White Matter Wm Research Articles

Comparison of Monoamine Oxidase-A, Aβ Plaques, Tau, and Translocator Protein Levels in Postmortem Human Alzheimer's Disease Brain.

Increased monoamine oxidase-A (MAO-A) activity in Alzheimer's disease (AD) may be detrimental to the point of neurodegeneration. To assess MAO-A activity in AD, we compared four biomarkers, Aβ plaques, tau, translocator protein (TSPO), and MAO-A in postmortem AD. Radiotracers were [18F]FAZIN3 for MAO-A, [18F]flotaza and [125I]IBETA for Aβ plaques, [124/125I]IPPI for tau, and [18F]FEPPA for TSPO imaging. Brain sections of the anterior cingulate (AC; gray matter GM) and corpus callosum (CC; white matter WM) from cognitively normal control (CN, n = 6) and AD (n = 6) subjects were imaged using autoradiography and immunostaining. Using competition with clorgyline and (R)-deprenyl, the binding of [18F]FAZIN3 was confirmed to be selective to MAO-A levels in the AD brain sections. Increases in MAO-A, Aβ plaque, tau, and TSPO activity were found in the AD brains compared to the control brains. The [18F]FAZIN3 ratio in AD GM versus CN GM was 2.80, suggesting a 180% increase in MAO-A activity. Using GM-to-WM ratios of AD versus CN, a >50% increase in MAO-A activity was observed (AD/CN = 1.58). Linear positive correlations of [18F]FAZIN3 with [18F]flotaza, [125I]IBETA, and [125I]IPPI were measured and suggested an increase in MAO-A activity with increases in Aβ plaques and tau activity. Our results support the finding that MAO-A activity is elevated in the anterior cingulate cortex in AD and thus may provide a new biomarker for AD in this brain region.

The Role of Susceptibility Weighted Imaging to Evaluate the Radiation Injury of Primary and Metastatic Brain Tumors

INTRODUCTION: Radiation injury is frequently seen in patients which have been resected from high-grade brain gliomas, medulloblastomas and metastatic lesions and given radiotherapy RT . Susceptibility-weighted imaging SWI is a MRI technique for detecting small vessels and the residue of blood in microhaemorrhages that can not be displayed with conventional MRI. The aim of this study is to investigate the ability of SWI to detect bleeding sites in patients who received RT due to primer and metastatic brain tumors. METHODS: 13 women mean age 37 ± 19.3 , 10 males mean age 37.3 ± 21 a total of 23 patients who have been irradiated with the pathological diagnosis of primary and metastatic brain tumors were included in the study. Supra and infratentorial SWI lesions were counted and compared with conventional MRI. Localizations were classified as cerebellar, brainstem, basal ganglia and cortical-subcortical, periventricular and deep white matter WM . Lesion counts and the largest lesion diameter were compared with the period after RT.RESULTS: Cerebellar lesions were seen in only 4 patients with medulloblastoma. The cortical-subcortical WM was the most common localization. SWI lesions have been detected most in ependymoma and least in metastases. The largest diameter of the lesions showed a linear relationship with time after RT. The SWI lesion number, operated tumor type, time after RT were not correlated with age and gender p

Fully automatic method for segmentation of brain tumor from multimodal magnetic resonance images using wavelet transformation and clustering technique

Fully automatic brain tumor segmentation is one of the critical tasks in magnetic resonance imaging MRI images. This proposed work is aimed to develop an automatic method for brain tumor segmentation process by wavelet transformation and clustering technique. The proposed method using discrete wavelet transform DWT for pre- and post-processing, fuzzy c-means FCM for brain tissues segmentation. Initially, MRI images are preprocessed by DWT to sharpen the images and enhance the tumor region. It assists to quicken the FCM clustering technique and classified into four major classes: gray matter GM, white matter WM, cerebrospinal fluid CSF, and background BG. Then check the abnormality detection using Fuzzy symmetric measure for GM, WM, and CSF classes. Finally, DWT method is applied in segmented abnormal region of images respectively and extracts the tumor portion. The proposed method used 30 multimodal MRI training datasets from BraTS2012 database. Several quantitative measures were calculated and compared with the existing. The proposed method yielded the mean value of similarity index as 0.73 for complete tumor, 0.53 for core tumor, and 0.35 for enhancing tumor. The proposed method gives better results than the existing challenging methods over the publicly available training dataset from MICCAI multimodal brain tumor segmentation challenge and a minimum processing time for tumor segmentation. © 2016 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 26, 305-314, 2016

Olfactory identification and white matter integrity in amnestic mild cognitive impairment: A preliminary study

Increasing evidence suggests that olfactory impairment is associated with an increased risk of conversion from mild cognitive impairment MCI to Alzheimer's disease. This study was to explore how olfactory identification relates to white matter WM integrity, using diffusion tensor imaging DTI in individuals with amnestic MCI. DTI was performed from nineteen individuals with amnestic MCI mean age: 69.95±8.20 years. Olfactory identification was assessed using the Cross-Cultural Smell Identification Test CC-SIT, a widely used test for odor identification involving a scratch and sniff test of 12 micro-encapsulated odorants. Cross-sectional voxel-wise analyses of relationships between CC-SIT scores and DTI indices were performed using Tract-Based Spatial Statistics. Higher CC-SIT scores were associated with lower mean, axial and radial diffusivities in areas such as the body and splenium of corpus callosum, frontal WM lateral orbitofrontal, caudal middle frontal, precentral, left superior frontal, and right pars opercularis, right superior longitudinal fasciculus, anterior and superior corona radiata, and internal and external capsules, while CC-SIT scores were not significantly associated with fractional anisotropy across all MCI participants. In individuals with amnestic MCI, impaired olfactory identification is associated with alterations in WM integrity expressed as a lower diffusivities value. This cross-sectional preliminary study suggests that olfactory impairment contributes to WM microstructural alterations in individuals with amnestic MCI. © 2016 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 26, 270-276, 2016

Processing Time Reduction: an Application in Living Human High-Resolution Diffusion Magnetic Resonance Imaging Data.

High Angular Resolution Diffusion Imaging (HARDI) is a type of brain imaging that collects a very large amount of data, and if many subjects are considered then it amounts to a big data framework (e.g., the human connectome project has 20 Terabytes of data). HARDI is also becoming increasingly relevant for clinical settings (e.g., detecting early cerebral ischemic changes in acute stroke, and in pre-clinical assessment of white matter-WM anatomy using tractography). Thus, this method is becoming a routine assessment in clinical settings. In such settings, the computation time is critical, and finding forms of reducing the processing time in high computation processes such as Diffusion Spectrum Imaging (DSI), a form of HARDI data, is very relevant to increase data-processing speed. Here we analyze a method for reducing the computation time of the dMRI-based axonal orientation distribution function h by using Monte Carlo sampling-based methods for voxel selection. Results evidenced a robust reduction in required data sampling of about 50% without losing signal's quality. Moreover, we show that the convergence to the correct value in this type of Monte Carlo HARDI/DSI data-processing has a linear improvement in data-processing speed of the ODF determination. Although further improvements are needed, our results represent a promissory step for future processing time reduction in big data.

Application of magnetic resonance diffusion tensor imaging technology in neonates with hypoxic-ischemic encephalopathy in the subacute stage

Objective To discuss the value of magnetic resonance (MR) diffusion tensor imaging (DTI) technology in the diagnosis of the apparent diffusion coefficient (ADC) and the fraction anisotropy (FA) of neonates with hypoxic-ischemic encephalopathy (HIE) in the subacute stage. Methods Ten cases of normal full-term neonates and 34 term neonates diagnosed with HIE in the subacute stage were investigated with conventional MR and DTI.Of the 34 cases, 15 cases were mild HIE, 12 cases were moderate HIE, 7 cases were severe HIE.ADC/FA values in different parts of the brain were analyzed.And the receiver operating characteristic (ROC) curve was used, the sensitivity and specificity of the FA in specific parts were also analyzed. Results (1)On convention MRI: according to the MRI scoring system, score of mild group was(2.6±1.7) points, moderate group was (3.0±1.5) points, severe group was (5.8±1.3) points.There was significant difference between mild group and severe group, moderate and severe group(P 0.05). FA values in posterior limb of internal capsule (PLIC), splenium had statistic difference between the HIE group and the controls.FA values in mild group were (0.317±0.018, 0.339±0.025), moderate group (0.295±0.025, 0.324±0.026) and severe group (0.252±0.039, 0.253±0.036) and control group (0.455±0.047, 0.372±0.032). (3) ROC analysis of the neonates diagnosed with HIE: the area under the ROC curve of FA values in PLIC, Splenium had statistic difference between mild group and moderate group (P<0.05). The area under the ROC curve in each group was 0.744(P=0.032), 0.658 (P=0.164). ROC curve was used to evaluate the diagnostic accuracy of FA values in PLIC between HIE group and control group, when FA value was lower than 0.337, 0.803 was the largest area under the ROC curve, and there was significant difference between them(P<0.01). Conclusions FA values can reflect the brain white matter WM injury of HIE neonates quantitatively, and its diagnostic veracity is better than ADC value and conventional MR during the subacute phase of HIE.The diagnostic veracity of FA values in PLIC is higher than other parts.When the FA value is lower than 0.337, there is good sensitivity and specificity in diagnosis of HIE, so DTI technology can provide accurate and objective basis for clinical treatment with good sensitivity and specificity about the diagnosis of HIE in early stage. Key words: Infant, newborn; Hypoxic-ischemic encephalopathy; Diffusion tensor imaging; Fraction anisotropy