Diffusion Tensor Imaging In Multiple Sclerosis

PARTâ… Diffusion tensor imaging for characterizing of brain plaque in multiple sclerosisObjective To study the characteristics of brain plaques in multiple sclerosis using diffusion tensor imaging, to demonstrate differences of ADC in acute and chronic MS plaques. Methods Conventional MRI and DTI examination were performed in 34 clinically defined MS patients. Plaques were divided into various groups according to Gd-enhancement pattern and the signal intensity on T1-weighted images. Study the manifestation of MS lesions on post processing DWI, ADC and FA map derived from DTI primary data and measure the ADC value of these lesions. Results On DWI,33(99.3ï¼…)of 35 acute lesions showed hyperintense and 5 lesions showed ring-like hyperintense. Both acute and chronic lesions showed increased ADC and decreased FA. The mean ADC value of chronic lesions was significantly higher than that of acute lesions. (12.43×10^-4mm²/s±3.78 vs 10.10×10^-4mm²/s±2.28, P=0.001)Ring-enhancing lesion showed higher ADC than non-ring enhancing lesions. In chronic lesions, the mean ADC of T1-hypointense area was significantly higher than that of T1-isointense lesions, The severe T1-hypointense lesions revealed the highest ADC. Disruption of fiber pathway were detected on FA map with good contrast of gray and white matter, the size of lesions on FA maps was increased compared with that on T2-weighted images. Conclusion DTI technique can detect pathological changes in various types of MS lesions in vivo. It may provide a more sensitive and efficient method of monitoring patients and assessing therapies.PARTâ…¡Quantification of normal-appearing white matter damage in multiple sclerosis by use of diffusion tensor imagingObjective To quantify the microscopic damage of normal-appearing white matter(NAWM)in MS and to investigate the related pathologic changes by using diffusion tensor imaging(DTI). Material and Methods DTI of whole brain was performed in 34 MS patients and 25 age-matched non-MS healthy volunteers. Apparent Diffusion Coefficient(ADC) and fractional anisotropy(FA)of 9 different NAWM regions were calculated for all participants. Results: ADC in MS group was increased in all regions of NAWM compared to controls(P＜0.05),significantly higher in the body of corpus callosum(CC), internal capsule, periventricular WM, frontal WM, parietal WM and occipital WM(P＜0.01). FA value in MS group was decreased in the body of corpus callosum, internal capsule, periventricular WM, frontal WM, parietal WM and occipital WM(P＜0.05), the genu and splenium of CC,middle cerebellar peduncle showed an insignificant trend of lower FA. Conclusion: This study provides insights into microscopic pathogenesis of NAWM in MS using DTI, quantitative analysis of DTI could be a useful method for evaluate the NAWM damage.PARTâ…¢Magnetic resonance imaging and diffusion tensor imaging of gray matter damage in multiple sclerosisObjective To study the Magnetic resonance imaging(MRI)characteristics of the gray matter lesions in multiple sclerosis(MS),and to investigate the occult damage in normal appearing gray matter(NAGM)by quantitative analysis using diffusion tensor imaging(DTI). Methods Conventional MRI and DTI were performed in 34 clinically defined MS patients and 25 non-MS healthy volunteers. Main signs of the GM lesions detected by conventional MRI were analyzed, including the distribution, numbers, shape, size, signal intensity and enhanced pattern. The ADC and FA value derived by DTI were measured in normal appearing deep gray matter for all participants and the differences between the two groups were compared. Results MRI examination revealed 83 lesions in cerebral gray matter, 18.7ï¼…of the total 443 lesions. The GM lesions distributed over all brain lobes especially frontal lobe.34,60,78 and 36 plaques were on T1WI,T2WI,FLAIR and reconstructed DWI images respectively, 9 small lesions were identified on DWI more easily than on T2WI and FALIR. ADC of the head of caudatum(7.98±0.676×10^-4mm²/s), putamen(7.36±0.532×10^-4mm²/s) and thalamus(7.70±0.438×10^-4mm²/s) in MS group was significantly higher than in healthy controls. Conclusion This study confirms the presence of GM damage in MS. It shows MRI characteristics of the macro-lesions, and combined FLAIR with DWI can improve the detection of GM lesions. Occult micro-change in NAGM can be evaluated by DTI quantitative analysis.PARTâ…£Three-Dimensional diffusion tensor tractography in multiple sclerosisObjective To study the change of white matter in multiple sclerosis using diffusion tensor tractography. Methods Conventional MRI and DTI examination were performed in 34 MS patients and 25 normal volunteers. Fiber tracts were reconstructed by fast marching technique(FMT). Study the change of fibers passing though MS lesions and in normal appearing white matter. Results White matter connectivity and it's trajectory, integrity were directly visualized on fiber tractography. Fiber tracts were transected by lesions and shifted due to adjacent plaques. Absence or shortening of remote fiber bundle could be shown. Reduction of fiber bundles in normal appearing corpus callosum could also be shown when compared to that of normal controls in the same age. Some false negative results occurred because of FA threshold value.Conclusion DTI-based fiber tractography is a promising technique for reconstruction of major fiber bundles in vivo. In spite of some limitations, it still has very wide perspective in MS investigation and clinical application.PARTâ…¤Combined magnetic resonance spectroscopy with diffusion tensor imaging in multiple sclerosisobjective To investigate the use of magnetic resonance spectroscopy(MRS)combined with diffusion tensor imaging(DTI)in multiple sclerosis. Methods 26 MS patients and 16 normal volunteers were examined by Multiple- voxel MRS on semioval center and whole brain DTI. NAA/Cr,Cho/Cr,ADC and FA were calculated in the regions of MS lesion in frontal lobe, contralateral normal appearing white matter(NAWM)and equivalent area of white matter in both frontal lobes in control group. Compared intergroup differences and analyzed the correlation of metabolite ratio and diffusion metrics. Results NAA/Cr was significantly lower in MS lesions(1.617±0.336) and NAWM(1.809±0.339)than that in normal controls(2.103±0.245).Cho/Cr was mildly higher in MS lesion and NAWM but showed no statistic changes when compared to controls. NAA/Cr correlate to ADC(r=-0.575, P=0.002)and FA(r=0.479,P=0.013)in MS lesion.Conclusion In MS lesion, axonal loss and demyelination can be detected together using the technique combined MRS with DTI, which provide potentially useful information about the histopathology and pathomechanism in MS disease.