Decreased Fractional Anisotropy Values Research Articles

Asymmetry, sex differences and age-related changes in the white matter in the healthy elderly: a tract-based study

BackgroundHemispherical asymmetry, sex differences and age-related changes have been reported for the human brain. Meanwhile it was still unclear the presence of the asymmetry or sex differences in the human brain occurred whether as a normal development or as consequences of any pathological changes. The aim of this study was to investigate hemispherical asymmetry, sex differences and age-related changes by using a tract-based analysis in the nerve bundles.Methods40 healthy elderly subjects underwent magnetic resonance diffusion tensor imaging, and we calculated fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values along the major white matter bundles.ResultsWe identified hemispherical asymmetry in the ADC values for the cingulate fasciculus in the total subject set and in males, and a sex difference in the FA values for the right uncinate fasciculus. For age-related changes, we demonstrated a significant increase in ADC values with advancing age in the right cingulum, left temporal white matter, and a significant decrease in FA values in the right superior longitudinal fasciculus.ConclusionIn this study, we found hemispherical asymmetry, sex differences and age-related changes in particular regions of the white matter in the healthy elderly. Our results suggest considering these differences can be important in imaging studies.

Changes in cerebellar functional connectivity and anatomical connectivity in schizophrenia: A combined resting‐state functional MRI and diffusion tensor imaging study

To examine the functional and anatomical connectivity of the cerebellum and their relationship in schizophrenia through resting-state functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI). Ten subjects with schizophrenia and 10 healthy controls underwent resting-state fMRI and DTI. Left and right cerebellar seed regions were used in a voxel-wise functional connectivity analysis of the cerebellum. Fractional anisotropy (FA) was measured to assess white matter integrity of the middle cerebellar peduncle (MCP) and superior cerebellar peduncle (SCP). Differences in functional connectivity and FA values between the two groups were determined by two-sample t-tests. The relationship between functional connectivity and FA values in both groups were assessed using Pearson s correlation. Decreased functional connectivity to the left middle temporal gyrus, bilateral middle cingulate cortex, right paracentral lobule, right thalamus, and bilateral cerebellum were found in subjects with schizophrenia when compared to healthy controls; while decreased FA values in the left SCP were found in subjects with schizophrenia compared to healthy controls. Significant correlation was observed between the functional connectivity of the left cerebellum-right paracentral lobule and right cerebellum-right thalamus and the FA values of the MCP in healthy controls. Findings of this multi-modal imaging study support functional and anatomical connectivity abnormalities and the role of the cerebellum in schizophrenia. They also indicate the need for further investigation regarding the relationship between functional and anatomical connectivity and its role in neuropathophysiology.

Fronto-temporal disconnectivity and symptom severity in children with autism spectrum disorder

Objectives. There is increasing evidence that many of the core behavioural impairments in autism spectrum disorders (ASD) emerge from disconnectivity of networks that are important for social communication. The present study aimed at investigating which specific fibre tracts are impaired in ASD and if possible alterations of white matter are associated with clinical symptomatology. Methods. Eighteen children with ASD and 18 carefully matched typically developing controls aged 6–12 years were examined using diffusion tensor imaging (DTI) and voxel-based morphometry (VBM). Fractional anisotropy (FA) values were correlated with symptom severity as indexed by the children's scores on the Autisms Diagnostic Observation Schedule (ADOS) and the Autism Diagnostic Interview-Revised (ADI-R). Results. Decreased FA values were identified for the fornix (FO), the superior longitudinal fasciculus (SLF) the corpus callosum and the uncinate fasciculus (UF) in the ASD group compared to controls, with most prominent differences in the UF bilaterally and the right SLF. FA values of affected fibre tracts were negatively associated with clinical measures of autistic symptomatology. We did not observe significantly altered grey or white matter concentration after correction for multiple comparisons. Conclusion. Our findings support the hypothesis of abnormal white matter microstructure of fronto-temporal cortical networks in ASD, which are associated with core symptoms of the disorder.

Altered brain microstructure assessed by diffusion tensor imaging in patients with chronic pancreatitis

ObjectiveIn patients with painful chronic pancreatitis (CP) there is increasing evidence of abnormal pain processing in the central nervous system. Using magnetic resonance (MR) diffusion tensor imaging, brain microstructure in...

Athetotic and Spastic Cerebral Palsy: Anatomic Characterization Based on Diffusion-Tensor Imaging

To evaluate the anatomy of deep gray and white matter structures in children with athetotic cerebral palsy (CP) and those with spastic CP by using diffusion-tensor (DT) imaging and to investigate whether these types of CP have unique anatomic correlates that can support their diagnosis and prognosis. This study was approved by the institutional review board of each participating institution, and written informed consent was obtained from the parents of each patient. DT imaging was used to retrospectively evaluate 19 children with clinically diagnosed athetotic CP (mean age, 3.4 years ± 3.3 [standard deviation]), 26 children with spastic CP (mean age, 3.3 years ± 3.2), and 31 healthy control subjects (mean age, 3.2 years ± 3.0). Fractional anisotropy (FA) and mean diffusivity (MD) were measured with a region of interest (ROI) method. The ROIs were drawn on bilateral deep gray and white matter structures, including projection fibers, association fibers, and commissural fibers. Statistical analysis was performed by using the Kruskal-Wallis test with Bonferroni correction. P < .05 indicated a significant difference. FA values in the athetotic CP group were significantly lower than those in the control and spastic CP groups for multiple structures, including deep gray and white matter (P < .05 and P = .0001, respectively); these differences were also associated with increasing MD (P < .05 and P < .001, respectively). On the other hand, in the spastic CP group, the significantly decreased FA values, compared with those of the normal group, were limited to several white matter structures (P < .05 and P = .0001). In children with athetotic CP, the extent of change on DT images due to early brain damage tends to be more diffuse, including multiple brain structures, compared with the changes in children with spastic CP.

Reduced genual corpus callosal white matter integrity in pathological gambling and its relationship to alcohol abuse or dependence

Objective. Magnetic resonance imaging (MRI) studies have demonstrated functional prefrontal cortical (PFC) abnormalities in pathological gambling (PG) and other psychiatric disorders characterized by impaired impulse control; e.g., cocaine dependence and bipolar disorder. These abnormalities are accompanied by impairments in white matter microstructures in the anterior (genual) corpus callosum (CC) in cocaine dependence and bipolar disorder. Prior studies have not examined white matter integrity in PG. We predicted impairments in genual CC white matter in PG. Methods. Nineteen participants with PG and 19 matched control participants underwent diffusion tensor imaging (DTI) to compare white matter integrity in the CC, as assessed using fractional anisotropy (FA). Results. In PG subjects as compared to control subjects, reduced FA values in the left and right genu of the CC were observed. Multiple regression analyses confirmed that PG status – in addition to age and past alcohol abuse/dependence (AA/AD) – was a significant predictor of genual FA values. Among PG participants, left and right genu FA values were negatively correlated with scores on the Behavioral Activation System Fun-Seeking (BAS-FS) subscale. Limitations. Limitations include a reliance on self-report measures of impulsivity and related constructs and a relatively small sample of PG subjects with past AA/AD. Conclusion. Findings of decreased FA values in the genu of the CC in PG subjects suggest that, like with other disorders of behavioral dyscontrol, white matter microstructural abnormalities contribute to the pathophysiology of PG. These differences appear particularly relevant to individuals with remitted AA/AD, highlighting the importance of considering co-occurring substance use disorders when investigating PG.

Cognitive status correlates with white matter alteration in Parkinson's disease

Patients with Parkinson's disease (PD) can develop mild cognitive impairment (PD-MCI), frequently progressing to dementia (PDD). Here, we aimed to elucidate the relationship between white matter alteration and cognitive status in PD and dementia with Lewy bodies (DLB) by using diffusion tensor imaging. We also compared the progression patterns of white and gray matter and the cerebral perfusion. We enrolled patients with PD cognitively normal (PD-CogNL, n = 32), PD-MCI (n = 28), PDD (n = 25), DLB (n = 29), and age- and sex-matched healthy control subjects (n = 40). Fractional anisotropy (FA) map of a patient group was compared with that of control subjects by using tract-based spatial statistics. For the patient cohort, intersubject voxel-wise correlation was performed between FA values and Mini-Mental Status Examination (MMSE) scores. We also evaluated the gray matter and the cerebral perfusion by conducting a voxel-based analysis. There were significantly decreased FA values in many major tracts in patients with PD-MCI, PDD, and DLB, but not in PD-CogNL, compared with control subjects. FA values in the certain white matter areas, particularly the bilateral parietal white matter, were significantly correlated with MMSE scores in patients with PD. Patients with PDD and DLB had diffuse gray matter atrophy. All patient groups had occipital and posterior parietal hypoperfusion when compared with control subjects. Our results suggest that white matter damage underlies cognitive impairment in PD, and cognitive impairment in PD progresses with functional alteration (hypoperfusion) followed by structural alterations in which white matter alteration precedes gray matter atrophy.

Cerebral Network Disruption as a Possible Mechanism for Impaired Recovery after Acute Pontine Stroke

Background: Recovery from stroke is presumed to be a function of a widespread cerebral network. Chronic white matter lesions (WML) have been proposed to be a predictor of poor outcome after acute stroke. We tested the hypothesis that the extent of WML has an effect on functional recovery in acute pontine stroke by disrupting the integrity of the supratentorial cerebral network. Methods: Seventeen patients with acute unilateral pontine stroke who had received a standardized stroke workup and additional diffusion tensor imaging (DTI) were studied. After grading the extent of WML according to the Fazekas scale and semiautomated lesion volume calculation, we compared patients with acute pontine infarction and advanced WML to those with absent or minimal WML regarding baseline characteristics, stroke subtype and clinical outcome. In addition, we used tract-based spatial statistics for voxel-wise analysis of the DTI-derived parameter fractional anisotropy in the white matter tracts. Results: The volume of WML ranged between 0.1 and 42.1 cm³ (mean = 15.9) and was graded as follows: 0 in 5.9%, 1 in 35.3%, 2 in 41.2% and 3 in 17.6%. Both patients with Fazekas grades 2–3 (p = 0.014) as well as those with larger WML volumes (p = 0.037) had severer functional deficits at the 3-month follow-up. White matter tracts displaying a significant decrease in fractional anisotropy values were the corpus callosum, the anterior thalamic radiation and the inferior fronto-occipital fasciculus. Conclusions: Chronic WML contribute to a less favorable clinical outcome after pontine stroke depending on (1) the extent of pre-existing WML and (2) the degree of disruption of cerebral connectivity as indicated by reduced tissue integrity in the white matter not affected by WML as detected by DTI and tract-based spatial statistics.

Fractional Anisotropy Changes After Several Weeks of Daily Left High-Frequency Repetitive Transcranial Magnetic Stimulation of the Prefrontal Cortex to Treat Major Depression

As part of a sham controlled treatment trial using daily left repetitive transcranial magnetic stimulation (rTMS), brain changes associated with 4 to 6 weeks of treatment were examined using diffusion tensor imaging to noninvasively evaluate prefrontal white matter (WM) microstructure. A decrease in fractional anisotropy values of the left prefrontal WM could indicate damage to the region. Diffusion tensor imaging was performed before and after 4 to 6 weeks of daily rTMS treatments. Mean fractional anisotropy levels associated with active rTMS and sham rTMS for the right and left prefrontal WM were assessed. Adequate images were acquired for 8 participants (active n = 4, sham n = 4) before and after rTMS. A mean increase was found for the left prefrontal WM. The mixed model revealed a trend toward a significant treatment group × region interaction effect (P = 0.11). Furthermore, simple region effects (left prefrontal WM vs right prefrontal WM) were at a trend toward significance for difference after treatment within the active rTMS group (P = 0.07), but not within the sham rTMS group (P = 0.88). Repetitive transcranial magnetic stimulation resulted in no evidence of damage to WM on the side of stimulation. Diffusion tensor imaging may offer a unique modality to increase our understanding of mechanisms of action for rTMS.

White matter impairment in heroin addicts undergoing methadone maintenance treatment and prolonged abstinence: A preliminary DTI study

Methadone maintenance treatment (MMT) might cause the impairments of neuropsychological and neurotransmitter function in opioid addicts. Whether long-term MMT could lead to the impairment of white matter (WM) in heroin addiction brain is unclear. This study compared the WM integrity in the bilateral frontal lobe, temporal lobe, splenium and genu of corpus collasum (CC) between MMT patients ( n = 13), former heroin addicts ( n = 11) in prolonged abstinence (PA), and healthy control subjects ( n = 15) using diffusion tensor imaging (DTI). Fractional anisotropy (FA), apparent diffusion coefficient (ADC) and eigenvalues ( λ ⊥, λ ||) were measured. The correlation between DTI measures and accumulated former heroin dose, total methadone consumption, and PA duration were determined. Although the PA subjects showed no difference in DTI measures relative to the controls, the extensive correlations between the former heroin consumption and the DTI measures were noted. The MMT subjects showed a decreased FA values in the left genu, as well as the increased ADC and λ ⊥ values in the left splenium of CC in comparison to the controls. Compared with the PA, the MMT subjects had a significantly increased ADC value in the bilateral splenium of CC. Importantly, the methadone dosage used in the MMT group was correlated with the FA value in the left splenium of CC and in the right frontal lobe. Our preliminary results suggest that methadone plays a role in the impairment of WM integrity in heroin users on long-term MMT and the normalization of WM injury may occur during abstinence.

Diffusion tensor imaging differences relate to memory deficits in diffuse traumatic brain injury

BackgroundMemory is one of the most impaired functions after traumatic brain injury (TBI). We used diffusion tensor imaging (DTI) to determine the structural basis of memory deficit. We correlated fractional anisotropy (FA) of the fasciculi connecting the main cerebral regions that are involved in declarative and working memory functions.MethodsFifteen patients with severe and diffuse TBI and sixteen healthy controls matched by age and years of education were scanned. The neuropsychological assessment included: Letter-number sequencing test (LNS), 2-back task, digit span (forwards and backwards) and the Rivermead profilet. DTI was analyzed by a tract-based spatial statics (TBSS) approach.ResultsWhole brain DTI analysis showed a global decrease in FA values that correlated with the 2-back d-prime index, but not with the Rivermead profile. ROI analysis revealed positive correlations between working memory performance assessed by 2-back d-prime and superior longitudinal fasciculi, corpus callosum, arcuate fasciculi and fornix. Declarative memory assessed by the Rivermead profile scores correlated with the fornix and the corpus callosum.ConclusionsDiffuse TBI is associated with a general decrease of white matter integrity. Nevertheless deficits in specific memory domains are related to different patterns of white matter damage.

Cerebellum Abnormalities in Idiopathic Generalized Epilepsy with Generalized Tonic-Clonic Seizures Revealed by Diffusion Tensor Imaging

Although there is increasing evidence suggesting that there may be subtle abnormalities in idiopathic generalized epilepsy (IGE) patients using modern neuroimaging techniques, most of these previous studies focused on the brain grey matter, leaving the underlying white matter abnormalities in IGE largely unknown, which baffles the treatment as well as the understanding of IGE. In this work, we adopted multiple methods from different levels based on diffusion tensor imaging (DTI) to analyze the white matter abnormalities in 14 young male IGE patients with generalized tonic-clonic seizures (GTCS) only, comparing with 29 age-matched male healthy controls. First, we performed a voxel-based analysis (VBA) of the fractional anisotropy (FA) images derived from DTI. Second, we used a tract-based spatial statistics (TBSS) method to explore the alterations within the white matter skeleton of the patients. Third, we adopted region-of-interest (ROI) analyses based on the findings of VBA and TBSS to further confirm abnormal brain regions in the patients. At last, considering the convergent evidences we found by VBA, TBSS and ROI analyses, a subsequent probabilistic fiber tractography study was performed to investigate the abnormal white matter connectivity in the patients. Significantly decreased FA values were consistently observed in the cerebellum of patients, providing fresh evidence and new clues for the important role of cerebellum in IGE with GTCS.

Neuroanatomical changes due to hearing loss and chronic tinnitus: A combined VBM and DTI study

Subjective tinnitus is the perception of sound in the absence of an external source. Tinnitus is often accompanied by hearing loss but not everyone with hearing loss experiences tinnitus. We examined neuroanatomical alterations associated with hearing loss and tinnitus in three groups of subjects: those with hearing loss with tinnitus, those with hearing loss without tinnitus and normal hearing controls without tinnitus. To examine changes in gray matter we used structural MRI scans and voxel-based morphometry (VBM) and to identify changes in white matter tract orientation we used diffusion tensor imaging (DTI). A major finding of our study was that there were both gray and white matter changes in the vicinity of the auditory cortex for subjects with hearing loss alone relative to those with tinnitus and those with normal hearing. We did not find significant changes in gray or white matter in subjects with tinnitus and hearing loss compared to normal hearing controls. VBM analysis revealed that individuals with hearing loss without tinnitus had gray matter decreases in anterior cingulate and superior and medial frontal gyri relative to those with hearing loss and tinnitus. Region-of-interest analysis revealed additional decreases in superior temporal gyrus for the hearing loss group compared to the tinnitus group. Investigating effects of hearing loss alone, we found gray matter decreases in superior and medial frontal gyri in participants with hearing loss compared to normal hearing controls. DTI analysis showed decreases in fractional anisotropy values in the right superior and inferior longitudinal fasciculi, corticospinal tract, inferior fronto-occipital tract, superior occipital fasciculus, and anterior thalamic radiation for the hearing loss group relative to normal hearing controls. In attempting to dissociate the effect of tinnitus from hearing loss, we observed that hearing loss rather than tinnitus had the greatest influence on gray and white matter alterations.

Fractional Anisotropy Levels Derived From Diffusion Tensor Imaging in Cervical Syringomyelia

Syringomyelia can result in major functional disability. Conventional imaging techniques frequently fail to detect the underlying cause of syringomyelia. The prediction as to whether syringomyelia might lead to neurological deficits is still challenging. We hypothesized that fractional anisotropy (FA) derived from diffusion tensor imaging (DTI) is a parameter to detect dynamic forms of syringomyelia. Six patients with cervical syringomyelia, all comparable in size, shape, and location, were examined, along with 2 volunteers. Patients underwent electrophysiological recordings (somatosensory evoked potentials, motor evoked potentials, silent periods). Magnetic resonance imaging (1.5 T) was performed with a 6-element spine coil. Anatomic images were acquired with a 3-dimensional, constructive interference in steady-state sequence, and DTI with an echo-planar imaging sequence (5-mm thickness, b value 800 s/mm) using the generalized autocalibrating partially parallel acquisitions technique. The positions were centered on the syrinx in the volunteers between the C2 and Th1. DTI data were interpolated to a spatial resolution of 0.5 mm. After calculation of a diffusion tensor in each pixel, an FA map was calculated and profiles of the FA values across the spinal cord were calculated in all slices. FA values were lower at the level of all examined syrinxes and reached normal values beyond them. Electrophysiological results correlated with the decrease in FA value. There were no presyrinx changes in the white matter tracts in terms of signs of FA changes beneath the syrinx. DTI of syringomyelia can demonstrate white matter fiber tracts around and beyond the syrinx consistent with electrophysiological values. DTI of the cervical spine can provide quantitative information about the pathological characteristics beyond the abnormalities visible on magnetic resonance imaging.

Correlation of quantitative sensorimotor tractography with clinical grade of cerebral palsy

The purpose of this study was to determine whether tract-specific diffusion tensor imaging measures in somatosensory and motor pathways correlate with clinical grades as defined using the Gross Motor Function Classification System (GMFCS) in cerebral palsy (CP) children. Quantitative diffusion tensor tractography was performed on 39 patients with spastic quadriparesis (mean age = 8 years) and 14 age/sex-matched controls. All patients were graded on the basis of GMFCS scale into grade II (n = 12), grade IV (n = 22), and grade V (n = 5) CP and quantitative analysis reconstruction of somatosensory and motor tracts performed. Significant inverse correlation between clinical grade and fractional anisotropy (FA) was observed in both right and left motor and sensory tracts. A significant direct correlation of mean diffusivity values from both motor and sensory tracts was also observed with clinical grades. Successive decrease in FA values was observed in all tracts except for left motor tracts moving from age/sex-matched controls to grade V through grades II and IV. We conclude that white matter tracts from both the somatosensory and the motor cortex play an important role in the pathophysiology of motor disability in patients with CP.

Local cerebral blood perfusion correlates with nerve fibre integrity in transient ischemic attack patients with middle cerebral artery stenosis: a pilot study

Recent advances in neuroimaging contribute a lot to the accurate diagnosis and evaluation of cerebrovascular diseases. To explore the relationship among blood perfusion, metabolism and brain structure integrity, 6 Chinese transient ischemic attack (TIA) patients with middle cerebral artery (MCA) stenosis were examined by xenon-enhanced computed tomography (Xe-CT), magnetic resonance spectroscopy (MRS) and diffusion tensor imaging (DTI) to compare cerebral blood flow (CBF) values, (choline + creatine)/ N-acetyl aspartate [(Cho + Cr)/NAA] values and fractional anisotropy (FA) values in the MCA territory. Our results showed that CBF values significantly decreased in the ipsilateral basal ganglion regions in all 5 cases with unilateral MCA stenosis, with a corresponding decrease of FA values in the same region. In conclusion, decreased blood perfusion may indicate nerve fibre damage in the dominating regions of stenosed arteries.

Correlation of CSF Proinflammatory Cytokines with MRI in Tuberculous Meningitis

To demonstrate the correlation of proinflammatory cytokines (PCs), intercellular adhesion molecule (sICAM-1), tumor necrosis factor-alpha (TNF-alpha), and interleukin-1beta (IL-1beta) in CSF of tuberculous meningitis (TBM) patients with magnetic resonance imaging (MRI) including diffusion tensor imaging (DTI) and also to look for the changes in imaging parameters after antitubercular treatment (ATT) in these patients. Forty patients with TBM (median age, 27.7 years) and 30 age-/sex-matched controls were included in this study. PCs were quantified from the CSF of TBM patients at the time of hospital admission (baseline). MRI including DTI was performed at the time of baseline study and 6 months after ATT. Significant positive correlation of PCs with fractional anisotropy (FA) values and post-contrast signal intensity (PCSI) collected from cerebral cortical regions was observed in TBM patients. A significant positive correlation of FA values with PCSI was also observed at both time points in patient groups. At baseline study significantly high FA values were observed in patients compared to controls. Significantly decreased FA values and PCSI were observed in the patients after 6 months of ATT compared to the baseline study. Results of this study suggest that the DTI-derived anisotropy have the potential to delineate meningeal inflammation and it may be used in assessment of therapeutic response in TBM patients as an additional method to conventional imaging.

Lineare longitudinale Abnahme der fraktionalen Anisotropie bei Patienten mit amyotrophischer Lateralsklerose. Vorläufige Ergebnisse

As potential therapies aimed at halting or slowing the decline in upper motor neuron function in patients with amyotrophic lateral sclerosis (ALS) or primary lateral sclerosis (PLS) are developed, a quantitative method for monitoring response will be necessary. Measurement of fractional anisotropy (FA) using diffusion tensor imaging (DTI) over time should parallel functional decline from upper motor neuron degeneration in these patients. Two patients with definite ALS were imaged at 3.0 T and FA values were obtained in the corticospinal tract every 3 months for 1 year. The FA values were compared to normal age-matched controls. Both patients showed linear decreases in FA values over time with R(2) values ranging from 0.93 to 0.99. The decline became statistically significant over the course of the study. Qualitative decreases in anisotropy were also evident on FA maps. If these trends can be validated in greater numbers of patients, DTI may serve as an objective quantitative biomarker for disease progression in patients with upper motor neuron disease.

White matter plasticity in the corticospinal tract of musicians: A diffusion tensor imaging study

With the advent of diffusion tensor imaging (DTI), the study of plastic changes in white matter architecture due to long-term practice has attracted increasing interest. Professional musicians provide an ideal model for investigating white matter plasticity because of their early onset of extensive auditory and sensorimotor training. We performed fiber tractography and subsequent voxelwise analysis, region of interest (ROI) analysis, and detailed slicewise analysis of diffusion parameters in the corticospinal tract (CST) on 26 professional musicians and a control group of 13 participants. All analyses resulted in significantly lower fractional anisotropy (FA) values in both the left and the right CST in the musician group. Furthermore, a right-greater-than-left asymmetry of FA was observed regardless of group. In the musician group, diffusivity was negatively correlated with the onset of musical training in childhood. A subsequent median split into an early and a late onset musician group (median=7 years) revealed increased diffusivity in the CST of the early onset group as compared to both the late onset group and the controls. In conclusion, these DTI-based findings might indicate plastic changes in white matter architecture of the CST in professional musicians. Our results imply that training-induced changes in diffusion characteristics of the axonal membrane may lead to increased radial diffusivity as reflected in decreased FA values.

Correlation between pyramidal tract degeneration and widespread white matter involvement in amyotrophic lateral sclerosis: A study with tractography and diffusion-tensor imaging

Our aim was to evaluate the location and extent of white matter involvement in patients with amyotrophic lateral sclerosis (ALS) using diffusion-tensor magnetic resonance imaging (DTI). We obtained fractional anisotropy (FA) values from the internal capsule and various white matter regions of 46 patients with sporadic ALS and 19 control subjects. In ALS patients, FA values in the internal capsule, frontal white matter, genu and splenium of the corpus callosum (p<0.001), parietal and temporal lobe white matter, and posterior cingulum (p<0.05) were significantly lower than in controls. FA values in frontal white matter were lower than in parietal white matter (p<0.001). Decreased FA values in frontal, parietal, and temporal white matter, and the genu of the corpus callosum, correlated significantly with those in the internal capsule (r=0.66 and p<0.001, r=0.47 and p=0.001, r=0.33 and p=0.021, r=0.41 and p=0.005, respectively). No such correlations were found for FA values in other white matter areas or in controls. Patient FA values generally were not correlated with disease duration. DTI demonstrated more widespread involvement of the cerebral white matter in ALS patients than previously believed. The severity of involvement in the frontal, temporal and parietal white matter correlated with severity in the pyramidal tract.