***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: OBJECTIVE The purpose of this study was to evaluate the fractional anisotropy values of several white matter tracts with the aim of differentiating a healthy population from persons with mild cognitive impairment or Alzheimer 's disease . SUBJECTS AND METHODS Seventy-nine patients with memory impairment and 16 volunteer controls participated in the study .  MRI was performed with a 1.5-T system . Conventional MR images and diffusion tensor images were obtained for all participants . The diffusion tensor imaging data were postprocessed , and low b-value , fractional anisotropy , and fractional anisotropy color-coded maps were calculated . With the three maps as an anatomic reference , fractional anisotropy was measured for hippocampal formations , superior longitudinal fascicles , posterior cingulate gyri , and the splenium of the corpus callosum . Kruskal-Wallis and Steel-type multiple-comparison nonparametric tests were performed for the statistical analysis . RESULTS The fractional anisotropy values for the splenium of the corpus callosum , bilateral posterior cingulate gyri , and bilateral superior longitudinal fascicles of patients with mild cognitive impairment and those with probable Alzheimer 's disease were significantly lower than the values of controls . No differences were found in hippocampal formations in any group . No significant difference was found in fractional anisotropy values in comparisons of mild cognitive impairment versus possible Alzheimer 's disease and probable Alzheimer 's disease or comparisons of probable Alzheimer 's disease and possible Alzheimer 's disease . CONCLUSION Diffusion tensor imaging is a promising technique for the evaluation of patients with probable mild cognitive impairment .  Early detection of the disease exp and s the treatment options , increasing the likelihood of a good clinical response and enhancing the quality of life of patients and their relatives . Further studies with larger population s are needed to confirm the role of diffusion tensor imaging in the evaluation of memory impairment The aim of this paper is to obtain discriminant features from two scalar measures of Diffusion Tensor Imaging ( DTI ) data , Fractional Anisotropy ( FA ) and Mean Diffusivity ( MD ) , and to train and test classifiers able to discriminate Alzheimer 's Disease ( AD ) patients from controls on the basis of features extracted from the FA or MD volumes . In this study , support vector machine ( SVM ) classifier was trained and tested on FA and MD data . Feature selection is done computing the Pearson 's correlation between FA or MD values at voxel site across subjects and the indicative variable specifying the subject class . Voxel sites with high absolute correlation are selected for feature extraction . Results are obtained over an on-going study in Hospital de Santiago Apostol collecting anatomical T1-weighted MRI volumes and DTI data from healthy control subjects and AD patients . FA features and a linear SVM classifier achieve perfect accuracy , sensitivity and specificity in several cross-validation studies , supporting the usefulness of DTI-derived features as an image-marker for AD and to the feasibility of building Computer Aided Diagnosis systems for AD based on them Diffusion tensor imaging ( DTI ) is a magnetic resonance imaging ( MRI ) technique that provides information on the fiber architecture of the brain by measuring water diffusion . Prior work has shown that neuronal degeneration in Alzheimer 's disease ( AD ) and mild cognitive impairment ( MCI ) alters this architecture . Since the conversion rate to AD is much higher for MCI patients than for normal healthy people , it is important to identify biomarkers with a predictive value on this conversion . In this study , we applied tract-based spatial statistics ( TBSS ) on data sets of 15 healthy controls , 15 AD patients , and 17 MCI patients . Of these MCI patients eight remained stable , whereas nine developed AD within the first 12 - 18 months of follow-up investigations . Analysis using TBSS combined with a maximum likelihood regression with r and om effects of the fornix , the corpus callosum , and the cingulum identified significant differences between these two types of MCI patients in fractional anisotropy ( FA ) and radial diffusivity ( DR ) . Thus , DTI reveals Alzheimer-specific changes in those MCI subjects that later convert , although they were clinical ly identical to the other MCI- patients at the time the data were acquired . This finding could lead to early identification of AD and thereby aid early clinical intervention 
    Output:
    
Evidence suggests that AD evolves through distinct patterns of WM disruption , in which retrogenesis or , alternatively , the Wallerian degeneration may prevail .