. Results On colourful FA maps, the normal cervical cord showed homogeneous dark blue intensity, indicating high anisotropy, and the surrounding cerebrospinal fluid (CSF) showed hypointense, indincating low anisotropy. On gray scale ADC、E1、E2and E3maps, the normal cervical cord showed homogenous isointense, indicating low diffusion strength, while the surrounding CSF showed hyperintense, indicating high diffusiong strength. The FA,2E1/(E2+E3) of the normal cord at the C1-2interverbral discs level were significantly lower than at the other levels(P<0.05), E1was significantly lower than at C4-5, C5-6level (P<0.05), ADC, MD, E⊥, E2and E3were significantly higher than at the other levels(P<0.05). The parameter values among the other levels didn’t differ significantly(P>0.05). El was significantly higher than E2and E3(P<0.01). There was no distinct difference between E2and E3(P>0.05).2E1/E2+E3was2.70±0.03。FA, ADC, MD, E⊥, E1,E2and E3differed significantly between20～30group and41～50、51～60、61～70groups(P<0.05)). FA, ADC, MD and E1differed significantly betwen31～40group and51～60,61～70groups. FA, ADC, MD and E1differed significantly between41-50and61-70group(P<0.05)).2E1/E2+E3showed no significant difference among all the age groups(P>0.05).With age, FA showed negative correlation, ADC, MD, El, E⊥, E2and E3exhibited positive correlation, and2E1/E2+E3showd no correlaton. On FT maps, the normal cervical cord and nervi spinales was clearly demonstrated. Conclusion It was satisfied to perform DTI on cervical cord by using SE-EPI sequence and3.0T MR scanner. The difference of DTI values between different segments and the correlation with age corresponded to the neuroanatomy and physical changes of the normal cervical cord, which could not be detected on conventional MRI, indicating DTI was more sensitive. FT could reflect the integrity and derection of the nerve fiber. PART II The features of diffusion tensor imaging and fiber tracking maps, quantitative analysis and clinical symptom related research for Cervical spondylotic myelopathyObjective To explor the feasibility of DTI and FT, new quantitative and noninvasive functional imaging techniques, in detecting spinal cord damage, evaluating damage degree and clinical application for CSM. Methods A total of30healthy controls and60patients with cervical spondylotic myelopathy underwent conventional MRI and DTI by using3.0T scanner. The patients were divided into four groups based on clinical symptom-mild (group A), moderate (group B), severe (group C) and serious (group D). Study the manifestation of DTI and FT and analyze the values of FA, ADC, MD, E1, E2, E3, E⊥and2E1/E2+E3. Results FA maps showed spinal cord compression, inhomogeneous light blue signal mixed with light green or red colour at the compression site. Gray scale ADC, E1, E2and E3maps exhibited inhomogeneous high intensity. FT showed discontinuation, interruption and raritas. It increased with the severity of clinical symptom. FA, ADC, MD, E2, E3, E⊥and2E1/E2+E3differed significantly betweed the healthy controls and the patients(P<0.05). FA, E2, E3and E⊥showed significant difference betweed the controls and A, B, C, D groups(P0.05). ADC, MD and2E1/E2+E3differed significantly between the controls and groupB, C and D(P<0.05).E1differed significantly between the controls and group D(P<0.05). FA, E3, E2and E⊥differed significangtly in group A, B, C and D(P<0.05). MD and ADC differed significantly between groupA and C, between groupA and D, between groupB and D (P<0.05).2E1/(E2+E3) showed significant difference between groupA and C, between group A and D, between group B and C, between B and D(P<0.05). E1showed no significant difference in the patients group(P>0.05). ADC, E2, E3, E⊥, and MD increased with the severity of clinical symptom, while FA,2E1/E2+E3decreased with it. E1showed no regulation. Conclusion DTI was sentitive in detecting spinal cord damage and could assess subtle structural damage and changes of the CSM. DTI could show early damage and quantify the damage degree. FA, E2, E3and E⊥were more sensitive. FT could show the site and the severity of the fiber damage. PART Ⅲ Comparation between diffusion tensor imaging and conventional MRI in evaluating spinal cord damage in cervical spondylotic myelopathyObjective Compare the parameter values between the injury cervical cord with T2WI hyperintensity, that with T2WI isointense and the normal cervical cord to explore the importance of DTI and convetional MRI in detecting spinal cord damamge in CSM. Methods A total of30healthy controls and60patients with cervical spondylotic myelopathy was perfprmed conventional MRI and DTI by using3.0T scanner. According to the signal of the damage cord on T2WI, the patients were divided into two groups:hyperintense (group A), isointense (group B). The control group was defined as group C. Study the features of DTI and FT and analyze the values of FA, ADC, MD, E1, E2, E3, E⊥and2E1/E2+E3. Results For patients with hyperintense on T2WI, FA maps showed inhomogeneous light blue or light green in the damage site, gray scale ADC, E1, E2and E3showed inhomogeneous high signal. For patients with isointensity on T2WI, they also had inhomogeneous light blue or light green in the damage site on FA maps showed and had inhomogeneous high signal on gray scale ADC, E1, E2and E3. The values of FA, ADC, MD, E⊥, E2, E3and2E1/(E2+E3) differed significantly between groupA、groupB and groupC (P<0.05). Eldid not have significant difference between group B and group C(P>0.05). E1showed significant difference between groupA and groupB, between groupA and groupC (P<0.05). The values of FA、2E1/(E2+E3) increased gradually, while ADC, MD值, E⊥, E2, and E3值increased gradually in group A, group B, groupC. Conclusion DTI was more sensitive than conventional MRI in detecting spinal cord damdge and could show precisely early subtle structural damage in CSM, which could help the clinicians to select the optimal therapeutic regimen and gain time for operantion. DTI could quantify the damage degree, make the diagnosis precise and provide information for predicting postoperative recovery. DTI could follow up the patients, evaluate therapeutic effect and provide objective evaluation on the conduction function recovery of the spinal cord. DTI was a noval quantitive functional imaging technique and had great importance in detecting chronic damage, determining therapeutic regimen and predicting prognosis of CSM.