Application of local gyrification index in the early diagnosis of Alzheimer disease / 中华放射学杂志

Objective To evaluate the role of local gyrification index (LGI) in the early diagnosis of Alzheimer disease(AD). Methods Thirty‐five amnestic‐type mild cognitive impairment patients (aMCI group), 34 mild AD patients (mild AD group) and 33 healthy volunteers (normal control group) were studied. All patients underwent high resolution MRI examination and mini‐mental state examination (MMSE). Using surface‐based morphometry, the FreeSurfer was employed to access LGI of vertex over every participant′s whole cortical surface, then we calculated the mean LGI (mLGI) of each subject′s left and right hemisphere separately. Taking age, gender and educational year as covariance, analysis of covariance was used to compare the difference of mLGI of left and right brain among 3 groups, then Bonferroni was done between every two groups. Analysis of covariance was applied to compare the difference of LGI of every participant among 3 groups, and Monte Carlo method was employed to perform multiple comparison corrections. The correlations between the MMSE scores and LGIs of the three groups were analyzed. Results Compared with normal control group(left 3.03±0.12,right 3.02±0.13), the mLGI of hemispheres in mild AD group(left 2.94±0.11,right 2.93±0.10) decreased respectively(P<0.05). The difference of mLGI of hemispheres between aMCI group(left 2.96 ± 0.10, right 2.96 ± 0.09) and normal control group had no statistical significance(P>0.05). The difference of mLGI of hemispheres between aMCI group and mild AD group also had no statistical significance(P>0.05). The aMCI group showed decrease of LGI in some brain regions located at the right temporal lobe, bilateral frontal and parietal lobe compared with the normal control group. While compared with aMCI group, decreased LGIs was presented in some brain regions located at bilateral temporal, occipital, frontal lobe and the right parietal lobe of mild AD group. There was a positive correlation between MMSE scores and LGIs of some brain regions in the bilateral temporal, occipital lobe, the left frontal lobe and the right parietal lobe in the three groups. Conclusion LGI is conductive in the early diagnosis of AD and can serve as an imaging marker for monitoring disease progresses.

Application of cerebral MR perfusion imaging using pulsed arterial spin labeling technique in patients with amnestic-type mild cognitive impairment and mild Alzheimer disease / 中华放射学杂志

Objective To study the value of relative cerebral blood flow(rCBF)changes in patients with amnestic-type mild cognitive impairment (aMCI)and mild Alzheimer disease(AD) using MRI pulsed arterial spin labeling(PASL).Methods A prospective study recruited 37 aMCI patients (aMCI group),30 mild AD patients(mild AD group) and 30 healthy volunteers (normal control group) from March 2011 to December 2013,MRI using PASL for cerebral perfusion imaging was performed and data of rCBF were collected.Taking age as covariate,analysis of variance (ANONA)was carried out to assess the difference of rCBF among all the three groups,then Bonferroni was done between every two groups.A follow-up examination using PASL was performed in the seventeen patients of the aMCI group.And paired t-test was used for comparing the longitudinal change of their rCBF data.Results Compared with the normal control group,the aMCI group showed significant increase of rCBF in bilateral posterior cingulate cortices and precuneus (cluster number 2 785,P＜0.05).While the mild AD group showed decrease of rCBF in the left inferior and superior parietal lobes,the angular,middle frontal lobe,as well as the right superior temporal lobe (cluster number 3 459-5 206,P＜0.05).When compared with the aMCI group,the mild AD group showed regional hypoperfusion in bilateral middle frontal lobes,the left precuneus,the right postcentral and inferior parietal lobe (cluster number 3 236-19 863,P＜0.05).In the longitudinal study of the 17 aMCI patients,an increased rCBF was found to coexist with reduced rCBF in the left inferior frontal and lateral occipital cortex,bilateral frontal poles and paracingulate gyrus,with hyperperfusion dominated.Increased rCBF was also detected in the left temporal lobe,the angular gyrus and precuneus,while decreased rCBF was present in the left putamen,the operculum and right corpus callosum (P＜0.05).Conclusions ASL perfusion imaging is a valuable method for dynamic monitoring of the cerebral perfusion changes in aMCI and AD patients.PASL will assist in finding a useful imaging biomarker for early diagnosis of AD.

MR diffusion tensor imaging voxel-based analysis of whole brain white matter in patients with amnestic-type mild cognitive impairment and mild Alzheimer disease / 中华放射学杂志

Objective To evaluate the microstructural integrity of white matter (WM) in patients with amnestic mild cognitive impairment (aMCI) and mild Alzheimer's disease (AD) using voxel-based analysis (VBA), and investigate the relationship between WM abnormalities and gray matter(GM) atrophy.Methods Thirty-three cases with aMCI, 32 cases with mild AD and 31 normal aging volunteers as control subjects were scanned on a 3.0 T MR system using diffusion tensor imaging (DTI) and three-dimensional spoiled gradient-recalled(3DSPGR) sequences. Fractional anisotropy (FA) maps and morphological images were preprocessed by SPM5 and voxel-based comparisons between the 2 patient groups and the control group were performed by t test. Results Relative to the control group, patients with aMCI showed significantly reduced FA value in bilateral frontal, temporal and left occipital WM, left anterior part of cingulum, left inferior parietal lobule, and the W M adjacent to the triangular part of the right lateral ventricle(k≥20 voxels).In mild AD,significantly reduced FA value was found in bilateral hippocampal,inferior parietal lobular,frontal,temporal,and occipital WM,bilateral corpus callosum,anterior part of cingulums,the WM adjacent to the triaangular part of the bilateral lateral ventricles,left temporal stem,left thalamus,right precuneus(k≥20 voxels).Significantly reduced GM volume was found in left hippocampus,parahippocampal gyrus,lingual gyrus and superior temporal gyrus,bilateral insulae and middle temporal gyri in aMCl group whencompared with control group(k≥50 voxels).In mild AD,significantly reduced GM volume was found in bilateral hippoeampi,parahippocampal gyri,amygdalae,thalami,temporal,parietal,frontal,occipital cortex(k≥50 voxels).The pattern of areas with reduced FA differs;from that of the GM volumetric reduction.No areas with significantlv reduced FA was detected in aMCl compared with mild AD. There was no significant correlation between FA value of WM in patient groups and Mini-Mental State Examination(MMSE)scores.Conclusions Voxel-based MRI DTI analysis of whole brain white matter can objectively reveal widespread white matter abnormalities in early-stage AD.The difierence between WM FA reduction pattern and GM volumetric reduction pattern indicates that the pathological WM changes in earlyslage AD were caused by multiple mechanisms. FA did not vary significantly in patients pr0gressing from aMCI to mild AD and can hardly reflect the severitv of cognitive function damage in these patients.

Tracking transplanted pancreatic islet cells in rats using magnetic resonance imaging / 复旦学报（医学版）

Objective To track superparamagnetic iron oxide (SPIO)-labeled pancreatic islet cells in rats using 3.0T magnetic resonance imaging (MRI), and to detect the survival and rejection of grafts after transplantation. Methods Twenty male Wistar rats and 5 male Lewis rats were included in the study. SPIO-labeled pancreatic islet cells were tracked using a GE 3.0T Signa Excite MRI scanner with an animal coil. The images of SPIO-labeled islet cells in rats after transplantation were compared with those of the unlabeled ones. FSE T2WI sequence and GRE T2*WI sequence were used for the detection. The sensitivity of images for detection of grafts was also compared. SPIO-labeled pancreatic islet cells isolated from Wistar and Lewis rats were transplanted into the liver of Wistar rats. Afterwards, the survival and rejection of islet cells were observed sequentially in these two growps. The rats in the syngeneic group were sacrificed 3 months post-transplantation, while the rats in the allogeneic group were sacrificed 3 weeks post-transplantation. MRI of the grafts were correlated with the pathological results. Results SPIO-labeled pancreatic islet cells were seen on MRI as distinct homogenous, hypointense spots in the liver. GRE T2*WI were more sensitive to the detection of SPIO-labeled islet cells than FSE T2WI. The relative count of hypointense spots in the syngeneic group were (90.03±9.52)%, (92.87±18.21)% and (86.25±24.81)%, respectively at 1 week, 2 weeks and 3 weeks after transplantation, while the relative count in the allogeneic group were (41.40±15.41)%, (33.41±14.01)% and (23.58±16.78)%, respectively. The difference between these counts was statistically significant (P<0.01). Iron particles were detected only in the SPIO-labeled cells. Three months post-transplantation, the grafts were found well-preserved in the liver of the rats of the syngeneic group, while only a few grafts were found in that of the allogeneic group. Conclusions MRI can be used to track SPIO-labeled islet cells in vivo, and has significant value in detecting the survival and rejection of grafts after transplantation in rats.

MRI segmentation in the diagnosis and clinical correlations of temporal lobe epilepsy / 中华放射学杂志

Objective To study the different patterns of hippocampal atrophy by MRI segmental analysis and to investigate the etiology and pathogenesis of temporal lobe epilepsy Methods GE 1 5 T Signa Horizon LX MRI scanner was used Oblique coronal T 1 weighted images perpendicular to the long axis of the hippocampus were obtained The mesial temporal structures were divided into four parts: the amygdala, hippocampal head, body and tail MRI patterns of atrophy in 50 patients with histologically confirmed hippocampal sclerosis were investigated by MRI volumetric measurement and segmental analysis, and the differences of clinical features and surgical outcome in different groups were compared Results Diffuse hippocampal atrophy was found in 22 of 50 patients (44%), 5 of the 50 patients (10%) showed diffuse atrophy involving both the amygdala and hippocampus 20 of the 50 patients (40%) had hippocampal focal atrophy and 8 of 50 patients (16%) had no obvious atrophy 38 of 50 (76%) hippocampal sclerosis had atrophy in the hippocampal body, 29 of 50 (58%) had hippocampal head atrophy, 24 of 50 (48%) had hippocampal tail atrophy, and the least involved part was the amygdala (16%, 8/50) 10 patients who had normal hippocampal volume showed focal hippocampal atrophy by segmental analysis Various patterns of hippocampal atrophy were found to be statistically related to the duration of epilepsy, the frequency of seizure and the outcome of surgery, respectively ( P 0 05) Conclusion MRI segmental analysis can improve the diagnostic sensitivity of temporal lobe epilepsy and help to investigate its etiology and pathogenesis