Diffusion Tensor Imaging And Diffusion Tensor Tractography On The Brain Of Normal And Subcortical Infraction: Clinical Study

Part one:The repeatability study of normal adult brain with DTIObjective:To evaluated intra-rater, inter-rater, and between-scan reproducibility, through measure the FA/ADC value of white matter fibers and gray matter nucleus with a clinical diffusion tensor imaging (DTI) protocol at 3.0T.Materials and Methods:8 normal adults (3 men,5 women; age range 23～29 years, mean age 25.3 years) were included in this study. All subjects have no neurological diseases or disorders affect the central nervous system. The examination all with GE Signa Excite 3.0T using 8 channels head coil. Use of EPI sequence with diffusion sensitive gradients in 25 directions, b value is equal to 1000 s/mm2.8 cases of subjects were performed three times DTI scan, we performed the first and second times of scan at the same day, and repeated the sequence to ensure the positioning line and location of the subjects consistency, a month later undergone the third scanning. With the help of AW4.3 workstation, using Functool software to obtain fractional anisotropy (FA) maps, apparent diffusion coefficient (ADC) maps and color coded the direction (DEC) maps. Placed regions of interest in seven different parts of bilateral hemispheres, respectively, using the software at different levels of color-coded map to delineate pyramidal tract. In order to compare the differences within the surveyor, a doctor measured the FA and ADC values three times in different parts of brain on eight subjects for the first time scan. In order to compare the differences between raters, three experienced radiologists measured the FA and ADC values of different structures of the eight subjects for the data first time scan on the same day. In order to compare the degree of variation of the data obtained at different scanning time points, one rater measured the three times scanning data of the eight subjects in the same day. We used the reliability analysis to compare reproducible and stability intra-rater, inter-rater and between-scan, and compare between every two groups (intra-rater, inter-rater and between-scan). Meanwhile we make comparision of pyramidal tract through diffusion tensor tractography reconstruction.Results: 1. The stability and precision of intra-rater on the data of single-scan(1) The ADC and the FA values measured by one rater with normal distribution. The same rater three times measurement acquired the ADC /FA values were not statistically significant difference (P≥0.682).(2) The reliability analysis showed a better consistency of three times measurements in different parts of brain. Alpha coefficients were greater than 0.947; intraclass correlation coefficients (ICC) were greater than 0.939, showed that intra-rater there have a higher reliability and repeatability. The coefficient of variation (CV) of ADC and FA values between three times measurements in different parts of brain were less than 1.8%, indicating that variation of the three times measurements to a lesser extent.2. The stability and precision of inter-rater on the data of single-scan(1) The ADC and FA values measured by three raters in line with the normal distribution. Comparison of the ADC and FA values of the three measurements by different raters at the same structures, have no statistically significant difference, and the minimum P value is 0.135 (P> 0.05).(2) Reliability analysis showed three measurements in different parts of brain of inter-rater have good agreement, Alpha coefficient between the 3 measurements were greater than 0.823; ICC were greater than 0.833, showing the different measurements between those who have a higher reliability and repeatability. The variant of ADC and the FA values acquired in different parts of the brain by different raters showed is less than 1.9%.3. The stability and precision of between-scan(1) Apart from the ADC values of centrum semiovale, posterior limb of internal capsule, lentiform nucleus and thalamic does not meet the normal distribution, other parts of the ADC and the FA values are in line with the normal distribution. Compare the ADC, FA values of three scans, there have no statistically significant difference, the minimum P value is 0.392 (P> 0.05).(2) The reliability analysis showed good agreement between 3 times scans, Alpha coefficients were greater than 0.801; intraclass correlation coefficients were greater than 0.796. In addition to the Alpha coefficient, ICC of the head of caudate nucleus, lenticular nucleus and thalamus is less than 0.9, the remaining structures of ADC and the FA values of intraclass correlation coefficients were larger than 0.9, showed a higher reliability and repeatability between the three times scan. In the three scans obtained in different parts, the coefficient of variation of ADC and FA values were less than 1.8%, indicating that variation of the three scans to a lesser extent.Conclusions:1.3.0T magnetic resonance DTI technology can be a very good method to display the anatomy of the brain gray and white matter on molecular level, which can precise location for the study and quantitative analysis of micro-structural changes in the brain.2. Intra-rater, inter-rater and between-scan have a higher stability and accuracy, provides a theoretical basis for the diagnosis and treatment monitoring in the nervous system.3. With the help of diffusion tensor tractography we can observe the pyramidal tract hree dimensional, provide a visualized method for the study of disease correlated with pyramidal. Part two:DTI study of age-related changes of pyramidal tract of normal adultObjectives:To investigate the anisotropy and diffusion characteristics of pyramidal tract of normal adult, describe the fractional anisotropy (FA) and apparent diffusion coefficient (ADC) and its relationship with age.Materials and Methods:95 cases of normal adult undergone MR examination, 47 cases were male and 48 cases female, aged from 20 to 79 years with an average 44.9 years. All subjects have no neurological diseases or disorders affect the central nervous system. The studies were divided into three groups according to age:20-39 years old for the young group (50 cases),40-59 years old middle-aged group (25 cases),60 years and over for the older group (20 cases). All Subjects underwent routine MR examination and DTI inspection (same with part one). With the help of Functool software, we delineate pyramidal tract on three planes (centrum semiovale, posterior limb of internal capsule and pedunculus cerebri). Then we measured the FA and ADC values. Depicts the diffusion and anisotropy characteristics of different brain structures, then the FA/ADC value of different brain structures of normal adults were compared multiply. They also were correlated with the age respectively and compared among three groups. P value less than 0.05 was considered as statistical significance..Results:1.The diffusion and anisotropic characteristics of normal pyramidal tract(1) The FA, ADC values of bilateral hemispheric symmetrical parts were not statistically significant difference (P> 0.05). The FA/ADC value was no significant difference between Men and women (P> 0.05).(2) The FA/ADC values of the difference planes were statistically significant.(3) To arrive at the FA/ADC value (x±s) of normal pyramidal tract on different levels.2. The correlation of FA/ADC of pyramidal tract in different structures with age (1) The FA value of centrum semiovale and posterior limb of internal capsule were negatively correlated with age, the FA values in pedunculus cerebri have a downward trend with age increase and have no statistical significance.(2)The ADC value of centrum semiovale were positively correlated with age, the ADC values in posterior limb of internal capsule have a incremental trend and have a downward trend in pedunculus cerebri with age increase.3. The comparison of FA and ADC of pyramidal tract in different levels among age groups(1) FA values between the groups:the FA value in centrum semiovale and posterior limb of internal capsule in all age groups was statistically significant difference.(2) ADC values between the groups:The ADC value of pyramidal tract in all levels has no statistically significant difference.Conclusions:1.The pyramidal tract has different anisotropic characteristics at different levels; there have higher level in posterior limb of internal capsule. With 3.0T MR scanner obtained the normal parameters of normal FA, ADC value in normal adults of different age groups. Provide important reference information for clinical studies about pyramidal tract-related diseases.2. Anisotropy of pyramidal tract in normal adult is related with age, and there is a certain patterns, with age increase, there will be a lower FA values and an increased ADC values.3. In different age groups, the FA, ADC value in most of the brain structure is expressed as the difference between elderly groups with middle-aged group and younger age group. This shows that after the age of 60 normal elderly brain micro-structures have a significant change, this normal age-related neurodegenerative can make for differentiation diagnosis with other similar nervous degenerative disease. Part three:Preliminary DTI study of cerebral infarction DTIObjective: Study of cerebral infarction with 3.0TMR for the use of DTI technology. Study the relationship between pyramidal tract with infarction lesions use DTT. Use FA, ADC, and eigenvector of involvement pyramidal tract to quantitative evaluation of anterograde and retrograde degeneration. Studies microscopic level changes of ipsilateral and contralateral pyramidal tract before and after rehabilitation.Materials and Methods:37 infraction patients (24 men,13 women; age range 31～80 years, mean age 44.9) were included in this study. According to fiber tractography (DTT) and based on the relationship between pyramidal tract with infarction, Divided into two groups (compression group and the destruction groups), pressure group have 18 patients, destruction group 19 cases. All patients were undergone conventional MR examination and DTI examination within 1 week the onset of illness. Using the U.S. National Institutes of Health Stroke Scale (NIHSS) standard acquire the score of every patient by a doctor of neurology the same day of examination. In destruction group there have 11 cases of patients undergone second times regular MRI and DTI examination after 3 to 6 months of onset. Place ROIs on centrum semiovale, posterior limb of internal capsule and cerebral peduncle in ipsilateral and contralateral hemispheres, respectively. Reconstruct the pyramidal tract of the affected side; observe the relationship between infarction and the pyramidal tract and the integrity of pyramidal tract. Compare the FA, ADC and eigenvector value of the same anatomical structures of affected side with uninjured side. Compared DTI parameters and NIHSS score of two groups. Compare the FA, ADC and eigenvector of ipsilateral, contralateral of two groups. P values are less than 0.05 was considered statistically significant difference.Conclusion:1. Morphological characteristics of involved pyramidal tract in two groups and the comparison of DTI parameters between two groups(1) Destruction groups DTT shows that the destruction of affected pyramidal tract partial deletion, partial interruption of the continuity of fiber bundles. In pressure group DTT showed infarction close to pyramidal tract and the pyramidal shape keep intact.(2) There has a statistically significant difference in FA values of bilateral pyramidal tract in two groups, ADC values in the bilateral cerebral hemispheres was no significant difference.(3) There has statistically significant difference between the two groups about the FA values of pyramidal tract in the ipsilateral cerebral peduncle level; compression group is higher than destruction group. There have statically significant difference between two groups at centrum semiovale level (uninjured side) and cerebral peduncle level (affected side). There has statically significant difference between two groups in NIHSS score.2. The DTI study of pyramidal tract of affected side and contralateral before and after treatmentDTI examination shows that the FA values have statistically significant difference before and after treatment between ipsilateral- ipsilateral and contralateral-contralateral hemispheres. The FA value in affected side shows a falling trend and in uninjured side shows a rising trend.Conclusion:1. Diffusion tensor fiber tractography can found the changes of pyramidal tract which conventional MRI can not be found; through three-dimensional reconstruction can show the relationship of infarction lesions between with the pyramidal tract. Determine pyramidal tract damage or compression is conducive to prognosis judgments.2. DTI can make a quantitative evaluation of involvement pyramidal tract; in early stage of infraction the FA value in compression is higher than damage groups. The FA value of affected pyramidal tract in damage groups has a falling trend, and we can use FA to quantitative evaluate the degree of pyramidal tract being involved.3. The FA value of pyramidal tract in uninjured side has a rising trend, can help explain the role of uninjured hemisphere in patients with cerebral infarction in the course of rehabilitation. With the help of fMRI can reveal the plasticity of neural function.