Study Of MRI Diagnosis And Diffusion Tensor Imaging Of Corpus Callosum Of Cerebral Multiple Sclerosis

【Objective】1.To investigate the MRI feature of cerebral multiple sclerosis,and to improve the knowledge and diagnosis level of cerebral multiple sclerosis.2.To investigate the feature and diagnostic value of corpus callosum in both healthy people and MS patients by 3.0T MR diffusion tensor imaging.【Materials and methods】1.SubjectsPart one:The clinic and MRI data of 32 patients with cerebral multiple sclerosis in Nanfang Hospital were collected during February 2002 to March 2008.Part two:15 patients with cerebral multiple sclerosis and 15 age-and gender-matched normal subjects in Nanfang Hospital underwent diffusion tensor imaging during May 2007 to March 2008.2.InstrumentsPart one:(1) Siemens Magnetom Vision 1.5T MRI. (2) GE Excite HD 3.0T MRI.Part two:GE Excite HD 3.0T MR3.Scanning sequencePart one:Conventional scanning of T1 WI,T2WI,Flair with 25 patients enhanced.Part two:Conventional scanning of T1 WI,T2WI,Flair.DTI was acquired with b values of 1000mm²/s,25 diffusion encoding gradient directions and the slice thickness was 5mm with no gap.4.Data processing and image analysisPart one:The MS plaques of the location,size,shape,MR signals and enhanced features,mass effect,the corpus callosum changes and brain atrophy were analyzed.Part two:All the original images of DTI were transferred to a workstation provided by GE corporation,and was corrected and noise reduced by Functool software(AW4.4 edition).The FA map,MD map,DEC map and T2WI with b value of 0 were generated automatically by processing.Each ROIs was drawn in two sides of genu and splenium of corpus callosum of all subjects on the image of FA map,and then the values of FA and MD were calculated.The ROIs were drawn in the same size and shape of case group and normal group with the same anatomical region avoiding lesions.The FA and MD values of genu and splenium of corpus callosum were compared between normal group and case group.The seed for fiber tracking was placed in the all corpus callosum in accordance with its anatomical structure on the midsagittal plane,followed by obtaining the corpus callosum fibers by the computer fiber automatically tracking.DTT was setted the conditions for the termination of follow up:FA＜0.20,MD＞0.01,step＜160.The conformation and course of corpus caUosum fiber were observed in three-dimensionally.5.Statistical analysisPart one:Descriptive statistical method was used on all data.Part two:All data were recorded as mean±standard deviation.SPSS13.0 software package was applied to statistical analysis.Statistical significance level was set asα=0.05,statistically significant difference was defined as P＜0.05.(1) The paired t-test or Wilcoxon signed-rank test was used for the comparison of two paired sample means and the independent sample t-test or Mann-Whitney U test for the comparisons of two independent sample means.(2) The best classification threshold was found through drawing ROC curve,and then calculating its sensitivity,specificity and accuracy.【Results】Part one1.30 cases had positive lesions of brain in the 32 cases of MS,with the sensitivity of 93.75%.Every MS patient had multiple lesions with predilection sites of cortical or juxtacortical,periventricle,centrum semiovale and corpus callosum.2.Most of the MS plaques were round or oval,with different sizes.Bilateral lesions were almost symmetrical in distribution.20 patients had "fight-angle demyelination",12 patients had "dirty-appearing white matter" and 11 patients had both manifestations.3.The lesions showed isointension,slight hypointension or hypointension on T1WI,and hyperintension on T2WI and Flair sequences.No enhancement was seen on most MS plaques,and if somewhat,nodular enhancement and ring-like enhancement were on the enhanced plaques.4.No or slight mass effect was viewed on MS plagues.5.17 among the 28 MS patients had abnormal signal on sagittal checking of corpus callosum,with the sensitivity of 60.71%(17/28),2 cases had abnormal signal at the sagittal T1 WI of 8 cases,2 cases at the sagittal T2WI of 5 cases and 13 cases at sagittal Flair of 15 cases.5 patients had atrophy of corpus callosum.6.10 MS patients had brain atrophy in different degrees.Part two1.No significantly abnormal signals were shown on the FA map,MD map and DEC map of the genu and splenium of corpus callosum in MS patients.2.Statistical difference was found in FA and MD values of the genu of corpus callosum compared with healthy controls and MS patients(P＜0.05).The FA values were decreased and MD values increased in the genu of corpus callosum of MS patients.The FA value tended to decline and the MD value tended to increase on the splenium of corpus callosum,but the difference was no statistically significant(P＞0.05).3.The classification threshold for the values of MD was 0.902×10^-3mm² / s with the sensitivity,specificity and accuracy of 0.800,0.733,0.767,and the classification threshold for the values of FA were 0.689 with the sensitivity, specificity and accuracy of 0.533,0.933,and 0.733 in the genu of corpus callosum.4.The performance of corpus callosum with diffusion tensor tractography in both healthy controls and MS patients:Fifteen corpus callosums of healthy controls, which were successfully reconstructed,consisted of frontal forceps connecting the bilateral frontal lobe,the body of corpus callosum connecting of the later frontal lobe and parietal lobe,and occipital forceps connecting of the bilateral lobe,and the fiber tracts of later body of corpus callosum and splenium of corpus callosum was divided into dorsal and ventral part,which accorded with descriptions withon neuroanatomy. Among the fiber bundles of corpus callosum reconstructed from the 15 MS patients, the fiber tracts of the body of corpus callosum was deleted in varying degrees at the reconstructed fiber bundle of 11 MS patients,of which one case was complicated with deletion of the occipital forceps of the fiber bundle and other one case with the left tapetum of the fiber bundle.The morphology of fiber tracts of corpus callosum was found with no obvious abnormality in 4 MS patients.【Conclusions】Part oneThe MRI findings of cerebral multiple sclerosis are specific,and the MRI features showed as follows are beneficial for correct diagnosis of MS:1.The MS plaque occurs in cortical or juxtacortical,periventricle,centrum semiovale and corpus callosum,most of them were round or oval.2.MS patient have multiple lesions and bilateral lesions are almost symmetrical in distribution.The signs of "right-angle demyelination" and "dirty-appearing white matter" are the more specific for MS.3.The majority of MS plaques are not enhanced,and also can show the nodular, ring-like or arc by T1 enhancement scanning.MS plagues show no or slight mass effect.4.Corpus callosum can always be affected by MS lesions,with the findings of diffusing,nodular,radiating signal abnormalities and irregular ependymal thickening. The sagittal FLAIR imaging for MRI is most evident. Part two1.The quantitative and morphologic study of corpus callosum in normal adults and MS patients can be made by the technique of 3.0T MR DTI and DTT.2.MS patient have occult injury in the genu of corpus callosum,which can be evidently diagnosed using DTI showing FA value be descending and MD value be increasing.3.DTT imaging on corpus callosum can show the abnormities of fiber bundles of corpus callosum in three-dimensionally,which is supplementary for FA and MD map and beneficial for the assessment and monitoring of MS.