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Diffusion tensor imaging segmentation of white matter structures using a Reproducible Objective Quantification Scheme (ROQS)

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NEUROimage 2007年第1期35卷 166-174页

作者： Niogi, Sumit N. Mukherjee, Pratik McCandliss, Brace D. Cornell Univ Weill Med Coll Sackler Inst Dev Psychobiol New York NY 10021 USA Cornell Univ Weill Med Coll Dept Physiol New York NY 10021 USA Univ Calif San Francisco Dept Radiol San Francisco CA 94143 USA

Reproducible Objective Quantification Scheme (ROQS) is a novel method for regional white matter measurements of diffusion tensor imaging (DTI) parameters that overcomes the limitations of previous approaches for analyzing large cohorts of subjects reliably. ROQS is a semi-automated technique that exploits the fiber orientation information from the diffusion tensor in conjunction with a binary masking and chain-linking algorithm to segment anatomically distinct white matter tracts for subsequent quantitative analysis of DTI parameters such as fractional anisotropy and apparent diffusion coefficient. When applied to 3-T whole-brain DTI of normal adult volunteers, ROQS is shown to segment the corpus callosum much faster than manual region of interest (ROI) delineation, and with better reproducibility and accuracy. (c) 2006 Elsevier Inc. All rights reserved.

关键词： Adult Algorithms Anisotropy Brain/anatomy & histology Corpus Callosum/anatomy & histology Corpus Callosum/physiology databases, Factual Diffusion Magnetic Resonance Imaging/statistics & numerical data Humans image processing, computer-assisted/statistics & numerical data Observer Variation Reference Values Reproducibility of Results

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Towards natural stimulation in MRI - Issues of data analysis

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NEUROimage 2007年第1期35卷 131-139页

作者： Malinen, Sanna Hlushchuk, Yevhen Hari, Riitta Helsinki Univ Technol Brain Res Unit Low Temp Lab FI-02015 Espoo Finland Helsinki Univ Technol Adv Magnet Imaging Ctr FI-02015 Espoo Finland Univ Helsinki Ctr Neurosci FI-00290 Helsinki Finland

in search for suitable tools to study brain activation in natural environments, where the stimuli are multimodal, poorly predictable and irregularly varying, we collected functional magnetic resonance imaging data from 6 subjects during a continuous 8-min stimulus sequence that comprised auditory (speech or tone pips), visual (video clips dominated by faces, hands, or buildings), and tactile finger stimuli in blocks of 6-33 s. Results obtained by independent component analysis (ICA) and general-linear-model-based analysis (GLM) were compared. ICA separated in the superior temporal gyros one independent component (IC) that reacted to all auditory stimuli and in the superior temporal sulcus another IC responding only to speech. Several distinct and rather symmetric vision-sensitive ICs were found in the posterior brain. An IC in the V5/MT region reacted to videos depicting faces or hands, whereas ICs in the V1/V2 region reacted to all video clips, including buildings. The corresponding GLM-derived activations in the auditory and early visual cortices comprised sub-areas of the ICA-revealed activations. ICA separated a prominent IC in the primary somatosensory cortex whereas the GLM-based analysis failed to show any touch-related activation. "Intrinsic" components, unrelated to the stimuli but spatially consistent across subjects, were discerned as well. The individual time courses were highly consistent in sensory projection cortices and more variable elsewhere. The ability to differentiate functionally meaningful composites of activated brain areas and to straightforwardly reveal their temporal dynamics renders ICA a sensitive tool to study brain responses to complex natural stimuli. (c) 2006 Elsevier Inc. All rights reserved.

关键词： Acoustic Stimulation Adult Brain/anatomy & histology Cerebrovascular Circulation data Interpretation, Statistical Female Hearing/physiology Humans image processing, computer-assisted/statistics & numerical data Magnetic Resonance Imaging/statistics & numerical data Male Photic Stimulation Physical Stimulation Principal Component Analysis Touch/physiology Vision, Ocular/physiology

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Non-normality and transformation of random fields, with an application to voxel-based morphometry

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NEUROimage 2007年第1期35卷 121-130页

作者： Viviani, Roberto Beschoner, Petra Ehrhard, Katja Schmitz, Bemd Thoene, Jan Univ Ulm Dept Psychiat 3 D-89075 Ulm Germany Univ Ulm Dept Radiol D-89075 Ulm Germany Univ Ulm Transfer Ctr Neurosci & Learning ZNL D-89075 Ulm Germany

Parametric tests of linear models for images modeled as random fields are based like ordinary univariate tests on distributional assumptions. It is here shown that the effect of departures from assumptions in random field tests is more pronounced than in the univariate condition. Simulations are presented investigating in detail the influence of smoothing, unbalancedness and leverages on empirical thresholds. In certain conditions, significance tests may become invalid. As a case study, the existence and effect of departures from normality of gray matter probability maps, commonly used in voxel-based morphometry, is investigated, as well as the effect of different transformation strategies involving estimating the degree of transformation from the data by maximum likelihood. The best results are achieved with a voxel-by-voxel transformation, suggesting heterogeneity of distributional form across the volume for this kind of data. (c) 2006 Elsevier Inc. All rights reserved.

关键词： Adult Algorithms Analysis of Variance Artifacts Brain Mapping Brain Mapping computer Simulation Humans image processing, computer-assisted/statistics & numerical data Linear Models Magnetic Resonance Imaging/statistics & numerical data Models, Statistical Monte Carlo Method Reference Values Regression Analysis

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Hybrid diffusion imaging

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NEUROimage 2007年第3期36卷 617-629页

作者： Wu, Yu-Chien Alexander, Andrew L. Univ Wisconsin Waisman Ctr Waisman Lab Brain Imaging & Behav Madison WI 53705 USA Univ Wisconsin Dept Radiol Madison WI 53706 USA Univ Wisconsin Dept Med Phys Madison WI 53706 USA Univ Wisconsin Dept Psychiat Madison WI 53706 USA

Diffusion measurements in the human central nervous system are complex to characterize and a broad spectrum of methods have been proposed. In this study, a comprehensive diffusion encoding and analysis approach, hybrid diffusion imaging (HYDI), is described. The HYDI encoding scheme is composed of multiple concentric "shells" of constant diffusion weighting, which may be used to characterize the signal behavior with low, moderate and high diffusion weighting. HYDI facilitates the application of multiple data analyses strategies including diffusion tensor imaging (DTI), multi-exponential diffusion measurements, diffusion spectrum imaging (DSI) and q-ball imaging (QBI). These different analysis strategies may provide complementary information. DTI measures (mean diffusivity and fractional anisotropy) may be estimated from either data in the inner shells or the entire HYDI data. Fast and slow diffusivities were estimated using a nonlinear least squares bi-exponential fit on geometric means of the HYDI shells. DSI measurements from the entire HYDI data yield empirical model-independent diffusion information and are well-suited for characterizing tissue regions with complex diffusion behavior. DSI measurements were characterized using the zero displacement probability and the mean-squared displacement. The outermost HYDI shell was analyzed using QBI analysis to estimate the orientation distribution function (ODF), which is useful for characterizing the directions of multiple fiber groups within a voxel. In this study, an HYDI encoding scheme with 102 diffusion-weighted measurements was obtained over most of the human cerebrum in under 30 min. (c) 2007 Elsevier Inc. All rights reserved.

关键词： Algorithms Brain/anatomy & histology computer Simulation data Interpretation, Statistical Diffusion Magnetic Resonance Imaging/methods Diffusion Magnetic Resonance Imaging/statistics & numerical data Humans image processing, computer-assisted/methods image processing, computer-assisted/statistics & numerical data Nerve Fibers/physiology

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Cell-oriented analysis in vivo using diffusion tensor imaging for normal-appearing brain tissue in multiple sclerosis

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NEUROimage 2007年第4期37卷 1278-1285页

作者： Terajima, Kenshi Matsuzawa, Hitoshi Tanaka, Keiko Nishizawa, Masatoyo Nakada, Tsutomu Niigata Univ Brain Res Inst Dept Neurol Niigata 9518585 Japan Niigata Univ Brain Res Inst Ctr Integrated Hunman Brain Sci Niigata 9518585 Japan

There have been several methods proposed so far using diffusion tensor imaging (DTI) for the assessment of normal-appearing brain tissue (NABT) injury in multiple sclerosis (MS). However, for these methods, the analyses of the NABT injury at the cellular level, wherein histological examinations can be used, still present challenging problems. We developed a method of segregating NABT into the following anatomical structures using lambda chart analysis associated with a two-dimensional Gaussian deconvolution of diffusion characteristic functions: 1) structures primarily composed of small neurons and glia;2) structures primarily composed of large neurons;3) structures primarily composed of short axons;and 4) structures primarily composed of long axons. Each segregated structure that had a distinctive diffusion characteristic was subjected to the statistical inference of DTI-derived parameters for 14 patients with conventional relapsing-remitting MS (RRMS) and 20 age-matched healthy volunteers. In all of the structures, the trace values were significantly higher and the fractional anisotropy values were significantly lower in the RRMS patients than in the healthy volunteers. Furthermore, the volume fractions of the structures primarily composed of short axons markedly decreased, whereas those of the structures primarily composed of small neurons and glia markedly increased. These results suggest that axonal loss and glial proliferation predominantly occurred in the subcortical white matter and adjacent deep cortical layer, namely, the juxtacortical region. This cell-oriented analysis of NABT injury using DTI confirmed in vivo the histological observation that the juxtacortical region is the most vulnerable site in MS. (C) 2007 Elsevier Inc. All rights reserved.

关键词： Adolescent Adult Algorithms Anisotropy Brain/cytology Brain/pathology data Interpretation, Statistical Diffusion Magnetic Resonance Imaging Female Humans image processing, computer-assisted/statistics & numerical data Male Middle Aged Multiple Sclerosis/pathology Multiple Sclerosis, Relapsing-Remitting/pathology Neuroglia/pathology Neurons/pathology Normal Distribution

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Virtual definition of neuronal tissue by cluster analysis of multi-parametric imaging (virtual-dot-com imaging)

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NEUROimage 2007年第1期35卷 58-69页

作者： Yovel, Yssi Assaf, Yaniv Tel Aviv Univ Fac Life Sci Dept Neurobiochem IL-69978 Tel Aviv Israel Tel Aviv Sourasky Med Ctr Levie Edersheim Gitter Inst Funct Brain Imaging Tel Aviv Israel

Individual mapping of cerebral, morphological, functionally related structures using MRI was carried, out using a, new multi-contrast acquisition and analysis framework, called virtual-dot-com imaging. So far, conventional anatomical MRI has been able to proyide gross segmentation of gray/white matter boundaries and a few sub-cortical structures. By combining a, handful of imaging contrasts mechanisms (T1, T2, magnetization transfer, T2* and proton density), we were able to further segment sub-cortical tissue to its sub-nuclei arrangement, a segmentation that is difficult based on conventional, single-contrast MRI. Using an automatic four-step image and signal processing algorithm, we segmented the thalamus to at least 7 subnuclei with high similarity across subjects and high statistical significance within subjects (p < 0.0001). The identified sub-nuclei resembled the known anatomical arrangement of the thalamus given in various atlases. Each cluster was characterized by a unique MRI contrast fingerprint. With this procedure, the weighted proportions of the different cellular compartments could be estimated, a property available to date only by histological analysis. Each sub-nucleus could be characterized in terms of normalized MRI contrast and compared to other sub-nuclei. The different weights of the contrasts (T1/T2/T2*/ PD/MT, etc.) for each sub-nuclei cluster might indicate the intracluster morphological arrangement of the tissue that it represents. The implications of this methodology are far-ranging, from non-invasive, in vivo, individual mapping of histologically distinct brain areas to automatic identification of pathological processes. (c) 2006 Elsevier Inc. All rights reserved.

关键词： Adult Algorithms Animals Cluster Analysis computer Graphics Humans image processing, computer-assisted/methods image processing, computer-assisted/statistics & numerical data Individuality Magnetic Resonance Imaging/methods Magnetic Resonance Imaging/statistics & numerical data Male Nerve Tissue/anatomy & histology Rats Thalamic Nuclei/anatomy & histology Thalamus/anatomy & histology

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Aging, grey matter, and blood flow in the anterior cingulate cortex

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NEUROimage 2007年第4期37卷 1346-1353页

作者： Vaidya, Jatin G. Paradiso, Sergio Ponto, Laura L. Boles McCormick, Laurie M. Robinson, Robert G. Univ Iowa Dept Psychiat & Radiol Iowa City IA 52242 USA

The anterior cingulate cortex (ACC) is thought to be the neuroanatornical interface between emotion and cognition. Because effective emotion-cognition interactions are essential to optimal decision making, clarifying how the functionality of the ACC changes in older age using functional imaging holds great promise for ultimately understanding what contributes to the psychological changes occurring in late life. However, the interpretation of functional imaging studies is complicated by the fact that aging is associated with changes in grey matter volume and in the cerebral vasculature. In the present study, we obtained high-resolution structural magnetic resonance (MR) imaging data and quantitative blood flow images to examine the association between aging, blood, flow, and grey matter volume in the ACC. Twenty-six healthy individuals between 25 and 79 years of age underwent quantitative [O-15]water positron emission tomography (PET) imaging. The ACC was traced onto tissue-classified images derived from Tl- and T2-weighted MRIs using previously defined methods. The ACC was divided into dorsal, rostral, and subgenual regions. Age was negatively correlated with blood flow in dorsal and rostral ACC regions. Effects were weaker but in a similar direction for the subgenual ACC. While older age and lower blood flow were both associated with smaller rostra] ACC grey matter volumes, mediation analysis revealed that grey matter volume only partially mediated the effect of age on blood flow in the rostral ACC. Neural alterations not detectable on MR images may lead to reduced blood flow due to fewer and/or less metabolically active neurons. Alternatively, lower blood flow may be a cause, rather than a consequence, of smaller grey matter volume in the ACC. (C) 2007 Elsevier Inc. All rights reserved.

关键词： Adult Aged Aging/physiology Cerebral Cortex/blood supply Cerebral Cortex/growth & development Cerebral Cortex/physiology Cerebrovascular Circulation/physiology data Interpretation, Statistical Emotions/physiology Fear/physiology Female Happiness Humans image processing, computer-assisted/statistics & numerical data Magnetic Resonance Imaging Male Middle Aged Neurons/physiology Photic Stimulation Positron-Emission Tomography

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A method for using blocked and event-related fMRI data to study "resting state" functional connectivity

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NEUROimage 2007年第1期35卷 396-405页

作者： Fair, Damien A. Schlaggar, Bradley L. Cohen, Alexander L. Miezin, Francis M. Dosenbach, Nico U. F. Wenger, Kristin K. Fox, Michael D. Snyder, Abraham Z. Raichle, Marcus E. Petersen, Steven E. Washington Univ Sch Med Dept Neurol St Louis MO 63110 USA Washington Univ Dept Psychol St Louis MO 63110 USA Washington Univ Sch Med Dept Radiol St Louis MO 63110 USA Washington Univ Sch Med Dept Anat & Neurobiol St Louis MO 63110 USA Washington Univ Sch Med Dept Pediat St Louis MO 63110 USA

Resting state functional connectivity MRI (feMRI) has become a particularly useful tool for studying regional relationships in typical and atypical populations. Because many investigators have already obtained large data sets of task-related fMRI, the ability to use this existing task data for resting state fcMRI is of considerable interest. Two classes of data sets could potentially be modified to emulate resting state data. These data sets include: (1) "interleaved" resting blocks from blocked or mixed blocked/event-related sets, and (2) residual timecourses from event-related sets that lack rest blocks. Using correlation analysis, we compared the functional connectivity of resting epochs taken from a mixed blocked/event-related design fMRI data set and the residuals derived from event-related data with standard continuous resting state data to determine which class of data can best emulate resting state data. We show that, despite some differences, the functional connectivity for the interleaved resting periods taken from blocked designs is both qualitatively and quantitatively very similar to that of "continuous" resting state data. In contrast, despite being qualitatively similar to "continuous" resting state data, residuals derived from event-related design data had several distinct quantitative differences. These results suggest that the interleaved resting state data such as those taken from blocked or mixed blocked/event-related fMRI designs are well-suited for resting state functional connectivity analyses. Although using event-related data residuals for resting state functional connectivity may still be useful, results should be interpreted with care. (c) 2006 Elsevier Inc. All rights reserved.

关键词： Adult Evoked Potentials/physiology Female Fixation, Ocular/physiology Humans image processing, computer-assisted/statistics & numerical data Language Linear Models Magnetic Resonance Imaging/statistics & numerical data Male Monte Carlo Method Nerve Net/physiology Oxygen/blood Photic Stimulation

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Combining the tools: Activation- and information-based fMRI analysis

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NEUROimage 2007年第4期38卷 666-668页

作者： Kriegeskorte, Nikolaus Bandettini, Peter NIMH Sect Funct Imaging Methods Lab Brain & Cognit Bethesda MD 20892 USA

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Cyto architecture of the cerebral cortex - More than localization

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NEUROimage 2007年第4期37卷 1061-1065页

作者： Amunts, K. Schleicher, A. Zilles, K. Res Ctr Juelich Inst Neurosci & Biophys Med INB 3 D-54428 Julich Germany BICW Julich Germany Univ Aachen Rhein Westfal TH Aachen Dept Psychiat & Psychotherapy D-52074 Aachen Germany C&O Vogt Inst Brain Res D-40225 Dusseldorf Germany

The present paper reviews that macroanatomical landmarks are problematic for a reliable and sufficiently precise localization of clusters of activation obtained by functional imaging because sulcal and gyral patterns are extremely variable and macroanatomical landmarks do not match (in nearly all cases) architectonically defined borders. It argues that cytoarchitectonic probabilistic maps currently offer the most precise tool for the localization of brain functions as obtained from functional imaging studies. Finally, it provides some examples that cytoarchitecture is more than localization with respect to a particular brain region because it reflects the inner organization of cortical areas and, furthermore, functional principles of the brain. (c) 2007 Elsevier Inc. All rights reserved.

关键词： Animals Auditory Cortex/anatomy & histology Auditory Cortex/physiology Brain Mapping Brain Mapping Cerebral Cortex/anatomy & histology Cerebral Cortex/cytology Cluster Analysis Humans image processing, computer-assisted/statistics & numerical data Macaca Models, Statistical Motor Cortex/anatomy & histology Motor Cortex/physiology Visual Cortex/anatomy & histology Visual Cortex/physiology

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