Reliability and validity of an algorithm for fuzzy tissue segmentation of MRI

Neuroimaging Phenotypes Associated With Risk and Resilience for Psychosis and Autism Spectrum Disorders in 22q11.2 Microdeletion Syndrome

Identification of biological risk factors that contribute to the development of complex neuropsychiatric disorders such as psychosis and autism spectrum disorder (ASD) is key for early intervention and detection. Furthermore, parsing the biological heterogeneity associated with these neuropsychiatric syndromes will help us understand the neural mechanisms underlying psychiatric symptom development. The 22q11.2 microdeletion syndrome (22q11DS) is caused by a recurrent genetic mutation that carries significantly increased risk for developing psychosis and/or ASD. In this review, I provide an brief introduction to 22q11DS and discuss common phenotyping strategies that are used to assess psychosis and ASD in this population. I then summarize neuroimaging phenotypes associated with psychosis and ASD in 22q11.DS. Next, I discuss challenges within the field and provide practical suggestions to overcome these obstacles. Finally, I discuss future directions for moving 22q11DS risk and resilience research forward.

Imaging genetics in neurodevelopmental psychopathology

Neurodevelopmental disorders are defined by highly heritable problems during development and brain growth. Attention-deficit/hyperactivity disorder (ADHD), autism spectrum disorders (ASDs), and intellectual disability (ID) are frequent neurodevelopmental disorders, with common comorbidity among them. Imaging genetics studies on the role of disease-linked genetic variants on brain structure and function have been performed to unravel the etiology of these disorders. Here, we reviewed imaging genetics literature on these disorders attempting to understand the mechanisms of individual disorders and their clinical overlap. For ADHD and ASD, we selected replicated candidate genes implicated through common genetic variants. For ID, which is mainly caused by rare variants, we included genes for relatively frequent forms of ID occurring comorbid with ADHD or ASD. We reviewed case-control studies and studies of risk variants in healthy individuals. Imaging genetics studies for ADHD were retrieved for SLC6A3/DAT1, DRD2, DRD4, NOS1, and SLC6A4/5HTT. For ASD, studies on CNTNAP2, MET, OXTR, and SLC6A4/5HTT were found. For ID, we reviewed the genes FMR1, TSC1 and TSC2, NF1, and MECP2. Alterations in brain volume, activity, and connectivity were observed. Several findings were consistent across studies, implicating, for example, SLC6A4/5HTT in brain activation and functional connectivity related to emotion regulation. However, many studies had small sample sizes, and hypothesis-based, brain region-specific studies were common. Results from available studies confirm that imaging genetics can provide insight into the link between genes, disease-related behavior, and the brain. However, the field is still in its early stages, and conclusions about shared mechanisms cannot yet be drawn.

Developmental variation in amygdala volumes among children with posttraumatic stress

This article examined associations between indices of maturation (age and Tanner stage) and amygdala volumes in 24 youth (aged 7-14) with posttraumatic stress disorder symptoms and a matched control group. Fifteen of the youth with exposure to trauma were also re-evaluated one year later. A positive association between maturation and right amygdala volumes was observed in the trauma group but not in controls. Associations with maturation remained when controlling for a number of possible covariates and over time. Developmentally younger youth (Tanner stage 1 and 2) showed increases and older (Tanner stage 3 and 4) decreases in right amygdala volumes.

Early adversity and combat exposure interact to influence anterior cingulate cortex volume in combat veterans

Objective

Childhood and combat trauma have been observed to interact to influence amygdala volume in a sample of U.S. military veterans with and without PTSD. This interaction was assessed in a second, functionally-related fear system component, the pregenual and dorsal anterior cingulate cortex, using the same sample and modeling approach.

Method

Anterior cingulate cortical tissues (gray + white matter) were manually-delineated in 1.5 T MR images in 87 U.S. military veterans of the Vietnam and Persian Gulf wars. Hierarchical multiple regression modeling was used to assess associations between anterior cingulate volume and the following predictors, trauma prior to age 13, combat exposure, the interaction of early trauma and combat exposure, and PTSD diagnosis.

Results

As previously observed in the amygdala, unique variance in anterior cingulate cortical volume was associated with both the diagnosis of PTSD and with the interaction of childhood and combat trauma. The pattern of the latter interaction indicated that veterans with childhood trauma exhibited a significant inverse linear relationship between combat trauma and anterior cingulate volume while those without childhood trauma did not. Such associations were not observed in hippocampal or total cerebral tissue volumes.

Conclusions

In the dorsal anterior cingulate cortex, as in the amygdala, early trauma may confer excess sensitivity to later combat trauma.

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Childhood and combat trauma may interact to influence anterior cingulate cortex.

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These findings partially replicate findings in amygdala.

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Formally similar relations are found in endocrinological and psychometric data.

Insular cortex abnormalities in psychotic major depression: relationship to gender and psychotic symptoms

Recent data suggests that psychotic major depression (PMD) may be a discrete disorder distinguishable from nonpsychotic major depression (NPMD), and that patients with PMD may be more similar to individuals with schizophrenia than individuals with NPMD. The insula is a brain region in which morphometric changes have been associated with psychotic symptom severity in schizophrenia and affective psychosis. It was hypothesized that insular volumes would be reduced in PMD compared to NPMD and controls, and insular volumes would correlate with psychosis but not depression severity. Insular gray matter volumes were measured in PMD and NPMD patients and matched healthy controls using magnetic resonance images and manual morphometry. Clinical measures of illness severity were obtained to determine their relationship with insular volume. Posterior insular volumes were significantly reduced in PMD compared to HC. There were also significant group-by-gender interactions for total, anterior and posterior insular volumes. Using Pearson product-moment correlations, anterior insular volumes did not correlate with depression severity. Left anterior insular volume was significantly correlated with total and positive symptom psychosis severity in the PMD group. Atypical insular morphometry may be related to the inability to distinguish between internally and externally generated sensory inputs characteristic of psychosis.

Preliminary evidence of abnormal white matter related to the fusiform gyrus in Williams syndrome: a diffusion tensor imaging tractography study

Williams syndrome (WS) is a genetic condition caused by a hemizygous microdeletion on chromosome 7q11.23. WS is characterized by a distinctive social phenotype composed of increased drive toward social engagement and attention toward faces. In addition, individuals with WS exhibit abnormal structure and function of brain regions important for the processing of faces such as the fusiform gyrus. This study was designed to investigate if white matter tracts related to the fusiform gyrus in WS exhibit abnormal structural integrity as compared to typically developing (TD; age matched) and developmentally delayed (DD; intelligence quotient matched) controls. Using diffusion tensor imaging data collected from 40 (20 WS, 10 TD and 10 DD) participants, white matter fibers were reconstructed that project through the fusiform gyrus and two control regions (caudate and the genu of the corpus callosum). Macro-structural integrity was assessed by calculating the total volume of reconstructed fibers and micro-structural integrity was assessed by calculating fractional anisotropy (FA) and fiber density index (FDi) of reconstructed fibers. WS participants, as compared to controls, exhibited an increase in the volume of reconstructed fibers and an increase in FA and FDi for fibers projecting through the fusiform gyrus. No between-group differences were observed in the fibers that project through the control regions. Although preliminary, these results provide further evidence that the brain anatomy important for processing faces is abnormal in WS.

Amygdalar, hippocampal, and thalamic volumes in youth at high risk for development of bipolar disorder

Children of parents with bipolar disorder (BD), especially those with attention deficit hyperactivity disorder (ADHD) and symptoms of depression or mania, are at significantly high risk for developing BD. As we have previously shown amygdalar reductions in pediatric BD, the current study examined amygdalar volumes in offspring of parents (BD offspring) who have not yet developed a full manic episode. Youth participating in the study included 22 BD offspring and 22 healthy controls of comparable age, gender, handedness, and IQ. Subjects had no history of a manic episode, but met criteria for ADHD and moderate mood symptoms. MRI was performed on a 3T GE scanner, using a 3D volumetric spoiled gradient echo series. Amygdalae were manually traced using BrainImage Java software on positionally normalized brain stacks. Bipolar offspring had similar amygdalar volumes compared to the control group. Exploratory analyses yielded no differences in hippocampal or thalamic volumes. Bipolar offspring do not show decreased amygdalar volume, possibly because these abnormalities occur after more prolonged illness rather than as a preexisting risk factor. Longitudinal studies are needed to determine whether amygdalar volumes change during and after the development of BD.

The feasibility of detecting neuropsychologic and neuroanatomic effects of type 1 diabetes in young children

OBJECTIVE

To determine if frequent exposures to hypoglycemia and hyperglycemia during early childhood lead to neurocognitive deficits and changes in brain anatomy.

RESEARCH DESIGN AND METHODS

In this feasibility, cross-sectional study, young children, aged 3 to 10 years, with type 1 diabetes and age- and sex-matched healthy control (HC) subjects completed neuropsychologic (NP) testing and magnetic resonance imaging (MRI) scans of the brain.

RESULTS

NP testing and MRI scanning was successfully completed in 98% of the type 1 diabetic and 93% of the HC children. A significant negative relationship between HbA1c and Wechsler Intelligence Scale for Children (WISC) verbal comprehension was observed. WISC index scores were significantly reduced in type 1 diabetic subjects who had experienced seizures. White matter volume did not show the expected increase with age in children with type 1 diabetes compared with HC children (diagnosis by age interaction, P=0.005). A similar trend was detected for hippocampal volume. Children with type 1 diabetes who had experienced seizures showed significantly reduced gray matter and white matter volumes relative to children with type 1 diabetes who had not experienced seizures.

CONCLUSIONS

It is feasible to perform MRI and NP testing in young children with type 1 diabetes. Further, early signs of neuroanatomic variation may be present in this population. Larger cross-sectional and longitudinal studies of neurocognitive function and neuroanatomy are needed to define the effect of type 1 diabetes on the developing brain.

Consequence of preterm birth in early adolescence: the role of language on auditory short-term memory

This study tested the hypothesis that preterm early adolescents' short-term memory is compromised when presented with increasingly complex verbal information and that associated neuroanatomical volumes would differ between preterm and term groups. Forty-nine preterm and 20 term subjects were evaluated at age 12 years with neuropsychological measures and magnetic resonance imaging (MRI). There were no differences between groups in simple short-term and working memory. Preterm subjects performed lower on learning and short-term memory tests that included increased verbal complexity. They had reduced right parietal, left temporal, and right temporal white matter volumes and greater bilateral frontal gray and right frontal white matter volumes. There was a positive association between complex working memory and the left hippocampus and frontal white matter in term subjects. While not correlated, memory scores and volumes of cortical regions known to subserve language and memory were reduced in preterm subjects. This study provides evidence of possible mechanisms for learning problems in former preterm infants.

[Time processing in the velo-cardio-facial syndrome (22q11) and its link with the caudate nucleus]

INTRODUCTION

Velocardiofacial syndrome (VCFS) is a neurogenetic disorder caused by a microdeletion on chromosome 22q11. Among other cognitive impairments and learning difficulties, affected individuals show difficulties in estimating time intervals (Debbané et al., 2005). Interestingly, neuroimaging studies have found an increased volume of the basal ganglia of people with VCFS (Eliez et al., 2002; Kates et al., 2004; Campbell et al., 2006). Given that the caudate nucleus represents a central component of the cerebral network underlying temporal perception skills, the present report proposes to examine potential relationships between cerebral alteration to the caudate nucleus and time estimation in individuals with VCFS.

METHODS

A group of 30 patients with VCFS and 38 age-matched healthy individuals participated in time perception and time reproduction tasks. In the time perception task, individuals listened to two sequential stimuli and had to choose the longer of both stimuli by pressing a button. In the time reproduction task, subjects listened to a succession of sounds and once this succession had stopped they had to reproduce the same rhythm with their dominant index. Cerebral MRI images were also obtained for each participant. A manual tracing procedure was performed to measure the basal ganglia volume.

RESULTS

Participants with VCFS demonstrated significantly poorer performances during the time perception and time reproduction tasks in comparison to the control participants. Further, increased volume of the caudate nucleus was found in individuals with VCFS. Correlational analyses revealed a significant relationship between the caudate nucleus's volume and the performances obtained in the time perception task for control participants. This correlation was not found for individuals with VCFS.

CONCLUSION

The present results suggest that cerebral alterations to the caudate nucleus in VCFS may alter the temporal perception function it sustains.

Cingulate gyrus morphology in children and adolescents with fetal alcohol spectrum disorders

Alcohol consumption during pregnancy can lead to a variety of cognitive and other birth defects, collectively termed fetal alcohol spectrum disorders (FASD), and including the Fetal Alcohol Syndrome (FAS). This study examined the impact of gestational alcohol exposure on the morphology of the cingulate gyrus, given this region's role in cognitive control, attention, and emotional regulation, all of which are affected in children with FASD. Thirty-one youth (ages 8-16) with histories of heavy prenatal alcohol exposure (n=21) and demographically matched comparison subjects (n=10) underwent structural magnetic resonance imaging. The cingulate gyrus was manually delineated, and parcellated volumes of grey and white matter were compared across groups. Alcohol-exposed individuals had significantly smaller raw cingulate grey matter, white matter, and tissue volumes compared with controls. After adjustment for respective cranial tissue constituents, only white matter volumes remained significantly reduced, and this held regardless of whether or not the child qualified for a diagnosis of FAS. A correlation between posterior cingulate grey matter volume and the WISC-III Freedom from Distractibility Index was also observed in alcohol-exposed children. These data suggest that cingulate white matter is compromised beyond global white matter hypoplasia in alcohol-exposed individuals, regardless of FAS diagnosis. The observed volumetric reductions in the cingulate gyrus may contribute to the disruptive and emotionally dysregulated behavioral profile commonly observed in this population.

Neuroimaging and neuropsychological follow-up study in a pediatric brain tumor patient treated with surgery and radiation

Intracranial tumors are the most common neoplasms of childhood, accounting for approximately 20% of all pediatric malignancies. Radiation therapy has led directly to significant increases in survival of children with certain types of intracranial tumors; however, given the aggressive nature of this therapy, children are at risk for exhibiting changes in brain structure, neuronal biochemistry, and neurocognitive functioning. In this case report, we present neuropsychological, magnetic resonance imaging, proton magnetic resonance spectroscopic imaging, and diffusion tensor imaging data for two adolescents (one patient with ependymal spinal cord tumor with intracranial metastases, and one healthy, typically developing control) from three time points as defined by the patient's radiation schedule (baseline before the patient's radiation therapy, 6 months following completion of the patient's radiation, and 27 months following the patient's radiation). In the patient, there were progressive decreases in gray and white matter volumes as well as early decreases in mean N-acetyl aspartate/choline (NAA/Cho) ratios and fractional anisotropy (FA) in regions with normal appearance on conventional MRI. At the last follow-up, NAA/Cho and FA tended to change in the direction to normal values in selected regions. At the same time, the patient had initial reduction in language and motor skills, followed by return to baseline, but later onset delay in visuospatial and visual perceptual skills. Results are discussed in terms of sensitivity of the four techniques to early and late effects of treatment, and avenues for future investigations.

Hippocampal volume and declarative memory function in combat-related PTSD

The proposition that declarative memory deficits are systematically related to smaller hippocampal volume was tested in a relatively large sample (n = 95) of U.S. military veterans with and without combat-related posttraumatic stress disorder. This correlative analysis was extended by including multiple measures of verbal and visual declarative memory and multiple memory-relevant regional brain volumes that had been shown to exhibit main effects of PTSD in prior work. Small-to-moderate effects were observed on verbal declarative memory in line with a recent meta-analysis; nevertheless, little or no evidence of systematic linear covariation between memory measures and brain volumes was observed.

Converging evidence for abnormalities of the prefrontal cortex and evaluation of midsagittal structures in pediatric posttraumatic stress disorder: an MRI study

Volumetric imaging research has shown abnormal brain morphology in posttraumatic stress disorder (PTSD) when compared with control subjects. We present results on a study of brain morphology in the prefrontal cortex (PFC) and midline structures, via indices of gray matter volume and density, in pediatric PTSD. We hypothesized that both methods would demonstrate aberrant morphology in the PFC. Further, we hypothesized aberrant brainstem anatomy and reduced corpus callosum volume in children with PTSD. Twenty-four children (aged 7-14) with history of interpersonal trauma and 24 age- and gender-matched controls underwent structural magnetic resonance imaging (sMRI). Images of the PFC and midline brain structures were first analyzed using volumetric image analysis. The PFC data were then compared with whole brain voxel-based techniques using statistical parametric mapping (SPM). The PTSD group showed significantly increased gray matter volume in the right and left inferior and superior quadrants of the PFC and smaller gray matter volume in the pons and posterior vermis areas by volumetric image analysis. The voxel-by-voxel group comparisons demonstrated increased gray matter density mostly localized to ventral PFC as compared with the control group. Abnormal frontal lobe morphology, as revealed by separate-complementary image analysis methods, and reduced pons and posterior vermis areas are associated with pediatric PTSD. Voxel-based morphometry may help to corroborate and further localize data obtained by volume of interest methods in PTSD.

Associations between performance on the Rey-Osterrieth Complex Figure and regional brain volumes in children with and without velocardiofacial syndrome

Ninety-two children with velocardiofacial syndrome (VCFS), a genetic disorder caused by a microdeletion of chromosome 22q11.2 and an age, race, and gender-ratio comparable sample of 59 control participants were included in the project. Participants received an MRI as well as a comprehensive neuropsychological battery; the primary outcome measure in the current report is the Rey-Osterrieth Complex Figure (ROCF). Children with VCFS performed less well on the ROCF and have lower whole brain volume compared to controls. After controlling for whole brain volume differences, children with VCFS have bilaterally less parietal lobe gray and white matter yet more frontal lobe white matter. Brain-behavior relationships include: (a) for both groups, parietal volumes (both gray and white matter) predicted ROCF Copy Organization performance and frontal volumes (both gray and white matter) predicted ROCF Copy Accuracy performance; (b) for controls, frontal white matter also predicted ROCF Copy Organization performance; (c) ROCF Recall Organization performance was best predicted by frontal gray matter volume only in our controls; ROCF Recall Accuracy performance was best predicted by frontal gray matter volume in both groups; and (d) in children with VCFS, performance on the ROCF-Copy Structural Elements Accuracy scale was predicted by right hemisphere white matter volume. Our hypotheses were also retested using IQ-matched and whole brain volume-matched subsamples. Identical results were obtained in these analyses. Assumptions about the organization of and the localization of the brain structures that subserve specific cognitive functions in the typically developing brain may not apply in the abnormally developing brain.

The impact of spermine synthase (SMS) mutations on brain morphology

Snyder-Robinson syndrome (SRS) is a form of X-linked mental retardation resulting from mutations in spermine synthase (SMS), which impact neurodevelopment and cognitive outcome. We obtained cerebral, cerebellum, hippocampus, and red nucleus volumes from two males with SRS and 24 age- and gender-matched typically developing controls using volumetric neuroimaging analyses. Total brain volume was enlarged in males with SRS while cerebellum, hippocampus, and red nucleus volumes tended to be reduced compared to controls. Mutations of the X chromosome may modulate the risk for mental retardation through altered early neurodevelopment, disruption in receptor function, and ongoing neural organization and plasticity. Disruption of SMS function may negatively affect regional brain volumes that subserve cognitive and motor abilities. This research provides valuable insight into the effects of polyamine function on brain development.

Effect of divalproex on brain morphometry, chemistry, and function in youth at high-risk for bipolar disorder: a pilot study

OBJECTIVE

Divalproex has been found efficacious in treating adolescents with and at high risk for bipolar disorder (BD), but little is known about the effects of mood stabilizers on the brain itself. We sought to examine the effects of divalproex on the structure, chemistry, and function of specific brain regions in children at high-risk for BD.

METHODS

A total of 24 children with mood dysregulation but not full BD, all offspring of a parent with BD, were treated with divalproex monotherapy for 12 weeks. A subset of 11 subjects and 6 healthy controls were scanned with magnetic resonance imaging (MRI, magnetic resonance spectroscopy [MRS], and functional MRI [fMRI]) at baseline and after 12 weeks.

RESULTS

There were no significant changes in amygdalar or cortical volume found over 12 weeks. Furthermore, no changes in neurometabolite ratios were found. However, we found the degree of decrease in prefrontal brain activation to correlate with degree of decrease in depressive symptom severity.

CONCLUSIONS

Bipolar offspring at high risk for BD did not show gross morphometric, neurometabolite, or functional changes after 12 weeks of treatment with divalproex. Potential reasons include small sample size, short exposure to medications, or lack of significant neurobiological impact of divalproex in this particular population.

Longitudinal brain volume changes in preterm and term control subjects during late childhood and adolescence

OBJECTIVE

Although preterm very low birth weight infants have a high prevalence of neuroanatomical abnormalities when evaluated at term-equivalent age, patterns of brain growth in prematurely born infants during school age and adolescence remain largely unknown. Our goal was to test the hypothesis that preterm birth results in long-term dynamic changes in the developing brain.

METHODS

We performed serial volumetric MRI studies at ages 8 and 12 years in 55 preterm infants born weighing 600 to 1250 g and 20 term control children who participated in the follow-up component of a prospective, randomized, placebo-controlled intraventricular hemorrhage prevention study.

RESULTS

Total brain volumes increased 2% to 3% between the ages of 8 and 12 years for both preterm and term children. These changes involved reductions in cerebral gray matter while white matter increased. Between 8 and 12 years of age, preterm subjects experienced a 2% decrease in left cerebral gray matter compared with a 10% reduction in left cerebral gray for term controls. For right cerebral gray matter, preterm children experienced a 3% decrease in volume between years 8 and 12, compared with 9% for term controls (group-by-time). In contrast, preterm subjects had a 10% increase in cerebral white matter volumes bilaterally between ages 8 and 12 years, compared with >26% increases for both hemispheres for term controls. Significant differences in regional volume changes between study groups were found in bilateral temporal gray and in parietal white matter.

CONCLUSIONS

Preterm birth continues to perturb the trajectory of cerebral development during late childhood and early adolescence with preterm children, showing both lower gray matter reduction and less white matter gain over time compared with term control subjects.

Neuroimaging correlates of parent ratings of working memory in typically developing children

The purpose of the present study was to investigate construct validity of parent ratings of working memory in children, using a multi-trait/multi-method design including neuroimaging, rating scales, and performance-based measures. Thirty-five typically developing children completed performance-based tests of working memory and nonexecutive function (EF) skills, received volumetric MRI, and were rated by parents on both EF-specific and broad behavior rating scales. After controlling for total cerebral volume and age, parent ratings of working memory were significantly correlated with frontal gray, but not temporal, parietal, or occipital gray, or any lobar white matter volumes. Performance-based measures of working memory were also moderately correlated with frontal lobe gray matter volume; however, non-EF parent ratings and non-EF performance-based measures were not correlated with frontal lobe volumes. Results provide preliminary support for the convergent and discriminant validity of parent ratings of working memory, and emphasize their utility in exploring brain-behavior relationships in children. Rating scales that directly examine EF skills may potentially have ecological validity, not only for "everyday" function, but also as correlates of brain volume. (JINS, 2009, 15, 31-41.).

Association between cerebral shape and social use of language in Williams syndrome

Williams syndrome (WS) is a neurogenetic disorder resulting from a hemizygous microdeletion at band 7q11.23. It is characterized by aberrant development of the brain and a unique profile of cognitive and behavioral features. We sought to identify the neuroanatomical abnormalities that are most strongly associated with WS employing signal detection methodology. Once identified with a Quality Receiver Operating Characteristic Curve (QROC), we hypothesized those brain regions distinguishing subjects with WS from controls would be linked to the social phenotype of individuals with this disorder. Thirty-nine adolescents and young adults with WS and 40 typically developing controls matched for age and gender were studied. The QROC identified a combination of an enlarged ventral anterior prefrontal cortex and large bending angle of the corpus callosum to distinguish between WS and controls with a sensitivity of 85.4% and specificity of 75.0%. Within the WS group, bending angle significantly correlated with ventral anterior prefrontal cortex size but not with other morphometric brain measures. Ventral anterior prefrontal size in subjects with WS was positively associated with the use of social engagement devices in a narrative task assessing the use of social and affective language. Our findings suggest that aberrant morphology of the ventral anterior prefrontal cortex is a pivotal contributing factor to the abnormal size and shape of the cerebral cortex and to the social-affective language use typical of individuals with WS.

Cross-validation of brain segmentation by SPM5 and SIENAX

Volumes of cerebral grey (GM) or white matter (WM) are often used as clinical observations or statistical covariates. Several automated segmentation tools can be used for this purpose, but they have not been validated against each other. We used the most common ones, SPM5 and SIENAX 2.4, to derive volumes of grey and white matter in 56 healthy subjects (mean age 49+/-13, range 22-80) and compared the two methods. Both methods yielded significant correlations with age in the expected directions, and estimates of parenchymal volumes were highly correlated. However, without use of prior probability maps, or priors, in SIENAX, GM was significantly underestimated in comparison to SPM (0.52+/-.06 vs 0.66+/-.07 L) and WM was significantly overestimated (0.48+/-.07 vs 0.46+/-.07 L). This error was associated with misclassification of GM as cerebrospinal fluid, especially in deep grey matter. Invoking prior probabilities in SIENAX resulted in excellent agreement with SPM: GM and WM volumes were found to be 0.64+/-0.07 L and 0.47+/-0.07 L, respectively. We conclude that SIENAX requires priors for accurate volumetric estimates, and then provides close agreement with SPM5.

Neuroanatomical abnormalities in adolescents with attention-deficit/hyperactivity disorder

OBJECTIVE

Several neuroanatomic abnormalities have been reported in patients with attention-deficit/hyperactivity disorder (ADHD). However, findings are not always consistent, perhaps because of heterogeneous subject samples. Studying youths with documented familial ADHD provides an opportunity to examine a more homogeneous population.

METHOD

Twenty-four youths with a confirmed history of familial ADHD and 10 control youths underwent high-resolution structural magnetic resonance imaging examinations. Archived magnetic resonance imaging scan data from 12 control youths were included in the analysis to increase statistical power. Individually drawn region-of-interest methods were used to examine the frontal lobe gyri and caudate.

RESULTS

Cerebral total tissue was similar between groups. The volumes of the right caudate and right inferior frontal lobe were larger in the ADHD youths compared with the control youths. Data from a subgroup of the ADHD youths suggest that increasing left caudate volume is associated with decreasing functional activation of this region.

CONCLUSIONS

Because previous studies have focused primarily on younger subjects or used an extended age range, the present results may reflect neurodevelopmental changes specific to late adolescence in familial ADHD.

Hippocampal and amygdalar volumes in psychotic and nonpsychotic unipolar depression

OBJECTIVE

The limbic system is thought to underlie dysfunctional affective and cognitive processes in individuals with depression. Neuroanatomical studies of subjects with depression have often examined hippocampal and amygdalar structures, since they are two key structures of the limbic system. Research has often but not always found reduced hippocampal volume in patients with major depression. The purpose of the present study was to examine differences in hippocampal and amygdalar volumes in patients with depression subtypes relative to healthy comparison subjects.

METHOD

Participants were 1) patients with major depression with psychosis, 2) patients with major depression without psychosis, and 3) healthy comparison subjects. To examine hippocampal and amygdalar volumes, all participants underwent structural magnetic resonance imaging (MRI). The authors further examined the effects of clinical and chronicity data on these two brain structures.

RESULTS

After age, gender, and total brain volume were controlled, depressed patients with psychosis had a significantly smaller mean amygdala volume relative to depressed patients without psychosis and healthy comparison subjects. There were no differences between depressed patients without psychosis and healthy comparison subjects. Correlational analyses suggested that age of depression onset was strongly associated with amygdala volume. No group differences in hippocampal volume were found.

CONCLUSIONS

There were no differences between depressed patients and healthy comparison subjects in hippocampal volume. However, psychotic but not nonpsychotic depression was associated with reduced amygdala volume. Reduced amygdala volume was not associated with severity of depression or severity of psychosis but was associated with age at onset of depression. Smaller amygdala volume may be a risk factor for later development of psychotic depression. In addition, chronicity of depression and depression subtype might be two important factors associated with hippocampal and amygdalar volumes in depression.

Relationship of temporal lobe volumes to neuropsychological test performance in healthy children

Ecological validity of neuropsychological assessment includes the ability of tests to predict real-world functioning and/or covary with brain structures. Studies have examined the relationship between adaptive skills and test performance, with less focus on the association between regional brain volumes and neurobehavioral function in healthy children. The present study examined the relationship between temporal lobe gray matter volumes and performance on two neuropsychological tests hypothesized to measure temporal lobe functioning (visual perception-VP; peabody picture vocabulary test, third edition-PPVT-III) in 48 healthy children ages 5-18 years. After controlling for age and gender, left and right temporal and left occipital volumes were significant predictors of VP. Left and right frontal and temporal volumes were significant predictors of PPVT-III. Temporal volume emerged as the strongest lobar correlate with both tests. These results provide convergent and discriminant validity supporting VP as a measure of the "what" system; but suggest the PPVT-III as a complex measure of receptive vocabulary, potentially involving executive function demands.

Brain volume reductions within multiple cognitive systems in male preterm children at age twelve

OBJECTIVES

To more precisely examine regional and subregional microstructural brain changes associated with preterm birth.

STUDY DESIGN

We obtained brain volumes from 29 preterm children, age 12 years, with no ultrasound scanning evidence of intraventricular hemorrhage or cystic periventricular leukomalacia in the newborn period, and 22 age- and sex-matched term control subjects.

RESULTS

Preterm male subjects demonstrated significantly lower white matter volumes in bilateral cingulum, corpus callosum, corticospinal tract, prefrontal cortex, superior and inferior longitudinal fasciculi compared with term male subjects. Gray matter volumes in prefrontal cortex, basal ganglia, and temporal lobe also were significantly reduced in preterm male subjects. Brain volumes of preterm female subjects were not significantly different from those of term female control subjects. Voxel-based morphometry results were not correlated with perinatal variables or cognitive outcome. Higher maternal education was associated with higher cognitive performance in preterm male subjects.

CONCLUSIONS

Preterm male children continue to demonstrate abnormal neurodevelopment at 12 years of age. However, brain morphology in preterm female children may no longer differ from that of term female children. The neurodevelopmental abnormalities we detected in preterm male subjects appear to be relatively diffuse, involving multiple neural systems. The relationship between aberrant neurodevelopment and perinatal variables may be mediated by genetic factors, environmental factors, or both reflected in maternal education level.

Craniofacioskeletal syndrome: an X-linked dominant disorder with early lethality in males

A syndrome with multisystem manifestations has been observed in three generations of a Caucasian family. The findings in seven females provide a composite clinical picture of microcephaly, short stature, small retroverted ears, full tip of the nose overhanging the columella, short philtrum, thin upper lip, soft tissue excrescences at the angle of the mouth, small mandible, small hands and feet with brachydactyly, finger V clinodactyly, flat feet, an excessive number of fingerprint arches, and mild impairment of cognitive function. Two males were more severely affected and died in the initial months of life. They showed intrauterine growth retardation, broad cranium with wide sutures and fontanelles, cardiac defects, small hands and feet with abnormal digital creases and small nails, and genital abnormalities. The affected males had low serum calcium in the neonatal period. Serum calcium, phosphorous, and parathormone levels in the females were normal. Radiographs showed cortical thickening of the long bones, underdevelopment of the frontal sinuses, narrow pelvis and hypoplasia of the middle phalanx of finger five. MRI of the brain showed slightly reduced brain volumes and an extra gyrus of the superior temporal region. X-inactivation studies showed near complete skewing in two affected females, but were not informative in three others. X-linkage as the mode of inheritance is proposed on the basis of different severity in males/females, complete skewing of X-inactivation in informative females, and a lod score (1.5) suggestive of linkage to markers in Xq26-q27.

Developmental trajectories of brain structure in adolescents with 22q11.2 deletion syndrome: a longitudinal study

The 22q11.2 deletion syndrome (22q11.2DS) is associated with very high rates of schizophrenia-like psychosis and cognitive deficits. Here we report the results of the first longitudinal study assessing brain development in individuals with 22q11.2DS. Twenty-nine children with 22q11.2DS and 29 age and gender matched controls were first assessed during childhood or early adolescence; Nineteen subjects with 22q11.2DS and 18 controls underwent follow-up during late adolescence-early adulthood. The 22q11.2DS subjects showed greater longitudinal increase in cranial and cerebellar white matter, superior temporal gyrus, and caudate nucleus volumes. They also had a more robust decrease in amygdala volume. Verbal IQ (VIQ) scores of the 22q11.2DS group that developed psychotic disorders declined significantly between assessments. Decline in VIQ in 22q11.2DS was associated with more robust reduction of left cortical grey matter volume. No volumetric differences were detected between psychotic and nonpsychotic subjects with 22q11.2DS. Brain maturation associated with verbal cognitive development in 22q11.2DS varies from that observed in healthy controls. Further longitudinal studies are likely to elucidate brain developmental trajectories in 22q11.2DS and their association to psychotic disorders and cognitive deficits in this population.

Brain, skull, and cerebrospinal fluid volumes in adult posttraumatic stress disorder

Children and adolescents with maltreatment-related posttraumatic stress disorder (PTSD) exhibit smaller intracranial tissue volume than controls. Linear relationships have also been observed between intracranial tissue volume and the age of maltreatment onset. The authors explored associations among adult PTSD, early trauma, and cerebral volumes in 99 combat veterans. A bone-based estimate of cranial volume was developed to adjust for variation in body size. Posttraumatic stress disorder was not associated with smaller cerebral tissue volume, but rather with smaller cerebrospinal fluid (CSF) and cranial volumes. These findings co-occurred with expected effects of alcoholism and aging on cerebral tissue and CSF volumes. The results point to early developmental divergences between groups with and without PTSD following adult trauma.

Altered neurodevelopment associated with mutations of RSK2: a morphometric MRI study of Coffin-Lowry syndrome

Coffin-Lowry syndrome (CLS) is a rare form of X-linked mental retardation caused by mutations of the RSK2 gene, associated with cognitive impairment and skeletal malformations. We conducted the first morphometric study of CLS brain morphology by comparing brain volumes from two CLS families with healthy controls. Individuals with CLS consistently showed markedly reduced total brain volume. Cerebellum and hippocampus volumes were particularly impacted by CLS and may be associated with specific interfamilial RSK2 mutations. We provide preliminary evidence that the magnitude of hippocampus volume deviation from that of controls may predict general cognitive outcome in CLS.

Anomalous sylvian fissure morphology in Williams syndrome

The unusual sensitivity and attraction to auditory stimuli in people with Williams syndrome (WS) has been hypothesized to be the consequence of atypical development of brain regions surrounding the Sylvian fissure. Planum temporale surface area, which is determined in part by Sylvian fissure patterning, was examined in 42 WS and 40 control participants to determine if anomalous Sylvian fissure morphology is present in WS. WS participants had significantly reduced leftward asymmetry of the planum temporale compared to control participants, due to a significant expansion in the size of the right planum temporale. The increased right planum temporale size was largely due to WS participants (24%) who had a right hemisphere Sylvian fissure that coursed horizontally and failed to ascend into the parietal lobe. This sulcal pattern is unusual in the right hemisphere and is more commonly found in the left hemisphere of typically developing individuals. There were no control participants with this type of right hemisphere Sylvian fissure pattern. The right hemisphere Sylvian fissure sulcal patterns were also related to a measure of cortical complexity and the amount of right hemisphere occipital lobe volume, suggesting that intrinsic genetic influences leading to anomalous visual system development in WS have widespread influences on cortical morphology that are similar in manner to extrinsic embryonic visual system lesions.

Hippocampal volume reduction in 22q11.2 deletion syndrome

Hippocampal volume reduction and decreased memory skills form a characteristic neurofunctional alteration observed in schizophrenia. Individuals affected with 22q11.2 deletion syndrome (22q11DS), while exhibiting memory deficits throughout development, are also at high risk for developing schizophrenia. The present study sought to investigate hippocampal volume reduction as separate of global grey matter reduction in a large, independent sample of individuals with 22q11DS. Volumetric data from structural magnetic resonance imaging was obtained for 43 individuals affected with 22q11DS, aged 6-39 years of age, as well as for 40 healthy individuals matched for age and gender. Drawing of the amygdala was included to enhance the delineation of the hippocampus, and circumscription of both the amygdala and the hippocampus were executed using an increased resolution matrix. After controlling for total grey volume reductions observed in affected individuals, a significant decrease in hippocampus volume was observed in the 22q11DS group, driven by significant bilateral volumetric reduction of the body of the hippocampus. These results are discussed in reference to memory and cerebral alterations already reported in 22q11DS. Further, the specific implications of hippocampus body volume reduction are outlined in light of its anatomical relationships and its function in memory. Finally, reduction of hippocampal volume in 22q11DS is examined in the context of psychiatric risk status associated to the deletion.

Regional differences of the prefrontal cortex in pediatric PTSD: an MRI study

Previous studies have revealed altered structural development of the frontal lobes and prefrontal cortex (PFC) in children with symptoms of posttraumatic stress disorder (PTSD). This study is the first to provide a detailed structural analysis of the PFC in children with and without PTSD symptoms. We compared gray and white matter volume in four subregions of the PFC between said groups, then explored whether volume was associated with PTSD symptom severity and functional impairment. PFC measurements were extracted from magnetic resonance imaging (MRI) data from a sample of 23 children (ages 7-14) with a history of trauma and symptoms of PTSD, who had undergone assessment for PTSD symptoms and functional impairment using the Child and Adolescent version of the Clinician-Administered PTSD Scale (CAPS-CA). These measurements were compared to data from an age-equivalent control group of 24 healthy children. Children with PTSD symptoms showed a significantly larger volume of gray matter in the delineated middle-inferior and ventral regions of the PFC than did control children. Decreased volume of gray matter in the dorsal PFC correlated with increased functional impairment scores. Results indicate that increased volume of the middle-inferior and ventral PFC may be associated with trauma and PTSD symptoms in children. Furthermore, the neuroanatomy of the dorsal PFC may influence the degree of functional impairment experienced by children with PTSD symptoms.

Decreased anterior cingulate volume in combat-related PTSD

BACKGROUND

Neuroanatomical data point to functional relationships between the anterior cingulate cortex (ACC) and subcortical centers regulating fear, in particular, the amygdala. Functional brain imaging has disclosed divergent patterns of ACC activation in persons with posttraumatic stress disorder (PTSD). In addition, two preliminary structural imaging studies have found evidence of smaller ACC volume in PTSD. We explored associations between PTSD and ACC volume in a relatively large sample of adult combat veterans in which PTSD, lifetime alcohol abuse/dependence, and Vietnam versus Gulf War service were crossed.

METHODS

Subjects were US military combat veterans of the Vietnam and Gulf Wars recruited from two metropolitan areas served by allied Department of Veterans Affairs PTSD treatment/research centers. Anterior cingulate cortex volume was analyzed as a function of grouping factors with and without adjustment for body size.

RESULTS

Posttraumatic stress disorder was associated with smaller anterior cingulate cortex volume. This effect persisted in subjects without histories of alcoholism, did not interact with cohort effects, and was not modified by adjustment for body size.

CONCLUSIONS

Anterior cingulate cortex volume is substantially smaller in association with combat-related PTSD, a finding broadly consistent with cingulate hypofunctionality in that disorder.

Abnormal patterns of cortical gyrification in velo-cardio-facial syndrome (deletion 22q11.2): an MRI study

Velo-cardio-facial syndrome (VCFS), also known as 22q11.2 deletion syndrome, is a common genetic condition associated with increased risk for developing schizophrenia. Given that cortical malformations play an integral role in the pattern of neuroanatomical alterations associated with VCFS, the aim of the present study was to quantify and localize gyral abnormalities. Magnetic resonance images were obtained on a 1.5 T scanner. The gyrification index (GI), a measure of the degree of cortical complexity, was differentially calculated for each lobe using a semi-automated protocol. The GI was calculated for 37 patients affected by VCFS as well as for 36 comparison individuals group-matched for age, handedness, and gender. The subjects affected by VCFS showed a significant decrease in the GI in the frontal and parietal lobes compared with the control group. The pattern of decreased gyrification in the frontal and parietal lobes further defines the structural changes associated with the syndrome and suggests underlying abnormalities in neural connectivity. Aberrant connectivity may be partially responsible for the cognitive and behavioral impairments in the syndrome, as well as the high incidence of schizophrenia among affected individuals.

Application of an objective method for localizing bilateral cortical FDG PET abnormalities to guide the resection of epileptic foci

PURPOSE

In order to improve the objective localization of bilateral cortical abnormalities in positron emission tomography (PET) image volumes, we developed a new three-dimensional image processing technique. The accuracy of this approach with respect to invasive subdural electroencephalography (EEG) data was assessed in a group of children with neocortical epilepsy.

METHODS

Glucose PET image volumes were obtained from 12 epileptic children (mean age 5.2 +/- 4.3 years). Bilateral cortical areas of abnormal glucose metabolism were objectively determined using two conditional criteria assessed against a normal database. The normal database was derived from a group of 15 adult controls (mean age 27.6 years). The spatial relationship between seizure onset electrodes and PET abnormalities was assessed using a conventional receiver operating characteristic (ROC) analysis as well as using a newly defined spatial proximity index (SPI), which characterizes the association between adjacent, but not coincident, abnormalities.

RESULTS

ROC analysis at the 2 standard deviation (SD) threshold, revealed an accuracy of 65% to detect seizure onset areas with a sensitivity of 64 +/- 17% and a specificity of 66 +/- 24%. Sensitivity decreased to 46 +/- 24% at the 3-SD threshold with a specificity of 80 +/- 21% (accuracy 75%). The average value for the SPI was determined as 3.82 +/- 1.65 which was 20% lower than the SPI value calculated using a simple in-plane two-dimensional asymmetry between homotopic cortical segments (4.52 +/- 3.82).

CONCLUSION

The presented image processing technique improves localization of cortical abnormalities and provides valuable imaging clues for placement of subdural EEG grids prior to surgical resection.

Cortical magnetic resonance imaging findings in familial pediatric bipolar disorder

BACKGROUND

Morphometric magnetic resonance imaging (MRI) studies of pediatric bipolar disorder (BD) have not reported on gray matter volumes but have reported increased lateral ventricular size and presence of white matter hyperintensities (WMH). We studied gray matter volume, ventricular-to-brain ratios (VBR), and number of WMH in patients with familial, pediatric BD compared with control subjects.

METHODS

Twenty subjects with BD (aged 14.6 +/- 2.8 years; 4 female) according to the Washington University in St. Louis Kiddie Schedule for Affective Disorders and Schizophrenia, each with a parent with BD, and 20 age-, gender-, and intelligence quotient-matched healthy control subjects (aged 14.1 +/- 2.8 years; 4 female) were scanned at 3 T. Most subjects were taking psychotropic medications. A high-resolution T1-weighted spoiled gradient echo three-dimensional MRI sequence was analyzed by BrainImage for volumetric measurements, and T2-weighted images were read by a neuroradiologist to determine presence of WMH.

RESULTS

After covarying for age and total brain volume, there were no significant differences between subjects with BD and control subjects in volume of cerebral (p = .09) or prefrontal gray matter (p = .34). Subjects with BD did not have elevated numbers of WMH or greater VBR when compared with control subjects.

CONCLUSIONS

Children and adolescents with familial BD do not seem to have decreased cerebral grey matter or increased numbers of WMH, dissimilar to findings in adults with BD. Gray matter decreases and development of WMH might be later sequelae of BD or unique to adult-onset BD.

Volumetric MRI measurement of caudate nuclei in antipsychotic-naive patients suffering from a first episode of psychosis

Magnetic resonance imaging (MRI) studies measuring basal ganglia volumes in first episode patients suggest that treatment with typical neuroleptics leads to alteration in these brain structures. However, caudate nuclei volumes (CNV) of untreated first-episode patients may even be smaller than in healthy controls. We investigated whether CNV of newly diagnosed neuroleptic-naive psychotic patients differ as compared to an age- and sex-matched healthy control group to detect possible treatment effects early in the course of this illness. Magnetic resonance images were acquired in 37 un-medicated psychotic patients and 37 healthy controls. Ten of the patients were re-examined after 12 weeks of treatment with the second generation antipsychotic quetiapine. Regions of interest (ROI) delineating the caudate nuclei bilaterally were drawn manually using Brain Image software. The neuroleptic-naive patients showed a mean CNV of 8.40 cc (SD=1.01) and the controls of 8.55 cc (SD=1.16). There was no significant difference between groups (F=.600; P=.441). In contrast to previous studies in patients treated with typical neuroleptics, this cross-sectional MRI study did not find significant differences in CNV of neuroleptic-naive first-episode patients compared to healthy controls.

Increased temporal lobe gyrification in preterm children

Preterm birth often results in significant learning disability, and previous magnetic resonance imaging (MRI) studies of preterm children have demonstrated reduction in overall cortical tissue with particular vulnerability in the temporal lobe. We measured cortical gyrification in 73 preterm and 33 term control children at 8 years of age and correlated these findings with tests of language ability to determine the associations among preterm birth, neurodevelopment and functional outcome. Preterm children demonstrated significantly increased bilateral temporal lobe gyrification index compared to term controls. Left temporal gyrification index was significantly negatively correlated with left temporal lobe gray matter volume as well as reading recognition scores in the preterm group. Cortical development in the temporal lobe appears to be differentially vulnerable to preterm birth.

Reduced amygdalar gray matter volume in familial pediatric bipolar disorder

OBJECTIVE

Subcortical limbic structures have been proposed to be involved in the pathophysiology of adult and pediatric bipolar disorder (BD). We sought to study morphometric characteristics of these structures in pediatric subjects with familial BD compared with healthy controls.

METHOD

Twenty children and adolescents with BD I (mean age = 14.6 years, four females) and 20 healthy age, gender, and IQ-matched controls underwent high-resolution magnetic resonance imaging at 3 T. Patients were mostly euthymic and most were taking medications. Amygdala, hippocampus, thalamus, and caudate volumes were determined by manual tracings from researchers blinded to diagnosis. Analyses of covariance were performed, with total brain volume, age, and gender as covariates.

RESULTS

No differences were found in the volumes of hippocampus, caudate, and thalamus between subjects with BD and controls. Subjects with BD had smaller volumes in the left and right amygdala, driven by reductions in gray matter volume. Exploratory analyses revealed that subjects with BD with past lithium or valproate exposure tended to have greater amygdalar gray matter volume than subjects with BD without such exposure.

CONCLUSIONS

Children and adolescents with early-onset BD may have reduced amygdalar volumes, consistent with other studies in this population. Prolonged medication exposure to lithium or valproate may account for findings in adults with BD of increased amygdalar volume relative to controls.

Gray matter alteration in dyslexia: converging evidence from volumetric and voxel-by-voxel MRI analyses

Affecting up to 4-10% of the population, dyslexia is a highly prevalent, childhood onset developmental disorder adversely influencing multiple domains of adaptive functioning throughout the lifespan. The present brain imaging study was conducted in order to investigate the neuroanatomical correlates of developmental dyslexia. The MRI brain scans of 10 males with dyslexia and 14 matched controls were analyzed with (1) a classical volumetric method measuring gray and white matter lobar volumes and (2) a voxel-by-voxel method. The voxel-by-voxel method identifies changes in tissue density and localizes morphologic alterations without limiting the analyses to predefined regions. Subsequent correlations between gray matter density and neuropsychological performance on specific phonological processing tasks (rhyme judgment) were conducted. Volumetric analyses revealed significantly reduced gray matter volumes in both temporal lobes in dyslexic individuals. The voxel-by-voxel analyses further localized changes to the left temporal lobe, revealing reduced gray matter density in the middle and inferior temporal gyri. Conversely, increased gray matter density was found in the precentral gyri bilaterally. As a combined group, the dyslexic and control subjects demonstrated positive correlations between performance on the rhyme judgment tasks and gray matter density in the middle and inferior frontal gyri, and the middle temporal gyri bilaterally. The current study indicates that dyslexia is associated with a structural gray matter deficit involving a complex fronto-temporal network implicated in phonological processing.

Segmented volumes of cerebrum and cerebellum in first episode schizophrenia with auditory hallucinations

The volumes of cerebral and cerebellar regions were measured in first episode schizophrenic patients with (n = 17) and without (n = 8) auditory hallucinations. Magnetic resonance images of cerebral and cerebellar regions were segmented into gray and white fractions using an algorithm for semiautomated fuzzy tissue segmentation. They were defined by using the semiautomated Talairach atlas-based parcellation method. Patients with auditory hallucinations showed larger temporal white matter, frontal gray matter, and temporal gray matter volumes than patients without auditory hallucinations. These findings suggest that auditory hallucinations in schizophrenic patients may be associated with neuropathological abnormalities in frontal and temporal brain regions.

An experiment of nature: brain anatomy parallels cognition and behavior in Williams syndrome

Williams syndrome (WS) is a neurogenetic-neurodevelopmental disorder characterized by a highly variable and enigmatic profile of cognitive and behavioral features. Relative to overall intellect, affected individuals demonstrate disproportionately severe visual-spatial deficits and enhanced emotionality and face processing. In this study, high-resolution magnetic resonance imaging data were collected from 43 individuals with WS and 40 age- and gender-matched healthy controls. Given the distinct cognitive-behavioral dissociations associated with this disorder, we hypothesized that neuroanatomical integrity in WS would be diminished most in regions comprising the visual-spatial system and most "preserved" or even augmented in regions involved in emotion and face processing. Both volumetric analysis and voxel-based morphometry were used to provide convergent approaches for detecting the hypothesized WS neuroanatomical profile. After adjusting for overall brain volume, participants with WS showed reduced thalamic and occipital lobe gray matter volumes and reduced gray matter density in subcortical and cortical regions comprising the human visual-spatial system compared with controls. The WS group also showed disproportionate increases in volume and gray matter density in several areas known to participate in emotion and face processing, including the amygdala, orbital and medial prefrontal cortices, anterior cingulate, insular cortex, and superior temporal gyrus. These findings point to specific neuroanatomical correlates for the unique topography of cognitive and behavioral features associated with this disorder.

Volumetric analysis of regional cerebral development in preterm children

Preterm birth is frequently associated with both neuropathologic and cognitive sequelae. This study examined cortical lobe, subcortical, and lateral ventricle development in association with perinatal variables and cognitive outcome. High-resolution volumetric magnetic resonance imaging scans were acquired and quantified using advanced image processing techniques. Seventy-three preterm and 33 term control children ages 7.3-11.4 years were included in the study. Results indicated disproportionately enlarged parietal and frontal gray matter, occipital horn, and ventricular body, as well as reduced temporal and subcortical gray volumes in preterm children compared with control subjects. Birth weight was negatively correlated with parietal and frontal gray, as well as occipital horn volumes. Intraventricular hemorrhage was associated with reduced subcortical gray matter. Ventricular cerebrospinal fluid was negatively correlated with subcortical gray matter volumes but not with white matter volumes. Maternal education was the strongest predictor of cognitive function in the preterm group. Preterm birth appears to be associated with disorganized cortical development, possibly involving disrupted synaptic pruning and neural migration. Lower birth weight and the presence of intraventricular hemorrhage may increase the risk for neuroanatomic abnormality.

A volumetric study of parietal lobe subregions in Turner syndrome

Turner syndrome, a genetic disorder that results from the complete or partial absence of an X chromosome in females, has been associated with specific impairment in visuospatial cognition. Previous studies have demonstrated a relationship between parietal lobe abnormalities and visuospatial deficits in Turner syndrome. We used high-resolution magnetic resonance imaging to measure parietal lobe subdivisions in 14 participants with Turner syndrome (mean age 13 years 5 months, SD 5 years) and 14 age-matched controls (mean age 13 years 5 months, SD 4 years 7 months) to localize neuroanatomical variations more closely. Scans were acquired and analyzed for 14 females with Turner syndrome. Analyses of variance were used to investigate differences in regional parietal lobes. Females with Turner syndrome showed a bilateral parietal lobe reduction, specifically in the superior parietal and postcentral gyri. Full-scale IQ scores were significantly positively correlated with postcentral tissue volume in the Turner syndrome group. Structural differences in the parietal lobe are localized specifically to the anterior and superior parietal lobe and might be related to the visuospatial and visuomotor deficits associated with Turner syndrome.

Sex differences in cerebral volumes of 8-year-olds born preterm

We investigate sex-associated effects of preterm birth on cerebral gray matter (GM) and white matter (WM) volumes. Preterm children (n=65) and 31 healthy, term control children had usable magnetic resonance imaging (MRI) data acquired at 8 years of age. Both GM and WM volumes were significantly reduced in the preterm group compared with controls. However, only males with preterm birth had significantly reduced WM compared with term males (P=.021), whereas WM volumes were equivalent in the female groups. Lower birth weight was associated with reduced WM in both boys and girls with preterm birth, whereas intraventricular hemorrhage (IVH) was associated with reduced GM in girls only. Positive correlations between GM and cognitive outcome were observed in girls with preterm birth but not boys. We conclude that preterm birth has a significant impact on brain development with increased risk for smaller GM and WM cerebral volumes. Males appear particularly vulnerable to adverse effects of preterm birth on WM development. However, girls with preterm birth show stronger correlations between neuro-anatomical variables and both neonatal risk factors and cognitive outcome, compared with boys. These findings indicate that the sex of the very preterm newborn influences the mechanisms by which the developing brain is affected.

Amygdala and hippocampal volumes in Turner syndrome: a high-resolution MRI study of X-monosomy

Turner syndrome (TS) results from partial or complete X-monosomy and is characterized by deficits in visuospatial functioning as well as social cognition and memory. Neuroimaging studies have demonstrated volumetric differences in the parietal region of females with TS compared to controls. The present study examined amygdala and hippocampus morphology in an attempt to further understand the neural correlates of psychosocial and memory functioning in TS. Thirty females with TS age 7.6-33.3 years (mean = 14.7 +/- 6.4) and 29 age-matched controls (mean age = 14.8 +/- 5.9; range = 6.4-32.7) were scanned using high resolution MRI. Volumetric analyses of the MRI scans included whole brain segmentation and manual delineation of the amygdala and hippocampus. Compared to controls, participants with TS demonstrated significantly larger left amygdala gray matter volumes, irrespective of total cerebral tissue and age. Participants with TS also showed disproportionately reduced right hippocampal volumes, involving both gray and white matter. Amygdala and hippocampal volumes appear to be impacted by X-monosomy. Aberrant morphology in these regions may be related to the social cognition and memory deficits often experienced by individuals with TS. Further investigations of changes in medial temporal morphology associated with TS are warranted.

Effects of X-monosomy and X-linked imprinting on superior temporal gyrus morphology in Turner syndrome

BACKGROUND

Turner syndrome (TS) results from complete or partial monosomy X. The cognitive phenotype of TS involves preservation of verbal skills with visuospatial functioning deficits. The superior temporal gyrus (STG), which is involved in language capacities, has not been investigated in TS.

METHODS

The STG was measured in 30 female subjects (mean age = 14.73 +/- 6.41; range = 7.56-33.30) with TS and 30 age-matched control subjects (mean age = 14.63 +/- 5.90; range = 6.35-32.65) using volumetric magnetic resonance imaging analyses.

RESULTS

-Right STG, including both gray and white matter volumes, was significantly larger in TS compared with control subjects. Overall left STG volume was not significantly different between groups, although left white matter volume was increased in the TS subjects. The TS subgroup with a maternally derived X chromosome (Xm) demonstrated more aberrant STG volumes compared with subjects with a paternally (Xp) derived X and control subjects. The difference in STG volumes between Xm and control subjects involved both white and gray matter. The Xm subjects differed from Xp subjects only in terms of gray matter.

CONCLUSIONS

These findings suggest that X-monosomy and X-linked imprinting negatively affect STG development, possibly by disrupting neural pruning mechanisms.

Improved detection of metastases on magnetic resonance images by digital tissue recognition: validation using VX-2 tumor in the rabbit

PURPOSE

To evaluate the ability of a prototype digital tissue recognition (DTR) system to improve the accuracy of detection of metastases on magnetic resonance (MR) images in the rabbit VX-2 tumor model.

MATERIALS AND METHODS

Multiple MR imaging (MRI) sequences, including pre-contrast and post-contrast enhanced T1-weighted, T2-weighted, proton-density, and fast short inversion time inversion recovery (FSTIR), were acquired for six rabbits implanted with VX-2 adenocarcinoma. For each rabbit, DTR used the MR intensity characteristics of a known tumor site to highlight other areas suspicious for tumor. Three independent veterinary radiologists with extensive experience in animal MRI interpreted the images for tumor both without and with the results of DTR. The conventional and DTR-assisted interpretations were compared to pathology.

RESULTS

Using DTR, the radiologists found an average of 13.2% more true positive sites with a 10.3% reduction in false positives compared to unassisted interpretation. The improvement for the radiologists was statistically significant (McNemar's test, P = 0.0004). The agreement between radiologists using DTR was consistently higher than for their conventional interpretations (kappa statistic).

CONCLUSION

Compared with conventional interpretation of MR images, the use of DTR provided a statistically significant improvement in the accuracy of locating more and smaller sites of tumor. This improvement was achieved without the benefit of post-contrast images.

Quantitative analysis of gray- and white-matter volumes and glucose metabolism in Sturge-Weber syndrome

The progressive nature of Sturge-Weber syndrome is well known, but the mechanisms of focal cortical and subcortical degeneration in this disorder are poorly understood. In the present study, we assessed the structural and functional integrity of gray and white matter in unihemispheric Sturge-Weber syndrome using quantitative magnetic resonance imaging (MRI) volumetry and MRI-based partial volume correction of [18F]fluorodeoxyglucose positron emission tomographic (PET) images. Gray- and white-matter volumes and glucose metabolism were measured in three brain regions (parieto-occipital underneath the angioma, temporal, and frontal) in six children with Sturge-Weber syndrome (two infants, ages 6 and 9 months; four older children, ages 4 to 14 years), all with unilateral parieto-occipital leptomeningeal angiomatosis. The gray-matter volumes ipsilateral to the angioma were smaller in all children, with the posterior regions underneath the angioma the most affected. In the infants, the white-matter volumes were increased in the region of the angioma, whereas in the regions remote from the angioma in the infants and in all regions of the older children, there were large decreases in white-matter volume. The decreases of frontal and temporal white-matter volume were more pronounced than the corresponding gray-matter volume decreases. The PET studies showed severe hypometabolism in the parieto-occipitalregion underneath the angioma in all of the children. However, the two infants showed glucose hypermetabolism in the frontal and temporal cortical gray matter, whereas these regions had relatively preserved metabolism in the older patients. These results demonstrate differential involvement of gray and white matter in Sturge-Weber syndrome. Both structural and functional abnormalities extend well beyond the angioma, indicating widespread abnormalities of growth and development of the affected hemisphere. Furthermore, whereas increased white-matter volume underlying the angioma may be seen in infants, ipsilateral white-matter regions outside the angioma show volume loss both in infants and in older patients. Extensive gray- and white-matter volume loss and hypometabolism ipsilateral to the angioma likely contribute to the frequently observed progressive cognitive dysfunction in these patients, regardless of the extent of the angioma.