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Resting-state and DTI Functional MRI Study in Aphasia

Author: WuJianMan
Tutor: LiYinGuan
School: Fujian Medical
Course: Medical Imaging and Nuclear Medicine
Keywords: aphasia functional magnetic resonance imaging resting-state regional homogeneity diffusion tensor imaging
CLC: R741
Type: Master's thesis
Year: 2011
Downloads: 131
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Abstract

Objectives(1)To study the changes of functional brain areas in patients with aphasia under resting-state by using regional homogeneity(ReHo).(2)To study the white matter of related brain areas and the connections fibers between them within human’s languish pathways combining DTI technology with patients’clinical scores estimated by ABC.Materials and Methods(1)Resting-sate sequence and DTI sequence scanning were performed using SIEMENS verio 3.0T magnetic resonance scanner in all of 23 controls and 21 patients. Each patient was conducted Aphasia Battery of Chinese test prescanning.(2)After acquiring all the subjects resting-state images data, the data was then preprocessed by using DPARSF software, all resting-state date was processed in turn by slice timing, realignment, normalization, Detrend, fliter (0.01Hz<f<0.08Hz),regression out the physiologic noise(respiration,heart beat)and Re-sampling .Then, regional homogeneity analysis, based on Kendall’s coefficient concordance(KCC) which measured the similarity of the time series of a given voxel to those of its nearest neighbors in a voxel-wise way, was used to generate individual ReHo map, one sample t test in groups and two sample t test between groups was statistically conducted subsequently, statistic level p=0.05.(3)For all of subjects’ DTI images, head motion was removed by aligning 30 diffusion-weighted scans to the unweighted B0(b=0 s/mm~2) image. Then, whole brain fiber tracking was performed in the DTI native space for each subject using interactive software TrackVis. Regions of BA44/45、BA6/9、BA22、BA41/42、BA21/37、BA39 were defined as ROIs ,each ROI indices (ROI FA、Line FA、Line count、Line mean Length)and each pair of ROIs indices(Line FA、Line count、Line mean Length)were abstracted finally for analysis using software TrackVis.Results(1)21 patients were undergone aphasia classification diagnosis according their scores estimated by ABC. 3 patients were Broca’s aphasia, 7 patients were transcortical aphasia, 9 patients were anomic aphasia, 1 patient was transcortical sensory aphasia.(2)The control group’s ReHo map showed that there existed extended high ReHo areas within human resting-state brain, including bilateral PCC/precuneus, MPFC, IPC, ITG which composed the default model network, and bilateral SMA, insula, MTC which composed its anti-correlation network as well.The result of two sample t test demonstrated that areas of right insula (BA13/45), left cingulate gyrus(BA31/24), right medial prefrontal cortex (BA32),right middle frontal gyrus (BA32/8), right middle cingulate gyru(sBA31)and right parahippocampal gyrus(BA37/19).they were statistic significantly higher ReHo in patients , however areas of left temporal gyrus (BA20),left temporal pole(BA38/47),left medial prefrontal cortex(BA10)and left inferior frontal gyrus(BA46)showed decreased ReHo.(3)One sample t test in controls showed that there were a large number of fibers connections in pairs of ROIs of BA9-21、BA9-37、BA9-39、BA9-41、BA6-21、BA6-22、BA6-37、BA6-39、BA6-41、BA44-39、BA44-21、BA44-41、BA45-21、BA45-37、BA45-39、BA45-41,while few fibers connections were detected in pairs of ROIs of BA9-22、BA9-42、BA44-22、BA44-22、BA44-37、BA45-42.Two sample t test results demonstrated that mean FA in regions of BA21/37/39/41/45/6/9,mean line FA in regions of BA44/45/6, line mean length in regions of BA22/45, mean line count in the region of BA45 were statistic significantly decreased in patients comparing controls.And mean line FA in pairs ROIs of BA45-21、BA45-37、BA45-39、BA45-41、BA6-42,line mean length in pair ROIs of BA6-42, mean line count in pairs ROIs of BA45-37、BA45-41 were statistic significantly decreased in patients as well.Conclusions(1)The preliminary studying results of human brain areas activities in resting-state using ReHo analysis revealed the two functional networks existing in resting-state may change, and main changes were decreased ReHo in some areas which formed the default model network in left hemisphere, while some areas which formed the default model network showed increased ReHo in right hemisphere. This might suggest there was the functional compensation of right hemisphere in aphasia patients.(2)DTI technology could view the connections fibers between areas within the two languish pathways( the STG、MTG pathway) objectively and precisely. DTI could also quantitative analyze the white matter of related brain areas and the connections fibers between them within human’s two languish pathways. Combining of patients’clinical scores estimated by ABC, it showed that the human’s languish processing mechanism model proposed by Price、Hickok and Poeppel could effectively interpret our results.

Resting-state and DTI Functional MRI Study in Aphasia

Abstract

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