Applications of multi-nuclear magnetic resonance spectroscopy at 7T

AIM: To discuss the advantages of ultra-high field (7T) for 1H and 13C magnetic resonance spectroscopy (MRS) studies of metabolism.METHODS: Measurements of brain metabolites were made at both 3 and 7T using 1H MRS. Measurements of glycogen and lipids in muscle were measured using 13C and 1H MRS respectively.RESULTS: In the brain, increased signal-to-noise ratio (SNR) and dispersion allows spectral separation of the amino-acids glutamate, glutamine and γ-aminobutyric acid (GABA), without the need for sophisticated editing sequences. Improved quantification of these metabolites is demonstrated at 7T relative to 3T. SNR was 36% higher, and measurement repeatability (% coefficients of variation) was 4%, 10% and 10% at 7T, vs 8%, 29% and 21% at 3T for glutamate, glutamine and GABA respectively. Measurements at 7T were used to compare metabolite levels in the anterior cingulate cortex (ACC) and insula. Creatine and glutamate levels were found to be significantly higher in the insula compared to the ACC (P < 0.05). In muscle, the increased SNR and spectral resolution at 7T enables interleaved studies of glycogen (13C) and intra-myocellular lipid (IMCL) and extra-myocellular lipid (EMCL) (1H) following exercise and re-feeding. Glycogen levels were significantly decreased following exercise (-28% at 50% VO2 max; -58% at 75% VO2 max). Interestingly, levels of glycogen in the hamstrings followed those in the quadriceps, despite reduce exercise loading. No changes in IMCL and EMCL were found in the study.CONCLUSION: The demonstrated improvements in brain and muscle MRS measurements at 7T will increase the potential for use in investigating human metabolism and changes due to pathologies.

Individualized brain mapping for navigated neuromodulation

The brain is a complex organ that requires precise mapping to understand its structure and function.Brain atlases provide a powerful tool for studying brain circuits,discovering biological markers for early diagnosis,and developing personalized treatments for neuropsychiatric disorders.Neuromodulation techniques,such as transcranial magnetic stimulation and deep brain stimulation,have revolutionized clinical therapies for neuropsychiatric disorders.However,the lack of fine-scale brain atlases limits the precision and effectiveness of these techniques.Advances in neuroimaging and machine learning techniques have led to the emergence of stereotactic-assisted neurosurgery and navigation systems.Still,the individual variability among patients and the diversity of brain diseases make it necessary to develop personalized solutions.The article provides an overview of recent advances in individualized brain mapping and navigated neuromodulation and discusses the methodological profiles,advantages,disadvantages,and future trends of these techniques.The article concludes by posing open questions about the future development of individualized brain mapping and navigated neuromodulation.

Shared and distinct abnormalities of brain magnetization transfer ratio in schizophrenia and major depressive disorder:a comparative voxel-based meta-analysis

Background:Patients with schizophrenia(SCZ)and major depressive disorder(MDD)share significant clinical overlap,although it remains unknown to what extent this overlap reflects shared neural profiles.To identify the shared and specific abnormalities in SCZ and MDD,we performed a whole-brain voxel-based meta-analysis using magnetization transfer imaging,a technique that characterizes the macromolecular structural integrity of brain tissue in terms of the magnetization transfer ratio(MTR).Methods:A systematic search based on Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines was conducted in PubMed,EMBASE,International Scientific Index(ISI)Web of Science,and MEDLINE for relevant studies up to March 2022.Two researchers independently screened the articles.Rigorous scrutiny and data extraction were performed for the studies that met the inclusion criteria.Voxel-wise meta-analyses were conducted using anisotropic effect size-signed differential mapping with a unified template.Meta-regression was used to explore the potential effects of demographic and clinical characteristics.Results:A total of 15 studies with 17 datasets describing 365 SCZ patients,224 MDD patients,and 550 healthy controls(HCs)were identified.The conjunction analysis showed that both disorders shared higher MTR than HC in the left cerebellum(P=0.0006)and left fusiform gyrus(P=0.0004).Additionally,SCZ patients showed disorder-specific lower MTR in the anterior cingulate/paracingulate gyrus,right superior temporal gyrus,and right superior frontal gyrus,and higher MTR in the left thalamus,precuneus/cuneus,posterior cingulate gyrus,and paracentral lobule;and MDD patients showed higher MTR in the left middle occipital region.Meta-regression showed no statistical significance in either group.Conclusions:The results revealed a structural neural basis shared between SCZ and MDD patients,emphasizing the importance of shared neural substrates across psychopathology.Meanwhile,distinct disease-specific characteristics could have implications for future differential diagnosis and targeted treatment.

Pre-coronavirus disease 2019 brain structure might be associated with social anxiety alterations during the pandemic

To the Editor:As the novel coronavirus disease 2019(COVID-19)pandemic rapidly spreads around the world,it has resulted in unprecedented economic loss,social turmoil,and detrimental effects on public mental health.In particular,the implementation of disease control measures such as nationwide lockdowns,social distancing,school closures,and home quarantine has given rise to a wide range of social anxiety(SA)around the world,from nonclinical manifestations to clinical social anxiety disorder(SAD).[1]Given the potentially severe impairments from SA and the limited mental health care resources,it is vital to identify whether there are vulnerability/risk neuropsychological factors contributing to the progression of SA during the pandemic.

Altered white matter microarchitecture in Parkinson’s disease:a voxel-based meta-analysis of diffusion tensor imaging studies

This study aimed to define the most consistent white matter microarchitecture pattern in Parkinson’s disease(PD)reflected by fractional anisotropy(FA),addressing clinical profiles and methodology-related heterogeneity.Web-based publication databases were searched to conduct a meta-analysis of whole-brain diffusion tensor imaging studies comparing PD with healthy controls(HC)using the anisotropic effect size–signed differential mapping.A total of 808 patients with PD and 760 HC coming from 27 databases were finally included.Subgroup analyses were conducted considering heterogeneity with respect to medication status,disease stage,analysis methods,and the number of diffusion directions in acquisition.Compared with HC,patients with PD had decreased FA in the left middle cerebellar peduncle,corpus callosum(CC),left inferior fronto-occipital fasciculus,and right inferior longitudinal fasciculus.Most of the main results remained unchanged in subgroup metaanalyses of medicated patients,early stage patients,voxel-based analysis,and acquisition with˂30 diffusion directions.The subgroup meta-analysis of medication-free patients showed FA decrease in the right olfactory cortex.The cerebellum and CC,associated with typical motor impairment,showed the most consistent FA decreases in PD.Medication status,analysis approaches,and the number of diffusion directions have an important impact on the findings,needing careful evaluation in future meta-analyses.

预防和管理2型糖尿病的饮食和营养干预策略

Nita G Forouhi和同事们认为,我们可以找到预防、管理和可能缓解2型糖尿病的饮食方法基本要点。饮食因素在2型糖尿病的预防和管理中至关重要。尽管在制定循证饮食指南方面取得了进展,但争议和困惑依然存在。在本文中,我们研究了现有证据,确定2型糖尿病饮食指南中哪些领域取得了共识,哪些还存在不确定性或争议。

Cortical thickness abnormalities in patients with first episode psychosis:a meta-analysis of psychoradiologic studies and replication in an independent sample

Background:Abnormalities of cortical thickness(CTh)in patients with their first episode psychosis(FEP)have been frequently reported,but findings are inconsistent.Objective:To define the most consistent CTh changes in patients with FEP by meta-analysis of publishedwholebrain studies.Methods:The meta-analysis used seed-based dmapping(SDM)software to obtain the most prominent regional CTh changes in FEP,and meta-regression analyses to explore the effects of demographics and clinical characteristics.The meta-analysis results were verified in an independent sample of 142 FEP patients and 142 age-and sex-matched healthy controls(HCs),using both a vertex-wise and a region of interest analysis,with multiple comparisons correction.Results:The meta-analysis identified lower CTh in the rightmiddle temporal cortex(MTC)extending to superior temporal cortex(STC),insula,and anterior cingulate cortex(ACC)in FEP compared with HCs.No significant correlations were identified between CTh alterations and demographic or clinical variables.These results were replicated in the independent dataset analysis.Conclusion:This study identifies a robust pattern of cortical abnormalities in FEP and extends understanding of gray matter abnormalities and pathological mechanisms in FEP.