***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: BACKGROUND AND PURPOSE : Previous neuropathologic studies in chronic hydrocephalus have suggested the presence of white matter damage , presumably from mechanical pressure due to ventricular enlargement and metabolic derangement . This study aim ed to investigate the diffusional properties of the CST in patients with iNPH by using DTI and to determine whether this method could be used as a new diagnostic tool to differentiate patients with iNPH from those with AD and PDD and control subjects . MATERIAL S AND METHODS : We enrolled 18 patients with iNPH , 11 patients with AD , 11 patients with PDD , and 19 healthy control subjects .  Diffusion tensor metrics of the segmented CST , including FA values , axial eigenvalues , and radial eigenvalues , were evaluated by using tract-specific analysis . The anisotropy color-coding tractography of the CST was visually evaluated . The DTI findings were compared among groups . RESULTS : Tract-specific analysis of the CST showed that FA values and axial eigenvalues were significantly increased ( P < .001 ) , whereas radial eigenvalues were not significantly altered , in patients with iNPH compared with other subjects . The CST tractographic images in patients with iNPH was visually different from those in other subjects ( P < .001 ) . In discriminating patients with iNPH from other subjects , the CST FA values had a sensitivity of 94 % and specificity of 80 % at a cutoff value of 0.59 . CONCLUSIONS : Our results suggest that patients with iNPH have altered microstructures in the CST . Quantitative and visual CST evaluation by using DTI may be useful for differentiating patients with iNPH from patients with AD or PDD or healthy subjects AIM To determine prospect ively if qualitative and quantitative diffusion tensor imaging ( DTI ) metrics of white matter integrity are better than conventional magnetic resonance imaging ( MRI ) metrics for discriminating cerebellar diseases . METHODS Conventional MRI images from 31 consecutive patients with ataxia and 12 controls were interpreted by a neuroradiologist given only a clinical indication of ataxia . An expert ataxologist , blinded to radiological findings , determined the clinical diagnosis , as well as ataxia severity and asymmetry for each patient . For qualitative analysis , a comparison of the cerebellar white matter in ataxic vs. control patients was made by visual inspection of directionally encoded color ( DEC ) images . For quantitative analysis , segmentation of the cerebellar white matter in the inferior , middle , and superior cerebellar peduncles ( ICP , MCP , and SCP ) was attempted using three methods : a region of interest method , a deterministic DTI tractography ( DDT ) method , and a probabilistic DTI tractography ( PDT ) method . A statistical comparison of the average fractional anisotropy ( FA ) in these tracts was made between subject groups , and correlated to clinical diagnosis , severity , and asymmetry . RESULTS Of the 31 consecutive patients with ataxia , the two largest subgroups had a clinical diagnosis of multiple system atrophy ( cerebellar subtype ; MSA-C ) , and spinocerebellar ataxia-1 ( SCA1 ) . Conventional MRI features , such as degree of pontocerebellar atrophy , correlated with ataxia severity , but were neither sensitive nor specific for the ataxia subtypes . PDT was the most accurate and least variable method of the three methods used for determining FA , especially in the ICP . Average FA in all ataxic patients was significantly decreased in the MCP , SCP and ICP and this decrease correlated to disease severity . Asymmetric ataxia correlated to proportionately larger contralateral MCP , ICP and SCP FA values . MCP , ICP , and SCP FA difference values formed distinct clusters that distinguished MSA-C from SCA-1 , and other ataxia syndromes . CONCLUSIONS Qualitative and quantitative reductions in DTI metrics of white matter integrity in the cerebellar peduncles correlated better to clinical features of patients with sporadic and hereditary ataxias than conventional structural MRI measures of pontocerebellar atrophy Background : Preliminary work has shown that diffusion tensor MRI ( DTI ) may contribute to the diagnosis of Parkinson ’s disease ( PD ) . Objectives : We conducted a large , prospect i ve , case control study to determine : ( 1 ) if fractional anisotropy ( FA ) and apparent diffusion coefficient ( ADC ) values on DTI in the basal ganglia and substantia nigra are different between patients with PD and healthy controls ; and ( 2 ) the predictive value of these parameters and their clinical utility . Methods : DTI imaging was carried out in patients with PD and controls .  FA and ADC values were obtained from various brain structures on the DTI scan using the diffusion tensor taskcard . The structures studied were : cau date , putamen , globus pallidus , thalamus and substantia nigra . Results : 151 subjects ( 73 PD patients , 41 men , 32 women ; mean age 63.6 years ) and 78 age and sex matched control subjects were studied . The FA value of the substantia nigra in patients with PD was lower compared with controls ( 0.403 vs 0.415 ; p = 0.001 ) . However , no significant differences were demonstrated for FA or ADC values of other structures . Multiple regression analysis revealed that the clinical severity of PD correlated inversely with the FA value in the substantia nigra in patients with PD ( regression coefficient −0.019 ) . No single FA value had both a high positive and negative predictive power for PD . Conclusions : We demonstrated in a large , prospect i ve , case control study that the FA value in the substantia nigra on DTI was lower in PD compared with healthy controls , and correlated inversely with the clinical severity of PD . Further longitudinal studies would be helpful to assess the clinical utility of serial FA measurements of the substantia nigra in objective quantification of disease progression and monitoring of the therapeutic response Objective : To determine whether apparent diffusion coefficient ( ADC ) values and fractional anisotropy ( FA ) values can detect early pathological involvement in multiple system atrophy ( MSA ) , and be used to differentiate MSA-P ( multiple system atrophy if parkinsonian features predominate ) from Parkinson ’s disease ( PD ) . Methods : We compared  ADC and FA  values in the pons , cerebellum and putamen of 61 subjects ( 20 probable MSA patients , 21 age matched PD patients and 20 age matched healthy controls ) using a 3.0 T magnetic resonance system . Results : ADC values in the pons , cerebellum and putamen were significantly higher , and FA values lower in MSA than in PD or controls . These differences were prominent in MSA lacking dorsolateral putaminal hyperintensity ( DPH ) or hot cross bun ( HCB ) sign . In differentiating MSA-P from PD using FA and ADC values , we obtained equal sensitivity ( 70 % ) and higher specificity ( 100 % ) in the pons than in the putamen and cerebellum . In addition , all patients that had both significant low FA and high ADC values in each of these three areas were MSA-P cases , and those that had both normal FA and ADC values in the pons were all PD cases . Our diagnostic algorithm based on these results accurately diagnosed 90 % of patients with MSA-P. Conclusion : FA and ADC values detected early pathological involvement prior to magnetic resonance signal changes in MSA . In particular , low FA values in the pons showed high specificity in discriminating MSA-P from PD . In addition , combined analysis of both FA and ADC values in all three areas was more useful than only one Introduction Progressive supranuclear palsy ( PSP ) is a neurodegenerative disease featuring parkinsonism , supranuclear ophthalmoplegia , dysphagia , and frontal lobe dysfunction . The corpus callosum which consists of many commissure fibers probably reflects cerebral cortical function . Several previous reports showed atrophy or diffusion abnormalities of anterior corpus callosum in PSP patients , but partitioning method used in these studies was based on data obtained in nonhuman primates . In this study , we performed a diffusion tensor analysis using a new partitioning method for the human corpus callosum . Methods Seven consecutive patients with PSP were compared with 29 age-matched patients with Parkinson ’s Disease ( PD ) and 19 age-matched healthy control subjects . All subjects underwent  diffusion tensor magnetic resonance imaging , and the corpus callosum was partitioned into five areas on the mid-sagittal plane according to a recently established topography of human corpus callosum ( CC1—prefrontal area , CC2—premotor and supplementary motor area , CC3—motor area , CC4—sensory area , CC5—parietal , temporal , and occipital area ) . Fractional anisotropy ( FA ) and apparent diffusion coefficient ( ADC ) were measured in each area and differences between groups were analyzed . Results In the PSP group , FA values were significantly decreased in CC1 and CC2 , and ADC values were significantly increased in CC1 and CC2 . Receiver operating characteristic analysis showed excellent reliability of FA and ADC analyses of CC1 for differentiating PSP from PD . Conclusion The anterior corpus callosum corresponding to the prefrontal , premotor , and supplementary motor cortices is affected in PSP patients . This analysis can be an additional test for further confirmation of the diagnosis of PSP 
    Output:
    
Conclusion : DTI may be a promising biomarker in parkinsonian syndromes and have a future role in differential diagnosis .