Changes in Structural Neural Networks in the Recovery Process of Motor Paralysis after Stroke.

In recent years, neurorehabilitation has been actively used to treat motor paralysis after stroke. However, the impacts of rehabilitation on neural networks in the brain remain largely unknown. Therefore, we investigated changes in structural neural networks after rehabilitation therapy in patients who received a combination of low-frequency repetitive transcranial magnetic stimulation (LF-rTMS) and intensive occupational therapy (intensive-OT) as neurorehabilitation. Fugl-Meyer assessment (FMA) for upper extremity (FMA-UE) and Action Research Arm Test (ARAT), both of which reflected upper limb motor function, were conducted before and after rehabilitation therapy. At the same time, diffusion tensor imaging (DTI) and three-dimensional T1-weighted imaging (3D T1WI) were performed. After analyzing the structural connectome based on DTI data, measures related to connectivity in neural networks were calculated using graph theory. Rehabilitation therapy prompted a significant increase in connectivity with the isthmus of the cingulate gyrus in the ipsilesional hemisphere (p < 0.05) in patients with left-sided paralysis, as well as a significant decrease in connectivity with the ipsilesional postcentral gyrus (p < 0.05). These results indicate that LF-rTMS combined with intensive-OT may facilitate motor function recovery by enhancing the functional roles of networks in motor-related areas of the ipsilesional cerebral hemisphere.

Evaluation of fMRI activation in hemiparetic stroke patients after rehabilitation with low-frequency repetitive transcranial magnetic stimulation and intensive occupational therapy.

Purpose: To evaluate activity changes associated with the intervention of low-frequency repetitive transcranial magnetic stimulation (rTMS) and intensive occupational therapy (OT) after stroke using functional magnetic resonance (fMRI).Methods: Seventy stroke patients were scanned while performing finger tapping tasks twice, before and 12 days after the intervention. Recovery of motor functions assessed using Fugl-Meyer Assessment (FMA) and Wolf Motor Function Test-Functional Ability Scale (WMFT-FAS) for upper extremity at each time point. An fMRI analysis was performed, and a region of interest (ROI) analysis was conducted using percentage signal changes (% SC) to determine the magnitude of activation.Results: FMA and WMFT-FAS were significantly increased from pre-intervention to post-intervention. Intervention related activations were seen in the ipsilesional premotor cortex (PMC) and primary motor cortex (M1), thalamo-cortico regions with the paretic hand movements. With the unaffected hand movements, significant clusters in the contralesional primary somatosensory cortex (S1), superior parietal cortex, and bilateral cerebellum were observed. The ROI-based analysis revealed that ipsilesional M1, contralesional PMC, and supplementary motor area (SMA) showed significantly higher results with the paretic hand movements, a trend toward a significant decrease in the contralesional S1 with the unaffected hand movements from the pre-intervention to post-intervention.Conclusions: Our findings suggest that gains in motor functions produced by the intervention of rTMS and intensive OT in hemiparesis stroke patients may be associated with the ipsilesional hemisphere and contralesional hemisphere as well. Identifying rTMS and OT intervention based on cortical patterns may help to implement rTMS in motor rehabilitation after stroke.Supplementary data for this article is available online at https://doi.org/10.1080/00207454.2021.1968858 .

Changes in brain morphometry after motor rehabilitation in chronic stroke.

PURPOSE: Recent studies have revealed structural changes after motor rehabilitation, but its morphological changes related to upper limb motor behaviours have not been studied exhaustively. Therefore, we aimed to map the grey matter (GM) changes associated with motor rehabilitation after stroke using voxel-based morphometry (VBM), deformation-based morphometry (DBM), and surface-based morphometry (SBM). METHODS: Forty-one patients with chronic stroke received twelve sessions of low-frequency repetitive transcranial magnetic stimulation plus intensive occupational therapy. MRI data were obtained before and after the intervention. Fugl-Meyer Assessment and Wolf Motor Function Test-Functional Ability Scale were assessed at the two-time points. We performed VBM, DBM, and SBM analyses using T1-weighted images. A correlation analysis was performed between cortical thickness in motor areas and clinical outcomes. RESULTS: Clinical outcomes significantly improved after the intervention. VBM showed significant GM volume changes in ipsilesional and contralesional primary motor regions. DBM results demonstrated GM changes contralesionally and ipsilesionally after the intervention. SBM results showed significant cortical thickness changes in posterior visuomotor coordination, precentral, postcentral gyri of the ipsilesional hemisphere and contralesional visuomotor area after the intervention. A combination of threshold p < .05, False Discovery Rate and p < .001 (uncorrected) were considered significant. In addition, cortical thickness changes of the ipsilesional motor areas were significantly correlated with the clinical outcome changes. CONCLUSIONS: We found GM structural changes in areas involved in motor, visuomotor and somatosensory functions after the intervention. Furthermore, our findings suggest that structural plasticity changes in chronic stroke could occur in the ipsilesional and contralesional hemispheres after motor rehabilitation.

Structural connectivity changes in the motor execution network after stroke rehabilitation.

BACKGROUND: Although quite a very few studies have tested structural connectivity changes following an intervention, it reflects only selected key brain regions in the motor network. Thus, the understanding of structural connectivity changes related to the motor recovery process remains unclear. OBJECTIVE: This study investigated structural connectivity changes of the motor execution network following a combined intervention of low-frequency repetitive transcranial magnetic stimulation (LF-rTMS) and intensive occupational therapy (OT) after a stroke using graph theory approach. METHODS: Fifty-six stroke patients underwent Fugl-Meyer Assessment (FMA), Wolf Motor Function Test-Functional Ability Scale (WMFT-FAS), diffusion tensor imaging (DTI), and T1 weighted imaging before and after the intervention. We examined graph theory measures related to twenty brain regions using structural connectomes. RESULTS: The ipsilesional and contralesional hemisphere showed structural connectivity changes post-intervention after stroke. We found significantly increased regional centralities and nodal efficiency within the frontal pole and decreased degree centrality and nodal efficiency in the ipsilesional thalamus. Correlations were found between network measures and clinical assessments in the cuneus, postcentral gyrus, precentral gyrus, and putamen of the ipsilesional hemisphere. The contralesional areas such as the caudate, cerebellum, and frontal pole also showed significant correlations. CONCLUSIONS: This study was helpful to expand the understanding of structural connectivity changes in both hemispheric networks during the motor recovery process following LF-rTMS and intensive OT after stroke.

White matter degeneration in diffuse axonal injury and mild traumatic brain injury observed with automatic tractography.

A better understanding of white matter tract damage in patients with diffuse axonal injury (DAI) and mild traumatic brain injury (MTBI) is important to obtain an objective basis for sequelae. The purpose of this study was to clarify the characteristics of white matter tract degeneration in DAI and MTBI using automated tractography. T1-weighted and diffusion tensor imaging (DTI) was performed on seven DAI and seven MTBI patients as well as on nine healthy subjects. Automated probabilistic tractography analysis was performed using FreeSurfer and TRACULA (tracts constrained by underlying anatomy) for the reconstruction of major nerve fibers. We investigated the difference between DTI quantitative values in each white matter nerve fiber between groups and attempted to evaluate the classification accuracy of DAI and MTBI using receiver operator curve analysis. Both DAI and MTBI appeared to exhibit axonal degeneration along the nerve fiber tract in a scattered manner. The mean diffusivity of the ampulla of the corpus callosum was significantly higher in DAI than that in MTBI patients, suggesting axonal degeneration of the corpus callosum in DAI patients. Using mean diffusivity of the right cingulum-angular bundle, DAI and MTBI could be discriminated with an area under the curve of 94%. Both DAI and MTBI exhibited scattered axonal degeneration; however, DAI appeared to exhibit more pronounced axonal degeneration in the ampulla of the corpus callosum than MTBI. Our results suggest that DAI and MTBI can be accurately distinguished using DTI.

White matter changes follow low-frequency repetitive transcranial magnetic stimulation plus intensive occupational therapy for motor paralysis after stroke: a DTI study using TBSS.

Intervention that combines low-frequency repetitive transcranial magnetic stimulation (rTMS) and intensive occupational therapy (OT) may improve brain function in post-stroke patients with motor paralysis. We aimed to clarify the brain region involved in motor function improvement following chronic stroke. We recruited 25 patients hospitalized for 15 days with post-stroke upper extremity paralysis to receive 12 sessions of low-frequency rTMS over the non-lesioned hemisphere and occupational therapy. In this study, 72% of the patients had suffered from intracranial haemorrhage. Imaging analysis was performed using diffusion tensor imaging (DTI) to assess changes in white matter after intervention. We investigated white matter change before and after intervention and the relationship between white matter structure and motor function recovery using tract-based spatial statistics. The intra-voxel directional coherence was significantly increased in the anterior limb of the internal capsule and anterior thalamic radiation on the lesional side following intervention. Mean diffusivity and radial diffusivity values of clusters in the superior corona radiata on the lesional side were negatively correlated with motor function recovery. White matter nerve fibre structures are involved in motor function improvement following rTMS and OT interventions. Our results show novel findings regarding the relationship between stroke neurorehabilitation and cerebral nerve structure.

MRI evaluation of motor function recovery by rTMS and intensive occupational therapy and changes in the activity of motor cortex.

Purpose/aim: An intervention that combines low-frequency repetitive transcranial magnetic stimulation and intensive occupational therapy can improve brain function in post-stroke patients with motor paralysis. The purpose of the present study is examined motor function recovery by repetitive transcranial magnetic stimulation and intensive occupational therapy and changes in the activity of motor cortex based on magnetic resonance imaging data.Materials and methods: In total, we assessed 30 patients with post-stroke upper extremity paralysis who were hospitalized for 12 sessions of low-frequency repetitive transcranial magnetic stimulation over the lesion-free hemisphere plus daily occupational therapy for 15 days. Imaging analysis was performed using 3-dimensional T1-weighted image and functional magnetic resonance imaging. Hemispheric dominance was assessed by functional magnetic resonance imaging using the laterality index. In addition, Seed-based functional connectivity analysis was used to evaluate functional connectivity between the precentral gyrus of the affected side and other areas.Results: A positive correlation was found between laterality index before intervention and the Brunnstrom recovery stage for hand/fingers (p < 0.05). The intervention resulted in significantly higher functional connectivity between the precentral gyrus of the affected side and that of the healthy side (false discovery rate corrected p < 0.05).Conclusions: We clarified that the recovery of motor function by intervention with low-frequency repetitive transcranial magnetic stimulation and occupational therapy and the increase of functional connectivity between the precentral gyrus on the affected side and the healthy side are related. These results facilitate prognostic predictions and evidence-based medical care.

Development of anisotropic phantoms using wood and fiber materials for diffusion tensor imaging and diffusion kurtosis imaging.

OBJECTIVE: Several studies have demonstrated that anisotropic phantoms can be utilized for diffusion magnetic resonance imaging. The purpose of our study was to examine whether wood is suitable as an anisotropic phantom material from the viewpoints of affordability and availability. In the current study, wood was used for restricted diffusion, and fibers were used for hindered diffusion. MATERIALS AND METHODS: Wood and fiber phantoms were made. Diffusion kurtosis images were acquired with three magnetic resonance scanners. Fractional anisotropy, radial diffusivity, axial diffusivity, radial kurtosis and axial kurtosis values were measured. The wood phantom was imaged, and its durability was confirmed. The phantoms were imaged in varying orientations within the magnetic field. The wood was observed using an optical microscope. RESULTS: Ten kinds of wood and the fiber had a diffusion metrics. The wood diffusion metrics suggested low variation over a period of 9 months. Changing the orientation of the phantoms within the magnetic field resulted in changes in diffusion metrics. Observation of wood vessels and fibers was conducted. DISCUSSION: Wood and fibers have anisotropy and are promising as phantom materials. The development of anisotropic phantoms that anyone can use is useful for diffusion magnetic resonance imaging research and clinical applications.

Relationship between motor function improvements and white matter structure after low-frequency repetitive transcranial magnetic stimulation plus intensive occupational therapy in chronic subcortical stroke patients.

This is a second paper on partly the same patient group and the same intervention, but with a different anatomical outcome measurement. An intervention that combines low-frequency repetitive transcranial magnetic stimulation and intensive occupational therapy may improve brain function in poststroke patients with motor paralysis. The aim of this study was to clarify whole-brain white matter structural changes after repetitive transcranial magnetic stimulation and occupational therapy. We recruited 25 patients hospitalized for 15 days with poststroke upper extremity paralysis to receive 12 sessions of low-frequency repetitive transcranial magnetic stimulation over the nonlesioned hemisphere and occupational therapy. Focal repetitive transcranial magnetic stimulation was applied over the primary motor area for the fingers of the nonlesioned hemisphere. Imaging analysis was carried out using diffusion tensor imaging to assess changes in white matter after the intervention. Graph-theoretical analysis was carried out to quantify the characteristics of brain white matter networks. We found a significant increase in global betweenness centrality (corrected P<0.05) and characteristic path length (corrected P<0.05) in the postintervention group. In addition, the global clustering coefficient (corrected P<0.05), small-worldness (corrected P<0.05), and global strength (corrected P<0.05) decreased in the postintervention group. Graph theory analysis suggested that our intervention increased the characteristic path length and led to more complicated neural circuits, indicating that synaptic connections may have increased across the entire network through structural plasticity following our intervention. Our results show novel findings on the relationship between stroke neurorehabilitation and cerebral nerve structure.

Development of a Surface Marker for Fractional Anisotropy Maps Using Wood in a Phantom Study.

PURPOSE: To improve imaging, a reliable setup method is critical for the accurate localization of lesions and surface markers. Because an anisotropic marker has not yet been validated for MRI, direct localization of surface markers is not yet feasible in fractional anisotropy (FA) maps. This study aimed to develop an anisotropic surface marker using wood for an FA map and to determine whether a wood marker is useful for various sequences. METHODS: Wood infiltrated with water was used to develop an anisotropic surface marker. The wood marker was compared with phantoms composed of clinically available markers, including MR-SPOTS Packets (Beekley Medical, Bristol, CT, USA), Breath Care Oral Refreshing Capsules (Kobayashi Pharmaceutical Co., Ltd., Osaka, Japan), and baby oil (Johnson & Johnson, New Brunswick, NJ, USA). Magnetic resonance images were acquired using the Achieva 3T TX MRI System (Philips HealthCare, Best, Netherlands) equipped with a QD head coil including T1- and T2-weighted imaging, proton-density-weighted imaging, T2*-weighted imaging, T1-weighted imaging spectral pre-saturation with inversion recovery, T2-weighted imaging spectral attenuated inversion recovery, proton-density-weighted imaging spectral attenuated inversion recovery, diffusion weighted imaging, and diffusion tensor imaging. Apparent diffusion coefficient, FA values, and signal-to-noise ratio (SNR) were measured and recorded, and the coefficient of variation was calculated for two consecutive imaging scans. The wood was observed using a microscope. RESULTS: Breath Care Oral Refreshing Capsules and baby oil were not observed in the FA map. The FA value of the MR-SPOTS Packets was 0.18. The FA value of the wood marker was 0.80. The coefficient of variation of the MR-SPOTS Packets and the wood marker were 0.0263 and 0.0013, respectively, in the FA map. Microscopic observation revealed a wood anisotropic structure. CONCLUSION: The wood maker enabled direct localization in the FA map. Hence, wood markers may be useful to radiologists and contribute to obtaining useful findings.

Correlation analysis of motor function improvement and brain structure for upper limb paralysis.

Intervention with combined low-frequency repetitive transcranial magnetic stimulation and intensive occupational therapy can improve brain function in poststroke patients with motor paralysis. We aimed to evaluate the relationship between brain structure at the time of intervention and the degree of motor function improvement using this combination therapy. Twenty-five patients with upper limb paralysis after stroke were hospitalized for 15 days to receive 12 sessions of low-frequency repetitive transcranial magnetic stimulation over the nonlesional hemisphere and occupational therapy. Imaging analysis was carried out using three-dimensional T1-weighted images. Correlation analysis between cortical thickness and upper limb motor function score was carried out using FreeSurfer. Correlation analysis between cortical thickness and motor function improvement was carried out by atlas-based analysis. FreeSurfer showed that significant positive correlations were found between cortical thickness of the postcentral or supramarginal gyrus of the diseased hemisphere and motor function improvements in nondominant hand paralysis (uncorrected P<0.001). Results using the atlas supported these results (P<0.05). The results of the analysis indicated that the effect of our proposed treatment could be related to the cortical thickness. In particular, it is considered that the cortical thickness of the postcentral gyrus or the supramarginal gyrus of the affected hemisphere plays an important role in such recovery in poststroke hemiparetic patients.

Diffusion Tensor Imaging Evaluation of Neural Network Development in Patients Undergoing Therapeutic Repetitive Transcranial Magnetic Stimulation following Stroke.

We aimed to investigate plastic changes in cerebral white matter structures using diffusion tensor imaging following a 15-day stroke rehabilitation program. We compared the detection of cerebral plasticity between generalized fractional anisotropy (GFA), a novel tool for investigating white matter structures, and fractional anisotropy (FA). Low-frequency repetitive transcranial magnetic stimulation (LF-rTMS) of 2400 pulses applied to the nonlesional hemisphere and 240 min intensive occupation therapy (OT) daily over 15 days. Motor function was evaluated using the Fugl-Meyer assessment (FMA) and Wolf Motor Function Test (WMFT). Patients underwent diffusion tensor magnetic resonance imaging (MRI) on admission and discharge, from which bilateral FA and GFA values in Brodmann area (BA) 4 and BA6 were calculated. Motor function improved following treatment (p < 0.001). Treatment increased GFA values for both the lesioned and nonlesioned BA4 (p < 0.05, p < 0.001, resp.). Changes in GFA value for BA4 of the lesioned hemisphere were significantly inversely correlated with changes in WMFT scores (R2 = 0.363, p < 0.05). Our findings indicate that the GFA may have a potentially more useful ability than FA to detect changes in white matter structures in areas of fiber intersection for any such future investigations.

Clinical features and predictive value of serum inflammatory markers of perivascular involvement in immunoglobulin G4-related disease.

Vascular and/or perivascular involvements of sclerotic inflammation (perivasculitis) are a complication of immunoglobulin G4-related disease (IgG4-RD). We sought to examine clinical manifestations of perivasculitis by computed tomography (CT) in patients with elevated serum IgG4 levels, and then to evaluate some potential predictors of perivasculitis in definite IgG4-RD patients. From a database of patients with serum IgG4 measurements, we selected 81 patients with elevated serum IgG4 levels (≥135 mg/dl). Perivasculitis was defined radiologically as thickened contrast-enhanced rind surrounding the aorta and its major artery on CT imaging. We found 15 patients with perivasculitis; 10 patients in the definite (n = 37), four in the possible (n = 18), and one in the excluded (n = 26) IgG4-RD groups. Clinical predictors of perivasculitis were investigated in 34 untreated patients with definite IgG4-RD. Patients with perivasculitis (n = 10) had significantly higher age at diagnosis (74.2 ± 8.8 vs 63.5 ± 9.9 years, P = 0.006), higher levels of serum IgG4 (754 vs 292 mg/dl, P = 0.007) and C-reactive protein (CRP, 0.52 mg/dl vs 0.10 mg/dl, P = 0.001) than patients without perivasculitis (n = 24). The sensitivity and specificity of serum CRP ≥0.25 mg/dl for identifying perivasculitis in the definite IgG4-RD group were 100 and 71%, respectively (area under the receiver operating characteristic curve 0.863). Our results indicate that IgG4-related perivasculitis was associated with elevated levels of serum CRP and older age, and that CRP may be a useful marker for detecting perivascular involvement in IgG4-RD.

White matter structure and clinical characteristics of stroke patients: A diffusion tensor MRI study.

Fractional anisotropy has been used in many studies that examined post-stroke changes in white matter. This study was performed to clarify cerebral white matter changes after stroke using generalized fractional anisotropy (GFA). White matter structure was visualized using diffusion tensor imaging in 72 patients with post-stroke arm paralysis. Exercise-related brain regions were examined in cerebral white matter using GFA. The relationship between GFA and clinical characteristics was examined. Overall, the mean GFA of the lesioned hemisphere was significantly lower than that of the non-lesioned hemisphere (P<0.05), the white matter of the lesioned side was severely affected by stroke. A weak negative correlation between GFA and time since stroke onset was found in Brodmann area 5 of the non-lesioned hemisphere. Age correlated negatively with GFA in Brodmann areas 5 and 7 of the lesioned hemisphere. Though these results may be due to a decrease in the frequency of use of the paralyzed limb over time, GFA overall was significantly and negatively affected by the subject's age. The GFA values of patients with paralysis of the dominant hand were significantly different from those of patients with paralysis of the nondominant hand in Brodmann areas 4 and 6 of the non-lesioned hemisphere and Brodmann area 4 of the lesioned hemisphere (P<0.05). The stroke size and location were not associated with GFA differences. Differences between the GFA of the lesioned and non-lesioned hemispheres varied depending on the affected brain region, age at onset of paralysis, and paralysis of the dominant or non-dominant hand.

Functional cortical reorganization after low-frequency repetitive transcranial magnetic stimulation plus intensive occupational therapy for upper limb hemiparesis: evaluation by functional magnetic resonance imaging in poststroke patients.

BACKGROUND: Low-frequency repetitive transcranial magnetic stimulation of the nonlesional hemisphere combined with occupational therapy significantly improves motor function of the affected upper limb in poststroke hemiparetic patients, but the recovery mechanism remains unclear. AIMS: To investigate the recovery mechanism using functional magnetic resonance imaging. METHODS: Forty-seven poststroke hemiparetic patients were hospitalized to receive 12 sessions of 40-min low-frequency repetitive transcranial magnetic stimulation over the nonlesional hemisphere and daily occupational therapy for 15 days. Motor function was evaluated with the Fugl-Meyer Assessment and Wolf Motor Function Test. The functional magnetic resonance imaging with motor tasks was performed at admission and discharge. The laterality index of activated voxel number in Brodmann areas 4 and 6 on functional magnetic resonance imaging was calculated (laterality index range of -1 to +1). Patients were divided into two groups based on functional magnetic resonance imaging findings before the intervention: group 1: patients who showed bilateral activation (n = 27); group 2: patients with unilateral activation (n = 20). RESULTS: Treatment resulted in improvement in Fugl-Meyer Assessment and Wolf Motor Function Test in the two groups (P < 0·01). The treatment also resulted in a significant increase in laterality index in group 1 (P < 0·05), suggesting a shift in activated voxels to the lesional hemisphere. Patients of group 2 showed a significant increase in lesional hemisphere activation (P < 0·05). CONCLUSIONS: The results of serial functional magnetic resonance imaging indicated that our proposed treatment can induce functional cortical reorganization, leading to motor functional recovery of the affected upper limb. Especially, it seems that neural activation in the lesional hemisphere plays an important role in such recovery in poststroke hemiparetic patients.

Lateralization of activity in the parietal cortex predicts the effectiveness of bilateral transcranial direct current stimulation on performance of a mental calculation task.

Transcranial direct current stimulation (tDCS) is a non-invasive technique that moderates cognitive and motor function. The effects of tDCS on cognitive and motor tasks vary among individuals. However, the source of the inter-individual variability remains unknown. The purpose of the present study was to examine whether the effect of bilateral tDCS on the performance of mental calculations differs among individuals according to the functional lateralization of parietal activity observed during a mental calculation task. Sixteen healthy subjects (11 males and five females, aged 20-23 years) participated. Laterality of parietal activity during a mental calculation task was evaluated using functional magnetic resonance imaging. Subjects also performed the mental calculation task pre-, during-, 30 min post-, and 60 min post-tDCS. Bilateral tDCS with the anode over the left parietal cortex and the cathode over the right parietal cortex shortened response times of the mental calculation task in subjects with left-hemispheric parietal lateralization, but not in subjects with bilateral parietal activation. This indicates that inter-individual variability in laterality of brain activity might be an important factor underlying the effect of bilateral tDCS. In conclusion, bilateral tDCS over the parietal cortex enhanced the performance of mental calculations in subjects with left-hemispheric parietal lateralization.

Effects of diffusional kurtosis imaging parameters on diffusion quantification.

Diffusional kurtosis imaging (DKI) is a new technique based on non-Gaussian water diffusion analysis. However, the original DKI protocol (six b values and 30 motion-probing gradient (MPG) directions) requires more than 10 min of scanning time, which is too long for daily clinical use. We aimed to find suitable b value, MPG direction, and diffusion time settings for faster DKI. Four normal healthy subjects participated in the study. All DKI data sets were acquired on a clinical 3T-MRI scanner (Philips Medical Systems) with use of three protocols of 0-7500 s/mm(2) b values, 6-32 MPG directions, and 23-80 ms diffusion time. There was a remarkable difference in the standard deviation (SD) of the mean DK values in the number of MPG directions. The mean DK values were significantly higher in the posterior limb of the internal capsule (p = 0.003, r = 0.924) and thalamus (p = 0.005, r = 0.903), whereas the mean DK values of the cerebrospinal fluid (CSF) (p = 0.001, r = -0.976) were significantly lower when we used a longer diffusion time. Our results indicate that the SD of the mean DK values was higher in 15 MPG directions than in 20 MPG directions and more. Because the mean DK values of the CSF were significantly lower when we used longer diffusion times, we expect longer diffusion times to be useful for DKI. We propose the following imaging parameters for clinical use: 0, 1000, and 2000 s/mm(2) b values; 20 MPG directions; Δ/δ 45.3/13.3 ms.

Effectiveness of low-frequency rTMS and intensive speech therapy in poststroke patients with aphasia: a pilot study based on evaluation by fMRI in relation to type of aphasia.

AIM: To assess the safety and clinical efficacy of low-frequency repetitive transcranial magnetic stimulation (LF-rTMS) combined with intensive speech therapy (ST) in poststroke patients with aphasia. SUBJECTS AND METHODS: Twenty-four patients with left-hemispheric stroke and aphasia were subjected. During 11-day hospitalization, each patient received 10 treatment sessions consisting of 40-min 1-Hz LF-rTMS and 60-min intensive ST, excluding Sundays. The scalp area for stimulation was selected based on the findings of fMRI with language tasks and the type of aphasia. LF-rTMS was applied to the inferior frontal gyrus (IGF) for patients with nonfluent aphasia and to the superior temporal gyrus (STG) for patients with fluent aphasia. RESULTS: On pretreatment fMRI, the most activated areas were in the left hemisphere (n=16) and right hemisphere (n=8). The types of aphasia were nonfluent (n=14) and fluent (n=10). The LF-rTMS was applied to the right STG (n=5), left STG (n=5), right IFG (n=11) and left IFG (n=3). Nonfluent aphasic patients showed significant improvement of auditory comprehension, reading comprehension and repetition. Fluent aphasic patients showed significant improvement in spontaneous speech only. CONCLUSION: The fMRI with aphasic type-based therapeutic LF-rTMS/intensive ST for chronic aphasia seems feasible and a potentially useful neurorehabilitative protocol.

Voxel- and atlas-based analysis of diffusion tensor imaging may reveal focal axonal injuries in mild traumatic brain injury -- comparison with diffuse axonal injury.

BACKGROUND: The diagnosis and management of mild traumatic brain injury (MTBI) continue to be subjects of debate, with varying opinions regarding the extent to which tissue-based impairments versus the impacts of other stressors cause ongoing disability. Detecting areas of the brain with abnormalities that can explain symptoms and behavior in patients with MTBI is important in order to confirm the diagnosis of MTBI. METHODS: In this study, we calculated diffusion maps from results of diffusion tensor imaging (DTI) performed in an apparently healthy control group. We then compared these maps with those of patients with MTBI (MTBI group) or diffuse axonal injury (DAI group). All diffusion maps were normalized to the International Consortium for Brain Mapping atlas for atlas-based analysis and were segmented and normalized by the Diffeomorphic Anatomical Registration Through Exponentiated Lie tool in SPM8 to reduce misregistration. RESULTS: All diffusion measures in the DAI group were lower than in the control group. There were significant differences in the body and splenium of the corpus callosum, fornix and right cerebral peduncle in the DAI group compared with the control group (P<.001). The MTBI group had higher axial diffusivity than the control group in the right corticospinal tract, left medial lemniscus, left inferior cerebellar peduncle, bilateral anterior limb of the internal capsule, right anterior corona radiata, bilateral cingulum (cingulate gyrus) and left superior frontooccipital fasciculus (P<.05). CONCLUSIONS: Voxel- and atlas-based analysis of DTI might suggest that patients with MTBI have focal axonal injury and that the pathophysiology is significantly different from that of DAI. These findings will help in the diagnosis of patients with MTBI.

Functional MRI-based therapeutic rTMS strategy for aphasic stroke patients: a case series pilot study.

Four poststroke patients with motor-dominant aphasia received 10 treatment sessions of low-frequency repetitive transcranial magnetic stimulation (rTMS). Each treatment session consisted of 1,200 pulses of stimulation and the site of stimulation was an area homologous to the most activated site on functional MRI performed prior to rTMS. Consequently, rTMS was applied to the right frontal lobe in two patients and to the left frontal lobe in two patients. Treatment resulted in improvement of language function in all four patients. Our therapeutic rTMS strategy seems to be a clinically feasible neurorehabilitative approach for poststroke aphasic patients.