A voxel-based method for the statistical analysis of gray and white matter density applied to schizophrenia

We describe a novel technique for characterizing regional cerebral gray and white matter differences in structural magnetic resonance images by the application of methods derived from functional imaging. The technique involves automatic scalp-editing of images followed by segmentation, smoothing, and spatial normalization to a symmetrical template brain in stereotactic Talairach space. The basic idea is (i) to convert structural magnetic resonance image data into spatially normalized images of gray (or white) matter density, effected by segmenting the images and smoothing, and then (ii) to use Statistical Parametric Mapping to make inferences about the relationship between gray (or white) matter density and symptoms (or other pathophysiological measures) in a regionally specific fashion. Because the whole brain sum of gray (or white) matter indices is treated as a confound, the analysis reduces to a characterization of relative gray (or white) matter density on a voxel by voxel basis. We suggest that this is a powerful approach to voxel-based statistical anatomy. Using the technique, we constructed maps of the regional cerebral gray and white matter density correlates of syndrome scores (distinct psychotic symptoms) in a group of 15 schizophrenic patients. There was a negative correlation between the score for the reality distortion syndrome and regional gray matter density in the left superior temporal lobe (P = 0.01) and regional white matter density in the corpus callosum (P < 0.001). These abnormalities may be associated with functional changes predisposing to auditory hallucinations and delusions. This method permits the detection of structural differences within the entire brain (as opposed to selected regions of interest) and may be of value in the investigation of structural gray and white matter abnormalities in a variety of brain diseases.     

In vivo morphometry of the intrasulcal gray matter in the human cingulate, paracingulate, and superior-rostral sulci: hemispheric asymmetries, gender differences and probability maps

Volumes of the intrasulcal gray matter were measured in three cerebral sulci located on the medial wall of the human frontal lobe: cingulate sulcus (CS), paracingulate sulcus (PCS), and superior-rostral sulcus (SRS). The measurements were carried out on T1-weighted 3-D high-resolution magnetic-resonance (MR) images acquired in 105 young right-handed volunteers (42 female and 63 male). Before the measurement, the images were transformed into a standardized stereotaxic space (Talairach and Tournoux [1988] Human Brain: 3-Dimensional Proportional System. An Approach to Cerebral Imaging. Stuttgart, New York: Georg Thieme Verlag), thus removing inter-individual differences in brain size. The intrasulcal gray matter was segmented in a semi-automatic manner. Significant gender differences were found in the volume of the CS (female > male) and the PCS (male > female). Hemispheric asymmetries were observed between the left and right volumes of the intrasulcal gray matter in the anterior (right > left) and posterior (left > right) segments of the CS, as well as between the left and right volumes of the PCS (left > right). There was no interaction between the asymmetries and gender. In addition, significant positive correlations were found between the left and right gray-matter volumes in the anterior (r = 0.43) and posterior (r = 0.66) segments of the CS, whereas significant negative correlations were observed between the gray-matter volumes of the anterior segment of the CS and those of the PCS (left hemisphere: r = -0.48; right hemisphere: r = -0.42). The observed hemispheric asymmetries in the CS and PCS gray-matter volumes are consistent with the proposed role of these structures in the integration of emotions with cognition (CS) and in the control of speech/vocalization (PCS). The pattern of inter-hemispheric correlations in the sulcal gray-matter points to an increasing asynchrony in the foetal development of primary (CS), secondary (SRS), and tertiary (PCS) sulci, respectively. The presence of negative correlations between the two neighbouring sulci (CS and PCS) suggests that a process of compensation could underlie interactions between adjacent primary and tertiary sulci. Besides the above volumetric analysis, we also provide average (probability) maps of the three sulci; the use of such maps for the parcellation of the medial frontal lobe and localization of "peaks" obtained in blood-flow activation studies is discussed.     

Lipoprotein profile in canine pancreatitis induced with oleic acid

In the treatment of children with brain tumors, balancing the efficacy of treatment against commonly observed side effects is difficult because of a lack of quantitative measures of brain damage that can be correlated with the intensity of treatment. We quantitatively assessed volumes of brain parenchyma on magnetic resonance (MR) images using a hybrid combination of the Kohonen self-organizing map for segmentation and a multilayer backpropagation neural network for tissue classification. Initially, we analyzed the relationship between volumetric differences and radiologists' grading of atrophy in 80 subjects. This investigation revealed that brain parenchyma and white matter volumes significantly decreased as atrophy increased, whereas gray matter volumes had no relationship with atrophy. Next, we compared 37 medulloblastoma patients treated with surgery, irradiation, and chemotherapy to 19 patients treated with surgery and irradiation alone. This study demonstrated that, in these patients, chemotherapy had no significant effect on brain parenchyma, white matter, or gray matter volumes. We then investigated volumetric differences due to cranial irradiation in 15 medulloblastoma patients treated with surgery and radiation therapy, and compared these with a group of 15 age-matched patients with low-grade astrocytoma treated with surgery alone. With a minimum follow-up of one year after irradiation, all radiation-treated patients demonstrated significantly reduced white matter volumes, whereas gray matter volumes were relatively unchanged compared with those of age-matched patients treated with surgery alone. These results indicate that reductions in cerebral white matter: 1) are correlated significantly with atrophy; 2) are not related to chemotherapy; and 3) are correlated significantly with irradiation. This hybrid neural network analysis of subtle brain volume differences with magnetic resonance may constitute a direct measure of treatment-induced brain damage.     

Interactive effects of three structurally different polychlorinated biphenyls in a rat liver tumor promotion bioassay

PURPOSE: Our goal was to validate linear and nonlinear intersubject image registration using an automated method (AIR 3.0) based on voxel intensity. METHOD: PET and MRI data from 22 normal subjects were registered to corresponding averaged PET or MRI brain atlases using several specific linear and nonlinear spatial transformation models with an automated algorithm. Validation was based on anatomically defined landmarks. RESULTS: Automated registration produced results that were superior to a manual nine parameter variant of the Talairach registration method. Increasing the degrees of freedom in the spatial transformation model improved the accuracy of automated intersubject registration. CONCLUSION: Linear or nonlinear automated intersubject registration based on voxel intensities is computationally practical and produces more accurate alignment of homologous landmarks than manual nine parameter Talairach registration. Nonlinear models provide better registration than linear models but are slower.     

High-resolution anatomy from in situ human brain

We have generated a spatially accurate, high-resolution three-dimensional (3D) volume of brain anatomy from cryosectioned whole human head. The head of a female cadaver was cryosectioned on a heavy duty cryomacrotome (PMV, Stockholm Sweden) modified for quantitative digital image capture. Serial images (1024(2), 24-bit) were captured directly from the cryoplaned specimen blockface in 500-micron intervals and reconstructed to a 3D data volume. Data were placed into the Talairach coordinate system to create a volume of brain anatomy for atlas reference. We resampled the volume at 500 microns along the sagittal, coronal, and horizontal planes and enhanced the images by digitally editing the background. The spatial resolution of the original digitized images provided sufficient anatomic detail to clearly delineate gray and white matter and neural structures, including major fiber pathways, subthalamic nuclei, and laminae. We developed a compact disk and controlling software program to enable the viewer to select planes of orientation, display, and copy individual to sections at higher resolution. Animation proved useful in the conveyance of system anatomy as structures are shown traversing through the neuroaxis. Postmortem cryosectioning paired with this computerized presentation allowed the complete 3D volume data to be distributed and shared as an educational, clinical, and research resource.     

Detection, visualization and animation of abnormal anatomic structure with a deformable probabilistic brain atlas based on random vector field transformations

This paper describes the design, implementation and preliminary results of a technique for creating a comprehensive probabilistic atlas of the human brain based on high-dimensional vector field transformations. The goal of the atlas is to detect and quantify distributed patterns of deviation from normal anatomy, in a 3-D brain image from any given subject. The algorithm analyzes a reference population of normal scans and automatically generates color-coded probability maps of the anatomy of new subjects. Given a 3-D brain image of a new subject, the algorithm calculates a set of high-dimensional volumetric maps (with typically 384(2) x 256 x 3 approximately 10(8) degrees of freedom) elastically deforming this scan into structural correspondence with other scans, selected one by one from an anatomic image database. The family of volumetric warps thus constructed encodes statistical properties and directional biases of local anatomical variation throughout the architecture of the brain. A probability space of random transformations, based on the theory of anisotropic Gaussian random fields, is then developed to reflect the observed variability in stereotaxic space of the points whose correspondences are found by the warping algorithm. A complete system of 384(2) x 256 probability density functions is computed, yielding confidence limits in stereotaxic space for the location of every point represented in the 3-D image lattice of the new subject's brain. Color-coded probability maps are generated, densely defined throughout the anatomy of the new subject. These indicate locally the probability of each anatomic point being unusually situated, given the distributions of corresponding points in the scans of normal subjects. 3-D MRI and high-resolution cryosection volumes are analyzed from subjects with metastatic tumors and Alzheimer's disease. Gradual variations and continuous deformations of the underlying anatomy are simulated and their dynamic effects on regional probability maps are animated in video format (on the accompanying CD-ROM). Applications of the deformable probabilistic atlas include the transfer of multi-subject 3-D functional, vascular and histologic maps onto a single anatomic template, the mapping of 3-D atlases onto the scans of new subjects, and the rapid detection, quantification and mapping of local shape changes in 3-D medical images in disease and during normal or abnormal growth and development.     

Neuroanatomical and cognitive mediators of age-related differences in episodic memory.

Aging is associated with declines in episodic memory. In this study, the authors used a path analysis framework to explore the mediating role of differences in brain structure, executive functions, and processing speed in age-related differences in episodic memory. Measures of regional brain volume (prefrontal gray and white matter, caudate, hippocampus, visual cortex), executive functions (working memory, inhibitory control, task switching, temporal processing), processing speed, and episodic memory were obtained in a sample of young and older adults. As expected, age was linked to reduction in regional brain volumes and cognitive performance. Moreover, neural and cognitive factors completely mediated age differences in episodic memory. Whereas hippocampal shrinkage directly affected episodic memory, prefrontal volumetric reductions influenced episodic memory via limitations in working memory and inhibitory control. Age-related slowing predicted reduced efficiency in temporal processing, working memory, and inhibitory control. Lastly, poorer temporal processing directly affected episodic memory. No direct effects of age on episodic memory remained once these factors were taken into account. These analyses highlight the value of a multivariate approach with the understanding of complex relationships in cognitive and brain aging. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Selective cortical and hippocampal volume correlates of Mattis Dementia Rating Scale in Alzheimer disease

OBJECTIVE: To examine whether each of the 5 Mattis Dementia Rating Scale (DRS) scores related to magnetic resonance imaging-derived volumes of specific cortical or limbic brain regions in patients with Alzheimer disease (AD). DESIGN: Relations between DRS measures and regional brain volume measures were tested with bivariate and multivariate regression analyses. SETTING: The Aging Clinical Research Center of the Stanford (Calif) University Department of Psychiatry and Behavioral Science and the Geriatric Psychiatry Rehabilitation Unit of the Veterans Affairs Palo Alto Health Care System, Palo Alto, Calif. PATIENTS AND OTHER PARTICIPANTS: Fifty patients with possible or probable AD. Magnetic resonance imaging data from 136 healthy control participants, age 20 to 84 years, were used to correct brain volumes for normal variation arising from intracranial volume and age. MAIN OUTCOME MEASURES: The DRS scores and volumes of regional cortical gray matter and of the hippocampus. RESULTS: Memory scores of the patients with AD were selectively related to hippocampal volumes. Attention and construction scores were related to several anterior brain volume measures, with attention showing a significantly greater association to right than left hemisphere measures. Initiation/perseveration scores were not significantly correlated with any measure of regional gray matter volume, but performance was related to prefrontal sulcal widening, with a greater association with the left than right sulcal volume. CONCLUSIONS: Certain DRS subtests are predictably correlated with selective regional brain volumes in AD. The specific relation between memory and hippocampal volumes and the nonsignificant relations between memory and regional cortical volumes suggest a dissociation between cortical and hippocampal contributions to explicit memory performance.     

The human brain age 7-11 years: a volumetric analysis based on magnetic resonance images

Volumetric magnetic resonance image (MRI)-based morphometry was performed on the brains of 30 normal children (15 males and 15 males) with a mean age of 9 years (range 7-11 years). This age range lies in a late but critical phase of brain growth where not volumetric increment will be small but when the details of brain circuity are being fine-tuned to support the operations of the adult brain. The brain at this age is 95% the volume of the adult brain. The brain of the female child is 93% the volume of the male child. For more than 95% of brain structures, the volumetric differences in male and female child brain are uniformly scaled to the volume difference of the total brain in the two sexes. Exceptions to this pattern of uniform scaling are the caudate, hippocampus and pallidum, which are disproportionately larger in female than male child brain, and the amygdala, which is disproportionately smaller in the female child brain. The patterns of uniform scaling are generally sustained during the final volumetric increment in overall brain size between age 7-11 and adulthood. There are exceptions to this uniform scaling of child to adult brain, and certain of these exceptions are sexually dimorphic. Thus, with respect to major brain regions, the cerebellum in the female but not the male child is already at adult volume while the brainstem in both sexes must enlarge more than the brain as a whole. The collective subcortical gray matter structures of the forebrain of the female child are already at their adult volumes. The volumes of these same structures in the male child, by contrast, are greater than their adult volumes and, by implication, must regress in volume before adulthood. The volume of the central white matter, on the other hand, is disproportionately smaller in female than male child brain with respect to the adult volumes of cerebral central white matter. By implication, relative volumetric increase of cerebral central white matter by adulthood must be greater in the female than male brain. The juxtaposed progressive and regressive patterns of growth of brain structures implied by these observations in the human brain have a soundly established precedent in the developing rhesus brain. There is emerging evidence that sexually dimorphic abnormal regulation of these terminal patterns of brain development are associated with gravely disabling human disorders of obscure etiology.     

A method for assessing the accuracy of intersubject registration of the human brain using anatomic landmarks

Several groups have developed methods for registering an individual's 3D MRI by deforming a standard template. This achievement leads to many possibilities for segmentation and morphology that will impact nuclear medical research in areas such as activation and receptor studies. Accordingly, there is a need for methods that can assess the accuracy of intersubject registration. We have developed a method based on a set of 128 anatomic landmarks per hemisphere, both cortical and subcortical, that allows assessment of both global and local transformation accuracy. We applied our method to compare the accuracy of two standard methods of intersubject registration, AIR 3.0 with fifth-order polynomial warping and the Talairach stereotaxic transformation (Talairach and Tournoux, 1988). SPGR MRI's (256 x 256 x 160) of six normal subjects (age 18-24 years) were derformed to match a standard template volume. To assess registration accuracy the landmarks were located on both the template volume and the transformed volumes by an experienced neuroanatomist. The resulting list of coordinates was analyzed graphically and by ANOVA to compare the accuracy of the two methods and the results of the manual analysis. ANOVA performed over all 128 landmarks showed that the Woods method was more accurate than Talairach (left hemisphere F = 2.8, P < 0.001 and right hemisphere F =2.4, P < 0.006). The Woods method provided a better brain surface transformation than did Talairach (F = 18.0, P < 0.0001), but as expected there was a smaller difference for subcortical structures and both had an accuracy <1 mm for the majority of subcortical landmarks. Overall, both the Woods and Talairach method located about 70% of landmarks with an error of 3 mm or less. More striking differences were noted for landmark accuracy 相似文献   

The representation of tonality and meter in children aged 7 and 9

For the purpose of developing multiple, complementary, fully labeled electronic brain atlases and an atlas-based neuroimaging system for analysis, quantification, and real-time manipulation of cerebral structures in two and three dimensions, we have digitized, enhanced, segmented, and labeled the following print brain atlases: Co-Planar Stereotaxic Atlas of the Human Brain by Talairach and Tournoux, Atlas for Stereotaxy of the Human Brain by Schaltenbrand and Wahren, Referentially Oriented Cerebral MRI Anatomy by Talairach and Tournoux, and Atlas of the Cerebral Sulci by Ono, Kubik, and Abernathey. Three-dimensional extensions of these atlases have been developed as well. All two- and three-dimensional atlases are mutually preregistered and may be interactively registered with an actual patient's data. An atlas-based neuroimaging system has been developed that provides support for reformatting, registration, visualization, navigation, image processing, and quantification of clinical data. The anatomical index contains about 1,000 structures and over 400 sulcal patterns. Several new applications of the brain atlas database also have been developed, supported by various technologies such as virtual reality, the Internet, and electronic publishing. Fusion of information from multiple atlases assists the user in comprehensively understanding brain structures and identifying and quantifying anatomical regions in clinical data. The multiple brain atlas database and atlas-based neuroimaging system have substantial potential impact in stereotactic neurosurgery and radiotherapy by assisting in visualization and real-time manipulation in three dimensions of anatomical structures, in quantitative neuroradiology by allowing interactive analysis of clinical data, in three-dimensional neuroeducation, and in brain function studies.     

Automatic tumor segmentation using knowledge-based techniques

A system that automatically segments and labels glioblastoma-multiforme tumors in magnetic resonance images (MRI's) of the human brain is presented. The MRI's consist of T1-weighted, proton density, and T2-weighted feature images and are processed by a system which integrates knowledge-based (KB) techniques with multispectral analysis. Initial segmentation is performed by an unsupervised clustering algorithm. The segmented image, along with cluster centers for each class are provided to a rule-based expert system which extracts the intracranial region. Multispectral histogram analysis separates suspected tumor from the rest of the intracranial region, with region analysis used in performing the final tumor labeling. This system has been trained on three volume data sets and tested on thirteen unseen volume data sets acquired from a single MRI system. The KB tumor segmentation was compared with supervised, radiologist-labeled "ground truth" tumor volumes and supervised k-nearest neighbors tumor segmentations. The results of this system generally correspond well to ground truth, both on a per slice basis and more importantly in tracking total tumor volume during treatment over time.     

Deficits in gray matter volume are present in schizophrenia but not bipolar disorder

Studies using magnetic resonance (MR) imaging have provided strong evidence that patients with schizophrenia as a group have structural brain abnormalities, including enlarged ventricles and sulci as well as smaller cortical gray matter volumes. This study was undertaken to investigate whether the brain abnormalities found in schizophrenia could be distinguished from those seen in bipolar disorder. The MR scans of 23 patients with schizophrenia were compared to those of 17 healthy community volunteers and 14 patients with bipolar disorder. Images were processed using computer-based image processing techniques to generate quantitative measures of cerebrospinal fluid (CSF), gray matter and white matter volumes. Compared to the community volunteers, the schizophrenia group had larger total CSF volumes while the bipolar group had larger ventricles. Smaller cortical gray matter volumes were found in the schizophrenia group, but not in the bipolar group. The schizophrenia group had regional deficits in gray matter volumes in comparison with both the community volunteers and the bipolar group. These findings suggest that the brain tissue abnormalities found in schizophrenia and bipolar disorder may be distinguishable using MR imaging.     

Characteristics of patients at risk for perioperative myocardial infarction after infrainguinal bypass surgery: an exploratory study

Two numerical brain phantoms were generated in order to investigate errors which might be included in the quantitative measurement of regional CBF with use of single photon emission computed tomography (SPECT). The first phantom simulated the normal brain, and effects of the limited spatial resolution of the SPECT scanner were evaluated for 4 tracer kinetic models of the conventional microsphere model, the intra-carotid bolus injection technique of 133Xe, 133Xe Kanno-Lassen method, and the IMP-autoradiography (IMP-ARG) method. The second phantom simulated the diseased brain with middle-carotid artery (MCA) occlusion, and effects of the limited first-pass extraction fraction were investigated for the microsphere model with various permeability-surface area products. The limited spatial resolution caused systematic underestimation of the radioactivity concentration in the gray matter regions, and systematic overestimation in the low CBF regions. These errors in the original radioactivity distribution were found to cause further systematic errors in the calculated regional CBF images. It was also found that these errors were highly dependent on the tracer kinetic model employed, e.g., regional CBF values were overestimated in the clearance and the Kanno-Lassen methods compared with the conventional microsphere method, whereas values were underestimated in the IMP-ARG method. It was also shown in this study that the limited first-pass extraction fraction caused significant underestimation in the calculated rCBF values. In addition, regional contrast can be reduced when using a tracer with small PS product.(ABSTRACT TRUNCATED AT 250 WORDS)     

Visual assessment of the accuracy of retrospective registration of MR and CT images of the brain

In a previous study we demonstrated that automatic retrospective registration algorithms can frequently register magnetic resonance (MR) and computed tomography (CT) images of the brain with an accuracy of better than 2 mm, but in that same study we found that such algorithms sometimes fail, leading to errors of 6 mm or more. Before these algorithms can be used routinely in the clinic, methods must be provided for distinguishing between registration solutions that are clinically satisfactory and those that are not. One approach is to rely on a human observer to inspect the registration results and reject images that have been registered with insufficient accuracy. In this paper, we present a methodology for evaluating the efficacy of the visual assessment of registration accuracy. Since the clinical requirements for level of registration accuracy are likely to be application dependent, we have evaluated the accuracy of the observer's estimate relative to six thresholds: 1-6 mm. The performance of the observers was evaluated relative to the registration solution obtained using external fiducial markers that are screwed into the patient's skull and that are visible in both MR and CT images. This fiducial marker system provides the gold standard for our study. Its accuracy is shown to be approximately 0.5 mm. Two experienced, blinded observers viewed five pairs of clinical MR and CT brain images, each of which had each been misregistered with respect to the gold standard solution. Fourteen misregistrations were assessed for each image pair with misregistration errors distributed between 0 and 10 mm with approximate uniformity. For each misregistered image pair each observer estimated the registration error (in millimeters) at each of five locations distributed around the head using each of three assessment methods. These estimated errors were compared with the errors as measured by the gold standard to determine agreement relative to each of the six thresholds, where agreement means that the two errors lie on the same side of the threshold. The effect of error in the gold standard itself is taken into account in the analysis of the assessment methods. The results were analyzed by means of the Kappa statistic, the agreement rate, and the area of receiver-operating-characteristic (ROC) curves. No assessment performed well at 1 mm, but all methods performed well at 2 mm and higher. For these five thresholds, two methods agreed with the standard at least 80% of the time and exhibited mean ROC areas greater than 0.84. One of these same methods exhibited Kappa statistics that indicated good agreement relative to chance (Kappa > 0.6) between the pooled observers and the standard for these same five thresholds. Further analysis demonstrates that the results depend strongly on the choice of the distribution of misregistration errors presented to the observers.     

Using functional magnetic resonance imaging to understand the mechanisms of consciousness

BACKGROUND: In order to elucidate mental functions that subserve human consciousness, brain activation was investigated in 12 normal, right-handed volunteers who performed tasks of selective attention, working memory, and sensorimotor coordination during the collection of multislice echoplanar functional magnetic resonance images. HYPOTHESIS: These functions are located in (and controlled by) distinct anatomical regions that can be identified by functional magnetic resonance imaging techniques. METHODS: In each subject, 100 10-slice data sets were acquired using a 1.5-T scanner and the blood oxygenation level dependent contrast technique. Time-series regression modeling estimated power in the magnetic resonance signal during the on/off phases of task performance. Comparison between subjects was made possible by the transformation of each data set into standard Talairach space. RESULTS: Activation maps were based on the median value of the fundamental power quotient at each voxel. Results showed the activation of prefrontal and parasagittal cortices in both the selective attention and working memory tasks, but they also revealed activation in both insular cortices and the posterior cingulate gyri. CONCLUSIONS: The results provide evidence for structures in the anterior right hemisphere and left medial frontal lobe for attentional tasks, although there appears to be an engagement of a widespread network of anterior brain structures, possibly with the inhibition of some posterior regions, during task performance. The sensorimotor coordination task showed activation regions similar to those seen in selective attention. Once learned, this task probably demands attention rather than overt conscious motor control. Clearly, the functions of attention, working memory, and sensorimotor coordination are not located in single, discrete brain areas. However, interactions and interplay between related areas were demonstrated, giving supporting evidence that complex mental operations rely on the coordinated activity of widely distributed brain regions that contribute to neural networks.     

Sequential changes in laminin and type IV collagen in the infarct zone--immunohistochemical study in rat myocardial infarction

The T1-weighted volumetric magnetic resonance images of 31 patients with intractable temporal lobe epilepsy, and 13 control subjects matched for age and sex, were subjected to semiautomated threshold analysis. The method used proved to be relatively fast and reliable. An index of temporal lobe interhemispheric asymmetry was extracted by thresholding high-signal (white matter) pixels. Patients had significantly more asymmetrical indices for white matter and hippocampal volumes that did control subjects, and the two indices were significantly correlated, providing evidence for the validity of the white matter index. Differences in both indices were consistent with decreased tissue on the side of the focus. In classification analyses a combination of these two indices correctly predicted the side of focus at a greater rate than did either used alone. Findings provide support for the hypothesis that seizure activity is associated with atrophy in both mesial and lateral temporal lobe structures.     

Quantitative MR volumetry in Alzheimer's disease. Topographic markers and the effects of sex and education

We determined topographic selectivity and diagnostic utility of brain atrophy in probable Alzheimer's disease (AD) and correlations with demographic factors such as age, sex, and education. Computerized imaging analysis techniques were applied to MR images in 32 patients with probable AD and 20 age- and sex-matched normal control subjects using tissue segmentation and three-dimensional surface rendering to obtain individualized lobar volumes, corrected for head size by a residualization technique. Group differences emerged in gray and white matter compartments particularly in parietal and temporal lobes. Logistic regression demonstrated that larger parietal and temporal ventricular CSF compartments and smaller temporal gray matter predicted AD group membership with an area under the receiver operating characteristic curve of 0.92. On multiple regression analysis using age, sex, education, duration, and severity of cognitive decline to predict regional atrophy in the AD subjects, sex consistently entered the model for the frontal, temporal, and parietal ventricular compartments. In the parietal region, for example, sex accounted for 27% of the variance in the parietal CSF compartment and years of education accounted for an additional 15%, with women showing less ventricular enlargement and individuals with more years of education showing more ventricular enlargement in this region. Topographic selectivity of atrophic changes can be detected using quantitative volumetry and can differentiate AD from normal aging. Differential effects of sex and years of education can also be detected by these methods. Quantification of tissue volumes in vulnerable regions offers the potential for monitoring longitudinal change in response to treatment.     

Structural brain correlates of verbal and nonverbal fluency measures in Alzheimer's disease.

This study examined the relationships between regional brain volumes and semantic, phonological, and nonverbal fluency in 32 participants with Alzheimer's disease (AD). Object but not animal semantic fluency correlated with frontal and temporal gray matter volumes. Phonological fluency was not significantly associated with any brain volume examined. Nonverbal fluency was selectively associated with bilateral frontal gray matter volumes. Hippocampal volumes, although markedly reduced in these patients, were not related to any of the fluency measures. Results lend evidence to the importance of the frontal lobes in the directed generation of nonverbal and verbal exemplars by AD patients. Furthermore, both left and right-hemisphere regions contribute to the generation of verbal and nonverbal exemplars. (PsycINFO Database Record (c) 2010 APA, all rights reserved)