Zhiye Chen

Mapping the brain in type II diabetes: Voxel-based morphometry using DARTEL

PURPOSE To investigate the pattern of brain volume changes of the brain in patients with type II diabetes mellitus using voxel-based morphometry. MATERIAL AND METHODS Institutional ethics approval and informed consent were obtained. VBM based on the high resolution three-dimensional T1-weighted fast spoiled gradient recalled echo MRI images was obtained from 16 type II diabetes patients (mean age 61.2 years) and 16 normal controls (mean age 59.6 years). All images were spatially preprocessed using Diffeomorphic Anatomical Registration using Exponentiated Lie algebra (DARTEL) algorithm, and the DARTEL templates were made from 100 normal subjects. Statistical parametric mapping was generated using analysis of covariance (ANCOVA). RESULTS An atrophy pattern of gray matter was seen in type II diabetes patients compared with controls that involved the right superior, middle, and inferior temporal gyri, right precentral gyrus, and left rolandic operculum region. The loss of white matter volume in type II diabetes mellitus was observed in right temporal lobe and left inferior frontal triangle region. ROI analysis revealed that the gray and white matter volume of right temporal lobe were significant lower in type II diabetes mellitus than that in controls (P<0.05). CONCLUSION This work demonstrated that type II diabetes mellitus patients mainly exhibited gray and white matter atrophy in right temporal lobe, and this finding supported that type II diabetes mellitus could lead to subtle diabetic brain structural changes in patients without dementia or macrovascular complications.

Diagnostic value of minimum apparent diffusion coefficient values in prediction of neuroepithelial tumor grading.

To retrospectively evaluate the diagnostic accuracy of diffusion weighted image (DWI) in the prediction of neuroepithelial tumors grading, and to appraise the apparent diffusion coefficient (ADC) value of neuroepithelial tumors with histologic findings as a reference standard.

Intracranial hemangiopericytoma: MR imaging findings and diagnostic usefulness of minimum ADC values

To describe the clinical and magnetic resonance (MR) imaging features of primary intracranial hemangiopericytoma (HPC), and to assess the usefulness of minimum apparent diffusion coefficient (MinADC) value of HPC in the differential diagnosis from meningioma.

Cerebral alterations of type 2 diabetes mellitus on MRI: A pilot study.

This study is to investigate gray matter volume, cortical thickness, and surface area of the brain in patients with type 2 diabetes mellitus (T2DM). High resolution T1-weighted MR images were obtained from eighteen T2DM and seventeen normal controls. All images were processed using our newly developed BrainLab toolbox. Declines of gray matter volume, cortical thickness, and surface area were found in T2DM patients. Significantly reduced ROIs of gray matter volume happened in subcortical gray nuclei (left caudate and right caudate), and significantly reduced ROIs of cortical thickness occurred in temporal lobe (left superior temporal gyrus), parietal lobe (left angular gyrus), and occipital lobe (right superior occipital gyrus, left middle occipital gyrus and right cuneus). Apparently reduced ROIs of surface area were mainly distributed in frontal lobe (right superior frontal gyrus (dorsal) and left paracentral lobule). The findings indicated that T2DM caused brain changes in specific regions. This work revealed neural alterations of T2DM, which had a great significance in early diagnosis of the disease.

Generation of infant anatomical models for evaluating electromagnetic field exposures

Realistic anatomical modeling is essential in analyzing human exposure to electromagnetic fields. Infants have significant physical and anatomical differences compared with other age groups. However, few realistic infant models are available. In this work, we developed one 12-month-old male whole body model and one 17-month-old male head model from magnetic resonance images. The whole body and head models contained 28 and 30 tissues, respectively, at spatial resolution of 1 mm × 1 mm × 1 mm. Fewer identified tissues in the whole body model were a result of the low original image quality induced by the fast imaging sequence. The anatomical and physical parameters of the models were validated against findings in published literature (e.g., a maximum deviation as 18% in tissue mass was observed compared with the data from International Commission on Radiological Protection). Several typical exposure scenarios were realized for numerical simulation. Dosimetric comparison with various adult and child anatomical models was conducted. Significant differences in the physical and anatomical features between adult and child models demonstrated the importance of creating realistic infant models. Current safety guidelines for infant exposure to radiofrequency electromagnetic fields may not be conservative.

The alteration of spontaneous low frequency oscillations caused by acute electromagnetic fields exposure

OBJECTIVE The motivation of this study is to evaluate the possible alteration of regional resting state brain activity induced by the acute radiofrequency electromagnetic field (RF-EMF) exposure (30min) of Long Term Evolution (LTE) signal. METHODS We designed a controllable near-field LTE RF-EMF exposure environment. Eighteen subjects participated in a double-blind, crossover, randomized and counterbalanced experiment including two sessions (real and sham exposure). The radiation source was close to the right ear. Then the resting state fMRI signals of human brain were collected before and after the exposure in both sessions. We measured the amplitude of low frequency fluctuation (ALFF) and fractional ALFF (fALFF) to characterize the spontaneous brain activity. RESULTS We found the decreased ALFF value around in left superior temporal gyrus, left middle temporal gyrus, right superior temporal gyrus, right medial frontal gyrus and right paracentral lobule after the real exposure. And the decreased fALFF value was also detected in right medial frontal gyrus and right paracentral lobule. CONCLUSIONS The study provided the evidences that 30min LTE RF-EMF exposure modulated the spontaneous low frequency fluctuations in some brain regions. SIGNIFICANCE With resting state fMRI, we found the alteration of spontaneous low frequency fluctuations induced by the acute LTE RF-EMF exposure.

Altered functional connectivity of amygdala underlying the neuromechanism of migraine pathogenesis

BackgroundThe amygdala is a large grey matter complex in the limbic system, and it may contribute in the neurolimbic pain network in migraine. However, the detailed neuromechanism remained to be elucidated. The objective of this study is to investigate the amygdala structural and functional changes in migraine and to elucidate the mechanism of neurolimbic pain-modulating in the migraine pathogenesis.MethodsConventional MRI, 3D structure images and resting state functional MRI were performed in 18 normal controls (NC), 18 patients with episodic migraine (EM), and 16 patients with chronic migraine (CM). The amygdala volume was measured using FreeSurfer software and the functional connectivity (FC) of bilateral amygdala was computed over the whole brain. Analysis of covariance was performed on the individual FC maps among groups.ResultsThe increased FC of left amygdala was observed in EM compared with NC, and the decreased of right amygdala was revealed in CM compared with NC. The increased FC of bilateral amygdala was observed in CM compared with EM. The correlation analysis showed a negative correlation between the score of sleep quality (0, normal; 1, mild sleep disturbance; 2, moderate sleep disturbance; 3, serious sleep disturbance) and the increased FC strength of left amygdala in EM compared with NC, and a positive correlation between the score of sleep quality and the increased FC strength of left amygdala in CM compared with EM, and other clinical variables showed no significant correlation with altered FC of amygdala.ConclusionsThe altered functional connectivity of amygdala demonstrated that neurolimbic pain network contribute in the EM pathogenesis and CM chronicization.

Altered functional connectivity architecture of the brain in medication overuse headache using resting state fMRI

BackgroundFunctional connectivity density (FCD) could identify the abnormal intrinsic and spontaneous activity over the whole brain, and a seed-based resting-state functional connectivity (RSFC) could further reveal the altered functional network with the identified brain regions. This may be an effective assessment strategy for headache research. This study is to investigate the RSFC architecture changes of the brain in the patients with medication overuse headache (MOH) using FCD and RSFC methods.Methods3D structure images and resting-state functional MRI data were obtained from 37 MOH patients, 18 episodic migraine (EM) patients and 32 normal controls (NCs). FCD was calculated to detect the brain regions with abnormal functional activity over the whole brain, and the seed-based RSFC was performed to explore the functional network changes in MOH and EM.ResultsThe decreased FCD located in right parahippocampal gyrus, and the increased FCD located in left inferior parietal gyrus and right supramarginal gyrus in MOH compared with NC, and in right caudate and left insula in MOH compared with EM. RSFC revealed that decreased functional connectivity of the brain regions with decreased FCD anchored in the right dorsal-lateral prefrontal cortex, right frontopolar cortex in MOH, and in left temporopolar cortex and bilateral visual cortices in EM compared with NC, and in frontal-temporal-parietal pattern in MOH compared with EM.ConclusionsThese results provided evidence that MOH and EM suffered from altered intrinsic functional connectivity architecture, and the current study presented a new perspective for understanding the neuromechanism of MOH and EM pathogenesis.

Cortical thinning in type 2 diabetes mellitus and recovering effects of insulin therapy

The purpose of this study was to explore the brain structural changes in type 2 diabetes and the effect of insulin on the brain using a surface-based cortical thickness analysis. High-resolution three-dimensional T1-weighted fast spoiled gradient recalled echo MRI were obtained from 11 patients with type 2 diabetes before and after insulin therapy. The cortical thickness over the entire brain was calculated, and cross-sectional and longitudinal surface-based cortical thickness analyses were also performed. Regional cortical thinning was demonstrated in the middle temporal gyrus, posterior cingulate gyrus, precuneus, right lateral occipital gyrus and entorhinal cortex bilaterally for patients with type 2 diabetes mellitus compared with normal controls. Cortical thickening was seen in the middle temporal gyrus, entorhinal cortex and left inferior temporal gyrus bilaterally after patients underwent 1 year of insulin therapy. These findings suggest that insulin therapy may have recovering effects on the brain cortex in type 2 diabetes mellitus. The precise mechanism should be investigated further.

MR findings of Rosai-Dorfman disease in sellar and suprasellar region

BACKGROUND Rosai-Dorfman disease (RDD) in sellar/suprasellar region is a rare intracranial disorder. The diagnostic evaluation of this condition using magnetic resonance imaging (MRI) has seldom been described previously. The purpose of our study was to describe MRI characteristics of sellar/suprasellar region RDD. METHODS Five patients with proved sellar/suprasellar region RDD from May 2005 to March 2010 were retrospectively reviewed. All the patients had undergone magnetic resonance scanning. The number, location, signal intensity (SI), and enhancement pattern of the lesions on MRI were retrospectively evaluated. RESULTS Pathological diagnosis of RDD was achieved in all 5 cases including 4 by surgery and 1 by biopsy. The most common presenting symptoms were headache (n = 4) and blurred vision (n = 3). On MRI, isolated suprasellar lesion was found in 2 cases. Suprasellar lesion combined with intrasellar, dural, intra-axial and orbital lesions was found in 3 cases. All lesions showed homogeneous isointense SI on T1-weighted images and hypointense to isointense SI on T2-weighted images except one lesion in the midbrain with slight hyperintense SI on T2-weighted images. All lesions showed homogeneous enhancement. CONCLUSION Homogenously enhancing sellar/suprasellar masses of hypointense to isointense SI on T2-weighted images are suggestive of RDD, and central hypointensity on T2-weighted images may be a specific finding. Intra-axial and extra-axial involvements may coexist with sellar/suprasellar region RDD. Although radiological findings can provide some evidence for this rare entity, differential diagnosis is still needed.