ABSTRACT
<p><b>BACKGROUND</b>Previous studies have shown that brain functional activity in the resting state is impaired in Alzheimer's disease (AD) patients. However, alterations in intrinsic brain activity patterns in mild cognitive impairment (MCI) patients are poorly understood. This study aimed to explore the differences in regional intrinsic activities throughout the whole brain between aMCI patients and controls.</p><p><b>METHODS</b>In the present study, resting-state functional magnetic resonance imaging (fMRI) was performed on 18 amnestic MCI (aMCI) patients, 18 mild AD patients and 20 healthy elderly subjects. And amplitude of low-frequency fluctuation (ALFF) method was used.</p><p><b>RESULTS</b>Compared with healthy elderly subjects, aMCI patients showed decreased ALFF in the right hippocampus and parahippocampal cortex, left lateral temporal cortex, and right ventral medial prefrontal cortex (vMPFC) and increased ALFF in the left temporal-parietal junction (TPJ) and inferior parietal lobule (IPL). Mild AD patients showed decreased ALFF in the left TPJ, posterior IPL (pIPL), and dorsolateral prefrontal cortex compared with aMCI patients. Mild AD patients also had decreased ALFF in the right posterior cingulate cortex, right vMPFC and bilateral dorsal MPFC (dMPFC) compared with healthy elderly subjects.</p><p><b>CONCLUSIONS</b>Decreased intrinsic activities in brain regions closely related to episodic memory were found in aMCI and AD patients. Increased TPJ and IPL activity may indicate compensatory mechanisms for loss of memory function in aMCI patients. These findings suggest that the fMRI based on ALFF analysis may provide a useful tool in the study of aMCI patients.</p>
Subject(s)
Aged , Female , Humans , Male , Alzheimer Disease , Amnesia , Brain , Cognitive Dysfunction , Magnetic Resonance ImagingABSTRACT
<p><b>BACKGROUND</b>Previous studies have shown that the functional brain activity in the resting state is impaired in Alzheimer's disease (AD) patients. However, most studies focused on the relationship between different brain areas, rather than the amplitude or strength of the regional brain activity. The purpose of this study was to explore the functional brain changes in AD patients by measuring the amplitude of the blood oxygenation level dependent (BOLD) functional MRI (fMRI) signals.</p><p><b>METHODS</b>Twenty mild AD patients and twenty healthy elderly subjects participated in the fMRI scan. The amplitude of low frequency fluctuation (ALFF) was calculated using REST software.</p><p><b>RESULTS</b>Compared with the healthy elderly subjects, the mild AD patients showed decreased ALFF in the right posterior cingulate cortex, right ventral medial prefrontal cortex, and in the bilateral dorsal medial prefrontal cortex. No brain region with increased ALFF was found in the AD group compared with the control group.</p><p><b>CONCLUSIONS</b>The reduced activity in the posterior cingulate cortex and medial prefrontal cortex observed in the present study suggest that the functional abnormalities of those areas are at an early stage of AD. The ALFF analysis may provide a useful tool in fMRI study of AD.</p>
Subject(s)
Aged , Female , Humans , Male , Middle Aged , Alzheimer Disease , Diagnosis , Case-Control Studies , Gyrus Cinguli , Magnetic Resonance Imaging , Methods , Prefrontal CortexABSTRACT
Objective We used blood oxygenation level dependent-functional MR imaging(BOLD- fMRI)to explore the characteristics of deactivation patterns in patients with anxiety disorders and the underlying neural mechanism of this disease.Methods Ten patients and ten healthy controls participated the experiments.All subjects performed the trait portion of the State-Trait anxiety Inventory(STAI-T)prior to the fMRI scans.The subjects underwent noninvasive functional magnetic resonance imaging while listening actively to emotionally neutral words alternating with no words(experiment 1)and threat related-words alternating with emotionally neutral words(experiment2).During fMRI scanning,subjects were instructed to closely listen to each stimuli word and to silently make a judgment of the word's valence.Data were analyzed with statistical parametric mapping(SPM 99).Individual and group analysis were conducted.Results Mean STAI-T score was significantly higher for patients group than that of controls(58?8 for patients group and 33?5 for controls,t=8.3,P
ABSTRACT
Objective To analyze and compare the MRI appearances of ovarian thecoma with pathologic findings in order to improve the knowledge of the disease.Methods Nineteen cases of ovarian thecoma confirmed by histopathology were analyzed.MRI morphological characteristics and signal intensity of the lesions were observed and compared with findings of pathomorphology.Correlation analysis between tumor size and amount of ascites was made.Results Ovarian thecoma displayed iso-or hypointense signal on T_1WI and significant hypointensity in the focal lesion on T_2WI.Hyperintensity occurred when cystic degeneration of the lesions existed.Fibrous septation was detected in some lesions.After enhancement,most lesions showed mild early enhancement with slight increase on the delayed phase.Pathological necrosis and cystic degeneration were seen in 9 cases which corresponded to the number and shape of the cystic lesions on MRI.A large amount of collagen hyperplastic was found between the oncocytes microscopically in 15 cases, which displayed significant hypointensity in the focal lesion on T_2WI;another 4 cases showed relatively less amounts of collagen hyperplastic and more oncocytes,which appeared moderate intensity in the focal leisom on T_2WI.The amount of ascites was not significantly correlated with the lesion size(r=0.43,P=0.10). Conclusions Hypointensity on T_2WI and mild enhancement pattern due to poor blood supply are the characteristics of ovarian thecoma.The MR findings can reflect the pathologic features of the tumor,which is helpful in the diagnosis and differential diagnosis.