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Parametric Mapping (parametric + mapping)

Distribution by Scientific Domains
Medical Sciences79%
Distribution within Medical Sciences
Neurology56%
Psychiatry20%

Kinds of Parametric Mapping

  • statistical parametric mapping
    		•

    Selected Abstracts

    Automated normalized FLAIR imaging in MRI-negative patients with refractory focal epilepsy

    EPILEPSIA, Issue 6 2009
    Niels K. Focke
    Summary Background:, Patients with focal epilepsy that is refractory to medical treatment are often considered candidates for resective surgery. Magnetic resonance imaging (MRI) has a very important role in the presurgical work-up of these patients, but is unremarkable in about one-third of cases. These patients are often deferred from surgery or have a less positive outcome if surgery is eventually undertaken. The aim of this study was to evaluate our recently described voxel-based technique using routine T2-FLAIR (fluid-attenuated inversion-recovery) scans in MRI-negative patients and to compare the results with video-EEG (electroencephalography) telemetry (VT) findings. Methods:, We identified 70 epilepsy patients with refractory focal seizures who underwent VT and had a normal routine MRI. T2-FLAIR scans were bias-corrected, and intensity and spatially normalized (nFSI) using Statistical Parametric Mapping 5 (SPM5) as previously described. Individual scans were then compared against a set of 25 normal controls using a voxel-based method. Results:, SPM5 identified 10 patients with suprathreshold clusters (14.3%). In 50% of these there was concordance between the lobe of the most significant cluster and the presumed lobe of seizure onset, as defined by VT. All cases were concordant with respect to lateralization of the putative focus. Conclusion:, Using nFSI we identified focal structural cerebral abnormalities in 11.4% of patients with refractory focal seizures, and normal conventional MRI, that were fully or partially concordant with scalp VT. This voxel-based analysis of FLAIR scans, which are widely available, could provide a useful tool in the presurgical evaluation of epilepsy patients. Ongoing work is to compare these imaging findings with the results of intracranial EEG and histology of surgical resections. [source]

    Altered Impulse Control in Alcohol Dependence: Neural Measures of Stop Signal Performance

    ALCOHOLISM, Issue 4 2009
    Chiang-shan Ray Li
    Background:, Altered impulse control has been implicated in the shaping of habitual alcohol use and eventual alcohol dependence. We sought to identify the neural correlates of altered impulse control in 24 abstinent patients with alcohol dependence (PAD), as compared to 24 demographics matched healthy control subjects (HC). In particular, we examined the processes of risk taking and cognitive control as the neural endophenotypes of alcohol dependence. Methods:, To this end, functional magnetic resonance imaging (fMRI) was conducted during a stop signal task (SST), in which a procedure was used to elicit errors in the participants. The paradigm allowed trial-by-trial evaluation of response inhibition, error processing, and post-error behavioral adjustment. Furthermore, by imposing on the subjects to be both fast and accurate, the SST also introduced a distinct element of risk, which participants may or may not avert during the task. Brain imaging data were analyzed with Statistical Parametric Mapping in covariance analyses accounting for group disparity in general performance. Results:, The results showed that, compared to HC, PAD demonstrated longer go trial reaction time (RT) and higher stop success rate (SS%). HC and PAD were indistinguishable in stop signal reaction time (SSRT) and post-error slowing (PES). In a covariance analysis accounting for go trial RT and SS%, HC showed greater activity in the left dorsolateral prefrontal cortex than PAD, when subjects with short and long SSRT were contrasted. By comparing PAD and HC directly during stop errors (SE), as contrasted with SS, we observed greater activity in PAD in bilateral visual and frontal cortices. Compared to HC, PAD showed less activation of the right dorsolateral prefrontal cortex during PES, an index of post-error behavioral adjustment. Furthermore, PAD who showed higher alcohol urge at the time of the fMRI were particularly impaired in dorsolateral prefrontal activation, as compared to those with lower alcohol urge. Finally, compared to HC subjects, PAD showed less activity in cortical and subcortical structures including putamen, insula, and amygdala during risk-taking decisions in the SST. Conclusion:, These preliminary results provided evidence for altered neural processing during impulse control in PAD. These findings may provide a useful neural signature in the evaluation of treatment outcomes and development of novel pharmacotherapy for alcohol dependence. [source]

    Early imaging correlates of subsequent motor recovery after stroke,

    ANNALS OF NEUROLOGY, Issue 5 2009
    Randolph S. Marshall MS
    Objective To determine whether functional magnetic resonance imaging activation obtained in the first few days after stroke correlates with subsequent motor recovery. Methods Twenty-three patients with hemiparesis after first-time stroke were scanned at 2.0 ± 0.9 days while performing a simple motor task. We defined recovery as the change in Fugl,Meyer score from time of scan to approximately 3 months later (90 ± 8 days). We performed three different tests to assess correlations between brain activation and change in Fugl,Meyer score: (1) multivariate (most sensitive to spatially diffuse activation); (2) voxel-wise Statistical Parametric Mapping (most sensitive to focal activation), and (3) primary motor cortex region-of-interest analysis (most sensitive to average activation within this region). All tests controlled for initial stroke severity and lesion volume, as well as other established clinical variables. Results The multivariate test was significant [F (595, 4,934) = 1.93; p < 0.001]. The Statistical Parametric Mapping test detected two small clusters of focal activity located in the ipsilesional postcentral gyrus and cingulate cortex (p < 0.05, corrected). The region-of-interest test was not significant. Interpretation There is a pattern of brain activation present in the first few days after stroke, of which the postcentral gyrus and cingulate cortex are a part, that correlates with subsequent motor recovery. This result suggests that there are recovery processes engaged early after stroke that could provide a target for intervention. Ann Neurol 2009;65:596,602 [source]

    Gray matter atrophy is related to long-term disability in multiple sclerosis

    ANNALS OF NEUROLOGY, Issue 3 2008
    Leonora K. Fisniku MRCP
    Objective To determine the relation of gray matter (GM) and white matter (WM) brain volumes, and WM lesion load, with clinical outcomes 20 years after first presentation with clinically isolated syndrome suggestive of multiple sclerosis (MS). Methods Seventy-three patients were studied a mean of 20 years from first presentation with a clinically isolated syndrome (33 of whom developed relapsing-remitting MS and 11 secondary-progressive MS, with the rest experiencing no further definite neurological events), together with 25 healthy control subjects. GM and WM volumetric measures were obtained from three-dimensional T1-weighted brain magnetic resonance images using Statistical Parametric Mapping 2. Results Significant GM (p < 0.001) and WM atrophy (p = 0.001) was seen in MS patients compared with control subjects. There was significantly more GM, but not WM atrophy, in secondary-progressive MS versus relapsing-remitting MS (p = 0.003), and relapsing-remitting MS versus clinically isolated syndrome (p < 0.001). GM, but not WM, fraction correlated with expanded disability status scale (rs = ,0.48; p < 0.001) and MS Functional Composite scores (rs = 0.59; p < 0.001). WM lesion load correlated with GM (rs = ,0.63; p < 0.001), but not with WM fraction. Regression modeling indicated that the GM fraction explained more of the variability in clinical measures than did WM lesion load. Interpretation In MS patients with a relatively long and homogeneous disease duration, GM atrophy is more marked than WM atrophy, and reflects disease subtype and disability to a greater extent than WM atrophy or lesions. Ann Neurol 2008 [source]

    Regional cerebral brain metabolism correlates of neuroticism and extraversion

    DEPRESSION AND ANXIETY, Issue 3 2006
    Thilo Deckersbach Ph.D.
    Abstract Factor-analytic approaches to human personality have consistently identified several core personality traits, such as Extraversion/Introversion, Neuroticism, Agreeableness, Consciousness, and Openness. There is an increasing recognition that certain personality traits may render individuals vulnerable to psychiatric disorders, including anxiety disorders and depression. Our purpose in this study was to explore correlates between the personality dimensions neuroticism and extraversion as assessed by the NEO Five-Factor Inventory (NEO-FFI) and resting regional cerebral glucose metabolism (rCMRglu) in healthy control subjects. Based on the anxiety and depression literatures, we predicted correlations with a network of brain structures, including ventral and medial prefrontal cortex (encompassing anterior cingulate cortex and orbitofrontal cortex), insular cortex, anterior temporal pole, ventral striatum, and the amygdala. Twenty healthy women completed an 18FFDG (18F-fluorodeoxyglucose) positron emission tomography (PET) scan at rest and the NEO-FFI inventory. We investigated correlations between scores on NEO-FFI Neuroticism and Extraversion and rCMRglu using statistical parametric mapping (SPM99). Within a priori search territories, we found significant negative correlations between Neuroticism and rCMRglu in the insular cortex and positive correlations between Extraversion and rCMRglu in the orbitofrontal cortex. No significant correlations were found involving anterior cingulate, amygdala, or ventral striatum. Neuroticism and Extraversion are associated with activity in insular cortex and orbitofrontal cortex, respectively. Depression and Anxiety 23:133,138, 2006. © 2006 Wiley-Liss, Inc. [source]

    ,-[11C]methyl-L-tryptophan uptake in patients with periventricular nodular heterotopia and epilepsy

    EPILEPSIA, Issue 5 2008
    Jun Natsume
    Summary Background:,-[11C]methyl-L-tryptophan (,-MTrp) positron emission tomography (PET) is a promising tool in the localization of the epileptogenic area in selected group of focal epilepsy patients. Electrophysiological evidence suggests the involvement of the neocortex in periventricular nodular heterotopia (PVNH). Purpose: To determine whether ,-MTrp PET can detect neocortical changes in patients with PVNH. Methods: Four patients (2 male, mean age 28, range 23,35 years) with PVNH and intractable seizures were studied. The functional image in each patient was compared with those from 21 healthy controls (mean age 34.6 ± 14.2 years) by using statistical parametric mapping (SPM). The location of increased ,-MTrp uptake was compared with the location of the EEG focus. A significant cluster was defined as a cluster with a height p = 0.005 and an extent threshold 100. Results:,-MTrp PET revealed increased cortical uptake in two of four patients. The area of increased ,-MTrp uptake in one patient was widespread. In the other patient, the area of increased uptake did not include the region where most seizures were generated on EEG. ,-MTrp PET did not show increased uptake in the heterotopic nodules in any of the patients. Conclusions:,-MTrp PET suggests abnormal metabolism of tryptophan in the neocortex. The increased uptake may be diffuse and may not co-localize with the EEG focus. This preliminary study suggests that ,-MTrp PET may be useful, in conjunction with other evaluations, in localizing epileptic focus in patients with PVNH and refractory seizures. [source]

    Decreased Dopamine D2/D3-Receptor Binding in Temporal Lobe Epilepsy: An [18F]Fallypride PET Study

    EPILEPSIA, Issue 8 2006
    Konrad J. Werhahn
    Summary:,Purpose: Although animal data are suggestive, evidence for an alteration of the extrastriatal dopaminergic system in human focal epilepsy is missing. Methods: To quantify D2/D3-receptor density, we studied seven patients with temporal lobe epilepsy (TLE) and nine age-matched controls with positron emission tomography (PET) by using the high-affinity dopamine D2/D3-receptor ligand [18F]Fallypride ([18F]FP) suitable for imaging extrastriatal binding. TLE was defined by interictal and ictal video-EEG, magnetic resonance imaging (MRI), and [18F]fluorodeoxyglucose ([18F]FDG)-PET and was due to hippocampal sclerosis (HS), based on histology in all patients. Primary analysis was based on regions of interest (ROIs) defined on individual MRIs. For each patient, binding potential (BP) was calculated by using the simplified reference tissue model, and the epileptogenic was compared with the unaffected hemisphere in each ROI. To confirm the results, an additional voxel-based group analysis was performed by using statistical parametric mapping. Results: Compared with controls, [18F]FP BP was significantly decreased in the epileptogenic temporal lobe in all patients. On ROI analysis, this reduction was evident in areas surrounding the seizure-onset zone at the pole (,34.2%) and lateral aspects (,32.9%) of the temporal lobe. Although the hippocampus [18F]FDG uptake (,8.1%) and hippocampal MR volume (,35.1%) were significantly reduced, no significant decrease of [18F]FP BP was found. Reduction of [18F]FP BP did not correlate with hippocampal atrophy. Conclusions: D2/D3-receptor binding is reduced at the pole and in lateral aspects of the epileptogenic temporal lobe in patients with mesial TLE and HS. This area might correspond to "the irritative zone," indicating that D2/D3 receptors might play a specific role in the pathophysiology of mesial TLE. [source]

    Development of the extended parametric meshless Galerkin method to predict the crack propagation path in two-dimensional damaged structures

    FATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 7 2009
    M. MUSIVAND-ARZANFUDI
    ABSTRACT The parametric meshless Galerkin method (PMGM) enhances the promising features of the meshless methods by utilizing the parametric spaces and parametric mapping, and improves their efficiency from the practical viewpoints. The computation of meshless shape functions has been usually a time-consuming and complicated task in the meshless methods. In the PMGM, the meshless shape functions are mapped from the parametric space to the physical space, and therefore, the necessary computational time to generate the meshless shape functions is saved. The extended parametric meshless Galerkin method (X-PMGM) even improves the parametric property of the PMGM by incorporating the partition of unity concepts. In this paper, the development of the X-PMGM is extended by incorporating a crack-tip formulation in X-PMGM for fracture analysis and prediction of crack propagation path in the damaged structures. In this formulation, meshless shape functions are enriched by discontinuous enrichment function as well as crack-tip enrichment functions. The obtained results show that the predicted crack growth path is in good agreement with the experimental results. [source]

    Superior temporal lobe dysfunction and frontotemporal dysconnectivity in subjects at risk of psychosis and in first-episode psychosis

    HUMAN BRAIN MAPPING, Issue 12 2009
    Nicolas A. Crossley
    Abstract Background: Superior temporal lobe dysfunction is a robust finding in functional neuroimaging studies of schizophrenia and is thought to be related to a disruption of fronto-temporal functional connectivity. However, the stage of the disorder at which these functional alterations occur is unclear. We addressed this issue by using functional MRI (fMRI) to study subjects in the prodromal and first episode phases of schizophrenia. Methods: Subjects with an at risk mental state (ARMS) for psychosis, a first psychotic episode (FEP), and controls were studied using fMRI while performing a working memory task. Activation in the superior temporal gyrus (STG) was assessed using statistical parametric mapping, and its relationship to frontal activation was examined using dynamic causal modeling. Results: The STG was differentially engaged across the three groups. There was deactivation of this region during the task in controls, whereas subjects with FEP showed activation and the response in subjects with ARMS was intermediately relative to the two other groups. There were corresponding differences in the effective connectivity between the STG and the middle frontal gyrus across the three groups, with a negative coupling between these areas in controls, a positive coupling in the FEP group, and an intermediate value in the ARMS group. Conclusions: A failure to deactivate the superior temporal lobe during tasks that engage prefrontal cortex is evident at the onset of schizophrenia and may reflect a disruption of fronto-temporal connectivity. Qualitatively similar alterations are evident in people with prodromal symptoms of the disorder. Hum Brain Mapp, 2009. © 2009 Wiley-Liss, Inc. [source]

    Simultaneously recorded EEG,fMRI: Removal of gradient artifacts by subtraction of head movement related average artifact waveforms

    HUMAN BRAIN MAPPING, Issue 10 2009
    Limin Sun
    Abstract Electroencephalograms (EEGs) recorded simultaneously with functional magnetic resonance imaging (fMRI) are corrupted by large repetitive artifacts generated by the switched MR gradients. Several methods have been proposed to remove these distortions by subtraction of averaged artifact templates from the ongoing EEG. Here, we present a modification of this approach which accounts for head movements to improve the extracted template. Using the fMRI analysis package statistical parametric mapping (SPM; FIL London) the head displacement is determined at each half fMRI-volume. The basic idea is to apply a moving average algorithm for template extraction but to include only epochs that were obtained at the same head position as the artefact to be removed. This approach was derived from phantom EEG measurements demonstrating substantial variations of the artefact waveform in response to movements of the phantom in the MRI magnet. To further reduce the residual noise, we applied a resampling algorithm which aligns the EEG samples in a strict adaptive manner to the fMRI timing. Finally, we propose a new algorithm to suppress residual artifacts such as those occasionally observed in case of brief strong movements, which are not reflected by the movement indicator because of the limited temporal resolution of the fMRI sequence. On the basis of EEG recordings of six subjects these measures combined reduce the residual artefact activity quantified in terms of the spectral power at the gradient repetition rate and its harmonics by roughly 20 to 50% (depending on the amount of movement) predominantly in frequencies beyond 30 Hz. Hum Brain Mapp, 2009. © 2009 Wiley-Liss, Inc. [source]

    Random fields,Union intersection tests for detecting functional connectivity in EEG/MEG imaging

    HUMAN BRAIN MAPPING, Issue 8 2009
    Felix Carbonell
    Abstract Electrophysiological (EEG/MEG) imaging challenges statistics by providing two views of the same underlying spatio-temporal brain activity: a topographic view (EEG/MEG) and tomographic view (EEG/MEG source reconstructions). It is a common practice that statistical parametric mapping (SPM) for these two situations is developed separately. In particular, assessing statistical significance of functional connectivity is a major challenge in these types of studies. This work introduces statistical tests for assessing simultaneously the significance of spatio-temporal correlation structure between ERP/ERF components as well as that of their generating sources. We introduce a greatest root statistic as the multivariate test statistic for detecting functional connectivity between two sets of EEG/MEG measurements at a given time instant. We use some new results in random field theory to solve the multiple comparisons problem resulting from the correlated test statistics at each time instant. In general, our approach using the union-intersection (UI) principle provides a framework for hypothesis testing about any linear combination of sensor data, which allows the analysis of the correlation structure of both topographic and tomographic views. The performance of the proposed method is illustrated with real ERP data obtained from a face recognition experiment. Hum Brain Mapp 2009. © 2009 Wiley-Liss, Inc. [source]

    Optic radiation changes after optic neuritis detected by tractography-based group mapping

    HUMAN BRAIN MAPPING, Issue 3 2005
    Olga Ciccarelli
    Abstract Postmortem data suggest that trans-synaptic degeneration occurs in the lateral geniculate nucleus after optic nerve injury. This study investigated in vivo the optic radiations in patients affected by optic neuritis using fast marching tractography (FMT), a diffusion magnetic resonance imaging (MRI) fiber tracking method, and group mapping techniques, which allow statistical comparisons between subjects. Seven patients, 1 year after isolated unilateral optic neuritis, and ten age and gender-matched controls underwent whole-brain diffusion tensor MR imaging. The FMT algorithm was used to generate voxel-scale connectivity (VSC) maps in the optic radiations in each subject in native space. Group maps of the left and right optic radiations were created in the patient and control group in a standardized reference frame using statistical parametric mapping (SPM99). The reconstructed optic radiations in the patient group were localized more laterally in the posterior part of the tracts and more inferiorly than in the control group. Patients showed reduced VSC values in both tracts compared with controls. These findings suggest that the group mapping techniques might be used to assess changes in the optic radiations in patients after an episode of optic neuritis. The changes we have observed may be secondary to the optic nerve damage. Hum Brain Mapp, 2005. © 2005 Wiley-Liss, Inc. [source]

    Coronary heart disease is associated with regional grey matter volume loss: implications for cognitive function and behaviour

    INTERNAL MEDICINE JOURNAL, Issue 7 2008
    O. P. Almeida
    Abstract Coronary heart disease (CHD) has been associated with impaired cognition, but the mechanisms underlying these changes remain unclear. We designed this study to determine whether adults with CHD show regional brain losses of grey matter volume relative to controls. We used statistical parametric mapping (SPM5) to determine regional changes in grey matter volume of T1 -weighted magnetic resonance images of 11 adults with prior history of myocardial infarction relative to seven healthy controls. All analyses were adjusted for total grey and white matter volume, age, sex and handedness. CHD participants showed a loss of grey matter volume in the left medial frontal lobe (including the cingulate), precentral and postcentral cortex, right temporal lobe and left middle temporal gyrus, and left precuneus and posterior cingulate. CHD is associated with loss of grey matter in various brain regions, including some that play a significant role in cognitive function and behaviour. The underlying causes of these regional brain changes remain to be determined. [source]

    A SPECT study of wandering behavior in Alzheimer's disease

    INTERNATIONAL JOURNAL OF GERIATRIC PSYCHIATRY, Issue 9 2005
    Yves Rolland
    Abstract Background Among behavior disturbance during Alzheimer's disease (AD), wandering is one of the most common. Different psychological processes have been suggested to explain the wandering behavior. The aim of this study was to examine whether wandering during AD was associated with cerebral perfusion patterns measured by (99,m)Tc-labeled bicisate (ECD) brain SPECT. Methods We compared SPECT scans of 13 AD subjects with wandering behavior (sex ratio M/F, 4/9; age, 73.1 years, SD 7.4; Mini Mental Status Examination score, median 20 interquartile range [16,23]), 13 AD subjects without wandering behavior (matched for age [,±,2 years], sex and MMSE score [,±,2 points]) and 13 healthy controls (matched for age [,±,2 years] and sex) without cognitive impairment. Wandering was defined on the Neuro-Psychiatric Inventory. Score of leukoaraiosis, assessed with the scale of Blennow and number of lacuna infarction were compared on CT scan. SPECT imaging was compared using statistical parametric mapping (SPM 2). Results There were no significant differences between the groups in term of educational level and CT scan analysis. SPECT imaging was consistent with the diagnosis of AD in both wanderers and AD subjects without wandering behavior. Despite similar clinical dementia severity, wanderers had more severely reduced regional cerebral blood flow (rCBF) in the left parietal-temporal lobe than AD subjects without wandering behavior. Conclusion Wandering behavior could be facilitated by a specific patterns of cerebral blood flow. Wandering, as a physical activity, could also enhance the recruitment of the cortical network. Copyright © 2005 John Wiley & Sons, Ltd. [source]

    A comparison between the accuracy of voxel-based morphometry and hippocampal volumetry in Alzheimer's disease

    JOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 3 2004
    Cristina Testa PhD
    Abstract Purpose To compare the accuracy of voxel-based morphometry (VBM) and region of interest (ROI)-based hippocampal volumetry to detect medial temporal lobe atrophy in Alzheimer's disease (AD). Materials and Methods A total of 27 AD patients (age 74 ± 9 years; 22 women; Mini-Mental State Exam [MMSE] 21 ± 4) and 25 controls (age 70 ± 8; 16 women; MMSE 29 ± 1) were studied. Accuracy of VBM to detect gray matter loss in those seven AD patients and 11 controls with similar ROI-based hippocampal measures and of ROI-based volumetry to detect gray matter loss in those four AD patients and five controls with similar VBM-based hippocampal measures was assessed. VBM was performed with statistical parametric mapping (SPM99). Results The area under the curve was 0.96 (95% C.I., 0.92,1.00) for VBM, 0.89 (95% C.I., 0.80,0.98) for ROI-based hippocampal measures, and 0.99 (95% C.I., 0.96,1.00) for both. In subjects with similar ROI-based hippocampal measures, VBM detected atrophy in AD patients at P < 0.0001, while in subjects with similar VBM-based hippocampal measure, volumetry was not significant (P = 0.11). Both measures independently contributed to discrimination (P = 0.004 and P = 0.032) in a logistic regression model. Conclusion These results indicate that VBM is more accurate, but the combination of both methods provides the highest accuracy for detection of hippocampal atrophy in AD. J. Magn. Reson. Imaging 2004;19:274,282. © 2004 Wiley-Liss, Inc. [source]

    Adjusted Scaling of FDG Positron Emission Tomography Images for Statistical Evaluation in Patients With Suspected Alzheimer's Disease

    JOURNAL OF NEUROIMAGING, Issue 4 2005
    Ralph Buchert PhD
    ABSTRACT Background and Purpose. Statistical parametric mapping (SPM) gained increasing acceptance for the voxel-based statistical evaluation of brain positron emission tomography (PET) with the glucose analog 2-[18F]-fluoro-2-deoxy-d-glucose (FDG) in patients with suspected Alzheimer's disease (AD). To increase the sensitivity for detection of local changes, individual differences of total brain FDG uptake are usually compensated for by proportional scaling. However, in cases of extensive hypometabolic areas, proportional scaling overestimates scaled uptake. This may cause significant underestimation of the extent of hypometabolic areas by the statistical test. Methods. To detect this problem, the authors tested for hyper metabolism. In patients with no visual evidence of true focal hypermetabolism, significant clusters of hypermetabolism in the presence of extended hypometabolism were interpreted as false-positive findings, indicating relevant overestimation of scaled uptake. In this case, scaled uptake was reduced step by step until there were no more significant clusters of hypermetabolism. Results. In 22 consecutive patients with suspected AD, proportional scaling resulted in relevant overestimation of scaled uptake in 9 patients. Scaled uptake had to be reduced by 11.1%± 5.3% in these cases to eliminate the artifacts. Adjusted scaling resulted in extension of existing and appearance of new clusters of hypometabolism. Total volume of the additional voxels with significant hypometabolism depended linearly on the extent of the additional scaling and was 202 ± 118 mL on average. Conclusions. Adjusted scaling helps to identify characteristic metabolic patterns in patients with suspected AD. It is expected to increase specificity of FDGPET in this group of patients. [source]

    Measurement of Whole-Brain Atrophy in Multiple Sclerosis

    JOURNAL OF NEUROIMAGING, Issue 2004
    Daniel Pelletier MD
    ABSTRACT Brain atrophy reflects the net result of irreversible and destructive pathological processes in multiple sclerosis (MS). The gross morphological changes can be accurately quantified using standard magnetic resonance imaging (MRI) acquisitions and various image analysis tools. The current methods used to assess whole-brain atrophy in patients with MS can be classified into 2 groups based on their reliance on segmentation and registration. Segmentation-based methods employed to measure whole-brain atrophy in MS include the brain parenchymal fraction, the index of brain atrophy, the whole-brain ratio, the brain to intracranial capacity ratio, fuzzy connectedness/Udupa's method, 3DVIEWNIX, the Alfano method, and SIENAX. Current registration-based methods used to measure whole-brain atrophy in MS include the brain boundary shift integral, SIENA, statistical parametric mapping, template-driven seg mentation, and voxel-based morphometry. Most of the methods presented here are sensitive to subtle changes in brain structures and have been successfully applied to MS as measures of whole-brain atrophy. Yet comparative studies of these methods are limited and are complicated by the lack of a gold standard for image acquisition, a segmentation algorithm, an image analysis method, or a reproducibility measure. Overall, the measure of whole-brain atrophy from MRI contributes to an appreciation of the dynamics of MS pathology and its relationship to the clinical course of MS. Determination of the relative reproducibility, precision, sensitivity, and validity of these methods will promote the use of whole-brain atrophy measures as components of comprehensive MRI-based outcome assessment in MS clinical trials. [source]

    Selective Arterial Distribution of Cerebral Hyperperfusion in Fabry Disease

    JOURNAL OF NEUROIMAGING, Issue 3 2001
    David F. Moore MD
    ABSTRACT Fabry disease is an X-linked recessive deficiency of lysosomal ,-galactosidase A associated with an increased risk of early onset cerebrovascular disease. The disorder is reported to affect the posterior circulation predominantly. This hypothesis was investigated directly by the measurement of regional cerebral blood flow with positron emission tomography (PET). Resting regional cerebral blood flow (rCBF) in 26 hemizygous patients with Fabry disease and 10 control participants was examined using H215O and PET. Statistical parametric mapping (SPM{t}, SPM99) and PET images of patients and controls were produced. Significantly increased SPM{t} clusters were then color coded and blended with a coregistered T1 magnetic resonance imaging (MRI) template. Cerebral arterial territory maps were digitized and rescaled. Custom OpenGL and ImageVision Library C++ code was written to allow a first-order affine transformation of the blended SPM{t} and MRI template onto the arterial territory map. The affine transformation was constrained by choosing corresponding cerebral landmark "tie points" between the SPM{t}, MRI template images and the cerebral arterial territory maps. The data demonstrated that the posterior circulation is the predominant arterial territory with a significantly increased rCBF in Fabry disease. No arterial distribution had a decreased rCBF. [source]

    Amnestic mild cognitive impairment in Parkinson's disease: A brain perfusion SPECT study,,

    MOVEMENT DISORDERS, Issue 3 2009
    Flavio Nobili MD
    Abstract The purpose of this study was to investigate cortical dysfunction in Parkinson's disease (PD) patients with amnestic deficit (PD-MCI). Perfusion single photon emission computed tomography was performed in 15 PD-MCI patients and compared (statistical parametric mapping [SPM2]) with three groups, i.e., healthy subjects (CTR), cognitively intact PD patients (PD), and common amnestic MCI patients (aMCI). Age, depression, and UPDRS-III scores were considered as confounding variables. PD-MCI group (P < 0.05, false discovery rate,corrected for multiple comparisons) showed relative hypoperfusion in bilateral posterior parietal lobe and in right occipital lobe in comparison to CTR. As compared to aMCI, MCI-PD demonstrated hypoperfusion in bilateral posterior parietal and occipital areas, mainly right cuneus and angular gyrus, and left precuneus and middle occipital gyrus. With a less conservative threshold (uncorrected P < 0.01), MCI-PD showed hypoperfusion in a left parietal region, mainly including precuneus and inferior parietal lobule, and in a right temporal-parietal-occipital region, including middle occipital and superior temporal gyri, and cuneus-precuneus, as compared to PD. aMCI versus PD-MCI showed hypoperfusion in bilateral medial temporal lobe, anterior cingulate, and left orbitofrontal cortex. PD-MCI patients with amnestic deficit showed cortical dysfunction in bilateral posterior parietal and occipital lobes, a pattern that can be especially recognized versus both controls and common aMCI patients, and to a lesser extent versus cognitively intact PD. The relevance of this pattern in predicting dementia should be evaluated in longitudinal studies. © 2008 Movement Disorder Society [source]

    Striatal subregional 6-[18F]fluoro- L -dopa uptake in early Parkinson's disease: A two-year follow-up study

    MOVEMENT DISORDERS, Issue 7 2006
    Anna Brück MD
    Abstract Thirty-one drug-naive patients with Parkinson's disease (PD) underwent 6-[18F]fluoro- L -dopa (F-dopa) positron emission tomography (PET) scan at the time of the diagnosis (baseline) and 2 years later in order to investigate F-dopa uptake in striatal and extrastriatal regions during the first years of early PD. Twenty-four healthy controls underwent one F-dopa PET scan. The regional differences in the striatal and extrastriatal regions were analyzed with statistical parametric mapping and automated region of interest analyses. Our study shows that the F-dopa uptake in unmedicated early PD is most severely decreased in the dorsal part of caudal putamen but significant decrease can be seen throughout the striatum compared with controls. During the first years of PD, there is a progressive regional decline in striatal F-dopa uptake, the dorsal part of caudal putamen being still the most severely affected region. The absolute decline is equal between the striatal subregions. This suggests that the decline of dopamine function starts from the dorsocaudal putamen, but once started, the rate of progression is equal between the subregions of the striatum. In contrast to the striatal decline, the increased cortical F-dopa uptake prevails at least during the first years of PD. © 2006 Movement Disorder Society [source]

    Neural correlates of memory in depression measured by brain perfusion SPECT at rest

    PSYCHIATRY AND CLINICAL NEUROSCIENCES, Issue 5 2009
    Hideki Azuma md
    Aim:, Brain metabolism activated studies have indicated associations between memory and the anterior cingulate cortex and hippocampus in patients with depression. The aim of the present study was therefore to investigate memory function, measured as performance on the Wechsler Memory Scale,Revised (WMS-R), and its relationship to brain perfusion using single-photon emission computed tomography (SPECT) at rest in patients with depression. Methods:, The Hamilton Rating Scale for Depression (HAMD) and WMS-R were measured for 17 patients with depression by an independent clinical evaluation team. Voxel-based correlation analyses were performed with statistical parametric mapping at an extent threshold of 200 voxels. Associations were controlled for state and trait factors. Results:, WMS-R measurements of verbal, visual, and general memory were inversely correlated with brain perfusion in the right anterior cingulate cortex, left premotor cortices, and both regions, respectively. The HAMD directly correlated with brain perfusion in the right anterior cingulate cortex. Conclusion:, Brain perfusion SPECT measurements of the anterior cingulate cortex at rest were associated with the severity of depression and immediate memory scores measured with the WMS-R. [source]

    SPECT and Alzheimer's Disease

    PSYCHOGERIATRICS, Issue 2 2002
    Siobhan Ni Bhriain
    Abstract: This article is review of the role of single photon emission tomography (SPECT) in the diagnosis and management of Alzheimer's disease (AD). It begins by describing AD in terms of diagnosis, pathology and current pharmacological treatment. The relevance of the pathological changes in relation to SPECT is outlined. This is discussed in terms of receptor abnormalities and atrophic changes which in turn effect cerebral blood flow. A detailed description of SPECT methodology describes how the quality of the image is effected by SPECT instrumentation, image reconstruction techniques and a number of subject factors. The article goes on to discuss the role SPECT in the diagnosis of AD and its potential for facilitating early diagnosis. The main focus here is on the changes which occur in cerebral blood flow in AD and the sensitivity and specificity of regional changes in cerebral blood flow is described. Image analysis is an area in which there has been many developments in the last number of years and the authors describe the differences between qualitative and quantitative image analysis, with a particular focus on statistical parametric mapping (SPM). There is a brief discussion concerning receptor ligands and their potential use in the diagnosis and management of AD, although this remains an undeveloped area in SPECT imaging as yet. Finally, the authors discuss the future possibilities for SPECT and AD, and conclude that there is considerable potential for SPECT in the diagnosis and management of AD with further refinement of image analysis techniques and the development of cholinergic receptor ligands. [source]

    Tau haplotype influences cerebral perfusion pattern in frontotemporal lobar degeneration and related disorders

    ACTA NEUROLOGICA SCANDINAVICA, Issue 5 2008
    B. Borroni
    Objective,,, The modulating factors on phenotypic expression of frontotemporal lobar degeneration (FTLD) remain still unknown. The aim of this study was to determine whether tau genetic variability modulates the brain functional and the clinical phenotypic expression of FTLD. Materials and methods,,, Clinical and neurological evaluations, a standardized neuropsychological assessments as well as a brain single photon emission tomography perfusion imaging studies were performed in 48 FTLD patients. Cerebral perfusion patterns were analysed according to H1 or H2 tau haplotypes by statistical parametric mapping and principal component analysis. Results,,, Two different patterns of cerebral dysfunction characterized the haplotypes, as hypoperfusion of frontal medial and cingulated cortex in H2-carriers and a prevalent involvement of posterior parietal regions in H1-carriers. Further, a significant increase of cerebrospinal fluid total tau and phospho tau levels was found in H2-carriers. Conclusions,,, These findings support a role of tau haplotype in modulating disease phenotype by influencing the hypoperfusion pattern and cerebrospinal fluid tau levels in FTLD. [source]

    Abnormal grey matter in victims of rape with PTSD in Mainland China: a voxel-based morphometry study

    ACTA NEUROPSYCHIATRICA, Issue 3 2010
    Shuang Ge Sui
    Sui SG, Wu MX, King ME, Zhang Y, Ling L, Xu JM, Weng XC, Duan L, Shan BC, Li LJ. Abnormal grey matter in victims of rape with PTSD in Mainland China: a voxel-based morphometry study. Objective: This study examined changes in brain grey matter in victims of rape (VoR) with and without post-traumatic stress disorder (PTSD). Previous research has focused on PTSD caused by various traumatic events, such as war and disaster, among others. Although considerable research has focused on rape-related PTSD, limited studies have been carried out in the context of Mainland China. Methods: The study included 11 VoR with PTSD, 8 VoR without PTSD and 12 healthy comparison (HC) subjects. We used voxel-based morphometry to explore changes in brain grey-matter density (GMD) by applying statistical parametric mapping to high-resolution magnetic resonance images. Results: Compared with HC, VoR with PTSD showed significant GMD reductions in the bilateral medial frontal cortex, left middle frontal cortex, middle temporal gyrus and fusiform cortex and significant GMD increases in the right posterior cingulate cortex, postcentral cortex, bilateral precentral cortex and inferior parietal lobule. Compared to VoR without PTSD, VoR with PTSD showed significant GMD reductions in the right uncus, left middle temporal gyrus, and the fusiform cortex, and increases in the left precentral cortex, inferior parietal lobule and right post-central cortex. Conclusion: The findings of abnormal GMD in VoR with PTSD support the hypothesis that PTSD is associated with widespread anatomical changes in the brain. The medial frontal cortex, precentral cortex, posterior cingulate cortex, post-central cortex and inferior parietal lobule may play important roles in the neuropathology of PTSD. [source]