| Leukoaraiosis (LA) was first proposed in 1987 by Hachinski. Most reasons are vascular factors.LA shows low-density by CT scan or high signal areas by MRI scan in perventricular or subcortical areas (centrum semiovale). It is a combination of causes white matter abnormalities. LA happens more common in people over age 60, often accompanied with dementia and cerebrovascular disease, also found in asymptomatic elderly people. With the progress of the disease, It can cause chronic progressive disorder of cognitive function, seriously affecting the quality of life and increased social burden.Diagnosis of leukoaraiosis has been dependent on the CT and MRI, demyelinating disease with or without changes, as well as the extent of demyelination can make preliminary judgments. Functional MRI makes MR imaging diagnosis from morphology to the direction of the function development. In addition to evaluation of anatomical structures, but also non-invasive evaluation of brain function in the situation. Diffusion weighted imaging (DWI) reflects the microscopic movement of water molecules, Brownian motion of water molecules are very sensitive. It can detect the water apparent diffusion coefficient (ADC) values in the living tissue; we study the disease status from cellular and molecular level. Diffusion tensor imaging (DTI) as a new technology that uses spin echo-echo planar imaging (SE-EPI) sequence, which is currently clinical practice in the fastest scanning techniques. Reflect the living tissue water diffusion of information, observe the trend of brain white matter tract organization, bypass, push, and interrupt and sabotage abnormal proliferation of tissue are anisotropic. Ordinary diffusion-weighted sequence can not reflect the diffusion anisotropy, while the DTI sequence applied in a number of diffusion gradient directions, and collected separately, and then draw a variety of data, obtained by calculating multiple images. Fractional anisotropy (FA )is used to quantitative analysis of key indicators.This study retrospectively analyzed 24 patients with leukoaraiosis patients and 8 healthy volunteers by CT, MRI, DWI and DTI scan, combined with its performance,related its parameters, and relevant literature, to observe the relevant parameters and the brain white matter serious degree of osteoporosis, to explore the micro-structural changes in white matter, cognitive function compare with different sex, clinical provide early diagnosis and hamper comprehensive assessment of cognitive function decline , improve quality of life and reduce the social burden.Method: We studied 24 patients with leukoaraiosis and 8 healthy people with a mean age of 63.3 years, and the control group of 8 patients, 2 males, 6 females, mean age was 54 years old; LA 24 patients, male 13 cases, 11 female, mean age was 65.5 years. All patients were examine by Siemens Avanto 1.5T superconducting MR scanner system . MRI included axial TlWI, T2WI, FLAIR, sagittal T2WI weighted images. T1WI axial used spin echo sequence, TR: 550ms, TE: 8.4ms. T2WI axial use fast spin echo sequence , TR: 4500ms, TE: 85ms. Axial FLAIR: TR: 9000ms,TE: 99ms, TI: 2458.6ms. Sagittal T2WI: TR: 3500ms, TE: 99ms. Axial diffusion-weighted imaging (DWI) using single-shot echo-planar sequence (EPI), in the X, Y, Z three directions imposed sensitive gradient, b = 0s/mm2 and b = 1000s/mm2, TR: 2900ms, TE: 89ms , scan time: 57s. Axial T1WI, T2WI, FLAIR, sagittal T2WI and DWI sequences thickness are 6.0mm, spacing 1.8mm, FOV 230mm×230mm. DTI using echo-planar pulse sequence (Echo Planar Imaging, EPI), diffusion gradient directions for the 20, b 0 and 1000s/mm2, scan level, parallel to the conventional MRI, slice thickness 5.0mm, spacing 1.5mm, TR 2700ms, TE 88ms, FOV 230mm×230mm. Excitation frequency of 4, scan time was 3.56min. DTI-facilitate multi-directional reconstruction, all patients scan anatomical image (t1-mpr-ns-tra-p2-iso) sequence, slice thickness 1.0mm, spacing 0.5mm, TR1900ms, TE3.37ms, FOV 256mm×256mm.All subjects caught using GE light speed 16-slice spiral CT examination: canthal line to listen to the baseline. Scan parameters: 120kV, 230mAs, slice thickness 5mm, matrix 512×512, window width 80, window 35.Scan after the completion of the original image sent to the Siemens workstation using Neuro 3D software for analysis and processing, the DTI as the superposition of the original image and anatomy, and tracing through the white matter imaging (Diffusion Tensor Tractography, DTT) for reconstruction of nerve fiber bundles. Select the lateral ventricle anterior horn, lateral horn, semi-oval center, genu of corpus callosum, corpus callosum selected regions of interest (Regionof Interest, ROI). Negative control group, region of interest measurement ADC, DCavg, FA values and CT values, LA group routine MRI scan on the light of the abnormal signalMeasure the ROI of leukoaraiosis ADC, DCavg, FA values and CT value.Results:Seen by the control group corpus callosum, centrum semiovale, posterior horn of lateral ventricle adjacent to lateral ventricle anterior horn next to the FA value was followed a downward trend. LA group of ADC, FA, DCavg values were normal control group and LA group of normal white matter by univariate analysis of variance were statistically significant. LA group the parameters of different grades can be seen, with the LA classification more and more, ADC, DCavg values were gradually increasing trend, FA values showed a decreasing trend. LA lesions in the lateral ventricle on the anterior horn, lateral horn, semi-oval center region of interest ADC, FA, DCavg values in different genders line independent samples T test, P> 0.05,No statistically significant. According to FA, DCavg value of the correlation coefficient between MMSE and indirectly infer the relationship between LA and cognitive function.Conclusion:DTI analysis of leukoaraiosis by the FA, DCavg value of conventional MRI, can detect abnormal changes in the microstructure of white matter, leukoaraiosis in the early diagnosis, early clinical intervention, blocked the decline of cognitive function.
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