Harmonizing T1-Weighted Images to Improve Consistency of Brain Morphology Among Different Scanner Manufacturers in Alzheimer's disease

BACKGROUND

Brain MRI scanner variability can introduce bias in measurements. Harmonizing scanner variability is crucial.

PURPOSE

To develop a harmonization method aimed at removing scanner variability, and to evaluate the consistency of results in multicenter studies.

STUDY TYPE

Retrospective.

POPULATION

Multicenter data from 170 healthy participants (males/females = 98/72; age = 73.8 ± 7.3) and 170 Alzheimer's disease patients (males/females = 98/72; age = 76.2 ± 8.5) were compared with reference data from another 340 participants.

FIELD STRENGTH/SEQUENCE

3-T, magnetization prepared rapid gradient echo and turbo field echo; 1.5-T, inversion recovery prepared fast spoiled gradient echo T1-weighted sequences.

ASSESSMENT

Gray matter (GM) brain images, obtained through segmentation of T1-weighted images, were utilized to evaluate the performance of the harmonization method using common orthogonal basis extraction (HCOBE) and four other methods (removal of artificial voxel effect by linear regression, RAVEL; Z_score; general linear model, GLM; ComBat). Linear discriminant analysis (LDA) was used to access the effectiveness of different methods in reducing scanner variability. The performance of harmonization methods in preserving GM volumes heterogeneity was evaluated by the similarity of the relationship between GM proportion and age in the reference and multicenter data. Furthermore, the consistency of the harmonized multicenter data with the reference data were evaluated based on classification results (train/test = 7/3) and brain atrophy.

STATISTICAL TESTS

Two-sample t-tests, area under the curve (AUC), and Dice coefficients were used to analyze the consistency of results from the reference and harmonized multicenter data. A P-value <0.01 was considered statistically significant.

RESULTS

HCOBE reduced the scanner variability from 0.09 before harmonization to 0.003 (ideal: 0, RAVEL/Z_score/GLM/ComBat = 0.087/0.003/0.006/0.013). GM volumes showed no significant difference (P = 0.52) between the reference and HCOBE-harmonized multicenter data. Consistency evaluation showed that AUC values of 0.95 for both reference and HCOBE-harmonized multicenter data (RAVEL/Z_score/GLM/ComBat = 0.86/0.86/0.84/0.89), and the Dice coefficient increased from 0.73 before harmonization to 0.82 (ideal: 1, RAVEL/Z_score/GLM/ComBat = 0.39/0.64/0.59/0.74).

DATA CONCLUSION

HCOBE may help to remove scanner variability and could improve the consistency of results in multicenter studies.

LEVEL OF EVIDENCE

2 TECHNICAL EFFICACY STAGE: 1.

Higher Blood-brain barrier permeability in patients with major depressive disorder identified by DCE-MRI imaging

BACKGROUND

Studies from animal models and clinical trials of blood and cerebrospinal fluid have proposed that blood-brain barrier (BBB) dysfunction in depression (MDD). But there are no In vivo proves focused on BBB dysfunction in MDD patients. The present study aimed to identify whether there was abnormal BBB permeability, as well as the association with clinical status in MDD patients using dynamic contrast-enhanced magnetic resonance (DCE-MRI) imaging.

METHODS

Patients with MDD and healthy adults were recruited and underwent DCE-MRI and structural MRI scans. The mean volume transfer constant (Ktrans) values were calculated for a quantitative assessment of BBB leakage. For each subject, the mean Ktrans values were calculated for the whole gray matter, white matter, and 90 brain regions of the anatomical automatic labeling template (AAL). The differences in Ktrans values between patients and controls and between treated and untreated patients were compared.

RESULTS

23 MDD patients (12 males and 11 females, mean age 28.09 years) and 18 healthy controls (HC, 8 males and 10 females, mean age 30.67 years) were recruited in the study. We found that the Ktrans values in the olfactory, caudate, and thalamus were higher in MDD patients compared to healthy controls (p<0.05). The Ktrans values in the orbital lobe, anterior cingulate gyrus, putamen, and thalamus in treated patients were lower than the patients never treated. There were positive correlations between HAMD total score with Ktrans values in whole brain WM, hippocampus and thalamus. The total HAMA score was positively correlated with the Ktrans of hippocampus.

CONCLUSION

These findings supported a link between blood-brain barrier leakage and depression and symptom severity. The results also suggested a role for non-invasive DCE-MRI in detecting blood-brain barrier dysfunction in depression patients.

Dopaminergic damage pattern predicts phenoconversion time in isolated rapid eye movement sleep behavior disorder

PURPOSE

The exact phenoconversion time from isolated rapid eye movement (REM) sleep behavior disorder (iRBD) to synucleinopathies remains unpredictable. This study investigated whole-brain dopaminergic damage pattern (DDP) with disease progression and predicted phenoconversion time in individual patients.

METHODS

Age-matched 33 iRBD patients and 20 healthy controls with 11C-CFT-PET scans were enrolled. The patients were followed up 2-10 (6.7 ± 2.0) years. The phenoconversion year was defined as the base year, and every 2 years before conversion was defined as a stage. Support vector machine with leave-one-out cross-validation strategy was used to perform prediction.

RESULTS

Dopaminergic degeneration of iRBD was found to occur about 6 years before conversion and then abnormal brain regions gradually expanded. Using DDP, area under curve (AUC) was 0.879 (90% sensitivity and 88.3% specificity) for predicting conversion in 0-2 years, 0.807 (72.7% sensitivity and 83.3% specificity) in 2-4 years, 0.940 (100% sensitivity and 84.6% specificity) in 4-6 years, and 0.879 (100% sensitivity and 80.7% specificity) over 6 years. In individual patients, predicted stages correlated with whole-brain dopaminergic levels (r =  - 0.740, p < 0.001).

CONCLUSION

Our findings suggest that DDP could accurately predict phenoconversion time of individual iRBD patients, which may help to screen patients for early intervention.

Typical metabolic pattern of 18F-FDG PET in Anti-NMDAR encephalitis in the acute and subacute phases and its correlation with T2 FLAIR-MRI features

BACKGROUND/AIMS

Early diagnosis of Anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis with non-invasive imaging modalities benefiting is crucial to guarantee prompt treatments decision-making and good prognosis for patients. The present study aimed to explore the correlation of MRI features with brain metabolism characteristics of 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET) and to describe the metabolic patterns in Anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis at acute and subacute phases. Twenty-four patients with anti-NMDAR encephalitis confirmed by serum and/or CSF tests at acute and subacute phases, 9 females and 15 males, with an age range of 6-80 years, were enrolled in this retrospective study as encephalitis group. 18F-FDG PET and MRI findings of all patients were investigated and interpreted with visual analysis. Chi-square test was performed to compare the diagnostic sensitivity between MRI and PET. Independent sample t-test was used to compare the standardized uptake value ratio (SUVR) of each ROI between the encephalitis group and control group, which consisted of 24 healthy volunteers of the same age and gender.

RESULTS

There was no statistical difference in the diagnostic sensitivity between FDG PET (23/24, 95.83%) and MRI (18/24, 75.00%) in anti-NMDAR encephalitis patients (P > 0.05). Three categories of abnormalities shown on T2 FLAIR, including shallow of sulci and swelling of brain tissue, increased signal in the sulci, increased signal on brain gray matter or adjacent white matter presented hypermetabolism on PET, excepting increased signal in brain linear structure with hypometabolism of the basal ganglia on PET. We identified 19 brain regions with hypermetabolism and 16 brain regions with hypometabolism that exhibited statistically significant changes in SUVRs between anti-NMDAR encephalitis group and control group (FDR P < 0.05).

CONCLUSION

Anteroposterior glucose metabolism gradient (frontal-temporal/parietal-occipital) is proved to be a typical pattern of anti-NMDAR encephalitis at the acute and subacute phases in both visual and statistical testing. Interestingly, the pattern is also commonly found in the anterior and posterior portions of the parietal lobe and cingular cortex, which may be a potential indicator for the diagnosis of this disorder. In addition, MRI is an important and reliable neuroimaging modality to assist in the correct evaluation of activity changes on individual 18F-FDG PET.

Metabolic Asymmetry Relates to Clinical Characteristics and Brain Network Abnormalities in Alzheimer's Disease

BACKGROUND

Metabolic asymmetry has been observed in Alzheimer's disease (AD), but different studies have inconsistent viewpoints.

OBJECTIVE

To analyze the asymmetry of cerebral glucose metabolism in AD and investigate its clinical significance and potential metabolic network abnormalities.

METHODS

Standardized uptake value ratios (SUVRs) were obtained from 18F-FDG positron emission tomography (PET) images of all participants, and the asymmetry indices (AIs) were calculated according to the SUVRs. AD group was divided into left/right-dominant or bilateral symmetric hypometabolism (AD-L/AD-R or AD-BI) when more than half of the AIs of the 20 regions of interest (ROIs) were < -2SD, >2SD, or between±1SD. Differences in clinical features among the three AD groups were compared, and the abnormal network characteristics underlying metabolic asymmetry were explored.

RESULTS

In AD group, the proportions of AD-L, AD-R, and AD-BI were 28.4%, 17.9%, and 18.5%, respectively. AD-L/AD-R groups had younger age of onset and faster rate of cognitive decline than AD-BI group (p < 0.05). The absolute values of AIs in half of the 20 ROIs became higher at follow-up than at baseline (p < 0.05). Compared with those in AD-BI group, metabolic connection strength of network, global efficiency, cluster coefficient, degree centrality and local efficiency were lower, but shortest path length was longer in AD-L and AD-R groups (p < 0.05).

CONCLUSION

Asymmetric and symmetric hypometabolism may represent different clinical subtypes of AD, which may provide a clue for future studies on the heterogeneity of AD and help to optimize the design of clinical trials.

Neurometabolism and Ventricular Dyssynchrony in Patients With Heart Failure and Reduced Ejection Fraction

BACKGROUND

The brain coordinates the heart through the autonomic nervous system (ANS). Numerous mediator signals along the brain-heart axis interact with the neuronal-metabolic system in heart failure (HF). Disturbances in cardio-neural interactions influence the disease progression in patients with HF.

OBJECTIVES

The purpose of this study was to investigate the interactome between ANS-associated neurometabolism and ventricular dyssynchrony in patients with heart failure with reduced ejection fraction (HFrEF). Further, we studied the association of neurometabolism with major arrhythmic events (MAEs).

METHODS

A total of 197 patients with HFrEF who underwent gated single-photon emission computed tomography myocardial perfusion imaging and the brain ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography were prospectively enrolled. Relationships between the brain metabolism and MAEs were assessed using Cox models and mediation analyses. Finally, metabolic central autonomic networks were constructed and statistically compared between patients with and without MAEs.

RESULTS

In total, 35 (17.8%) patients experienced MAEs during a median follow-up of 3.1 years. In patients with HFrEF (age 58 years [IQR: 50-64 years], left ventricular ejection fraction: 20.0% [IQR: 15.0%-25.0%]), glucose hypometabolism in the insula, hippocampus, amygdala, cingulate gyrus, and caudate nucleus were independent predictors for MAEs (all P < 0.05). Cerebral hypometabolism was related to ventricular dyssynchrony, which was the predominant risk factor of MAEs. Additionally, patients who experienced MAEs presented hypoconnectivity in the metabolic central autonomic network compared with those without MAEs (P < 0.05).

CONCLUSIONS

We found an interaction of the neuronal metabolic-ventricular dyssynchronization axis in HF, which might be related to MAEs. This new brain-heart axis could expand our understanding of the distinct pathomechanisms of HFrEF.

Crossed cerebellar diaschisis-related supratentorial hemodynamic and metabolic status measured by PET/MR in assessing postoperative prognosis in chronic ischemic cerebrovascular disease patients with bypass surgery

Objective

Cerebral ischemic status is an indicator of bypass surgery. Both hemodynamics and glucose metabolism are significant factors for evaluating cerebral ischemic status. The occurrence of crossed cerebellar diaschisis (CCD) is influenced by the degree of supra-tentorial perfusion and glucose metabolism reduction. This study aimed to investigate the relationship between the CCD-related supra-tentorial blood flow and metabolic status before bypass surgery in patients with chronic and symptomatic ischemic cerebrovascular disease and the prognosis of surgery.

Methods

Twenty-four participants with chronic ischemic cerebrovascular disease who underwent hybrid positron emission tomography (PET)/magnetic resonance (MR) before bypass surgery were included. Arterial spin labeling (ASL)-MR and FDG-PET were used to measure blood flow and metabolism, respectively. The PET images were able to distinguish CCD. The supratentorial asymmetry index (AI) and volume in the decreased blood flow region, decreased metabolism region and co-decreased region on the affected side, except for the infarct area, were respectively obtained before bypass surgery. The neurological status was determined using the National Institutes of Health Stroke Scale (NIHSS) and modified Rankin Scale (mRS) scores. Differences between CCD-positive (CCD +) and CCD-negative (CCD−) groups were investigated.

Results

Fourteen (58%) of the 24 patients were diagnosed as CCD +. Before surgery, the NIHSS and mRS scores of the CCD + were significantly higher than those of the CCD− (1.0(1.0) vs. 0.0(1.0), P = 0.013; 1.0(1.5) vs. 0.0(1.5), P = 0.048). After the surgery, the NIHSS and mRS scores of the CCD + showed a significant decrease (0.0(1.0) to 0.0(0.0), P = 0.011; 0.0(0.5) to 0.0(0.0), P = 0.008). Significant differences were observed in the supra-tentorial decreased metabolism region (all Ps ≤ 0.05) between the CCD + and CCD− groups, but no differences were observed in the preprocedural decreased supratentorial blood flow region (P > 0.05). The preprocedural NIHSS score was strongly correlated with the metabolism AI value in the decreased metabolism region (r = 0.621, P = 0.001) and the co-decreased region (r = 0.571, P = 0.004).

Conclusions

Supratentorial blood flow and metabolism are important indicators of CCD. This study showed that CCD + patients benefited more from bypass surgery than CCD− patients. Staging based on CCD-related supra-tentorial blood flow and metabolic status by hybrid PET/MR may help to personalize treatment.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12149-022-01766-0.

Increased blood-brain barrier permeability of the thalamus and the correlation with symptom severity and brain volume alterations in schizophrenia patients

BACKGROUND

Cumulative evidence of microvascular dysfunction has suggested the blood-brain barrier (BBB) disruption in schizophrenia, while the direct in vivo evidence from patients is inadequate. In this study, using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) methods, we tried to test the hypothesis that there was increased BBB permeability in schizophrenia patients, and correlated with the clinical characters, and brain volumetric alterations.

METHODS

Structural MRI and DCE-MRI data from 29 schizophrenia patients and 18 age- and sex- matched controls (HC) were obtained. We calculated the volume transfer constant (K^trans) value and compared the difference between two groups. The regions with the abnormal K^trans value were extracted as ROIs (thalamus), and the correlation with the clinical characters and grey matter volume were analysed.

RESULTS

The results revealed that, compared with the HC, the volume transfer constant (K^trans) value of the bilateral thalamus in the schizophrenia group was increased (p < 0.001). There were significant positive correlations between thalamic mean K^trans value with disease duration (p < 0.05) and symptom severity (p < 0.001). Analysis of the thalamic subregions revealed that the BBB disruption was significant in pulvinar, especially the medial pulvinar nucleus (PuM) and lateral pulvinar nucleus (PuL) (p < 0.001). The K^trans value of the whole brain, thalamus, and thalamic subregions was negatively correlated with their volume separately.

CONCLUSION

These results provided the first in vivo evidence of BBB disruption of thalamus in schizophrenia patients, and the BBB dysfunction might contribute to the pathological brain structural alterations in schizophrenia.

Modulation effect of substantia nigra iron deposition and functional connectivity on putamen glucose metabolism in Parkinson's disease

Neurodegeneration of the substantia nigra affects putamen activity in Parkinson's disease (PD), yet in vivo evidence of how the substantia nigra modulates putamen glucose metabolism in humans is missing. We aimed to investigate how substantia nigra modulates the putamen glucose metabolism using a cross‐sectional design. Resting‐state fMRI, susceptibility‐weighted imaging, and [¹⁸F]‐fluorodeoxyglucose‐PET (FDG‐PET) data were acquired. Forty‐two PD patients and 25 healthy controls (HCs) were recruited for simultaneous PET/MRI scanning. The main measurements of the current study were R2* images representing iron deposition (28 PD and 25 HCs), standardized uptake value ratio (SUVr) images representing FDG‐uptake (33 PD and 25 HCs), and resting state functional connectivity maps from resting state fMRI (34 PD and 25 HCs). An interaction term based on the general linear model was used to investigate the joint modulation effect of nigral iron deposition and nigral‐putamen functional connectivity on putamen FDG‐uptake. Compared with HCs, we found increased iron deposition in the substantia nigra (p = .007), increased FDG‐uptake in the putamen (left: P_FWE < 0.001; right: P_FWE < 0.001), and decreased functional connectivity between the substantia nigra and the anterior putamen (left P_FWE < 0.001, right: P_FWE = 0.007). We then identified significant interaction effect of nigral iron deposition and nigral‐putamen connectivity on FDG‐uptake in the putamen (p = .004). The current study demonstrated joint modulation effect of the substantia nigra iron deposition and nigral‐putamen functional connectivity on putamen glucose metabolic distribution, thereby revealing in vivo pathological mechanism of nigrostriatal neurodegeneration of PD.

Assessment of cerebral glucose metabolism in patients with heart failure by 18F-FDG PET/CT imaging

BACKGROUND

To evaluate the cerebral metabolism in patients with heart failure (HF).

METHODS

One hundred and two HF patients were prospectively enrolled, who underwent gated 99mTc-sestamibi single photon emission computed tomography (SPECT)/CT, cardiac and cerebral 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT. Fifteen healthy volunteers served as controls. Patients were stratified by extent of hibernating myocardium (HM) and left ventricular ejection fraction (LVEF) into 4 groups where Group1: HM < 10% (n = 33); Group2: HM ≥ 10%, LVEF < 25% (n = 34); Group3: HM ≥ 10%, 25% ≤ LVEF ≤ 40% (n = 16) and Group 4: LVEF > 40% (n = 19). The standardized uptake value (SUV) in the whole brain (SUVwhole-brain) and the SUV ratios (SUVR) in 24 cognition-related brain regions were determined. SUVwhole-brain and SUVRs were compared between the 4 patient groups and the healthy controls.

RESULTS

SUVwhole-brain (r = 0.245, P = 0.013) and SUVRs in frontal areas, hippocampus, and para-hippocampus (r: 0.213 to 0.308, all P < 0.05) were correlated with HM. SUVwhole-brain differed between four patient groups and the healthy volunteers (P = 0.016) and SUVwhole-brain in Group 1 was lower than that in healthy volunteers (P < 0.05). SUVRs of Group 3 in frontal areas were the highest among four patient subgroups (P < 0.05).

CONCLUSIONS

Cerebral metabolism in the whole brain was reduced but maintained in cognition-related frontal areas in HF patients with HM and moderately impaired global left ventricular function.

Deep Learning With 18F-Fluorodeoxyglucose-PET Gives Valid Diagnoses for the Uncertain Cases in Memory Impairment of Alzheimer's Disease

Objectives: Neuropsychological tests are an important basis for the memory impairment diagnosis in Alzheimer’s disease (AD). However, multiple memory tests might be conflicting within-subjects and lead to uncertain diagnoses in some cases. This study proposed a framework to diagnose the uncertain cases of memory impairment.

Methods: We collected 2,386 samples including AD, mild cognitive impairment (MCI), and cognitive normal (CN) using 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) and three different neuropsychological tests (Mini-Mental State Examination, Alzheimer’s Disease Assessment Scale-Cognitive Subscale, and Clinical Dementia Rating) from the Alzheimer’s Disease Neuroimaging Initiative (ADNI). A deep learning (DL) framework using FDG-PET was proposed to diagnose uncertain memory impairment cases that were conflicting between tests. Subsequent ANOVA, chi-squared, and t-test were used to explain the potential causes of uncertain cases.

Results: For certain cases in the testing set, the proposed DL framework outperformed other methods with 95.65% accuracy. For the uncertain cases, its positive diagnoses had a significant (p < 0.001) worse decline in memory function than negative diagnoses in a longitudinal study of 40 months on average. In the memory-impaired group, uncertain cases were mainly explained by an AD metabolism pattern but mild in extent (p < 0.05). In the healthy group, uncertain cases were mainly explained by a non-energetic mental state (p < 0.001) measured using a global deterioration scale (GDS), with a significant depression-related metabolism pattern detected (p < 0.05).

Conclusion: A DL framework for diagnosing uncertain cases of memory impairment is proposed. Proved by longitudinal tracing of its diagnoses, it showed clinical validity and had application potential. Its valid diagnoses also provided evidence and explanation of uncertain cases based on the neurodegeneration and depression mental state.

A Comparative Study of Structural and Metabolic Brain Networks in Patients With Mild Cognitive Impairment

Background: Changes in the metabolic and structural brain networks in mild cognitive impairment (MCI) have been widely researched. However, few studies have compared the differences in the topological properties of the metabolic and structural brain networks in patients with MCI.

Methods: We analyzedmagnetic resonance imaging (MRI) and fluoro-deoxyglucose positron emission tomography (FDG-PET) data of 137 patients with MCI and 80 healthy controls (HCs). The HC group data comes from the Alzheimer’s Disease Neuroimaging Initiative (ADNI) database. The permutation test was used to compare the network parameters (characteristic path length, clustering coefficient, local efficiency, and global efficiency) between the two groups. Partial Pearson’s correlation analysis was used to calculate the correlations of the changes in gray matter volume and glucose intake in the key brain regions in MCI with the Alzheimer’s Disease Assessment Scale-Cognitive (ADAS-cog) sub-item scores.

Results: Significant changes in the brain network parameters (longer characteristic path length, larger clustering coefficient, and lower local efficiency and global efficiency) were greater in the structural network than in the metabolic network (longer characteristic path length) in MCI patients than in HCs. We obtained the key brain regions (left globus pallidus, right calcarine fissure and its surrounding cortex, left lingual gyrus) by scanning the hubs. The volume of gray matter atrophy in the left globus pallidus was significantly positively correlated with comprehension of spoken language (p = 0.024) and word-finding difficulty in spontaneous speech item scores (p = 0.007) in the ADAS-cog. Glucose intake in the three key brain regions was significantly negatively correlated with remembering test instructions items in ADAS-cog (p = 0.020, p = 0.014, and p = 0.008, respectively).

Conclusion: Structural brain networks showed more changes than metabolic brain networks in patients with MCI. Some brain regions with significant changes in betweenness centrality in both structural and metabolic networks were associated with MCI.

Variations of Brain Functional Connectivity in Alcohol-Preferring and Non-Preferring Rats with Consecutive Alcohol Training or Acute Alcohol Administration

Alcohol addiction is regarded as a series of dynamic changes to neural circuitries. A comparison of the global network during different stages of alcohol addiction could provide an efficient way to understand the neurobiological basis of addiction. Two animal models (P-rats screened from an alcohol preference family, and NP-rats screened from an alcohol non-preference family) were trained for alcohol preference with a two-bottle free choice method for 4 weeks. To examine the changes in the neural response to alcohol during the development of alcohol preference and acute stimulation, different trials were studied with resting-state fMRI methods during different periods of alcohol preference. The correlation coefficients of 28 regions in the whole brain were calculated, and the results were compared for alcohol preference related to the genetic background/training association. The variety of coherence patterns was highly related to the state and development of alcohol preference. We observed significant special brain connectivity changes during alcohol preference in P-rats. The comparison between the P- and NP-rats highlighted the role of genetic background in alcohol preference. The results of this study support the alterations of the neural network connection during the formation of alcohol preference and confirm that alcohol preference is highly related to the genetic background. This study could provide an effective approach for understanding the neurobiological basis of alcohol addiction.

Gout Is Not Just Arthritis: Abnormal Cortical Thickness and Structural Covariance Networks in Gout

Background: Hyperuricemia is the cause of gout. The antioxidant and neuroprotective effects of uric acid seem to benefit some patients with central nervous system injury. However, changes in the brain structure have not been discovered in patients with gout.

Object: Clarify the changes in cortical thickness in patients with gout and the alteration of the structural covariance networks (SCNs) based on cortical thickness.

Methods: We collected structural MRIs of 23 male gout patients and 23 age-matched healthy controls. After calculating and comparing the difference in cortical thickness between the two groups, we constructed and analyzed the cortical thickness covariance networks of the two groups, and we investigated for any changes in SCNs of gout patients.

Results: Gout patients have thicker cortices in the left postcentral, left supramarginal, right medial temporal, and right medial orbitofrontal regions; and thinner cortices were found in the left insula, left superior frontal, right pericalcarine, and right precentral regions. In SCN analysis, between-group differences in global network measures showed that gout patients have a higher global efficiency. In regional network measures, more nodes in gout patients have increased centrality. In network hub analysis, we found that the transfer of the core hub area, rather than the change in number, may be the characteristic of the gout's cortical thickness covariance network.

Conclusion: This is the first study on changes in brain cortical thickness and SCN based on graph theory in patients with gout. The present study found that, compared with healthy controls, gout patients show regional cortical thinning or thickening, and variation in the properties of the cortical thickness covariance network also changed. These alterations may be the combined effect of disease damage and physiological compensation. More research is needed to fully understand the complex underlying mechanisms of gout brain variation.

The integrity of the white matter in first-episode schizophrenia patients with auditory verbal hallucinations: An atlas-based DTI analysis

Auditory verbal hallucination (AVH) is one of the most remarkable symptoms of schizophrenia, with great impact on patients' lives and unclear pathogenesis. Neuroimaging studies have indicated that the development of AVHs is associated with white matter alteration, however, there are still inconsistencies in specific findings across previous investigations. The present study aimed to investigate the characteristics of the microstructural integrity of white matter (WM) in first-episode schizophrenia patients who experience auditory hallucinations. Atlas-based Diffusion Tensor Imaging (DTI) analysis was performed to evaluate the white matter integrity in 37 first-episode schizophrenia patients with AVH, 60 schizophrenia patients without AVH, and 50 healthy controls. Compared with the healthy controls group, AVH showed decreased mean fractional anisotropy (FA) in the genu and body of corpus callosum, right posterior corona radiata, left superior corona radiata, left external capsule, right superior fronto-occipital fasciculus, and higher mean diffusivity (MD) in genu of corpus callosum and left fornix and stria terminalis; whereas the nAVH group showed a much more significant reduction of FA and increased MD in broader brain regions. In addition, a significant positive correlation between FA and the severity of AVHs was observed in right posterior corona radiate. These observations collectively demonstrated that a certain degree of preserved fronto-temporal and interhemispheric connectivity in the early stage of schizophrenia might be associated with the brain capability to generate AVHs.

Altered coupling between resting-state glucose metabolism and functional activity in epilepsy

OBJECTIVE

Altered functional activities and hypometabolism have been found in medial temporal lobe epilepsy patients with hippocampal sclerosis (mTLE-HS). Hybrid PET/MR scanners provide opportunities to explore the relationship between resting-state energy consumption and functional activities, but whether repeated seizures disturb the bioenergetic coupling and its relationship with seizure outcomes remain unknown.

METHODS

¹⁸ F-FDG PET and resting-state functional MRI (rs-fMRI) scans were performed with hybrid PET/MR in 26 patients with mTLE-HS and in healthy controls. Energy consumption was quantified by ¹⁸ F-FDG standardized uptake value ratio(SUVR) relative to cerebellum. Spontaneous neural activities were estimated using regional homogeneity (ReHo), fractional amplitude of low frequency fluctuations (fALFF) from rs-fMRI. Between-group differences in SUVR and rs-fMRI derived metrics were evaluated by two-sample t test. Voxel-wise spatial correlations were explored between SUVR and ReHo, fALFF across gray matter and compared between groups. Furthermore, the relationships between altered fALFF/SUVR and ReHo/SUVR coupling and surgical outcomes were evaluated.

RESULTS

Both the patients and healthy controls showed significant positive correlations between SUVR and rs-fMRI metrics. Spatial correlations between SUVR and fMRI-derived metrics across gray matter were significantly higher in patients with mTLE-HS compared with healthy controls (fALFF/SUVR, P < 0.001; ReHo/SUVR, P = 0.022). Higher fALFF/SUVR couplings were found in patients who had Engel class IA after surgery than all other (P = 0.025), while altered ReHo/SUVR couplings (P = 0.097) were not.

CONCLUSION

These findings demonstrated altered bioenergetic coupling across gray matter and its relationship with seizure outcomes, which may provide novel insights into pathogenesis of mTLE-HS and potential biomarkers for epilepsy surgery planning.

Age-related atrophy of cortical thickness and genetic effect of ANK3 gene in first episode MDD patients

Brain ageing is thought to be related to geriatric depression, but the relationship between ageing and depression among middle aged individuals is unknown. The present study aimed to evaluate whether the age-related reduction of brain cortical thickness (CT) can be found in adult first-episode MDD patients, as well as to identify the possible genetic effect of the ANK3 gene polymorphism age-relates CT reduction. This study recruited 153 first-episode MDD patients with a disease duration < 2 years and 276 healthy controls (HC), and the CT of 68 whole brain regions and two ANK3 SNPs (rs1994336 and rs10994359) were analyzed. The results showed that although the CT of both groups was negative correlated with age, the MDD group had significant greater age-related decrease in CT than the HC group (–9.35 × 10⁻³ mm/year for MDD vs. –1.23 × 10⁻³ mm/year for HC in the left lateral orbitofrontal lobe). The multivariate analysis of covariance (MANCOVA) results yielded significant interactions of diagnosis × age, genotype × age and diagnosis × genotype interaction for rs10994359. In HC, the C allele showed a protective effect on age-related CT reduction. The reduction in CT with age was several times as greater in non-C carriers as in C carriers (–3.54 × 10⁻³ vs.–0.15 × 10⁻³ mm/year in left supramarginal gyrus) for HC. However, this protective effect disappeared in patients with MDD. We did not find a clear effect of rs1994336 on the age-related CT reduction. The findings indicate that the widespread accelerated brain ageing occurs early in adult-onset depression and this ageing may be a pathological mechanisms of depression rather than an outcome of the disease. The ANK3 rs10994359 polymorphism may partially affect regional cortical ageing in MDD.

Sleeve Gastrectomy Rescuing the Altered Functional Connectivity of Lateral but Not Medial Hypothalamus in Subjects with Obesity

BACKGROUND

Lateral and medial hypothalamus (LH and MH) play important roles in energy balance. Changed hypothalamic function has been found in subjects with obesity. However, the effect of bariatric surgery on the function of the two sub-regions has been poorly investigated.

METHODS

Thirty-eight subjects with obesity and 34 age- and sex-matched normal-weight controls were included. Seventeen of the 38 subjects underwent laparoscopic sleeve gastrectomy. Functional magnetic resonance imaging data and metabolic parameters were collected to investigate functional connectivity networks of the two hypothalamic sub-regions as well as the influence of sleeve gastrectomy on the two networks in subjects with obesity.

RESULTS

Compared to normal-weight controls, pre-surgical subjects had increased functional connectivity (FC) in the reward region (putamen) within the LH network, and increased FC in somatosensory cortical area (insula), as well as decreased FC in the cognitive control regions (prefrontal regions) within the MH network. After the surgery, post-surgical FC of the putamen within the LH network changed towards the patterns found in the control group. Furthermore, the changes in fasting glucose before and after the surgery were associated with the changes in FC of the putamen within the LH network.

CONCLUSIONS

The FC within the LH and MH networks were changed in subjects with obesity. Part of these altered FC was rescued after the surgery.

Subthreshold depression may exist on a spectrum with major depressive disorder: Evidence from gray matter volume and morphological brain network

BACKGROUND

Subthreshold depression (StD) is a prevalent condition that may increase the risk of incident major depressive disorder (MDD). However, the relationship between StD and MDD remains unclear.

METHODS

A total of 153 adult subjects, including 53 drug-naive MDD, 50 StD and 50 healthy control (HC) subjects, underwent a T1-weighted magnetic resonance imaging scan, and the gray matter volume (GMV) alterations among the three groups were quantitatively analyzed using voxel-based morphometry (VBM). Then, to capture the whole-brain connectivity characteristics, we constructed morphological brain networks (MBN) based on the similarity among brain regions of individual VBM images and compared the network connection strengths among the three groups.

RESULTS

The StD and MDD subjects had similar patterns of GMV reductions in the orbitofrontal cortex and left temporal gyrus, although the magnitude of the reductions was smaller in StD subjects. Moreover, a total of 21 morphological connections were significantly different among the three groups. For the majority of the different connections (15/21), the connection strength of the StD group took an intermediate position between that of the MDD and HC groups.

LIMITATIONS

There is still a lack of a consistent definition of StD, and the age range of the subjects in this study was wide. Meanwhile the mechanisms and biological significance of the MBN remains to be clarified.

CONCLUSIONS

These results may support the hypothesis that depression is better expressed as a spectrum and that StD exists on a spectrum with MDD.

Distinct relationships of amyloid-beta and tau deposition to cerebral glucose metabolic networks in Alzheimer's disease

Extracellular accumulation of amyloid-beta peptides and intracellular neurofibrillary tangles (NFTs) of hyperphosphorylated tau proteins are the two cardinally pathological hallmarks of Alzheimer's disease (AD). However, their exact roles in the mechanisms of AD progression are not well established. Given that AD is a disconnection syndrome and hypometabolism is one of its most important neurodegenerative indicators, we hypothesized amyloid-beta and tau burden may disturb the glucose metabolic network of AD. Here we investigated the relationship of these two factors to regional metabolic network properties using multimodal positron emission tomography (PET) imaging data. Participants included six groups covering from cognitively normal controls, patients with early cognitive impairment (MCI), late MCI, mild AD, moderate AD to severe AD who underwent amyloid-beta PET, tau PET and fluorodeoxyglucose (FDG) PET. Glucose metabolic network of each group was constructed and relations of amyloid-beta and tau to regional metabolic network measurements were investigated. Results revealed distinct associations of these two hallmarks to metabolic networks: amyloid-beta were positively related to metabolic network measurements at relative early phases of AD, while tau burden showed a negative relationship at late phase of AD. These results supported the notion that amyloid-beta and tau accumulation may contribute independently to mechanisms of AD. Furthermore, these findings might also provide connectivity evidence for the speculation that amyloid-beta deposition is protective to neuronal activity.

Tau PET Distributional Pattern in AD Patients with Visuospatial Dysfunction

BACKGROUND

Visuospatial dysfunction is one predominant symptom in many atypical Alzheimer's disease (AD) patients, however, until now its neural correlates still remain unclear. For the accumulation of intracellular hyperphosphorylated tau proteins is a major pathogenic factor in neurodegeneration of AD, the distributional pattern of tau could highlight the affected brain regions associated with specific cognitive deficits.

OBJECTIVE

We investigated the brain regions particularly affected by tau accumulation in patients with visuospatial dysfunction to explore its neural correlates.

METHODS

Using 18F-AV-1451 tau positron emission tomography (PET), voxel-wise two-sample t-tests were performed between AD patients with obvious visuospatial dysfunction (VS-AD) and cognitively normal subjects, AD patients with little-to-no visuospatial dysfunction (non VS-AD) and cognitively normal subjects, respectively.

RESULTS

Results showed increased tau accumulations mainly located in occipitoparietal cortex, posterior cingulate cortex, precuneus, inferior and medial temporal cortex in VS-AD patients, while increased tau accumulations mainly occurred in the inferior and medial temporal cortex in non VS-AD patients.

CONCLUSION

These findings suggested that occipitoparietal cortex, posterior cingulate cortex and precuneus, which were particularly affected by increased tau accumulation in VS-AD patients, may associate with visuospatial dysfunction of AD.

Sleeve Gastrectomy Recovering Disordered Brain Function in Subjects with Obesity: a Longitudinal fMRI Study

OBJECTIVE

Bariatric surgery could recover regional dysfunction of cerebral cortex. However, it is unknown whether bariatric surgery could recover the global-level dysfunction in subjects with obesity. The aim of this study was to investigate the effect of bariatric surgery on global-level dysfunction in subjects with obesity by resting-state functional magnetic resonance imaging (fMRI).

METHODS

Resting-state fMRI was used to investigate dysfunction of whole-brain in 34 subjects with obesity and 34 age-and gender-matched normal-weight subjects, in which 17 subjects with obesity received sleeve gastrectomy. Fractional amplitude of low-frequency fluctuation (fALFF) and functional connectivity (FC) among the whole brain were used to estimate the brain functional differences among the preoperative subjects, postoperative subjects, and the controls.

RESULTS

The preoperative subjects compared to controls had decreased resting-state activities in reward processing and cognitive control regions such as orbitofrontal cortex, middle frontal gyrus, superior frontal gyrus, and gyrus rectus. It was important that increased FC was also found in these regions. Correlation analysis showed that body mass index (BMI) was associated with these decreased activity and increased FC. More importantly, the dysfunction in these regions was recovered by the bariatric surgery.

CONCLUSIONS

These results suggest that bariatric surgery-induced weight loss could reverse the global-level dysfunction in subjects with obesity. The dysfunction in these regions might play a key role in the development of obesity, which might serve as a biomarker in the treatment of obesity.

A human brain tau PET template in MNI space for the voxel-wise analysis of Alzheimer's disease

BACKGROUND

Positron emission tomography (PET) imaging techniques of tau retention in the human brain are important for mechanistic studies of Alzheimer's disease (AD). However, the method for effectively conducting voxel-wise analysis on tau PET images still needs to be improved. In the present study, we introduced a tau PET template for the human brain in Montreal Neurological Institute (MNI) space for the convenient and reliable voxel-wise analysis of tau PET images in AD studies.

NEW METHOD

Twenty-four AD patients and 22 controls were used to construct the tau PET template, and an additional 22 subjects (11 AD patients and 11 controls) were enrolled to evaluate the performance of the template. Thirty regions (28 cortical and 2 subcortical regions) throughout the brain were used to evaluate the accuracy of the tau PET template.

RESULTS

A significant relationship (R² = 0.848, P < 0.001) was found between the standardized uptake value ratios (SUVRs) obtained by the tau PET template and magnetic resonance imaging (MRI)-aided approach, and the paired-sample t-test showed no significant difference (P = 0.62) between the values. These two approaches revealed consistent brain regions with high tau retention.

COMPARISON WITH EXISTING METHODS

The tau PET template was comparable with the traditional MRI-aided strategy. Furthermore, compared to the MRI-aided approach, the tau PET template was more convenient and easier to use. More importantly, in most clinical settings, AD patients who underwent PET/computed tomography (CT) typically do not have MR images, in which case the traditional MRI-aided approach would not be applicable. Our tau PET template overcame this deficiency and may serve as a useful tool in AD research.

CONCLUSIONS

This tau PET template performed well and may serve as a useful tool in future AD studies.

A population stereotaxic positron emission tomography brain template for the macaque and its application to ischemic model

PURPOSE

Positron emission tomography (PET) is a non-invasive imaging tool for the evaluation of brain function and neuronal activity in normal and diseased conditions with high sensitivity. The macaque monkey serves as a valuable model system in the field of translational medicine, for its phylogenetic proximity to man. To translation of non-human primate neuro-PET studies, an effective and objective data analysis platform for neuro-PET studies is needed.

MATERIALS AND METHODS

A set of stereotaxic templates of macaque brain, namely the Institute of High Energy Physics & Jinan University Macaque Template (HJT), was constructed by iteratively registration and averaging, based on 30 healthy rhesus monkeys. A brain atlas image was created in HJT space by combining sub-anatomical regions and defining new 88 bilateral functional regions, in which a unique integer was assigned for each sub-anatomical region.

RESULTS

The HJT comprised a structural MRI T1 weighted image (T1WI) template image, a functional FDG-PET template image, intracranial tissue segmentations accompanied with a digital macaque brain atlas image. It is compatible with various commercially available software tools, such as SPM and PMOD. Data analysis was performed on a stroke model compared with a group of healthy controls to demonstrate the usage of HJT.

CONCLUSION

We have constructed a stereotaxic template set of macaque brain named HJT, which standardizes macaque neuroimaging data analysis, supports novel radiotracer development and facilitates translational neuro-disorders research.

MicroRNA-577 promotes the sensitivity of chronic myeloid leukemia cells to imatinib by targeting NUP160

OBJECTIVE

To explore the effect of microRNA-577 on the drug sensitivity of chronic myeloid leukemia (CML) and the underlying mechanism.

PATIENTS AND METHODS

Quantitative Real Time-Polymerase Chain Reaction (qRT-PCR) was used to detect the expression of microRNA-577 in peripheral blood of patients with chronic myeloid leukemia. Meanwhile, the expression of microRNA-577 was detected in CML cell line after imatinib treatment. Cell counting kit-8 (CCK-8) and flow cytometry assay were applied to verify the effect of microRNA-577 on cell proliferation and cycle. NUP160 was identified as a target gene of microRNA-577 by dual-luciferase reporter gene assay. Cell reverse test was performed to figure out whether microRNA-577 can enhance the sensitivity of CML to imatinib.

RESULTS

QRT-PCR results revealed that microRNA-577 level was notably decreased in peripheral blood of patients with CML, and microRNA-577 could inhibit the proliferation and cycle of CML cells. In addition, the result of dual-luciferase reporting assay indicated that microRNA-577 had a binding relationship with NUP160, and up-regulation of microRNA-577 in CML cell lines reduced the expression of NUP160, and vice versa. Lastly, cell reverse experiments confirmed that microRNA-577 can alleviate the resistance of CML to imatinib.

CONCLUSIONS

We found that microRNA-577 promotes the sensitivity of chronic myeloid leukemia cells to imatinib by down-regulating the expression of NUP160.

Mutation and association analyses of dementia-causal genes in Han Chinese patients with early-onset and familial Alzheimer's disease

Alzheimer's disease (AD) is the most common cause of dementia in the elderly. It shares clinical and pathological features with other types of dementia, such as vascular dementia (VaD), Lewy body dementia (LBD), and frontotemporal dementia (FTD). We have hypothesized that there might be an overlapping molecular mechanism and genetic basis to the different types of dementia. In this study, we analyzed the mutation pattern of dementia-causal genes in 169 Han Chinese patients with familial and early-onset AD by using whole exome sequencing or targeted resequencing. We identified 9 potentially pathogenic mutations in the AD-causal genes APP, PSEN1, PSEN2, and 6 mutations in a group of non-AD dementia-causal genes including the FTD-causal gene GRN and the VaD-causal gene NOTCH3. A common splice-site variant rs514492 in the FTD-causal gene VCP showed a positive association with AD risk (P = 0.0003, OR = 1.618), whereas the rare missense variant rs33949390 (p. R 1628P) in the LBD-causal gene LRRK2 showed a protective effect on AD risk (P = 0.0004, OR = 0.170). The presence of putative pathogenic mutations and risk variants in these causal genes for different types of dementia in clinically diagnosed familial and early-onset AD patients suggests a need to screen for mutations of the dementia-causal genes in cases of AD to avoid misdiagnosis. These mutations also support the idea that there are overlapping pathomechanisms between AD and other forms of dementia.

Genome-wide identification and comparison of mRNAs, lncRNAs and circRNAs in porcine intramuscular, subcutaneous, retroperitoneal and mesenteric adipose tissues

Many types of RNAs, including messenger RNAs (mRNAs), long noncoding RNAs (lncRNAs) and circular RNAs (circRNAs), play crucial roles in regulating fat cell differentiation and tissue development. However, the expression profiles of these RNAs in different adipose tissues are still largely unknown. To shed light on this issue, we performed a transcriptome analysis of mRNAs, lncRNAs and circRNAs obtained from intramuscular adipose tissue, subcutaneous adipose tissue, retroperitoneal adipose tissue and mesenteric adipose tissue of Chinese Erhualian pigs. A number of differentially expressed mRNAs, lncRNAs and circRNAs were identified among the four adipose tissues. Tissue-specific analysis indicated that circRNAs exhibited the highest tissue specificity among mRNAs, lncRNAs and circRNAs, whereas intramuscular adipose tissue had the most tissue-specific genes among the four adipose tissues. Gene Ontology analysis showed that differentially expressed mRNAs among groups were involved mainly in lipid metabolism and immune inflammatory response processes. Furthermore, the co-expression network construction of mRNAs-lncRNAs revealed that several important lncRNAs, such as MSTRG.426159 and MSTRG.604206, might associate with lipid metabolic process. Taken together, these data provide a genome-wide resource of mRNAs, lncRNAs and circRNAs potentially involved in porcine fat metabolism, thus improving understanding of their function in diverse adipose tissues.

Changes in cerebral glucose metabolism after acupuncture at KI3 in spontaneously hypertensive rats: a positron emission tomography study

Objective:

The aim of this study was to explore the effect of acupuncture stimulation at KI3 on brain glucose metabolism in spontaneously hypertensive rats (SHRs).

Methods:

Brain glucose metabolism in SHRs after acupuncture stimulation at KI3 was detected using 18F-2-fluorodeoxy-D-glucose positron emission tomography (18F-FDG-PET). SHRs were randomly divided into three groups: no treatment (SHR group); acupuncture at KI3 (KI3 group); and sham acupuncture (Sham group). Wistar Kyoto (WKY) rats were used as a normal blood pressure (BP) control group. Rats were subjected to 10 min of acupuncture once a day for 7 days. BP and positron emission tomography–computed tomography (PET-CT) were measured after the first acupuncture session and after 7 days of treatment.

Results:

The results showed that BP was lower in the KI3 group than in the SHR group, both 30–60 min after the first acupuncture session and 24–48 h after the 7-day treatment. Compared with the WKY group, the SHR group had lower glucose metabolism in the motor cortex, sensory cortex, basal ganglia, corpus callosum, caudate putamen, and visual cortex. Compared with the untreated/sham-treated SHR control groups, cerebral glucose metabolism was lower in the medulla oblongata, thalamus, dorsal thalamus, orbital cortex, and hypothalamus after acupuncture at KI3, while it was higher in the olfactory cortex and inferior phrenic muscle.

Conclusion:

Our results show that, in SHRs, needling at KI3 reduces high BP, most likely by altering the activation of cerebral regions.

MAGE-A is frequently expressed in triple negative breast cancer and associated with epithelial-mesenchymal transition

Epithelial-mesenchymal transition (EMT) is a crucial step in tumor metastasis. Triple negative (TN) breast cancer, a high metastasis phenotype, has been verified to be associated with EMT. Melanoma associated antigen-A (MAGE-A) is exclusively expressed in cancers with high aggressiveness as well as unfavorable prognosis and likely to be associated with EMT of triple negative breast cancer (TNBC). The aim of the study is to analyze the expression profile of MAGE-A in breast cancer and the correlation between MAGE-A and EMT of TNBC. Immunohistochemistry (IHC) was performed to assess the prevalence of MAGE-A, vimentin, E-cadherin and β-catenin in breast cancer tissues and correlate them with clinical pathological parameters. The association between MAGE-A and EMT markers was also evaluated. Scratch assay and transwell invasion assay were carried out to evaluate the impact of MAGE-A down-regulation on migration and invasion of the breast cancer cells. Real-time PCR was also conducted to evaluate alterations in EMT markers with decrease in MAGE-A. The results showed that MAGE-A was absent in normal tissue but expressed in tumor samples with the incidence of 49.17% (P=0.008). MAGE-A staining was higher in TNBC (76.47%, 13/17), followed by HER-2(+) (53.85%, 7/13) and Luminal set (43.33%, 39/90), and it was significantly correlated with ER (-), PR (-), HER-2 (-), lymph nodes involvement and higher histological grade (P<0.05). E-cadherin-positivity was frequent in Luminal set (94.44%, 85/90) and linked to ER (+), negative lymph nodes and lower histological grade (P<0.05). Vimentin expression was often observed in TNBC (70.56%, 12/17) and ER (-), PR (-), lymph nodes (+) groups (P<0.05). Expression of β-catenin was prevalent in Luminal set (93.33%, 84/90) and correlated with ER (+), PR (+) and lower histological grade (P<0.05). MAGE-A was inversely associated with E-cadherin (P=0.011) and β-catenin (P=0.048) but expressed in the same trend with vimentin (P=0.000). Migration and invasion of MDA-MB-231 were inhibited when MAGE-A decreased. Increase in epithelial markers and decline in mesenchymal indicators were also seen with MAGE-A reduction. Snail, Slug, ZEB1 and ZEB2 were also down-regulated. In conclusion, MAGE-A may be responsible for high aggressiveness and EMT of TNBC and can be a new choice for targeted therapy.

A stereotaxic MRI template set of mouse brain with fine sub-anatomical delineations: Application to MEMRI studies of 5XFAD mice

PURPOSE

Manganese-enhanced magnetic resonance imaging (MEMRI) can help us trace the active neurons and neuronal pathway in transgenic mouse AD model. 5XFAD has been widespread accepted as a valuable model system for studying brain dysfunction progresses in the courses of AD. To further understand the development of AD at early stages, an effective and objective data analysis platform for MEMRI studies should be constructed.

MATERIALS AND METHODS

A set of stereotaxic templates of mouse brain in Paxinos and Franklin space, "the Institute of High Energy Physics Mouse Template", or IMT for short, was constructed by iteratively registration and averaging. An atlas image was reconstructed from the Paxinos and Franklin atlas figures and each sub-anatomical segmentation was assigning a unique integer. An analysis SPM plug-in toolbox was further created, that automates and standardizes the time-consuming processes of brain extraction, tissue segmentation, and statistical analysis for MEMRI scans.

RESULTS

The IMT comprised a T2WI template image, a MEMRI template image, intracranial tissue segmentations, and accompany with a digital mouse brain atlas image, in which 707 sub-anatomical brain regions are delineated. Data analyses were performed on groups of developing 5XFAD mice to demonstrate the usage of IMT, and the results shows that abnormal neuronal activity occurs at early stage in 5XFAD mice.

CONCLUSION

We have constructed a stereotaxic template set of mouse brain named IMT with fine delineations of sub-anatomical structures, which is compatible with SPM. It will give a widely range of researchers a standardized coordinate system for localization of any mouse brain related data.

Abnormal Metabolic Connectivity in Rats at the Acute Stage of Ischemic Stroke

Stroke at the acute stage is a major cause of disability in adults, and is associated with dysfunction of brain networks. However, the mechanisms underlying changes in brain connectivity in stroke are far from fully elucidated. In the present study, we investigated brain metabolism and metabolic connectivity in a rat ischemic stroke model of middle cerebral artery occlusion (MCAO) at the acute stage using 18F-fluorodeoxyglucose positron emission tomography. Voxel-wise analysis showed decreased metabolism mainly in the ipsilesional hemisphere, and increased metabolism mainly in the contralesional cerebellum. We used further metabolic connectivity analysis to explore the brain metabolic network in MCAO. Compared to sham controls, rats with MCAO showed most significantly reduced nodal and local efficiency in the ipsilesional striatum. In addition, the MCAO group showed decreased metabolic central connection of the ipsilesional striatum with the ipsilesional cerebellum, ipsilesional hippocampus, and bilateral hypothalamus. Taken together, the present study demonstrated abnormal metabolic connectivity in rats at the acute stage of ischemic stroke, which might provide insight into clinical research.

Altered regional and circuit resting-state activity in patients with occult spastic diplegic cerebral palsy

BACKGROUND

Very few studies have been made to investigate functional activity changes in occult spastic diplegic cerebral palsy (SDCP). The purpose of this study was to analyze whole-brain resting state regional brain activity and functional connectivity (FC) changes in patients with SDCP.

METHODS

We examined 12 occult SDCP and 14 healthy control subjects using resting-state functional magnetic resonance imaging. The data were analyzed using Resting-State fMRI Data Analysis Toolkit (REST) software. The regional homogeneity (ReHo), amplitude of low-frequency fluctuations (ALFF), and whole brain FC of the motor cortex and thalamus were analyzed and compared between the occult SDCP and control groups.

RESULTS

Compared with the control group, the occult SDCP group showed decreased ReHo regions, including the bilateral frontal, parietal, and temporal lobes, the cerebellum, right cingulate gyrus, and right lenticular nucleus, whereas an increased ReHo value was observed in the left precuneus, calcarine, fusiform gyrus, and right precuneus. Compared with the control group, no significant differences in ALFF were noted in the occult SDCP group. With the motor cortex as the region of interest, the occult SDCP group showed decreased connectivity regions in the bilateral fusiform and lingual gyrus, but increased connectivity regions in the contralateral precentral and postcentral gyrus, supplementary motor area, and the ipsilateral postcentral gyrus. With the thalamus being regarded as the region of interest, the occult SDCP group showed decreased connectivity regions in the bilateral basal ganglia, cingulate, and prefrontal cortex, but increased connectivity regions in the bilateral precentral gyrus, the contralateral cerebellum, and inferior temporal gyrus.

CONCLUSIONS

Resting-state regional brain activities and FC changes in the patients with occult SDCP exhibited a special distribution pattern, which is consistent with the pathology of the disease.

An Automatic Method for Generating an Unbiased Intensity Normalizing Factor in Positron Emission Tomography Image Analysis After Stroke

Positron emission tomography (PET) imaging of functional metabolism has been widely used to investigate functional recovery and to evaluate therapeutic efficacy after stroke. The voxel intensity of a PET image is the most important indicator of cellular activity, but is affected by other factors such as the basal metabolic ratio of each subject. In order to locate dysfunctional regions accurately, intensity normalization by a scale factor is a prerequisite in the data analysis, for which the global mean value is most widely used. However, this is unsuitable for stroke studies. Alternatively, a specified scale factor calculated from a reference region is also used, comprising neither hyper- nor hypo-metabolic voxels. But there is no such recognized reference region for stroke studies. Therefore, we proposed a totally data-driven automatic method for unbiased scale factor generation. This factor was generated iteratively until the residual deviation of two adjacent scale factors was reduced by < 5%. Moreover, both simulated and real stroke data were used for evaluation, and these suggested that our proposed unbiased scale factor has better sensitivity and accuracy for stroke studies.

Clinical Factors Associated with Brain Volume Reduction in Systemic Lupus Erythematosus Patients without Major Neuropsychiatric Manifestations

The aim of the study was to find structural brain changes in systemic lupus erythematosus patients without major neuropsychiatric manifestations [non-neuropsychiatric systemic lupus erythematosus (non-NPSLE)] using quantitative magnetic resonance imaging (MRI) and possible associations with clinical characteristics. 89 non-NPSLE patients with normal conventional MRI and 84 healthy controls (HCs) were recruited. The whole brain gray matter volume (GMV) and white matter volume (WMV) were calculated for each individual. We found obvious GMV and WMV reduction in the systemic lupus erythematosus (SLE) group compared with HCs. Female patients showed significant reduction of GMV and WMV compared with male patients. Patients treated with immunosuppressive agents (ISA) showed less WMV reduction than those without. Cognitive impairment was the most common subclinical neuropsychiatric manifestation and had a prevalence of 46.1%. Association between WMV reduction with cognitive impairment was found. Thus, we concluded that structural brain atrophy could happen even before occurrence of obvious neuropsychiatric signs and symptoms and was associated with subclinical symptoms such as cognitive impairment. ISA treatment might have a protective effect on the brain atrophy. Early treatment might prevent the progressive damage to the brain. More studies are needed to fully understand the complicated underlying mechanisms of brain atrophy in SLE.

Associations Among Suicidal Ideation, White Matter Integrity and Cognitive Deficit in First-Episode Schizophrenia

Objective: The study was aimed to investigate the possible associations among suicidal ideation, brain white matter (WM) integrity and cognitive deficit in first-episode schizophrenia (FES) using diffusion tensor imaging. Methods: The sample contained 18 FES patients with suicidal ideation (SI+), 45 FES patients without suicidal ideation (SI-) and 44 healthy controls. The Calgary Depression Scale for Schizophrenia was used to measure the suicidal ideation and depression symptoms. The whole brain WM integrity and three domains of cognitive function: working memory, verbal comprehension as well as processing speed were compared between the three groups. Results: Compared with SI-, SI+ showed preserved WM integrity as indicated by significantly higher factional anisotropy (FA) or lower mean diffusivity (MD) in multiple WM tracts, and higher FA coupled with lower MD in bilateral posterior corona radiata. Compared with SI-, SI+ were more depressed and had less cognitive deficit in working memory and verbal comprehension. The fiber tracts in bilateral posterior corona radiata connect to the precuneus as shown by probabilistic tractography, and their WM integrity disruptions were found to be positively associated with the cognitive deficits in the FES patients. Discussion: Preserved WM integrity may be a risk factor for suicidal ideation in FES patients. One possible explanation is that it contributes to preserved cognitive function, especially in working memory and verbal comprehension, which may be associated with greater insight and could lead to increased depression and suicidal ideation. The posterior corona radiata and the precuneus may be linked to the related biological processes.

A Conscious Resting State fMRI Study in SLE Patients Without Major Neuropsychiatric Manifestations

Neuropsychiatric systemic lupus erythematosus (NPSLE) is one of the main causes of death in patients with systemic lupus erythematosus (SLE). Signs and symptoms of NPSLE are heterogeneous, and it is hard to diagnose, and treat NPSLE patients in the early stage. We conducted this study to explore the possible brain activity changes using resting state functional magnetic resonance imaging (rs-fMRI) in SLE patients without major neuropsychiatric manifestations (non-NPSLE patients). We also tried to investigate the possible associations among brain activity, disease activity, depression, and anxiety. In our study, 118 non-NPSLE patients and 81 healthy controls (HC) were recruited. Rs-fMRI data were used to calculate the regional homogeneity (ReHo) in all participants. We found decreased ReHo values in the fusiform gyrus and thalamus and increased ReHo values in the parahippocampal gyrus and uncus. The disease activity was positively correlated with ReHo values of the cerebellum and negatively correlated with values in the frontal gyrus. Several brain areas showed correlations with depressive and anxiety statuses. These results suggested that abnormal brain activities might occur before NPSLE and might be the foundation of anxiety and depression symptoms. Early detection and proper treatment of brain dysfunction might prevent the progression to NPSLE. More studies are needed to understand the complicated underlying mechanisms.

Stereotaxic 18F-FDG PET and MRI templates with three-dimensional digital atlas for statistical parametric mapping analysis of tree shrew brain

BACKGROUND

Tree shrews are proposed as an alternative animal model to nonhuman primates due to their close affinity to primates. Neuroimaging techniques are widely used to study brain functions and structures of humans and animals. However, tree shrews are rarely applied in neuroimaging field partly due to the lack of available species specific analysis methods.

NEW METHOD

In this study, 10 PET/CT and 10 MRI images of tree shrew brain were used to construct PET and MRI templates; based on histological atlas we reconstructed a three-dimensional digital atlas with 628 structures delineated; then the digital atlas and templates were aligned into a stereotaxic space. Finally, we integrated the digital atlas and templates into a toolbox for tree shrew brain spatial normalization, statistical analysis and results localization.

RESULTS

We validated the feasibility of the toolbox by simulated data with lesions in laterodorsal thalamic nucleus (LD). The lesion volumes of simulated PET and MRI images were (12.97±3.91)mm³ and (7.04±0.84)mm³. Statistical results at p<0.005 showed the lesion volumes of PET and MRI were 13.18mm³ and 8.06mm³ in LD.

COMPARISON WITH EXISTING METHOD(S)

To our knowledge, we report the first PET template and digital atlas of tree shrew brain. Compared to the existing MRI templates, our MRI template was aligned into stereotaxic space. And the toolbox is the first software dedicated for tree shrew brain analysis.

CONCLUSIONS

The templates and digital atlas of tree shrew brain, as well as the toolbox, facilitate the use of tree shrews in neuroimaging field.

Distinct Roles of Dopamine Receptors in the Lateral Thalamus in a Rat Model of Decisional Impulsivity

The thalamus and central dopamine signaling have been shown to play important roles in high-level cognitive processes including impulsivity. However, little is known about the role of dopamine receptors in the thalamus in decisional impulsivity. In the present study, rats were tested using a delay discounting task and divided into three groups: high impulsivity (HI), medium impulsivity (MI), and low impulsivity (LI). Subsequent in vivo voxel-based magnetic resonance imaging revealed that the HI rats displayed a markedly reduced density of gray matter in the lateral thalamus compared with the LI rats. In the MI rats, the dopamine D1 receptor antagonist SCH23390 or the D2 receptor antagonist eticlopride was microinjected into the lateral thalamus. SCH23390 significantly decreased their choice of a large, delayed reward and increased their omission of lever presses. In contrast, eticlopride increased the choice of a large, delayed reward but had no effect on the omissions. Together, our results indicate that the lateral thalamus is involved in decisional impulsivity, and dopamine D1 and D2 receptors in the lateral thalamus have distinct effects on decisional impulsive behaviors in rats. These results provide a new insight into the dopamine signaling in the lateral thalamus in decisional impulsivity.