Regional Brain Volume Changes Research Articles

Talairach-Based Parcellation of Neonatal Brain Magnetic Resonance Imaging Data: Validation of a New Approach

Talairach-based parcellation (TP) of human brain magnetic resonance imaging (MRI) data has been used increasingly in clinical research to make regional measurements of brain structures in vivo. Recently, TP has been applied to pediatric research to elucidate the changes in regional brain volumes related to several neurological disorders. However, all freely available tools have been designed to parcellate adult brain MRI data. Parcellation of neonatal MRI data is very challenging owing to the lack of strong signal contrast, variability in signal intensity within tissues, and the small size and thus difficulty in identifying small structures used as landmarks for TP. Hence the authors designed and validated a new interactive tool to parcellate brain MRI data from newborns and young infants. The authors' tool was developed as part of a postprocessing pipeline, which includes registration of multichannel MR images, segmentation, and parcellation of the segmented data. The tool employs user-friendly interactive software to visualize and assign the anatomic landmarks required for parcellation, after which the planes and parcels are generated automatically by the algorithm. The authors then performed 3 sets of validation experiments to test the precision and reliability of their tool. Validation experiments of intra-and interrater reliability on data obtained from newborn and 1-year-old children showed a very high sensitivity of >95% and specificity >99.9%. The authors also showed that rotating and reformatting the original MRI data results in a statistically significant difference in parcel volumes, demonstrating the importance of using a tool such as theirs that does not require realignment of the data prior to parcellation. To the authors' knowledge, the presented approach is the first TP method that has been developed and validated specifically for neonatal brain MRI data. Their approach would also be valuable for the analysis of brain MRI data from older children and adults.

Talairach‐Based Parcellation of Neonatal Brain Magnetic Resonance Imaging Data: Validation of a New Approach

ABSTRACTBackground and Purpose. Talairach‐based parcellation (TP) of human brain magnetic resonance imaging (MRI) data has been used increasingly in clinical research to make regional measurements of brain structures in vivo. Recently, TP has been applied to pediatric research to elucidate the changes in regional brain volumes related to several neurological disorders. However, all freely available tools have been designed to parcellate adult brain MRI data. Parcellation of neonatal MRI data is very challenging owing to the lack of strong signal contrast, variability in signal intensity within tissues, and the small size and thus difficulty in identifying small structures used as landmarks for TP. Hence the authors designed and validated a new interactive tool to parcellate brain MRI data from newborns and young infants. Methods. The authors' tool was developed as part of a postprocessing pipeline, which includes registration of multichannel MR images, segmentation, and parcellation of the segmented data. The tool employs user‐friendly interactive software to visualize and assign the anatomic landmarks required for parcellation, after which the planes and parcels are generated automatically by the algorithm. The authors then performed 3 sets of validation experiments to test the precision and reliability of their tool. Results. Validation experiments of intra‐and interrater reliability on data obtained from newborn and 1‐year‐old children showed a very high sensitivity of >95% and specificity >99.9%. The authors also showed that rotating and reformatting the original MRI data results in a statistically significant difference in parcel volumes, demonstrating the importance of using a tool such as theirs that does not require realignment of the data prior to parcellation. Conclusions. To the authors' knowledge, the presented approach is the first TP method that has been developed and validated specifically for neonatal brain MRI data. Their approach would also be valuable for the analysis of brain MRI data from older children and adults.

Cerebral Damage in Epilepsy: A Population‐based Longitudinal Quantitative MRI Study

Whether cerebral damage results from epileptic seizures remains a contentious issue. We report on the first longitudinal community-based quantitative magnetic resonance imaging (MRI) study to investigate the effect of seizures on the hippocampus, cerebellum, and neocortex. One hundred seventy-nine patients with epilepsy (66 temporal lobe epilepsy, 51 extratemporal partial epilepsy, and 62 generalized epilepsy) and 90 control subjects underwent two MRI brain scans 3.5 years apart. Automated and manual measurement techniques identified changes in global and regional brain volumes and hippocampal T2 relaxation times. Baseline hippocampal volumes were significantly reduced in patients with temporal lobe epilepsy and could be attributed to an antecedent neurologic insult. Rates of hippocampal, cerebral, and cerebellar atrophy were not syndrome specific and were similar in control and patient groups. Global and regional brain atrophy was determined primarily by age. A prior neurologic insult was associated with reduced hippocampal and cerebellar volumes and an increased rate of cerebellar atrophy. Significant atrophy of the hippocampus, neocortex, or cerebellum occurred in 17% of patients compared with 6.7% of control subjects. Patients with and without significant volume reduction were comparable in terms of seizure frequency, antiepileptic drug (AED) use, and epilepsy duration, with no identifiable risk factors for the development of atrophy. Overt structural cerebral damage is not an inevitable consequence of epileptic seizures. In general, brain volume reduction in epilepsy is the cumulative effect of an initial precipitating injury and age-related cerebral atrophy. Significant atrophy developed in individual patients, particularly those with temporal lobe and generalized epilepsy. Longer periods of observation may detect more subtle effects of seizures.

Hormone replacement therapy and age-related brain shrinkage: regional effects

Neuroprotective properties of estrogen have been established in animal models, but clinical trials of hormone replacement therapy (HRT) produced contradictory results. We examined the impact of HRT on age-related regional changes in human brain volume. Six brain regions were measured twice, five years apart, in 12 healthy women who took HRT and in matched controls who did not. The controls showed a typical pattern of differential brain shrinkage in the association cortices and the hippocampus with no change in the primary visual cortex. In contrast, women who took HRT showed comparable shrinkage of the hippocampus but no significant shrinkage of the neocortex. Future large scale studies may benefit from applying regional rather than global measures in assessment of brain integrity.

Temporal lobe volume changes in people at high risk of schizophrenia with psychotic symptoms.

Magnetic resonance imaging (MRI) has demonstrated abnormalities of brain structure, particularly of the temporal lobes, in schizophrenia. These are thought to be neurodevelopmental in origin, but when they become evident is unknown. To determine if temporal lobe volumes reduce during the development of symptoms of schizophrenia in initially well people at high risk of this disorder. A group of 66 people who had at least two first- or second-degree relatives with schizophrenia and a control group of 20 healthy people had a structural MRI scan of the whole brain which was repeated after approximately 2 years. Regions of interest, specifically the amygdala-hippocampus complex and the temporal lobes, were traced semi-automatically by three masked raters with good inter-and intrarater reliability. Regional brain volume changes over 2 years did not differ between high-risk and healthy participants. Within the high-risk group, the 19 people with psychotic symptoms (12 at first assessment) had a mean reduction of 2163 mm(3) in the right temporal lobe compared with 97 mm(3) in the 47 without symptoms (P=0.02). Our findings suggest that people at high risk of schizophrenia with psychotic symptoms show reductions in temporal lobe volumes.

Anatomical MRI of the Developing Human Brain: What Have We Learned?

To critically review and integrate the existing literature on magnetic resonance imaging (MRI) studies of the normally developing brain in childhood and adolescence and discuss the implications for clinical MRI studies. Changes in regional brain volume with age and differences between the sexes are summarized from reports in refereed journal articles pertaining to MRI of the developing human brain. White matter volume increases with age. Gray matter volumes increase during childhood and then decrease before adulthood. On average, boys have larger brains than girls; after correction for overall brain volume the caudate is relatively larger in girls, and the amygdala is relatively larger in boys. Differences are of clinical interest given gender-related differences in the age of onset, symptomatology, and prevalence noted for nearly all childhood-onset psychiatric disorders. Attention-deficit/hyperactivity disorder is frequently used as an example to demonstrate these points. Understanding the developmental trajectories of normal brain development and differences between the sexes is important for the interpretation of clinical imaging studies.

Regional brain volume change over the life-time course of schizophrenia

The concept that schizophrenia has its antecedents in neurodevelopment has long been debated and has been at the forefront of research on this disorder over the last decade. However new recent evidence from controlled longitudinal studies indicates that some of the structural brain anomalies observed in schizophrenia may continue to progress sporadically after the onset of clinical illness. The studies vary in cohort composition, stage of illness studied, duration of follow-up interval, and specific brain regions with findings. Nevertheless, the findings as a whole suggest that the brain changes in size throughout the lifespan of an individual and to a greater extent in schizophrenia. While the detected abnormalities could be explained by various technical artifacts, or physiological epi-phenomena, that they result from an ongoing neurochemical, physiological or morphological process characteristic of the underlying basis for the disorder is an intriguing possibility that lends itself to possible future intervention.

5262945 Method for quantification of brain volume from magnetic resonance images

A simple, rapid and semi-automated method of MRI analysis based on mathematical modelling of MRI pixel intensity histograms. The method is accurate and reliable for regional analysis of brain, central and subarachnoid CSF volumes. The method can be used to reveal significant age-related changes in regional brain volumes which cannot be determined utilizing traced central CSF volumes or subarachnoid CSF volumes. The method can be used to quantify brain structure in healthy aging and brain disease.

The dexamethasone suppresion test and quantitative cerebral anatomy in depression

To determine whether structural brain abnormalities in patients with depression are related to cortisol state, we examined the relationship between the dexamethasone suppression test (DST) and brain magnetic resonance imaging (MRI) in 40 inpatients with severe depression referred for electroconvulsive therapy (ECT). Prior to ECT, 27 (68%) of the patients exhibited nonsuppression on the DST. Frontal lobe volume was negatively correlated with peak post-dexamethasone cortisone (r= −0.37) and was 13% smaller in DST nonsuppressors than suppressors; these findings were no longer significant after adjustments for age, geneder, and cranial size. Lateral and third ventricular volumes were also correlated with peak postdexamethasone cortisol (r = 0.34 and 0.33, respectively), but not after adjustments for age, gender, and cranial size. Subcortical hyperintensity was associated with peak postdexamethasone cortisol and was more common in DST nonsuppressors than suppressors. Again these findings were no longer significant after adjustments for age. Finally, longitudinal DST and brain MRI studies in 11 of these patients revealed no changes in regional brain volumes nor in postdexamethasone cortisol up to six months after ECT. However, within individual patients, postdexamethasone cortisol was positively (and significantly) correlated with frontal lobe volume.

Method for quantification of brain, ventricular, and subarachnoid CSF volumes from MR images.

We describe a simple, rapid, and semiautomated method of MR analysis based on mathematical modeling of MR pixel intensity histograms. The method is shown to be accurate and reliable for regional analysis of brain, central, and subarachnoid CSF volumes. Application of the method to five young and six older subjects revealed significant age-related changes in regional brain volumes whereas no difference was found for traced central CSF volumes or subarachnoid CSF volumes. We conclude that this is a simple method that can be applied to further studies of quantification of brain structure in healthy aging and brain disease.

Age-related changes in regional cerebral blood flow and brain volume in healthy subjects.

Using the xenon-133 inhalation method, we studied the age-related decline in regional cerebral blood flow, calculated as the initial slope index (ISI), in neurologically normal subjects without any risk factors for cerebral arteriosclerosis (154 men and 123 women), ranging in age from 19 to 88 years. The decline in the ISI was rapid in younger age groups and gradual in older age groups. The ISI was higher in women than in men older than 40 years. Using computed tomography, we studied the age-related decline in brain volume index (BVI; 100% X brain volume/cranial cavity volume) in neurologically normal subjects without any risk factors for cerebral arteriosclerosis (92 men and 49 women), ranging in age from 37 to 86 years. The decline in the BVI was gradual in younger age groups and rapid in older age groups. The BVI was higher in women than in men older than 60 years.