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Structural Magnetic Resonance Imaging (structural + magnetic_resonance_imaging)
Selected AbstractsIncreased right amygdala volume in lithium-treated patients with bipolar I disorderACTA PSYCHIATRICA SCANDINAVICA, Issue 2 2010J. Usher Usher J, Menzel P, Schneider-Axmann T, Kemmer C, Reith W, Falkai P, Gruber O, Scherk H. Increased right amygdala volume in lithium-treated patients with bipolar I disorder. Objective:, The amygdala plays a major role in processing emotional stimuli. Fourteen studies using structural magnetic resonance imaging (MRI) have examined the amygdala volume in paediatric and adult patients with bipolar disorder (BD) compared with healthy controls (HC) and reported inconsistent findings. Lithium has been found to increase grey matter volume, and first evidence points towards an effect on regional brain volume such as the amygdala. Method:, We examined the amygdala volume of euthymic patients with BD treated with lithium (n = 15), without lithium (n = 24) and HC (n = 41) using structural MRI. Results:, Patients treated with lithium exhibited in comparison to HC a larger right absolute (+17.9%, P = 0.015) and relative (+18%, P = 0.017) amygdala volume. There was no significant difference in amygdala volume between patients without lithium treatment and HC. Conclusion:, Lithium appears to have a sustained effect on a central core region of emotional processing and should therefore be considered in studies examining BD. [source] Hippocampal volume assessment in temporal lobe epilepsy: How good is automated segmentation?EPILEPSIA, Issue 12 2009Heath R. Pardoe Summary Purpose:, Quantitative measurement of hippocampal volume using structural magnetic resonance imaging (MRI) is a valuable tool for detection and lateralization of mesial temporal lobe epilepsy with hippocampal sclerosis (mTLE). We compare two automated hippocampal volume methodologies and manual hippocampal volumetry to determine which technique is most sensitive for the detection of hippocampal atrophy in mTLE. Methods:, We acquired a three-dimensional (3D) volumetric sequence in 10 patients with left-lateralized mTLE and 10 age-matched controls. Hippocampal volumes were measured manually, and using the software packages Freesurfer and FSL-FIRST. The sensitivities of the techniques were compared by determining the effect size for average volume reduction in patients with mTLE compared to controls. The volumes and spatial overlap of the automated and manual segmentations were also compared. Results:, Significant volume reduction in affected hippocampi in mTLE compared to controls was detected by manual hippocampal volume measurement (p < 0.01, effect size 33.2%), Freesurfer (p < 0.01, effect size 20.8%), and FSL-FIRST (p < 0.01, effect size 13.6%) after correction for brain volume. Freesurfer correlated reasonably (r = 0.74, p << 0.01) with this manual segmentation and FSL-FIRST relatively poorly (r = 0.47, p << 0.01). The spatial overlap between manual and automated segmentation was reduced in affected hippocampi, suggesting the accuracy of automated segmentation is reduced in pathologic brains. Discussion:, Expert manual hippocampal volumetry is more sensitive than both automated methods for the detection of hippocampal atrophy associated with mTLE. In our study Freesurfer was the most sensitive to hippocampal atrophy in mTLE and could be used if expert manual segmentation is not available. [source] Non-spatial expertise and hippocampal gray matter volume in humansHIPPOCAMPUS, Issue 10 2008Katherine Woollett Abstract Previous work suggests that spatial expertise in licensed London taxi drivers is associated with differences in hippocampal gray matter volume relative to IQ-matched control subjects. Here we examined whether non-spatial expertise is associated with similar hippocampal gray matter effects. We compared medical doctors who, like taxi drivers, acquire a vast amount of knowledge over many years, with IQ-matched control subjects who had no tertiary education. Whole brain analysis of structural magnetic resonance imaging (MRI) scans using voxel-based morphometry (VBM) failed to identify any differences in gray matter volume between the groups, including in the hippocampus. Moreover, amount of medical experience that ranged from 0.5 to 22.5 yr did not correlate with gray matter volume in the hippocampus or elsewhere in the brain. We conclude that intensively acquiring a large amount of knowledge over many years is not invariably associated with hippocampal gray matter volume differences. Instead it would seem that hippocampal gray matter volume effects are more likely to be observed when the knowledge acquired concerns a complex and detailed large-scale spatial layout. © 2008 Wiley-Liss, Inc. [source] A forward application of age associated gray and white matter networks,HUMAN BRAIN MAPPING, Issue 10 2008Adam M. Brickman Abstract To capture patterns of normal age-associated atrophy, we previously used a multivariate statistical approach applied to voxel based morphometry that identified age-associated gray and white matter covariance networks (Brickman et al. [2007]: Neurobiol Aging 28:284,295). The current study sought to examine the stability of these patterns by forward applying the identified networks to an independent sample of neurologically healthy younger and older adults. Forty-two younger and 35 older adults were imaged with standard high-resolution structural magnetic resonance imaging. Individual images were spatially normalized and segmented into gray and white matter. Covariance patterns that were previously identified with scaled subprofile model analyses were prospectively applied to the current sample to identify to what degree the age-associated patterns were manifested. Older individuals were also assessed with a modified version of the Mini Mental State Examination (mMMSE). Gray matter covariance pattern expression discriminated between younger and older participants with high optimal sensitivity (100%) and specificity (90.5%). While the two groups differed in the degree of white matter pattern expression (t (75) = 5.26, P < 0.001), classification based on white matter expression was relatively low (sensitivity = 80% and specificity = 61.9%). Among older adults, chronological age was significantly associated with increased gray matter pattern expression (r (32) = 0.591, P < 0.001) but not with performance on the mMMSE (r (31) = ,0.314, P = 0.085). However, gray matter pattern expression was significantly associated with performance on the mMMSE (r (31) = ,0.405, P = 0.024). The findings suggest that the previously derived age-associated covariance pattern for gray matter is reliable and may provide information that is more functionally meaningful than chronological age. Hum Brain Mapp 2008. © 2007 Wiley-Liss, Inc. [source] Cortical sources of the early components of the visual evoked potentialHUMAN BRAIN MAPPING, Issue 2 2002Francesco Di Russo Abstract This study aimed to characterize the neural generators of the early components of the visual evoked potential (VEP) to isoluminant checkerboard stimuli. Multichannel scalp recordings, retinotopic mapping and dipole modeling techniques were used to estimate the locations of the cortical sources giving rise to the early C1, P1, and N1 components. Dipole locations were matched to anatomical brain regions visualized in structural magnetic resonance imaging (MRI) and to functional MRI (fMRI) activations elicited by the same stimuli. These converging methods confirmed previous reports that the C1 component (onset latency 55 msec; peak latency 90,92 msec) was generated in the primary visual area (striate cortex; area 17). The early phase of the P1 component (onset latency 72,80 msec; peak latency 98,110 msec) was localized to sources in dorsal extrastriate cortex of the middle occipital gyrus, while the late phase of the P1 component (onset latency 110,120 msec; peak latency 136,146 msec) was localized to ventral extrastriate cortex of the fusiform gyrus. Among the N1 subcomponents, the posterior N150 could be accounted for by the same dipolar source as the early P1, while the anterior N155 was localized to a deep source in the parietal lobe. These findings clarify the anatomical origin of these VEP components, which have been studied extensively in relation to visual-perceptual processes. Hum. Brain Mapping 15:95,111, 2001. © 2001 Wiley-Liss, Inc. [source] Computer-based morphometry of brainINTERNATIONAL JOURNAL OF IMAGING SYSTEMS AND TECHNOLOGY, Issue 2 2010Bang-Bon Koo Abstract Over the past decade, the importance of probing the anatomy of the brain has reemerged as an important field of neuroscience. In combination with functional imaging techniques, the rapid advancement of neuroimaging techniques,such as magnetic resonance imaging,and their growing applicability in studying brain morphometry has led to great advances in neuroscience research. Considering the requirements of the diverse technologies,from image processing to statistics,in performing morphometry of the brain, it is critical to have an overall understanding of this subject. The major objective of this review is to provide a practical introduction to this field. The review starts by covering basic concepts and techniques that are commonly used in morphometry of structural magnetic resonance imaging and then extends to further technical perspectives. © 2010 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 20, 117,125, 2010 [source] Structural brain abnormalities in adolescents with autism spectrum disorder and patients with attention deficit/hyperactivity disorderTHE JOURNAL OF CHILD PSYCHOLOGY AND PSYCHIATRY AND ALLIED DISCIPLINES, Issue 12 2007Sarah Brieber Background:, Although autism spectrum disorder (ASD) and attention deficit/hyperactivity disorder (ADHD) are two distinct neurodevelopmental diseases, they share behavioural, neuropsychological and neurobiological characteristics. For the identification of endophenotypes across diagnostic categories, further investigations of phenotypic overlap between ADHD and autism at the behavioural, neurocognitive, and brain levels are needed. Methods:, We examined regional grey matter differences and similarities in children and adolescents with ASD and ADHD in comparison to healthy controls using structural magnetic resonance imaging (MRI) and voxel-based morphometry. Results:, With regard to clinical criteria, the clinical groups did not differ with respect to ADHD symptoms; however, only patients with ASD showed deficits in social communication and interaction, according to parental rating. Structural abnormalities across both clinical groups compared to controls became evident as grey matter reductions in the left medial temporal lobe and as higher grey matter volumes in the left inferior parietal cortex. In addition, autism-specific brain abnormalities were found as increased grey matter volume in the right supramarginal gyrus. Conclusions:, While the shared structural deviations in the medial temporal lobe might be attributed to an unspecific delay in brain development and might be associated with memory deficits, the structural abnormalities in the inferior parietal lobe may correspond to attentional deficits observed in both ASD and ADHD. By contrast, the autism-specific grey matter abnormalities near the right temporo-parietal junction may be associated with impaired ,theory of mind' abilities. These findings shed some light on both similarities and differences in the neurocognitive profiles of ADHD and ASD patients. [source] Voxel-based morphometry depicts central compensation after vestibular neuritisANNALS OF NEUROLOGY, Issue 2 2010Peter zu Eulenburg MD Objective Patients who have had vestibular neuritis (VN) show a remarkable clinical improvement especially in gait and posture >6 months after disease onset. Methods Voxel-based morphometry was used to detect the VN-induced changes in gray and white matter by means of structural magnetic resonance imaging. Twenty-two patients were compared an average 2.5 years after onset of VN to a healthy sex-and age-matched control group. Results Our analysis revealed that all patients had signal intensity increases for gray matter in the medial vestibular nuclei and the right gracile nucleus and for white matter in the area of the pontine commissural vestibular fibers. A relative atrophy was observed in the left posterior hippocampus and the right superior temporal gyrus. Patients with a residual canal paresis also showed an increase of gray matter in middle temporal (MT)/V5 bilaterally. Interpretation These findings indicate that the processes of central compensation after VN seem to occur in 3 different sensory systems. First of all, the vestibular system itself showed a white matter increase in the commissural fibers as a direct consequence of an increased internuclei vestibular crosstalk of the medial vestibular nuclei. Second, to regain postural stability, there was a shift to the somatosensory system due to an elevated processing of proprioceptive information in the right gracile nucleus. Third, there was a bilateral increase in the area of MT/V5 in VN patients with a residual peripheral vestibular hypofunction. This seems to be the result of an increased importance of visual motion processing. ANN NEUROL 2010;68:241,249 [source] | |||||||||||||