Structural and functional connectivity abnormalities of the default mode network in patients with Alzheimer's disease and mild cognitive impairment within two independent datasets.

Alzheimer's disease (AD) is a chronic neurodegenerative disease characterized by progressive dementia, and amnestic mild cognitive impairment (aMCI) has been defined as a transitional stage between normal aging and AD. Accumulating evidence has shown that altered functional connectivity (FC) and structural connectivity (SC) in the default mode network (DMN) is the prominent hallmarks of AD. However, the relationship between the changes in SC and FC of the DMN is not yet clear. In the present study, we derived the FC and SC matrices of the DMN with functional magnetic resonance imaging (fMRI) and diffusion-weighted imaging (DWI) data and further assessed FC and SC abnormalities within a discovery dataset of 120 participants (39 normal controls, 34 patients with aMCI and 47 patients with AD), as well as a replication dataset of 122 participants (43 normal controls, 37 patients with aMCI and 42 patients with AD). Disrupted SC and FC were found among DMN components (e.g., the posterior cingulate cortex (PCC), medial prefrontal cortex (mPFC), and hippocampus) in patients in the aMCI and AD groups in the discovery dataset; most of the disrupted connections were also identified in the replication dataset. More importantly, some SC and FC elements were significantly correlated with the cognitive ability of patients with aMCI and AD. In addition, we found structural-functional decoupling between the PCC and the right hippocampus in patients in the aMCI and AD groups. These findings of the alteration of DMN connectivity in neurodegenerative cohorts deepen our understanding of the pathophysiological mechanisms of AD.

Value of 3D Pseudo-continuous Arterial Spin Labeling Magnetic Resonance Perfusion Imaging in Evaluating Posterior Circulation Ischemia in the Elderly.

Objective To investigate the value of 3D pseudo-continuous arterial spin labeling (3D-pCASL) magnetic resonance perfusion technique in evaluating posterior circulation ischemia (PCI) of the elderly beyond 80 years old and to offer the evidence of PCI of the elderly for clinical diagnosis. Methods Totally 53 male subjects older than 80 years were recruited in this study,including 20 subjects with clinically diagnosed PCI and 33 normal subjects. All the subjects underwent routine brain magnetic resonance imaging and 3D-pCASL sequence on a 3.0T magnetic resonance imaging system with 8 channel brain coil. Two post-labeling delay (PLD) time (PLD=1525 ms and PLD=2525 ms) of 3D-pCASL were used in this study to increase the accuracy of cerebral blood flow (CBF) change of posterior circulation region. We used SPM12 software to measure mean CBF values of bilateral occipital lobes and bilateral cerebellums. Independent sample t-test and rank-sum test were performed to evaluate the difference of CBF changes of anterior circulation and posterior circulation in two groups at two PLD time,the difference of CBF changes of bilateral occipital lobes and bilateral cerebellums in two groups of two PLD time,and the difference of increment of CBF between two PLD interval between two groups. Results In case group,the CBF value of the anterior circulation was significantly higher than that of posterior circulation at both two PLD time points (PLD=1525 ms and PLD=2525 ms)(P=0.000,P=0.000);in control group,the CBF value of the anterior circulation was significantly higher than that of the posterior circulation only at PLD=1525ms (P=0.025). The CBF values at bilateral occipital lobes and bilateral cerebellums at two PLD time points (PLD=1525 ms and PLD=2525 ms) were significantly higher in case group than in control group(P=0.003,P=0.002,P=0.000,P=0.001,P=0.000,P=0.001,P=0.002,P=0.014,respectively). Compared with the control group,the difference was statistically significant in bilateral occipital lobes and cerebellums with a smaller △CBF between two PLD interval in case group (P=0.004,P=0.001,P=0.001,P=0.025). Conclusion Multiple PLD time points need to be used in 3D-pCASL in diagnosing PCI of the elderly because the posterior circulation is slow in these patients. 3D-pCASL technique is sensitive in detecting decreased CBF in posterior circulation and therefore can be used to predict posterior circulation stroke in the elderly.

[Validation of standardized uptake values for ¹8F-FDG in normal organs: comparison of whole-body PET/CT and PET/MRI].

OBJECTIVE: To validate whether PET/MR could provide a semi-quantitative measurement (SUV(max)) comparable to that produced by PET/CT in normal organs. METHODS: 277 subjects underwent an ordinary ¹8F-FDG PET/CT followed by a PET/MR scan with a 25-45 min interval. Region of interest (ROIs) were drawn in 4 reference normal organs/tissues in both MRAC-PET and CTAC-PET images and the liver and erector spinae in the dual-time point PET/CT images. RESULTS: 259 malignant and 21 benign lesions, pathologically confirmed, were detected in the 220 subjects. SUV(max) derived from PET/CT (SUV(max)-CT) and PET/MR (SUV(max)-MRI) was highly correlated over the reference organ ROIs (r = 0.62-0.73), except lung (r = 0.44). The SUV(max)-MRI was significantly lower than the respective SUV(max)-CT in all 4 organs and after delay-correction in liver and muscle. CONCLUSION: The results indicate that PET/MR can provide reliable measurement in physiological organs.

[Quantitative T2 mapping evaluates the repaired articular cartilage].

OBJECTIVE: To evaluate the value of T2 mapping in monitoring the repaired cartilage after matrix-associated autologous chondrocyte implantation/transplantation (MACI/MACT). METHODS: Four patients (10 plug cartilages) were examined three times by T2 mapping at 1, 3, and 6 months using a 3.0 Tesla MR scan system. Quantitative mean (full-thickness) T2 values were calculated in the transplanted area and control cartilage. Paired t-tests were used to compare the T2 values between transplanted and control cartilage. For analysis of longitudinal T2 values, one-way analyses of variance were performed among 1, 3, and 6 months after MACI. RESULTS: The mean T2 values of the transplanted area at 1, 3, and 6 months after MACI were (82.40±15.23), (71.09±13.06), (53.80±4.86) ms, respectively. There were significant differences between the transplanted and control cartilage at 1 and 3 months (both P<0.01) after MACI, but not at 6 months (P=0.196). There were significant differences among T2 values of 1, 3, and 6 months after MACI in transplanted area (P=0.03). CONCLUSION: T2 mapping provides a useful tool for monitoring the biochemical development of the transplanted cartilage and can be used to evaluate the cartilage repair noninvasively.

[Diagnosing radiation-induced liver injury in rabbit using 3.0 Tesla magnetic resonance diffusion-weighted imaging].

OBJECTIVE: To evaluate the clinical value of magnetic resonance (MR) diffusion-weighted imaging (DWI) for diagnosing radiation-induced liver injury (RILI) and detecting changes in hepatic pathology at different post-irradiation times. METHODS: Male New Zealand white rabbits received no irradiation (C0, control group; n = 10) or irradiation of 50 Gy/10F once every other day by virtual three dimensional conformal radiotherapy (3D-CRT) for one day (C1; n = 10), three days (C2; n = 10), two weeks (C3; n = 10), one month (C4; n = 10) or two months (C5; n = 10). One member of all groups were sacrificed for DWI examination and pathologic study on post-irradiation day 1, day 3, week 2, month 1 and month 2. The apparent diffusion coefficient (ADC) values were measured using a range of b values (50, 300, 600, 800 and 1000 s/mm2). RESULTS: Hematoxylin-eosin (H-E) staining showed that livers of rabbits in the C3, C4 and C5 groups had the characteristic features of veno-occlusive disease. DWI examination showed that the irradiated livers of rabbits in C2, C3, C4 and C5 groups had significantly lower ADC values than the livers of the non-irradiated rabbits at b values of 300, 600, 800 and 1000 s/mm2 (P less than 0.05). When the b value was 600 s/mm2, the best negative correlation between ADC values and pathological stage was seen for the irradiated livers (Spearman's rank, r = -0.459, P less than 0.01). The threshold ADC value to distinguish the normal group (C0) from an irradiated group (more than or equal toC1) was 1.955 * 10-3 mm2/s at 600 s/mm2 b value. When the b value was 1000 s/mm2, the threshold ADC value to predict an irradiated group with normal H-E staining (C1) from an irradiated group with abnormal H-E staining (more than or equal toC2) was 1.5250 * 10-3 mm2/s; the ADC threshold value was 1.5150 * 10-3 mm2/s to predict groups C0-2 and groups C3-5. CONCLUSION: DWI has high sensitivity for detecting RILI at three days after irradiation with proper b values. Use of the ADC value is feasible for estimating the evolutionary process of pathological features of RILI damage. DWI may represent an important clinical tool for detection of early pathological changes in RILI.

Single-cell BCR and transcriptome analysis reveals peripheral immune signatures in patients with thyroid-associated ophthalmopathy.

Thyroid-associated ophthalmopathy (TAO) is the most prevalent orbital disease in adults caused by an autoimmune disorder, which can lead to disfigurement and vision impairment. Developing effective treatments for this condition presents challenges due to our limited understanding of its underlying immune aberrations. In this study, we profiled the immune components in the peripheral blood of patients with TAO as well as healthy individuals, utilizing single-cell RNA sequencing and B-cell receptor repertoires (BCR) analysis. We observed a significant reduction in the proportions of regulatory B cells (Bregs) and type 2 conventional dendritic cells (DCs) in patients with TAO during the active phase. Conversely, there was a significant increase in the proportion of type 1 DCs. Further analysis of cell differentiation trajectory revealed potential impairment in the transition of B cells towards Breg phenotype during the active phase of TAO. Besides, the activation process of TAO appeared to involve inflammation and immune dysfunction, as indicated by the dynamic changes in the activities of key regulators. The abnormalities in the peripheral immune system, such as the reduced capacity of Bregs to suppress inflammation, were primarily driven by the enhanced interaction among Breg, DCs, and monocytes (i.e., CD22-PTPRC and BTLA-TNFRSF14). Collectively, our findings offer a comprehensive insight into the molecular regulation and cellular reconfiguration during the active phase of TAO at the single-cell level, in order to explore the pathogenesis of TAO and provide new ideas for the future treatment of TAO.

The circulating IL-35+ regulatory B cells are associated with thyroid associated opthalmopathy.

BACKGROUND: Thyroid-associated ophthalmopathy (TAO) is the most common orbital disease in adults, potentially leading to disfigurement and visual impairment. However, the causes of TAO are not fully understood. IL-35+B cells are a newly identified regulatory B cells (Bregs) in maintaining immune balance in various autoimmune diseases. Yet, the influence of IL-35+Bregs in TAO remains unexplored. METHODS: This study enrolled 36 healthy individuals and 14 TAO patients. We isolated peripheral blood mononuclear cells and stimulated them with IL-35 and CpG for 48 h. Flow cytometry was used to measure the percentages of IL-35+Bregs. RESULTS: The percentage of circulating IL-35+Bregs was higher in TAO patients, and this increase correlated positively with disease activity. IL-35 significantly increased the generation of IL-35+Bregs in healthy individuals. However, B cells from TAO patients exhibited potential impairment in transitioning into IL-35+Breg phenotype under IL-35 stimulation. CONCLUSIONS: Our results suggest a potential role of IL-35+Bregs in the development of TAO, opening new avenues for understanding disease mechanisms and developing therapeutic approaches.

[Research advances in medical imaging for radiation-induced liver injury].

The applications of three dimensional conformal radiotherapy(3-DCRT)in the abdomen has been associated with the increased incidence of radiation-induced liver injury(RILI). Timely and appropriate evaluation of RILI is particularly important for the design and modification of clinical management of tumors. This article reviews the pathological and serological features of RILI, focusing on in the application of medical imaging.

[T2 mapping and knee thickness measurement in healthy young adults using quantitative 3.0T magnetic resonance imaging].

OBJECTIVE: To investigate the T2 values and knee thickness in healthy young adults using 3.0 T magnetic resonance imaging(MRI) . METHODS: Totally 40 volunteers(18-30 years old) with body mass index between 18.5-24.0 kg/m(2) were divided into two groups(22 men and 18 women) according to their gender. Also in addition, each group was divided into two subgroups(right knee and left knee) . The T2 values and the thickness of the areas on the medial condyle of femur, the lateral condyle of femur, the medial tibial plateau, the lateral tibial plateau, and the patella of the knee cartilage were measured. RESULTS: The T2 values and the thickness of the right and left knee cartilages showed no significant differences between men and women (P>0.05) . Also, the T2 values in the five parts of the knee cartilage also were not significantly different between men and women (P>0.05) . However, the thickness of the 5 parts of the knee cartilage significantly differed between men and women(P<0.05) . CONCLUSIONS: The thickness of the knee cartilage may different between male and female young adults. The T2 values of the cartilage may be not affected by the gender.

Altered spontaneous activity in Alzheimer's disease and mild cognitive impairment revealed by Regional Homogeneity.

Alzheimer's disease (AD), the most prevalent cause of dementia in the elderly, is characterized by progressive cognitive and intellectual deficits. Most patients with mild cognitive impairment (MCI) are thought to be in a very early stage of AD. Resting-state functional magnetic resonance imaging reflects spontaneous brain activities and/or the endogenous/background neurophysiological process of the human brain. Regional Homogeneity (ReHo) can provide a fast method for mapping regional activity across the whole brain. Little has been previously published about where or how spontaneous activity differs between MCI and AD, although many previous fMRI studies have shown that the activity pattern is altered in MCI/AD. In the present study, we first used the ReHo method to explore differences in regional spontaneous activities throughout the whole brain between normal controls (NC) and people with MCI and with AD. A one-way ANOVA was performed to determine the regions in which the ReHo differs between the three groups, and then a post hoc analysis was performed to evaluate differences in the pattern among the three groups. Finally a correlation analysis was done between the ReHo index of these regions and clinical variables in order to evaluate the relationship between ReHo and cognitive measures in the AD and MCI groups. An exploratory classification analysis also demonstrated that ReHo measures were able to correctly separate subjects in 71.4% of the cases. Altered brain spontaneous activations were found in the medial prefrontal cortex, the bilateral posterior cingulate gyrus/precuneus and the left inferior parietal lobule (IPL) in both MCI and AD. In MCI, the ReHo index in the left IPL was higher than that of the NC, which could indicate the presence of a compensatory mechanism in MCI. More obviously, the correlation analysis indicated that the lower the memory and other cognitive abilities, the lower the ReHo in patients with MCI and AD. Combining our findings with the results in earlier studies, we propose that the spontaneous activity pattern in the resting state could potentially be used as a clinical marker for MCI/AD.

[An experimental study on rabbit liver by 3.0 Tesla magnetic resonance diffusion-weighted imaging].

OBJECTIVE: To explore the methodology as well as the features, quantificational index, and reference standard of 3.0 Tesla magnetic resonance (MR) diffusion-weighted imaging (DWI) on the normal rabbit's liver. METHODS: Twenty New Zealand white rabbits were enrolled and DWI was performed after anesthetics with multi-b values at 3.0 T MR scanner. Apparent diffusion coefficient (ADC) values as well as the difference between maximum and minimum ADC values, signal strength (SH), noise signal (SD), signal to noise ratio (SNR), and quality index (QI) were recorded and analyzed. RESULTS: With b value increased, the ADC values decreased accordingly (P < 0.001). The difference between maximum and minimum ADC values with b = 1000 s/mm2 was the least (good stability), b = 600 s/mm2 was the second least, and b = 300 s/mm2 was greatest (bad stability). The SH decreased at the same time (P < 0.001), but the difference among DWI with b =600, 800, and 1000 s/mm2 was not statistically significant (P > 0.05). The SD decreased at the same time (P < 0.001), but the difference between DWI with b = 800 s/mm2 and b = 1000 s/mm2 was not statistically significant (P > 0.05). The SNR decreased at the same time (P < 0.001), but there were no significant differences between DWI with b = 600 s/mm2 and b = 800 s/mm2 or b = 600 s/mm2 and b = 1000 s/mm2 (P > 0.05). The SNR of DWI with b = 800 s/mm2 and b = 1000 s/mm2 was lower. The QI decreased at the same time (P < 0. 001) , but the difference between DWI with b = 800 s/mm2 and b = 1000 s/mm was not statistically significant (P > 0.05). CONCLUSION: When 3.0 T MR DWI is applied for rabbit liver, it is better to use b = 600 s/mm2 for reducing scanning time and assuring better diffusion weights, quantity of images, and stability of ADC measurement.

Effects of intense pulsed light treatment on tear cytokines and clinical outcomes in meibomian gland dysfunction.

Meibomian gland dysfunction (MGD) has become a prevalent ocular surface disorder. Its pathogenesis is regarded as a self-perpetuating inflammatory vicious circle. Intense Pulsed Light (IPL) treatment was recently applied to improve the meibomian gland function and reduce symptoms of MGD. However, studies investigating the change of specific inflammatory cytokines during IPL treatment remained sparse. To further figure out how IPL treatment modulates the inflammatory cytokines in tears of MGD, we therefore performed a cross-sectional study and enrolled 32 patients from March 2019 to December 2020. The patients received 3 sessions of IPL treatment (10 to 16 J/cm2) at 4-week interval. The signs and symptoms of MGD were evaluated by ocular surface disease index (OSDI), tear film breakup time (TBUT), and meibomian gland yield secretion score (MGYSS). The clinical evaluators and tear samples were analyzed at baseline and at each IPL treatment session. Concentrations of (chemokine ligand) CXCL1, (C-C motif chemokine) CCL11, (tumor necrosis factor) TNF-α, (interferon) IFN-γ, (interleukin) IL-2, IL-6 and (tissue inhibitor of metalloproteinase) TIMP-1were measured by Quantibody Human Dry Eye Disease Array1. OSDI significantly decreased after IPL treatment compared with baseline. TBUT and MGYSS increased consecutively during treatment. CXCL1, CCL11, TNF-α, IFN-γ, IL-2, IL-6 presented significantly decrease and TIMP-1 showed significantly increase from the pretreatment baseline. The changed concentrations of TNF-α, IFN-γ, IL-2, TIMP-1 correlated with TBUT, the changed values of CXCL1, TNF-α, IFN-γ, CCL11, IL-2, IL-6, TIMP-1 correlated with MGYSS, and the changed concentrations of CXCL1, IFN-γ, CCL11, IL-2, IL-6 correlated with TIMP-1. The data supported IPL treatment could significantly relieve both signs and symptoms of MGD. The therapeutic effect of IPL treatment may originate from regulation of inflammatory cytokines including CXCL1, TNF-α, IFN-γ, CCL11, IL-2, IL-6, and TIMP-1.

Altered Volume and Structural Connectivity of the Hippocampus in Alzheimer's Disease and Amnestic Mild Cognitive Impairment.

Background: Hippocampal atrophy is a characteristic of Alzheimer's disease (AD). However, alterations in structural connectivity (number of connecting fibers) between the hippocampus and whole brain regions due to hippocampal atrophy remain largely unknown in AD and its prodromal stage, amnestic mild cognitive impairment (aMCI). Methods: We collected high-resolution structural MRI (sMRI) and diffusion tensor imaging (DTI) data from 36 AD patients, 30 aMCI patients, and 41 normal control (NC) subjects. First, the volume and structural connectivity of the bilateral hippocampi were compared among the three groups. Second, correlations between volume and structural connectivity in the ipsilateral hippocampus were further analyzed. Finally, classification ability by hippocampal volume, its structural connectivity, and their combination were evaluated. Results: Although the volume and structural connectivity of the bilateral hippocampi were decreased in patients with AD and aMCI, only hippocampal volume correlated with neuropsychological test scores. However, positive correlations between hippocampal volume and ipsilateral structural connectivity were displayed in patients with AD and aMCI. Furthermore, classification accuracy (ACC) was higher in AD vs. aMCI and aMCI vs. NC by the combination of hippocampal volume and structural connectivity than by a single parameter. The highest values of the area under the receiver operating characteristic (ROC) curve (AUC) in every two groups were all obtained by combining hippocampal volume and structural connectivity. Conclusions: Our results showed that the combination of hippocampal volume and structural connectivity (number of connecting fibers) is a new perspective for the discrimination of AD and aMCI.

[A diffusion tensor magnetic resonance imaging for studying white matter changes in patients with mild cognitive impairment.].

OBJECTIVES: To measure the microstructural differences in the brains of participants with amnestic mild cognitive impairment (aMCI) and compare with a control group using a magnetic resonance diffusion tensor imaging (DTI) technique with fully automated image analysis tools. METHODS: A standardized clinical and neuropsychological evaluation was conducted on each subject. 31 participants (15 participants with aMCI, 16 healthy elderly adults) underwent magnetic resonance imaging (MRI)-based DTI. To control the effects of anatomical variation, the diffusion images of all participants were registered to standard anatomical space. Voxel-by-voxel comparisons showed significant regional reductions in white matter regions of fractional anisotropy (FA) in the participants with aMCI as compared with the controls. RESULTS: Significantly decreased FA value measurements (P < 0.001) were observed in the right frontal white matter in participants with aMCI. Moreover, there was a statistically significant difference between the patients with aMCI and controls in considering the small regions of bilateral superior frontal gyrus white matter (P < 0.001). CONCLUSIONS: White matter damage of frontal lobe may play an important role in histopathologic changes associated with amnestic mild cognitive impairment.

Aberrant Hippocampal Functional Connectivity Is Associated with Fornix White Matter Integrity in Alzheimer's Disease and Mild Cognitive Impairment.

BACKGROUND: Alzheimer's disease (AD) is the most common cause of dementia in older individuals, and amnestic mild cognitive impairment (aMCI) is currently considered the prodromal stage of AD. The hippocampus and fornix interact functionally and structurally, with the fornix being the major efferent white matter tract from the hippocampus. OBJECTIVE: The main aim of this study was to examine the impairments present in subjects with AD or aMCI and the relationship of these impairments with the microstructure of the fornix and the functional connectivity (FC) and gray matter volume of the hippocampus. METHODS: Forty-four AD, 34 aMCI, and 41 age- and gender-matched normal controls (NCs) underwent neuropsychological assessments and multimode MRI. We chose the bilateral hippocampi as the region of interest in which gray matter alterations and FC with the whole brain were assessed and the fornix body as the region of interest in which the microstructural integrity of the white matter was observed. We also evaluated the relationship among gray matter alterations, the abnormal FC of the hippocampus and the integrity of the fornix in AD/aMCIResults:Compared to the NC group, the AD and aMCI groups demonstrated decreased gray matter volume, reduced FC between the bilateral hippocampi and several brain regions in the default mode network and control network, and damaged integrity of the fornix body (decreased fractional anisotropy and increased diffusivity). We also found that left hippocampal FC with some regions, the integrity of the fornix body, and cognition ability were significantly correlated. Therefore, our findings suggest that damage to white matter integrity may partially explain the reduced resting-state FC of the hippocampus in AD and aMCI. CONCLUSION: AD and aMCI are diseases of disconnectivity including not only functional but also structural disconnectivity. Damage to white matter integrity may partially explain the reduced resting-state FC in AD and aMCI. These findings have significant implications for diagnostics and modeling and provide insights for understanding the disconnection syndrome in AD.

Characterizing white matter connectivity in Alzheimer's disease and mild cognitive impairment: An automated fiber quantification analysis with two independent datasets.

Alzheimer's disease (AD) is a chronic neurodegenerative disease characterized by progressive dementia. Diffusion tensor imaging (DTI) has been widely used to show structural integrity and delineate white matter (WM) degeneration in AD. The automated fiber quantification (AFQ) method is a fully automated approach that can rapidly and reliably identify major WM fiber tracts and evaluate WM properties. The main aim of this study was to assess WM integrity and abnormities in a cohort of patients with amnestic mild cognitive impairment (aMCI) and AD as well as normal controls (NCs). For this purpose, we first used AFQ to identify 20 major WM tracts and assessed WM integrity and abnormalities in a cohort of 120 subjects (39 NCs, 34 aMCI patients and 47 AD patients) in a discovery dataset and 122 subjects (43 NCs, 37 aMCI patients and 42 AD patients) in a replicated dataset. Pointwise differences along WM tracts were identified in the discovery dataset and simultaneously confirmed in the replicated dataset. Next, we investigated the utility of DTI measures along WM tracts as features to distinguish patients with AD from NCs via multilevel cross validation using a support vector machine. Correlation analysis revealed the identified microstructural WM alterations and classification output to be highly associated with cognitive ability in the patient groups, suggesting that they may be a robust biomarker of AD. This systematic study provides a pipeline to examine WM integrity and its potential clinical application in AD and may be useful for studying other neurological and psychiatric disorders.

Radiomic Features of Hippocampal Subregions in Alzheimer's Disease and Amnestic Mild Cognitive Impairment.

Alzheimer's disease (AD) is characterized by progressive dementia, especially in episodic memory, and amnestic mild cognitive impairment (aMCI) is associated with a high risk of developing AD. Hippocampal atrophy/shape changes are believed to be the most robust magnetic resonance imaging (MRI) markers for AD and aMCI. Radiomics, a method of texture analysis, can quantitatively examine a large set of features and has previously been successfully applied to evaluate imaging biomarkers for AD. To test whether radiomic features in the hippocampus can be employed for early classification of AD and aMCI, 1692 features from the caudal and head parts of the bilateral hippocampus were extracted from 38 AD patients, 33 aMCI patients and 45 normal controls (NCs). One way analysis of variance (ANOVA) showed that 111 features exhibited statistically significant group differences (P < 0.01, Bonferroni corrected). Among these features, 98 were significantly correlated with Mini-Mental State Examination (MMSE) scores in AD and aMCI subjects (P < 0.01). The support vector machine (SVM) model demonstrated that radiomic features allowed us to distinguish AD from NC with an accuracy of 86.75% (specificity = 88.89% and sensitivity = 84.21%) and an area under curve (AUC) of 0.93. In conclusion, these findings provide evidence showing that radiomic features are beneficial in detecting early cognitive decline, and SVM classification analysis provides encouraging evidence for using hippocampal radiomic features as a potential biomarker for clinical applications in AD.

Cognition-related white matter integrity dysfunction in Alzheimer's disease with diffusion tensor image.

Alzheimer's disease (AD) is a worldwide progressive neurodegenerative disorder in the elderly. Previous research has indicated that Alzheimer's disease impairs white matter (WM) tracts. Anatomical and neuroimaging studies have indicated that WM tracts are associated with cognitive function. Whether the abnormal WM integrity in AD is associated with cognitive impairments and the clinical symptoms is still not clear. To this end, we investigated the relationship between the impairments in WM tracts and the decline of cognitive ability in AD. Diffusion tensor imaging (DTI) data were collected from 38 AD patients and 30 normal, cognitively healthy volunteers. The tract-based spatial statistics (TBSS) approach was used to compare the fractional anisotropy (FA) and mean diffusivity (MD) values between the two groups. WM tracts (cingulum, superior longitudinal fasciculus (SLF), uncinate fasciculus (UF), and inferior longitudinal fasciculus (ILF)) associated with cognition function were extracted for region of interest (ROI)-based analysis. Significantly decreased FA values and increased MD values of the cognition-related WM tracts were observed in the AD group compared with the normal cognition (NC) group. In addition, we further demonstrated that the decreased FA values and increased MD values of the cognition-related WM tracts were significantly correlated with MMSE scores. These results indicated that abnormal changes in WM integrity are observed following AD. Finally, we used support vector machine (SVM) with a repeated, stratified 10-fold cross-validated classifier to evaluate the ability of FA and MD values to discriminate disease. The accuracy of the SVM using cognition-related WM as classified features was higher than that using non-cognition-related tracts. Most importantly, our results showed the relationship between abnormal WM tracts and cognitive ability in AD. These findings further suggested that AD-related impairments in cognition-related WM tracts may influence the cognitive ability of AD patients.

Frequency-Dependent Altered Functional Connections of Default Mode Network in Alzheimer's Disease.

Alzheimer's disease (AD) is a neurodegenerative disorder associated with the progressive dysfunction of cognitive ability. Previous research has indicated that the default mode network (DMN) is closely related to cognition and is impaired in Alzheimer's disease. Because recent studies have shown that different frequency bands represent specific physiological functions, DMN functional connectivity studies of the different frequency bands based on resting state fMRI (RS-fMRI) data may provide new insight into AD pathophysiology. In this study, we explored the functional connectivity based on well-defined DMN regions of interest (ROIs) from the five frequency bands: slow-5 (0.01-0.027 Hz), slow-4 (0.027-0.073 Hz), slow-3 (0.073-0.198 Hz), slow-2 (0.198-0.25 Hzs) and standard low-frequency oscillations (LFO) (0.01-0.08 Hz). We found that the altered functional connectivity patterns are mainly in the frequency band of slow-5 and slow-4 and that the decreased connections are long distance, but some relatively short connections are increased. In addition, the altered functional connections of the DMN in AD are frequency dependent and differ between the slow-5 and slow-4 bands. Mini-Mental State Examination scores were significantly correlated with the altered functional connectivity patterns in the slow-5 and slow-4 bands. These results indicate that frequency-dependent functional connectivity changes might provide potential biomarkers for AD pathophysiology.

Diffusion-weighted magnetic resonance imaging in diagnosis of Creutzfeldt-Jakob disease.

BACKGROUND: Creutzfeldt-Jakob disease (CJD), a rare disease, is uncharacterized by computed tomography (CT) and magnetic resonance imaging (MRI). This study was aimed to evaluate the diffusion-weighted MRI (DWI) manifestations of CJD and to discuss their diagnostic value. METHODS: The findings of T(1)-weighted MRI (T(1)WI), T(2)-weighted MRI (T(2)WI), DWI and post-contrast MRI in 5 patients (3 patients with biopsy-proven CJD and 2 patients with clinically-proven CJD) were retrospectively analyzed in this study. RESULTS: Four out of the 5 patients had cerebral atrophy of various degrees. One patient showed symmetric high signal intensity at the bilateral globus pallidus and the head of the caudate nucleus, with very high signal in the cerebral cortex on the DWI. This patient only had symmetric slightly high signal at the bilateral globus pallidus and putamen on T(2)WI. One patient had high signal intensity at the basal ganglia and cerebral cortex on DWI, but abnormal T(2) signal intensity at the bilateral paraventricular white matter on MRI. Two patients presented with widely gyri-like high signal intensity at the cortex on DWI, but routine MRI showed bilateral paraventricular long T(2) signal intensity in 1 patient and no abnormal findings in another. No abnormalities were shown by both routine MRI and DWI in the last patient. CONCLUSIONS: DWI is more sensitive than its conventional counterpart in the depiction of CJD. DWI is more sensitive to detect cortical abnormal signal intensity in CJD not detected by T(2)WI.