Resonance Images Of Human Brain Research Articles

Comparative Analysis of Pulse Sequence Scenarios of Nuclear Magnetic Resonance Imaging of Human Brain

Comparative Analysis of Pulse Sequence Scenarios of Nuclear Magnetic Resonance Imaging of Human Brain

A Hybrid Approach for Fast 3D Segmentation of Brain Tumor

Brain tumor segmentation and its study are tricky assignments of medical image processing due to complexity and variance of tumors however, forms a decisive factor for quantitative exploration of the spatial data in magnetic resonance imaging of human brain. In that mode, this modality of image has developed into a valuable investigative means in medicinal domain for detecting irregularity and discrepancy in human brain. The accuracy of segmentation method relies on its capability to discriminate different tissue, classes, discretely. Consequently there is an essential need to evaluate this capability prior to employing the segmentation method on medical images. In this paper, a semi-automatic segmentation technique is proposed to carry out the analysis and study of proficient pathologies of brain tumor of human brain. The task of segmentation is carried out integrating region growing with active contour methodologies. The evaluation of proposed methodology has been carried out on multislice image of MRI data and compared with other semi automatic and automatic techniques. It is observed by the experimental results that proposed system has the ability to accomplish fast segmentation and exact modeling of tumors in brain with a gratifying accuracy in order to support future treatment planning.

Full anatomical labeling of magnetic resonance images of human brain by registration with multiple atlases

The problem of automatic segmentation of magnetic resonance (MR) images of human brain into anatomical structures is considered. Currently, the most popular segmentation algorithms are based on the registration (matching) of the input image with (to) an atlas--an image for which an expert labeling is known. Segmentation on the basis of registration with multiple atlases allows one to better take into account anatomical variability and thereby to compensate, to some extent, for the errors of matching to each individual atlas. In this work, a more efficient (in speed and memory) implementation is proposed of one of the best multiatlas label fusion algorithms in order to obtain a labeling of the input image. The algorithm is applied to the problem of segmentation of brain MR images into 43 anatomical regions with the use of the publicly available IBSR database, in contrast to the original work, where the authors provide test results for the problem of extraction of a single anatomical structure, the hippocampus.

Is magnetic resonance imaging of human brain is harmful?

In human brains, there are a lot of macroscopic (∼100nm) magnetite granules. Exposure of the patient’s head in high strength magnetic fields could lead to penetrance of those particles into brain neurons and their staying there for a long period. That conclusion is the consequence of calculations based on the equations describing the dynamics of those particles under the action of ponderomotive magnetic, elastic and viscous forces. The role of iron in brain metabolism is not conclusively clear but there is evidence of the connection between excess iron and neurodegenerative diseases. In this regard, we consider it necessary to look more carefully at the matter of safety for brain magnetic resonance imaging.

In vivo double quantum filtered sodium magnetic resonance imaging of human brain

Sodium signal from ordered environments can be selectively detected using a double-quantum magic angle (DQ-MA) sequence. This study presents the first DQ-MA sodium images of the human brain and evaluates the effect of preparation time (τ) on the signal. Three phantoms of saline, agar gel, and xanthan gum were used to test the correct functioning of the DQ-MA sequence. Five healthy volunteers were imaged using DQ-MA with varying τ to determine the optimal preparation time. DQ-MA images were acquired with 1 or 2 averages and nominal resolution of 15 mm isotropic in 3.5 or 7 min, respectively. In addition, higher nominal resolution (8.4 mm isotropic) DQ-MA images were acquired from another subject in 48 min. Post hoc simulations were performed to explain the effect of τ on imaging results. The DQ-MA sequence generates signal from only the xanthan gum phantom, correctly suppressing signal from environments in which the time-averaged quadrupolar interaction is expected to be zero (saline, agar). This sequence generates signal throughout the brain with maximum detection when τ=3 ms. The existence of DQ-MA signal in the human brain indicates the presence of sodium nuclei in ordered environments and provides a novel contrast mechanism.

Intensity inhomogeneity correction for magnetic resonance imaging of human brain at 7T

To evaluate the performance and efficacy for intensity inhomogeneity correction of various sequences of the human brain in 7T MRI using the extended version of the unified segmentation algorithm. Ten healthy volunteers were scanned with four different sequences (2D spin echo [SE], 3D fast SE, 2D fast spoiled gradient echo, and 3D time-of-flight) by using a 7T MRI system. Intensity inhomogeneity correction was performed using the "New Segment" module in SPM8 with four different values (120, 90, 60, and 30 mm) of full width at half maximum (FWHM) in Gaussian smoothness. The uniformity in signals in the entire white matter was evaluated using the coefficient of variation (CV); mean signal intensities between the subcortical and deep white matter were compared, and contrast between subcortical white matter and gray matter was measured. The length of the lenticulostriate (LSA) was measured on maximum intensity projection (MIP) images in the original and corrected images. In all sequences, the CV decreased as the FWHM value decreased. The differences of mean signal intensities between subcortical and deep white matter also decreased with smaller FWHM values. The contrast between white and gray matter was maintained at all FWHM values. LSA length was significantly greater in corrected MIP than in the original MIP images. Intensity inhomogeneity in 7T MRI can be successfully corrected using SPM8 for various scan sequences.

Neurophysiological Architecture of Functional Magnetic Resonance Images of Human Brain

We investigated large-scale systems organization of the whole human brain using functional magnetic resonance imaging (fMRI) data acquired from healthy volunteers in a no-task or 'resting' state. Images were parcellated using a prior anatomical template, yielding regional mean time series for each of 90 regions (major cortical gyri and subcortical nuclei) in each subject. Significant pairwise functional connections, defined by the group mean inter-regional partial correlation matrix, were mostly either local and intrahemispheric or symmetrically interhemispheric. Low-frequency components in the time series subtended stronger inter-regional correlations than high-frequency components. Intrahemispheric connectivity was generally related to anatomical distance by an inverse square law; many symmetrical interhemispheric connections were stronger than predicted by the anatomical distance between bilaterally homologous regions. Strong interhemispheric connectivity was notably absent in data acquired from a single patient, minimally conscious following a brainstem lesion. Multivariate analysis by hierarchical clustering and multidimensional scaling consistently defined six major systems in healthy volunteers-- corresponding approximately to four neocortical lobes, medial temporal lobe and subcortical nuclei- - that could be further decomposed into anatomically and functionally plausible subsystems, e.g. dorsal and ventral divisions of occipital cortex. An undirected graph derived by thresholding the healthy group mean partial correlation matrix demonstrated local clustering or cliquishness of connectivity and short mean path length compatible with prior data on small world characteristics of non-human cortical anatomy. Functional MRI demonstrates a neurophysiological architecture of the normal human brain that is anatomically sensible, strongly symmetrical, disrupted by acute brain injury, subtended predominantly by low frequencies and consistent with a small world network topology.

Functional magnetic resonance imaging of human brain during motor behavior

Functional magnetic resonance imaging of human brain during motor behavior

Three-dimensional functional magnetic resonance imaging of human brain on a clinical 1.5-T scanner.

Functional magnetic resonance imaging (fMRI) is a tool for mapping brain function that utilizes neuronal activity-induced changes in blood oxygenation. An efficient three-dimensional fMRI method is presented for imaging brain activity on conventional, widely available, 1.5-T scanners, without additional hardware. This approach uses large magnetic susceptibility weighting based on the echo-shifting principle combined with multiple gradient echoes per excitation. Motor stimulation, induced by self-paced finger tapping, reliably produced significant signal increase in the hand region of the contralateral primary motor cortex in every subject tested.

Two-dimensional registration of magnetic resonance brain images.

A fully automated two-dimensional image registration technique based on cross correlation is presented. This technique is evaluated using magnetic resonance images of human brain. Results indicate that this algorithm is capable of accurately estimating both linear and angular offsets.

Superimposition of generator sources of epileptic spikes estimated by dipole tracing method on magnetic resonance images of human brain

Superimposition of generator sources of epileptic spikes estimated by dipole tracing method on magnetic resonance images of human brain