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Automatic anatomical brain MRI segmentation combining label propagation and decision fusion

NEUROimage 2006年第1期33卷 115-126页

作者： Heckemann, Rolf A. Hajnal, Joseph V. Aljabar, Paul Rueckert, Daniel Hammers, Alexander Univ London Imperial Coll Sci Technol & Med MRC Clin Sci Ctr Imaging Sci Dept London W12 0HS England Univ London Imperial Coll Sci Technol & Med Dept Comp London W12 0HS England Univ London Imperial Coll Sci Technol & Med MRC Clin Sci Ctr Div Neurosci & Mental Hlth London W12 0HS England

Regions in three-dimensional magnetic resonance (MR) brain images can be classified using protocols for manually segmenting and labeling structures. For large cohorts, time and expertise requirements make this approach impractical. To achieve automation, an individual segmentation can be propagated to another individual using an anatomical correspondence estimate relating the atlas image to the target image. The accuracy of the resulting target labeling has been limited but can potentially be improved by combining multiple segmentations using decision fusion. We studied segmentation propagation and decision fusion on 30 normal brain MR images, which had been manually segmented into 67 structures. Correspondence estimates were established by nonrigid registration using free-form deformations. Both direct label propagation and an indirect approach were tested. Individual propagations showed an average similarity index (SI) of 0.754 +/- 0.016 against manual segmentations. Decision fusion using 29 input segmentations increased SI to 0.836 +/- 0.009. For indirect propagation of a single source via 27 intermediate images, SI was 0.779 +/- 0.013. We also studied the effect of the decision fusion procedure using a numerical simulation with synthetic input data. The results helped to formulate a model that predicts the quality improvement of fused brain segmentations based on the number of individual propagated segmentations combined. We demonstrate a practicable procedure that exceeds the accuracy of previous automatic methods and can compete with manual delineations. (c) 2006 Elsevier Inc. All rights reserved.

关键词： Adult Algorithms Automatic data processing Brain/anatomy & histology Decision Support Techniques Female Humans image processing, computer-assisted/statistics & numerical data Magnetic Resonance Imaging/statistics & numerical data Male Middle Aged Models, Statistical Quality Control Reference Values

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Parallel networks operating across attentional deployment and motion processing: A multi-seed partial least squares fMRI study

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NEUROimage 2006年第4期29卷 1192-1202页

作者： Caplan, JB Luks, TL Simpson, GV Glaholt, M McIntosh, AR Baycrest Ctr Geriatr Care Rotman Res Inst Toronto ON M6A 2E1 Canada Univ Calif San Francisco Dynam Neuroimaging Lab San Francisco CA 94143 USA

Anticipatory deployment of attention may operate through networks of brain areas that modulate the representations of to-be-attended items in advance of their occurrence through top-down control. Luks and Simpson (2004) (Luks, T.L., Simpson, G.V., 2004. Preparatory deployment of attention to motion activates higher order motion-processing brain regions. Neuroimage 22, 1515-1522) found activations in both control areas and sensory areas during anticipatory deployment of attention to visual motion in the absence of stimuli. In the present follow-up analysis, we tested which network activity during anticipatory deployment of attention is functionally connected with task-related network activity during subsequent selective processing of motion stimuli. Following a cue (anticipatory phase), participants monitored a sequence of complex motion stimuli for a target motion pattern (task phase). We analyzed fMR signal using a partial least squares analysis with previously identified cue- and motion-related voxels as seed regions. The method identified two networks that covaried with the activity of seed regions during the cue and motion-stimulus-processing phases of the task. We suggest that the first network, involving ventral intraparietal sulcus, superior parietal lobule and motor areas, is related to anticipatory and sustained visuomotor attention. Operating in parallel to this visuomotor attention network, there is a second network, involving visual occipital areas, frontal areas as well as angular and supramarginal gyri, that may underlie anticipatory and sustained visual attention processes. (c) 2005 Elsevier Inc. All rights reserved.

关键词： Adult Attention/physiology Brain Mapping Brain Mapping Cerebral Cortex/physiology Cues Female Frontal Lobe/physiology Humans image processing, computer-assisted/statistics & numerical data Least-Squares Analysis Magnetic Resonance Imaging/statistics & numerical data Male Mathematical Computing Motion Perception/physiology Motor Cortex/physiology Nerve Net/physiology Occipital Lobe/physiology Orientation/physiology Parietal Lobe/physiology Pattern Recognition, Visual/physiology Psychomotor Performance/physiology Size Perception/physiology

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Functional localization in the human cerebellum based on voxelwise statistical analysis: A study of 90 patients

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NEUROimage 2006年第1期30卷 36-51页

作者： Schoch, B Dimitrova, A Gizewski, ER Timmann, D Univ Duisburg Essen Dept Neurosurg D-45122 Essen Germany Univ Duisburg Essen Dept Neurol D-45122 Essen Germany Univ Duisburg Essen Dept Neuroradiol D-45122 Essen Germany

The aim of the present study was to examine somatotopy in the cerebellar cortex and a possible differential role of the cerebellar cortex and nuclei in functional outcome. Clinical findings and 3D MRI-based cerebellar lesions site were compared in a group of 90 patients with focal cerebellar lesion using International Cooperative Ataxia Rating Scale (ICARS) and voxel-based lesion-symptom mapping (VLSM). Separate analysis was performed in patients with acute and chronic ischemic lesions (n = 43) and patients with acute and chronic surgical lesions (n = 47). Thirty-eight patients were included after resection of a cerebellar tumor in childhood or adolescence. The most significant lesion symptom correlations were observed in the subgroup with acute ischemic lesions. Limb ataxia was significantly correlated with lesions of the interposed (NI) and part of the dentate nuclei (ND), ataxia of posture and gait with lesions of the fastigial nuclei (NF) including NI. Correlations with cortical lesions were less significant and present in the superior cerebellum only. Upper limb ataxia was correlated with lesions of vermal, paravermal and hemispheral lobules IV-V and VI, lower limb ataxia with lesions of vermal, paravermal and hemispheral lobules III and VI, dysarthria with lesions of paravermal and hemispheral lobules V and VI and ataxia of posture and gait with lesions of vermal and paravermal lobules II, III and IV. In the subgroups with chronic focal lesions, similar correlations were observed with lesions of the cerebellar nuclei, but significantly less correlations with lesions of the cerebellar cortex. Functional localization based on VLSM backs findings in previous animal and functional brain images studies in healthy human subjects. The lesion site appears to be critical for motor recovery. Lesions affecting the cerebellar nuclei are not fully compensated at any age and independent of the pathology in humans. (c) 2005 Elsevier Inc. All rights reserved.

关键词： Adult Aged Brain Damage, Chronic/etiology Brain Damage, Chronic/physiopathology Brain Mapping Brain Mapping Cerebellar Cortex/physiopathology Cerebellar Diseases/etiology Cerebellar Diseases/physiopathology Cerebellar Nuclei/physiopathology Female Humans image processing, computer-assisted/statistics & numerical data Imaging, Three-Dimensional Magnetic Resonance Imaging/statistics & numerical data Male Mathematical Computing Middle Aged Neurologic Examination/statistics & numerical data Recovery of Function

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Reproducibility and reliability of MR measurements in white matter: Clinical implications

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NEUROimage 2006年第2期32卷 637-642页

作者： Vavasour, Irene M. Clark, Campbell M. Li, David K. B. MacKay, Alex L. Univ British Columbia Dept Radiol Vancouver BC V6T 2B5 Canada Univ British Columbia Dept Psychiat Vancouver BC V6T 2B5 Canada Univ British Columbia Dept Phys & Astron Vancouver BC V6T 2B5 Canada

The purpose of this study was to determine the reproducibility and reliability of five MRI-derived measurements, namely, total water content (WC), myelin water content (MWC), mean T-2 relaxation time (GMT(2)), T-1 relaxation time (T-1) and magnetization transfer ratio (MTR). Five controls were scanned 5 times over 1 year. The five MR measurements were made for 5 white matter regions. All measurements were found to be highly reproducible. MTR bad a low reliability coefficient because all individual values were similar. Therefore, MTR would be most sensitive in detecting changes from normal. WC had a high reliability coefficient in all regions. For MWC, GMT(2) and T-1, the overall reliability coefficients were high but for some individual regions were low. The high coefficients suggest that these measurements, although different between normal subjects, are consistent over time. They could be used to explore natural differences in the normal population, but due to the large spread in normal values, larger sample sizes are needed to detect pathological changes. (c) 2006 Elsevier Inc. All rights reserved.

关键词： Adult Corpus Callosum/anatomy & histology Female Follow-Up Studies Humans image processing, computer-assisted/statistics & numerical data Internal Capsule/anatomy & histology Magnetic Resonance Imaging/statistics & numerical data Male Mathematical Computing Middle Aged Myelin Sheath/metabolism Reproducibility of Results

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Optimization of dynamic measurement of receptor kinetics by wavelet denoising

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NEUROimage 2006年第2期30卷 444-451页

作者： Alpert, NM Reilhac, A Chio, TC Selesnick, I Massachusetts Gen Hosp Div Nucl Med Boston MA 02129 USA McConnell Brain Imaging Ctr Montreal Neurol Inst Montreal PQ Canada Polytech Univ Dept Elect & Comp Engn Brooklyn NY 11201 USA

The most important technical limitation affecting dynamic measurements with PET is low signal-to-noise ratio (SNR). Several reports have suggested that wavelet processing of receptor kinetic data in the human brain can improve the SNR of parametric images of binding potential (1111). However, it is difficult to full), assess these reports because objective standards have not been developed to measure the tradeoff between accuracy (e.g. degradation of resolution) and precision. This paper employs a realistic simulation method that includes all major elements affecting image formation. The simulation was used to derive an ensemble of dynamic PET ligand (C-11-raclopride) experiments that was subjected to wavelet processing. A method for optimizing wavelet denoising is presented and used to analyze the simulated experiments. Using optimized wavelet denoising, SNR of the four-dimensional PET data increased by about a factor of two and SNR of three-dimensional BP maps increased by about a factor of 1.5. Analysis of the difference between the processed and unprocessed means for the 4D concentration data showed that more than 80% of voxels in the ensemble mean of the wavelet processed data deviated by less than 3%. These results show that a 1.5x increase in SNR can be achieved with little degradation of resolution. This corresponds to injecting about twice the radioactivity, a maneuver that is not possible in human studies without saturating the PET camera and/or exposing the subject to more than permitted radioactivity. (c) 2005 Elsevier Inc. All rights reserved.

关键词： Algorithms Antipsychotic Agents/diagnostic use Brain/radionuclide imaging computer Simulation Humans image processing, computer-assisted/statistics & numerical data Kinetics Neostriatum/radionuclide imaging Positron-Emission Tomography/statistics & numerical data Raclopride/diagnostic use Raclopride/diagnostic use Radiopharmaceuticals/diagnostic use Radiopharmaceuticals/diagnostic use Receptors, Drug/physiology Reproducibility of Results

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A method for generating reproducible evidence in fMRI studies

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NEUROimage 2006年第2期29卷 383-395页

作者： Liou, M Su, HR Lee, JD Aston, JAD Tsai, AC Cheng, PE Acad Sinica Inst Stat Sci Taipei 115 Taiwan

Insights into cognitive neuroscience from neuroimaging techniques are now required to go beyond the localisation of well-known cognitive functions. Fundamental to this is the notion of reproducibility of experimental outcomes. This paper addresses the central issue that functional magnetic resonance imaging (fMRI) experiments will produce more desirable information if researchers begin to search for reproducible evidence rather than only p value significance. The study proposes a methodology for investigating reproducible evidence without conducting separate fMRI experiments. The reproducible evidence is gathered from the separate runs within the study. The associated empirical Bayes and ROC extensions of the linear model provide parameter estimates to determine reproducibility. Empirical applications of the methodology suggest that reproducible evidence is robust to small sample sizes and sensitive to both the magnitude and persistency of brain activation. It is demonstrated that research findings in fMRI studies would be more compelling with supporting reproducible evidence in addition to standard hypothesis testing evidence. (c) 2005 Elsevier Inc. All rights reserved.

关键词： Algorithms Bayes Theorem Brain Mapping/methods Brain Mapping/methods Cerebral Cortex/physiology data Interpretation, Statistical Humans image processing, computer-assisted/methods image processing, computer-assisted/statistics & numerical data Linear Models Magnetic Resonance Imaging/methods Magnetic Resonance Imaging/statistics & numerical data Reproducibility of Results ROC Curve Sample Size

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Controlled Support MEG imaging

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NEUROimage 2006年第3期33卷 878-885页

作者： Nagarajan, Srikantan S. Portniaguine, Oleg Hwang, Dosik Johnson, Chris Sekihara, Kensuke Univ Calif San Francisco Dept Radiol Biomagnet Imaging Lab San Francisco CA 94122 USA Univ Utah Sch Comp Sci Comp & Imaging Inst Salt Lake City UT 84108 USA Tokyo Metropolitan Univ Dept Elect Syst & Engn Tokyo 1910065 Japan

In this paper, we present a novel approach to imaging sparse and focal neural current sources from MEG (magnetoencephalography) data. Using the framework of Tikhonov regularization theory, we introduce a new stabilizer that uses the concept of controlled support to incorporate a priori assumptions about the area occupied by focal sources. The paper discusses the underlying Tikhonov theory and its relationship to a Bayesian formulation which in turn allows us to interpret and better understand other related algorithms. (c) 2006 Elsevier Inc. All rights reserved.

关键词： Algorithms Bayes Theorem Brain/anatomy & histology computer Simulation Humans image processing, computer-assisted/statistics & numerical data Magnetoencephalography/methods Magnetoencephalography/methods Magnetoencephalography/statistics & numerical data Magnetoencephalography/statistics & numerical data Monte Carlo Method Reproducibility of Results

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Contribution of alcoholism to brain dysmorphology in HIV infection: Effects on the ventricles and corpus callosum

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NEUROimage 2006年第1期33卷 239-251页

作者： Pfefferbaum, Adolf Rosenbloom, Margaret J. Rohlfing, Torsten Adalsteinsson, Elfar Kemper, Carol A. Deresinski, Stanley Sullivan, Edith V. Stanford Univ Sch Med Dept Psychiat & Behav Sci Stanford CA 94305 USA SRI Int Neurosci Program Menlo Pk CA 94025 USA Harvard Mit Div Hlth Sci & Technol Boston MA 02115 USA MIT Dept Elect Engn & Comp Sci Boston MA 02115 USA Stanford Univ Sch Med Div Infect Dis Dept Med Stanford CA 94305 USA Santa Clara Valley Med Ctr Stanford CA 94305 USA

Nonrigid registration and atlas-based parcellation methods were used to compare the volume of the ventricular system and the cross-sectional area of the midsagittal corpus callosum on brain MRIs from 272 subjects in four groups: patients with HIV infection, with and without alcoholism comorbidity, alcoholics, and controls. Prior to testing group differences in regional brain metrics, each measure was corrected by regression analysis for significant correlations with supratentorial cranial volume and age, observed in 121 normal control men and women, whose age spanned six decades. Disregarding HIV disease severity, we observed a graded pattern of modest enlargement of the total ventricular system (0.28 SD for uncomplicated HIV, 0.65 SD for HIV comorbid with alcoholism, and 0.72 SD for the alcoholism group). The pattern of callosal thinning showed a similar but small (similar to 0.5 SD) graded effect. A different pattern emerged, however, when HIV severity in the context of alcoholism comorbidity was factored into the analysis. Substantially greater volume abnormalities were present in individuals with a history of an AIDS-defining event or low CD4+ T cell counts (<= 200 mm(3)) irrespective of alcoholism comorbidity, and the effect of HIV severity was disproportionately exacerbated by alcoholism comorbidity, with 1 SD size deficit in the germ of corpus callosurn and nearly 2 SD greater volume of the frontal and body regions of the ventricles for the AIDS + alcohol comorbid group. The differences in brain volumes between the AIDS groups with vs. without alcoholism could not be attributed to differences in HIV disease severity, defined by CD4+ count, viral load, or Karnofsky score. The substantial effect of the alcoholism-AIDS interaction on ventricular and callosal dysmorphology, in the context of the modest changes observed in non-AIDS, nonalcohol abusing ffIV-infected individuals, highlight the need to consider alcohol use disorders as a major risk factor for neuropa

关键词： Adult Alcoholism/complications Alcoholism/complications Alcoholism/pathology Alcoholism/pathology Brain/pathology CD4-Positive T-Lymphocytes/physiology Cerebral Ventricles/pathology Corpus Callosum/pathology Echo-Planar Imaging Female HIV Infections/complications HIV Infections/pathology Humans image processing, computer-assisted/statistics & numerical data Karnofsky Performance Status Karnofsky Performance Status Male Middle Aged Viral Load Viral Load

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Segmentation of subcortical brain structures using fuzzy templates

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NEUROimage 2005年第4期28卷 915-924页

作者： Zhou, J Rajapakse, JC Nanyang Technol Univ Sch Comp Engn Bioinformat Res Ctr Singapore 639798 Singapore

We propose a novel method to automatically segment subcortical structures of human brain in magnetic resonance images by using fuzzy templates. A set of fuzzy templates of the structures based on features such as intensity, spatial location, and relative spatial relationship among structures are first created from a set of training images by defining the fuzzy membership functions and by fusing the information of features. Segmentation is performed by registering the fuzzy templates of the structures on the test image and then by fusing them with the tissue maps of the test image. The final decision is taken in order to optimize the certainty in the intensity, location, relative position, and tissue content of the structure. Our method does not require specific expert definition of each structure or manual interactions during segmentation process. The technique is demonstrated with the segmentation of five structures: thalamus, putamen, caudate, hippocampus, and amygdala;the performance of the present method is comparable with previous techniques. (c) 2005 Elsevier Inc. All rights reserved.

关键词： Algorithms Artifacts Artificial Intelligence Brain/anatomy & histology Brain/physiology Brain Mapping Brain Mapping Functional Laterality/physiology Fuzzy Logic Humans image processing, computer-assisted/statistics & numerical data Magnetic Resonance Imaging/statistics & numerical data Reproducibility of Results

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Quantitative angiographic analysis of right ventricular global function in normal Incidences and in patients with coronary artery disease

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ANGIOLOGY 2005年第2期56卷 137-142页

作者： Batyraliev, TA Pershukov, IV Birand, A Erenler, O Sani Konukoglu Med Ctr Gaziantep Turkey Reg Clin Hosp Voronezh Russia Cukurova Univ Adana Turkey

At present right ventriculography data cannot be accurately estimated owing to the absence of software for quantitative analysis of the right ventricle (RV) volumes and function. The aim of this study was to use existing software for left ventriculography analysis to estimate right ventricular volumes and function in patients without coronary lesions and in those with coronary artery disease (CAD). Thirty-two patients without significant lesions of coronary arteries and 20 patients with CAD were examined with left ventriculography and right atriography. Each examination was performed in 2 projections: 30 degrees right anterior oblique (RAO 30 degrees) and 600 left anterior oblique (LAO 60 degrees) projections. Correction factor (CF) was obtained by finding the ratio between stroke volumes of the left and right ventricles, The mean CF was 0.9243 +/- 0.2887 for patients without CAD and 0.8758 +/- 0.2232 for patients with CAD. Such calculation is the easiest and quite accurate method of determining RV volumes and function by using existing software of quantitative angiographic analysis.

关键词： Adult Aged Coronary Angiography/statistics & numerical data Coronary Angiography/statistics & numerical data Coronary Disease/radiography data Interpretation, Statistical Female Humans image processing, computer-assisted/statistics & numerical data Male Middle Aged Prognosis Reference Values Sensitivity and Specificity Software Stroke Volume/physiology Ventricular Dysfunction, Left/radiography Ventricular Dysfunction, Right/radiography Ventricular Function, Left/physiology Ventricular Function, Right/physiology Ventriculography, First-Pass/statistics & numerical data Ventriculography, First-Pass/statistics & numerical data

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