Comparison of convolutional-neural-networks-based method and LCModel on the quantification of in vivo magnetic resonance spectroscopy

BACKGROUND

Quantification of metabolites concentrations in institutional unit (IU) is important for inter-subject and long-term comparisons in the applications of magnetic resonance spectroscopy (MRS). Recently, deep learning (DL) algorithms have found a variety of applications on the process of MRS data. A quantification strategy compatible to DL base MRS spectral processing method is, therefore, useful.

MATERIALS AND METHODS

This study aims to investigate whether metabolite concentrations quantified using a convolutional neural network (CNN) based method, coupled with a scaling procedure that normalizes spectral signals for CNN input and linear regression, can effectively reflect variations in metabolite concentrations in IU across different brain regions with varying signal-to-noise ratios (SNR) and linewidths (LW). An error index based on standard error (SE) is proposed to indicate the confidence levels associated with metabolite predictions. In vivo MRS spectra were acquired from three brain regions of 43 subjects using a 3T system.

RESULTS

The metabolite concentrations in IU of five major metabolites, quantified using CNN and LCModel, exhibit similar ranges with Pearson's correlation coefficients ranging from 0.24 to 0.78. The SE of the metabolites shows a positive correlation with Cramer-Rao lower bound (CRLB) (r=0.46) and  absolute CRLB (r=0.81), calculated by multiplying CRLBs with the quantified metabolite content.

CONCLUSION

In conclusion, the CNN based method with the proposed scaling procedures can be employed to quantify in vivo MRS spectra and derive metabolites concentrations in IU. The SE can be used as error index, indicating predicted uncertainties for metabolites and sharing information similar to the absolute CRLB.

Update on meningioma: Clinical-radiological and radio-pathological correlation

Meningiomas are tumors that originate in the arachnoid villi and are the most common non-glial neoplasm in the central nervous system. The clinical manifestations associated with meningioma depend, fundamentally, on its location. The location in the cerebral convexity is the most frequent, especially in the frontal lobes, manifesting with headache, motor disturbances, seizures and even neurocognitive disorders. There are 15 histologic subtypes of meningioma and three histologic grades. Within these, grades two and three have a worse prognosis and a higher rate of recurrence, as well as a radiological behavior that is generally more aggressive. Although there are some imaging features that can suggest a specific subtype, the definitive diagnosis will always require histological/molecular confirmation.

Sex hormones as correlates of oxidative stress in the adult brain

Oxidative stress, an imbalance between the production of reactive oxygen species and available antioxidant capacity, is implicated in multiple psychiatric disorders and neurodegenerative conditions. Peripheral and preclinical studies suggest oxidative stress differs by biological sex and covaries with estrogens. However, limited knowledge exists on the effect of circulating sex hormones on oxidative stress in the brain in humans in vivo. We aimed to examine the relationship of circulating estrogen with regional concentrations of brain glutathione (GSH) as a marker of oxidative stress. GSH was measured using magnetic resonance spectroscopy (MRS) at 7 Tesla in the dorsal anterior cingulate cortex (ACC), ventromedial prefrontal cortex (VMPFC), and left dorsolateral prefrontal cortex (DLPFC) in 34 individuals (18 females and 16 males). We observed an inverse correlation of estradiol with DLPFC GSH, as well as a trend inverse correlation of estrone with DLPFC GSH, in the combined sample of males and females and in females only. No significant sex differences were observed for GSH levels in the brain. Our study provides evidence of diminished DLPFC GSH in females with higher estradiol, suggesting circulating sex hormones may be important factors to consider in future studies examining brain GSH levels related to psychiatric and other disorders.

Radiology findings in neurocysticercosis: A case report

Neurocysticercosis is a serious underreported tropical disease caused by the ingestion of Taenia solium eggs through fecal-oral contact. The infection can affect any organ but frequently affects the central nervous system, eyes, and muscles, and is able to remain dormant for years in the brain. Medical imaging is crucial in making the diagnosis of neurocysticercosis as there are no identifiable clinical symptoms of the condition. In this case, we present a 71-year-old man with neurocysticercosis diagnosed by CT scan, MRI and MR spectroscopy. Calcified nodules were found with surrounding vasogenic edema on CT scan. Magnetic Resonance Imaging (MRI) showed multiple lesions that were hypointense on T1-weighted image, hyperintense rim on T2-weighted image, with ring enhancement on postcontrast scanning characterizing granular nodular stage and multiple lesions that were hypointense on T1-weighted image and no signal on T2-weighted image characterizing nodular calcified stage of the disease. MR Spectroscopy showed decreased levels of choline, creatine, NAA, NAA/Cr and Cho/Cr ratio with increased levels of lactate and lipid.

Changes in levels of the antioxidant glutathione in brain and blood across the age span of healthy adults: A systematic review

Aging is characterized by a gradual decline of the body's biological functions, which can lead to increased production of reactive oxygen species (ROS). Antioxidants neutralize ROS and maintain balance between oxidation and reduction. If ROS production exceeds the ability of antioxidant systems to neutralize, a damaging state of oxidative stress (OS) may exist. The reduced form of glutathione (GSH) is the most abundant antioxidant, and decline of GSH is considered a marker of OS. Our review summarizes the literature on GSH variations with age in healthy adults in brain (in vivo, ex vivo) and blood (plasma, serum), and reliability of in vivo magnetic resonance spectroscopy (MRS) measurement of GSH. A systematic PubMed search identified 35 studies. All in vivo MRS studies (N = 13) reported good to excellent reproducibility of GSH measures. In brain, 3 out of 4 MRS studies reported decreased GSH with age, measured in precuneus, cingulate, and occipital regions, while 1 study reported increased GSH with age in frontal and sensorimotor regions. In post-mortem brain, out of 3 studies, 2 reported decreased GSH with age in hippocampal and frontal regions, while 1 study reported increased GSH with age in a frontal region. Oxidized glutathione disulfide (GSSG) was reported to be increased in caudate with age in 1 study, suggesting OS. Although findings in the brain lacked a clear consensus, the majority of studies suggested a decline of GSH with age. The low number of studies (particularly ex vivo) and potential regional differences may have contributed to variability in the findings in brain. In blood, in contrast, GSH levels predominately were reported to decrease with advancing age (except in the oldest-old, who may represent a select group of particularly successful agers), while GSSG findings lacked consensus. The larger number of studies assessing age-specific GSH level changes in blood (N = 16) allowed for more robust consensus across studies than in brain. Overall, the literature suggests that aging is associated with increased OS in brain and body, but the timing and regional distribution of changes in the brain require further study. The contribution of brain OS to brain aging, and the effect of interventions to raise brain GSH levels on decline of brain function, remain understudied. Given that reliable tools to measure brain GSH exist, we hope this paper will serve as a catalyst to stimulate more work in this field.

In vivo cortical glutathione response to oral fumarate therapy in relapsing-remitting multiple sclerosis: A single-arm open-label phase IV trial using 7-Tesla 1H MRS

BACKGROUND

This is an open-label, single-arm, single-center pilot study using 7-Tesla in vivo proton magnetic resonance spectroscopy (1H MRS) to measure brain cortical glutathione concentration at baseline before and during the use of oral fumarates as a disease-modifying therapy for multiple sclerosis. The primary endpoint of this research was the change in prefrontal cortex glutathione concentration relative to a therapy-naïve baseline after one year of oral fumarate therapy.

METHODS

Brain glutathione concentrations were examined by 1H MRS in single prefrontal and occipital cortex cubic voxels (2.5 × 2.5 × 2.5 cm3) before and during initiation of oral fumarate therapy (120 mg b.i.d. for 7 days and 240 mg b.i.d. thereafter). Additional measurements of related metabolites glutamate, glutamine, myoinositol, total N-acetyl aspartate, and total choline were also acquired in voxels centered on the same regions. Seven relapsing-remitting multiple sclerosis patients (4 f / 3 m, age range 28-50 years, mean age 40 years) naïve to fumarate therapy were scanned at pre-therapy baseline and after 1, 3, 6 and 12 months of therapy. A group of 8 healthy volunteers (4 f / 4 m, age range 33-48 years, mean age 41 years) was also scanned at baseline and Month 6 to characterize 1H-MRS measurement reproducibility over a comparable time frame.

RESULTS

In the multiple sclerosis cohort, general linear models demonstrated a significant positive linear relationship between prefrontal glutathione and time either linearly across all time points (+0.05 ± 0.02 mM/month, t(27) = 2.6, p = 0.02) or specifically for factor variable Month 12 (+0.6 ± 0.3 mM/12 months, t(24) = 2.2, p = 0.04) relative to baseline. No such effects of time on glutathione concentration were demonstrated in the occipital cortex or in the healthy volunteer group. Changes in occipital total choline were further observed in the multiple sclerosis cohort as well as prefrontal total choline and occipital glutamine and myoinositol in the control cohort throughout the study duration.

CONCLUSIONS

While the open-label single-arm pilot study design and abbreviated control series cannot support firm conclusions about the influence of oral fumarate therapy independent of test-retest factors or normal biological variation in a state of either health or disease, these results do justify further investigation at a larger scale into the potential relationship between prefrontal cortex glutathione increases and oral fumarate therapy in relapsing-remitting multiple sclerosis.

Neurochemistry-enriched dynamic causal models of magnetoencephalography, using magnetic resonance spectroscopy

We present a hierarchical empirical Bayesian framework for testing hypotheses about neurotransmitters' concertation as empirical prior for synaptic physiology using ultra-high field magnetic resonance spectroscopy (7T-MRS) and magnetoencephalography data (MEG). A first level dynamic causal modelling of cortical microcircuits is used to infer the connectivity parameters of a generative model of individuals' neurophysiological observations. At the second level, individuals' 7T-MRS estimates of regional neurotransmitter concentration supply empirical priors on synaptic connectivity. We compare the group-wise evidence for alternative empirical priors, defined by monotonic functions of spectroscopic estimates, on subsets of synaptic connections. For efficiency and reproducibility, we used Bayesian model reduction (BMR), parametric empirical Bayes and variational Bayesian inversion. In particular, we used Bayesian model reduction to compare alternative model evidence of how spectroscopic neurotransmitter measures inform estimates of synaptic connectivity. This identifies the subset of synaptic connections that are influenced by individual differences in neurotransmitter levels, as measured by 7T-MRS. We demonstrate the method using resting-state MEG (i.e., task-free recording) and 7T-MRS data from healthy adults. Our results confirm the hypotheses that GABA concentration influences local recurrent inhibitory intrinsic connectivity in deep and superficial cortical layers, while glutamate influences the excitatory connections between superficial and deep layers and connections from superficial to inhibitory interneurons. Using within-subject split-sampling of the MEG dataset (i.e., validation by means of a held-out dataset), we show that model comparison for hypothesis testing can be highly reliable. The method is suitable for applications with magnetoencephalography or electroencephalography, and is well-suited to reveal the mechanisms of neurological and psychiatric disorders, including responses to psychopharmacological interventions.

Continuous Automated Analysis Workflow for MRS Studies

Magnetic resonance spectroscopy (MRS) can non-invasively measure levels of endogenous metabolites in living tissue and is of great interest to neuroscience and clinical research. To this day, MRS data analysis workflows differ substantially between groups, frequently requiring many manual steps to be performed on individual datasets, e.g., data renaming/sorting, manual execution of analysis scripts, and manual assessment of success/failure. Manual analysis practices are a substantial barrier to wider uptake of MRS. They also increase the likelihood of human error and prevent deployment of MRS at large scale. Here, we demonstrate an end-to-end workflow for fully automated data uptake, processing, and quality review.The proposed continuous automated MRS analysis workflow integrates several recent innovations in MRS data and file storage conventions. They are efficiently deployed by a directory monitoring service that automatically triggers the following steps upon arrival of a new raw MRS dataset in a project folder: (1) conversion from proprietary manufacturer file formats into the universal format NIfTI-MRS; (2) consistent file system organization according to the data accumulation logic standard BIDS-MRS; (3) executing a command-line executable of our open-source end-to-end analysis software Osprey; (4) e-mail delivery of a quality control summary report for all analysis steps.The automated architecture successfully completed for a demonstration dataset. The only manual step required was to copy a raw data folder into a monitored directory.Continuous automated analysis of MRS data can reduce the burden of manual data analysis and quality control, particularly for non-expert users and multi-center or large-scale studies and offers considerable economic advantages.

GABA, glutamate and excitatory-inhibitory ratios measured using short-TE STEAM MRS at 7-Tesla: Effects of macromolecule basis sets and baseline parameters

Rationale and objectives

Macromolecules (MMs) affect the precision and accuracy of neurochemical quantification in magnetic resonance spectroscopy. A measured MM basis is increasingly used in LCModel analysis combined with a spline baseline, whose stiffness is controlled by a parameter named DKNTMN. The effects of measured MM basis and DKNTMN were investigated.

Materials and methods

Twenty-six healthy subjects were prospectively enrolled and scanned twice using a short echo-time Stimulated Echo Acquisition Mode (STEAM) at 7-T. Using LCModel, analyses were conducted using the simulated MM basis (MMsim) with DKNTMN 0.15 and an MM basis measured inhouse (MMmeas) with DKNTMN of 0.15, 0.30, 0.60 and 1.00. Cramér-Rao lower bound (CRLB) and the concentrations of gamma-aminobutyric acid (GABA), glutamate and excitatory-inhibitory ratio (EIR), in addition to MMs were statistically analyzed. Measurement stability was evaluated using coefficient of variation (CV).

Results

CRLBs of GABA were significantly lower when using MMsim than MMmeas; those of glutamate were 2-3. GABA concentrations were significantly higher in the analysis using MMsim than MMmeas where concentrations were significantly higher with DKNTMN of 0.15 or 0.30 than 0.60 or 1.00. Difference in glutamate concentration was not significant. EIRs showed the same difference as in GABA depending on the DKNTMN values. CVs between test-retest scans were relatively stable for glutamate but became larger as DKNTMN increased for GABA and EIR.

Conclusion

Neurochemical quantification depends on the parameters of the basis sets used for fitting. Analysis using MMmeas with DKNTMN of 0.30 conformed best to previous studies and is recommended.

Increased brain 1H-MRS glutamate and lactate signals following maximal aerobic capacity exercise in young healthy males: an exploratory study

Physical exercise involves increased neuronal activity of many brain structures, but 1H-MRS investigations on the effects of human brain glutamate (Glu) concentrations on acute exercise have been sparse. Previous studies consistently found increases in brain lactate (Lac) concentrations following graded exercise up to 85% of the predicted maximal heart rate. However, the reported effects on brain concentrations of glutamine and glutamate were not consistent. This study aimed to determine the effect of acute intense graded maximal exercise on 1H-MRS signals related to concentrations of Glu, glutamate+glutamine (Glx), and Lac. Young adult males were randomly divided into two groups and subjected to 1H-MRS when resting (NE) or shortly after cessation of the intense graded exercise intended to pass the anaerobic threshold (E). 1H-MRS spectra were acquired from the large voxel encompassing the occipito-parietal cortex only once. Estimates of Glu, Glx, and Lac concentrations were calculated in institutional units by normalizing to a spectroscopic signal originating from creatine-containing compounds (Cr). Concentrations of Glu, Glx, and Lac were respectively 11%, 12.6%, and 48.5% higher in E than in NE (p < 0.001). The increased brain Lac signal in the exercising group indicated that in our experiment, vigorous exercise resulted in passing the anaerobic threshold and lactate apparently entered the brain. Concomitantly glutamate-related resonance signals from the vicinity of the occipito-parietal cortex were significantly increased; physiological mechanisms underlying these phenomena require further study. Future studies should evaluate whether the normalization rate of these concentrations is a marker of general physical fitness.

Abnormal immune system response in the brain of women with Fibromyalgia after experimental endotoxin challenge

Background

The pathophysiology of fibromyalgia (FM) is thought to include an overactive immune system, leading to central nervous system sensitization, allodynia, and hyperalgesia. We aimed to test this theory using an experimental immune system activation procedure and neuroimaging with magnetic resonance spectroscopic imaging (MRSI).

Methods

Twelve women with FM and 13 healthy women (healthy controls; HC) received 0.3 or 0.4 ng/kg endotoxin and underwent MRSI before and after the infusion. Changes in brain levels of choline (CHO), myo-inositol (MI), N-Acetylaspartate (NAA), and MRSI-derived brain temperature were compared between groups and dosage levels using mixed analyses of variance.

Results

Significant group-by-time interactions in brain temperature were found in the right thalamus. Post-hoc testing revealed that brain temperature increased by 0.55 °C in the right thalamus in FM (t(10) = -3.483, p = 0.006), but not in HCs (p > 0.05). Dose-by-time interactions revealed brain temperature increases in the right insula after 0.4 ng/kg (t(12) = -4.074, p = 0.002), but not after 0.3 ng/kg (p > 0.05). Dose-by-time interactions revealed decreased CHO in the right Rolandic operculum after 0.4 ng/kg endotoxin (t(13) = 3.242, p = 0.006) but not 0.3 ng/kg. In the left paracentral lobule, CHO decreased after 0.3 ng/kg (t(9) = 2.574, p = 0.030) but not 0.4 ng/kg. Dose-by-time interactions affected MI in several brain regions. MI increased after 0.3 ng/kg in the right Rolandic operculum (t(10) = -2.374, p = 0.039), left supplementary motor area (t(9) = -2.303, p = 0.047), and left occipital lobe (t(10) = -3.757, p = 0.004), with no changes after 0.4 ng/kg (p > 0.05). Group-by time interactions revealed decreased NAA in the left Rolandic operculum in FM (t(13) = 2.664, p = 0.019), but not in HCs (p > 0.05). A dose-by-time interaction showed decreased NAA in the left paracentral lobule after 0.3 ng/kg (t(9) = 3.071, p = 0.013) but not after 0.4 ng/kg (p > 0.05). In the combined sample, there was a main effect of time whereby NAA decreased in the left anterior cingulate (F[1,21] = 4.458, p = 0.047) and right parietal lobe (F[1,21] = 5.457, p = 0.029).

Conclusion

We found temperature increases and NAA decreases in FM that were not seen in HCs, suggesting that FM patients may have abnormal immune responses in the brain. The 0.3 and 0.4 ng/kg had differential effects on brain temperature and metabolites, with neither dose effecting a stronger response overall. There is insufficient evidence provided by the study to determine whether FM involves abnormal central responses to low-level immune challenges.

Differentiation of astrocytoma between grades II and III using a combination of methionine positron emission tomography and magnetic resonance spectroscopy

Objective

This study aimed to establish a method for differentiating between grades II and III astrocytomas using preoperative imaging.

Methods

We retrospectively analyzed astrocytic tumors, including 18 grade II astrocytomas (isocitrate dehydrogenase (IDH)-mutant: IDH-wildtype = 8:10) and 56 grade III anaplastic astrocytomas (37:19). We recorded the maximum methionine (MET) uptake ratios (tumor-to-normal: T/N) on positron emission tomography (PET) and three MRS peak ratios: choline (Cho)/creatine (Cr), N-acetyl aspartate (NAA)/Cr, and Cho/NAA, between June 2015 and June 2020. We then evaluated the cut-off values to differentiate between grades II and III. We compared the grading results between contrast enhancement effects on MR and combinational diagnostic methods (CDM) on a scatter chart using the cutoff values of the T/N ratio and MRS parameters.

Results

The IDH-mutant group showed significant differences in the Cho/NAA ratio between grades II and III using univariate analysis; however, multiple regression analysis results negated this. The IDH-wildtype group showed no significant differences between the groups. Contrast enhancement effects also showed no significant differences in IDH status. Accordingly, regardless of the IDH status, no statistically independent factors differentiated between grades II and III. However, CDMs showed higher sensitivity and negative predictive value in distinguishing them than MRI contrast examinations for both IDH statuses. We demonstrated a significantly higher diagnostic rate of grade III than of grade II with CDM, which was more striking in the IDH-mutant group than in the wild-type group.

Conclusions

CDM could be valuable in differentiating between grade II and III astrocytic tumors.

Systemic inflammation and cortical neurochemistry in never-medicated first episode-psychosis individuals

Studies of cellular and cytokine profiles have contributed to the inflammation hypothesis of schizophrenia; however, precise markers of inflammatory dysfunction remain elusive. A number of proton magnetic resonance spectroscopy (1H-MRS) studies in patients with first-episode psychosis (FEP) have shown higher brain levels of metabolites such as glutamate, myo-inositol (mI) and choline-containing compounds (tCho), suggesting neuroinflammation. Here, we present peripheral inflammatory profiles in antipsychotic-naive FEP patients and age-and-sex matched healthy controls, as well as cortical glutamate, mI and tCho levels using 1H-MRS. Inflammatory profiles were analyzed using cytokine production by peripheral blood mononuclear cells, that were either spontaneous or stimulated, in 48 FEP patients and 23 controls. 1H-MRS of the medial prefrontal cortex was obtained in 29 FEP patients and 18 controls. Finally, 16 FEP patients were rescanned after 4 weeks of treatment (open-label) with Risperidone. FEP patients showed a higher proportion of proinflammatory Th1/Th17 subset, and an increased spontaneous production of Interleukin (IL)-6, IL-2 and IL-4 compared with the control group. Results obtained from 1H-MRS showed no significant difference in either glutamate, mI or tCho between FEP and control groups. At baseline, CD8% showed a negative correlation with glutamate in FEP patients; after 4 weeks of risperidone treatment, the FEP group exhibited a decrease in glutamate levels which positively correlated with CD4 + T cells. Nevertheless, these correlations did not survive correction for multiple comparisons. FEP patients show evidence of immune dysregulation, affecting both the innate and adaptive immune response, with a predominantly Th2 signature. These findings, along with the changes produced by antipsychotic treatment, could be associated with both systemic and central inflammatory processes in schizophrenia.

Cross-sectional study of retrospective self-reported childhood emotional neglect and inhibitory neurometabolite levels in the pregenual anterior cingulate cortex in adult humans

High childhood emotional maltreatment (CM-EMO) is reported in mood and anxiety disorders. The associations with an increased risk for psychopathology are not fully understood. One potential factor may be through alterations in gamma-Aminobutyric acid (GABA). The pregenual anterior cingulate cortex (pgACC) is an important brain region for emotion processing and its' GABA levels were previously implicated in mood and anxiety disorders pathophysiology. We examined the association between the self-reported CM-EMO in adulthood and GABA + levels in the pgACC and in a control region, anterior mid cingulate cortex. GABA+ and total creatine (tCr) were measured in the pgACC and aMCC voxels in seventy-four healthy volunteers (32 (43%) women, ages 19-54, age [standard deviation] = 27.1 [6.5]) using proton magnetic resonance spectroscopy at 7 T. Childhood Trauma Questionnaire was completed by adult participants to measure retrospective self-reported experience of emotional neglect (CM-EMO-NEG) and emotional abuse (CM-EMO-AB) during childhood. Linear mixed models tested the interaction between the region and the two subscales, and GABA+/tCr ratios, with an adjusted alpha = 0.025. Following, linear models, including with covariates were tested. There was an interaction effect between region and CM-EMO-NEG (B = -0.007, p = 0.009), driven by a negative relationship between CM-EMO-NEG and GABA+/tCr in the pgACC (B = -0.004, p = 0.013). Results for CM-EMO-NEG were robust to inclusion of different covariates (ps < 0.035). There was no interaction effect for the CM-EMO-AB (B = 0.007, p = 0.4). Limitations include cross-sectional measurement and retrospective nature of the CTQ. The findings indicate preliminary importance of inhibitory neurometabolite concentrations in the pgACC for retrospective reporting of CM-EMO-NEG.

Meta-analytic evidence of elevated choline, reduced N-acetylaspartate, and normal creatine in schizophrenia and their moderation by measurement quality, echo time, and medication status

BACKGROUND

Brain metabolite abnormalities measured with magnetic resonance spectroscopy (MRS) provide insight into pathological processes in schizophrenia. Prior meta-analyses have not yet answered important questions about the influence of clinical and technical factors on neurometabolite abnormalities and brain region differences. To address these gaps, we performed an updated meta-analysis of N-acetylaspartate (NAA), choline, and creatine levels in patients with schizophrenia and assessed the moderating effects of medication status, echo time, measurement quality, and other factors.

METHODS

We searched citations from three earlier meta-analyses and the PubMed database after the most recent meta-analysis to identify studies for screening. In total, 113 publications reporting 366 regional metabolite datasets met our inclusion criteria and reported findings in medial prefrontal cortex (MPFC), dorsolateral prefrontal cortex, frontal white matter, hippocampus, thalamus, and basal ganglia from a total of 4445 patient and 3944 control observations.

RESULTS

Patients with schizophrenia had reduced NAA in five of the six brain regions, with a statistically significant sparing of the basal ganglia. Patients had elevated choline in the basal ganglia and both prefrontal cortical regions. Patient creatine levels were normal in all six regions. In some regions, the NAA and choline differences were greater in studies enrolling predominantly medicated patients compared to studies enrolling predominantly unmedicated patients. Patient NAA levels were more reduced in hippocampus and frontal white matter in studies using longer echo times than those using shorter echo times. MPFC choline and NAA abnormalities were greater in studies reporting better metabolite measurement quality.

CONCLUSIONS

Choline is elevated in the basal ganglia and prefrontal cortical regions, suggesting regionally increased membrane turnover or glial activation in schizophrenia. The basal ganglia are significantly spared from the well-established widespread reduction of NAA in schizophrenia suggesting a regional difference in disease-associated factors affecting NAA. The echo time findings agree with prior reports and suggest microstructural changes cause faster NAA T2 relaxation in hippocampus and frontal white matter in schizophrenia. Separating the effects of medication status and illness chronicity on NAA and choline abnormalities will require further patient-level studies. Metabolite measurement quality was shown to be a critical factor in MRS studies of schizophrenia.

Magnetic resonance study of visceral, subcutaneous, liver and pancreas fat changes after 12 weeks intermittent fasting in obese participants with prediabetes

BACKGROUND

It is not clear whether there are differences in proportions of fat loss from visceral:subcutaneous depots by probiotic supplementation, ethnicity or sex during weight loss; or whether visceral/pancreatic fat depot changes are related to changes in HbA1c. Our objective is to investigate whether weight loss from different fat depots is related to these factors during weight loss achieved by intermittent fasting.

METHOD

Prediabetes participants on 5:2 intermittent fasting were randomized 1:1 to either daily probiotic or placebo for 12 weeks. Twenty-four patients had magnetic resonance imaging data at baseline and 12 weeks.

RESULTS

After 12 weeks of intermittent fasting, subcutaneous fat (%) changed from 35.9 ± 3.1 to 34.4 ± 3.2, visceral fat (%) from 15.8 ± 1.3 to 14.8 ± 1.2, liver fat (%) from 8.7 ± 0.8 to 7.5 ± 0.7 and pancreatic fat (%) from 7.7 ± 0.5 to 6.5 ± 0.5 (all p< 0.001). Changes in weight, HbA1c, SAT, VAT, LF and PF did not differ significantly between probiotic and placebo groups.

CONCLUSION

Overall weight loss was correlated with fat loss from subcutaneous depots. Losses from different fat depots did not correlate with changes in HbA1c or differ by probiotic supplementation, ethnicity or sex.

Functional MRI markers for treatment-resistant depression: Insights and challenges

Imaging studies of treatment-resistant depression (TRD) have examined brain activity, structure, and metabolite concentrations to identify critical areas of investigation in TRD as well as potential targets for treatment interventions. This chapter provides an overview of the main findings of studies using three imaging modalities: structural magnetic resonance imaging (MRI), functional MRI (fMRI), and magnetic resonance spectroscopy (MRS). Decreased connectivity and metabolite concentrations in frontal brain areas appear to characterize TRD, although results are not consistent across studies. Treatment interventions, including rapid-acting antidepressants and transcranial magnetic stimulation (TMS), have shown some efficacy in reversing these changes while alleviating depressive symptoms. However, comparatively few TRD imaging studies have been conducted, and these studies often have relatively small sample sizes or employ different methods to examine a variety of brain areas, making it difficult to draw firm conclusions from imaging studies about the pathophysiology of TRD. Larger studies with more unified hypotheses, as well as data sharing, could help TRD research and spur better characterization of the illness, providing critical new targets for treatment intervention.

Efficacy of high-frequency repetitive transcranial magnetic stimulation in a family with spinocerebellar ataxia type 3: A case report

Introduction

Spinocerebellar ataxia type 3 (SCA3) is a common autosomal dominant hereditary ataxia, which is caused by a cytosine-adenine-guanine (CAG) repeat expansion on the causative gene ATXN3, usually with lower extremity ataxia as the first symptom, and effective treatment is scarce. Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive technique that regulates the cerebellum and the neural network connected to it.

Methods

Herein, we report familial cases of SCA3 in two nephews and their aunt, each of whom was treated with high-frequency (5 Hz) rTMS. The rTMS treatment lasted 2 weeks, once daily for 5 consecutive days a week, about 20 minutes each session. The Scale for the Assessment and Rating of Ataxia (SARA), the International Cooperative Ataxia Rating Scale (ICARS), and proton magnetic resonance spectroscopy (¹H-MRS) examination were evaluated before and after rTMS treatment.

Results

We found that the ICARS scores improved significantly (p = 0.04), and the NAA/Cr values were elevated in vermis and both cerebellar hemispheres after rTMS treatment.

Conclusion

Our study suggested that high-frequency rTMS therapy can contribute to the improvement of cerebellar NAA/Cr value of SCA3 patients, and improve posture and gait as well as limb kinetic function in SCA3 patients.

Altered neurometabolite levels in the brains of patients with depression: A systematic analysis of magnetic resonance spectroscopy studies

BACKGROUND

Numerous magnetic resonance spectroscopy (MRS) studies have reported metabolic abnormalities in the brains of patients with depression, although inconsistent results have been reported. The aim of this study was to explore changes in neurometabolite levels in patients with depression across large-scale MRS studies.

METHOD

A total of 307 differential metabolite entries associated with depression were retrieved from 180 MRS studies retrieved from the Metabolite Network of Depression Database. The vote-counting method was used to identify consistently altered metabolites in the whole brain and specific brain regions of patients with depression.

RESULTS

Only few differential neurometabolites showed a stable change trend. The levels of total choline (tCho) and the tCho/N-acetyl aspartate (NAA) ratio were consistently higher in the brains of patients with depression, and that the levels of NAA, glutamate and glutamine (Glx), and gamma-aminobutyric acid (GABA) were lower. For specific brain regions, we found lower Glx levels in the prefrontal cortex and lower GABA concentrations in the occipital cortex. We also found lower concentrations of NAA in the anterior cingulate cortex and prefrontal cortex. The levels of tCho were higher in the prefrontal cortex and putamen.

CONCLUSION

Our results revealed that most altered neurometabolites in previous studies lack of adequate reproducibility. Through vote-counting method with large-scale studies, downregulation of glutamatergic neurometabolites, impaired neuronal integrity, and disturbed membrane metabolism were found in the pathobiology of depression, which contribute to existing knowledge of neurometabolic changes in depression. Further studies based on a larger dataset are needed to confirm our findings.

BDNF rs6265 Met carriers with alcohol use disorder show greater age-related decline of N-acetylaspartate in left dorsolateral prefrontal cortex

BACKGROUND

Brain-derived neurotrophic factor (BDNF) is implicated in neuronal and glial cell growth and differentiation, synaptic plasticity, and apoptotic mechanisms. A single-nucleotide polymorphism of the BDNF rs6265 gene may contribute to the pattern and magnitude of brain metabolite abnormalities apparent in those with an Alcohol Use Disorder (AUD). We predicted that Methionine (Met) carriers would demonstrate lower magnetic resonance spectroscopy (MRS) measures of N-acetylaspartate level (NAA) and greater age-related decline in NAA than Valine (Val) homozygotes.

METHODS

Veterans with AUD (n=95; 46±12 years of age, min = 25, max = 71) were recruited from VA Palo Alto residential treatment centers. Single voxel MRS, at 3 Tesla, was used to obtain NAA, choline (Cho) and creatine (Cr) containing compounds from the left dorsolateral prefrontal cortex (DLPFC). Metabolite spectra were fit with LC Model and NAA and Cho were standardized to total Cr level and NAA was also standardized to Cho.

RESULTS

Val/Met (n=35) showed markedly greater age-related decline in left DLPFC NAA/Cr level than Val/Val (n=60); no differences in mean metabolite levels were observed between Val/Met and Val/Val. Val/Met demonstrated greater frequency of history of MDD and higher frequency of cannabis use disorder over 12 months prior to study.

CONCLUSIONS

The greater age-related decline in left DLPFC NAA/Cr and the higher frequency of MDD history and Cannabis Use disorder in BDNF rs6265 Met carriers with AUD are novel and may have implications for non-invasive brain stimulation targeting the left DLFPC and other psychosocial interventions typically utilized in the treatment of AUD.

Direct changes of neurometabolic concentrations in the pregenual anterior cingulate cortex among obsessive-compulsive patients after repetitive transcranial magnetic stimulation treatment

BACKGROUND AND AIM

Although Repetitive Transcranial Magnetic Stimulation (rTMS) is a promising new noninvasive brain stimulation therapy, its underlying mechanisms of action remain unknown. OCD patients exhibit impaired response control and attention shifting, which is linked to some brain areas such as anterior cingulate cortex and basal ganglia. OCD patients also display altered neurometabolic concentrations in cortical cortical-striatal-thalamic-cortical (CSTC). In this study, we aimed to elucidate efficacy of rTMS treatment in alleviating related symptoms and pregenual anterior cingulate cortex (pACC) neurometabolites.

METHODS

OCD patients were randomly divided into either drug (n = 23) or drug + rTMS (n = 29) groups, and those in the latter group subjected to 4-week rTMS treatment. All participants were visited twice, at baseline and follow-up after four weeks. During both visits, all patients were subjected to 1H-MRS, then Yale-Brown Obsessive Compulsive Scale (Y-BOCS) and the Global Assessment Function (GAF) used to assess severity of obsessive-compulsive symptoms. We also evaluated synchronous anxiety and depression by Beck Anxiety Inventory (BAI), Beck Depression Inventory (BDI), Hamilton Anxiety Scale (HAM-A) and Hamilton Depression Scale (HAM-D).

RESULTS

After 4 weeks of treatment, patients in the Drug + rTMS group displayed significantly lower Y-BOCS (p = 0.038), BDI (p = 0.009), HAM-D (p = 0.013), HAM-A (p = 0.012) scores than their counterparts in the Drug group. Conversely, patients in the Drug + rTMS group had significantly higher tNAA concentrations (p = 0.030) than those in the Drug group. Notably, the Drug + rTMS group exhibited higher, but insignificant Glu (p = 0.055) and Glx (p = 0.068) concentrations compared to the Drug group. Partial correlation analysis revealed a significant negative correlation between post HAM-A scores and 4-week change of pACC glutamate levels in the Drug + rTMS group (r = -0.434, p = 0.02).

CONCLUSION

rTMS treatment is an efficacious treatment therapy for OCD, mainly by inducing changes in neurometabolites.

Magnetic resonance spectroscopy (MRS) identification of chemically painful lumbar discs leads to improved 6-, 12-, and 24-month outcomes for discogenic low back pain surgeries

PURPOSE

MRS was shown to reliably quantify relative levels of degenerative pain biomarkers, differentiating painful versus non-painful discs in patients with chronic discogenic low back pain (DLBP), and this correlates with surgical success rates. We now report results based on more patients and longer follow-up.

METHODS

Disc MRS was performed in DLBP patients who subsequently received lumbar surgery. Custom post-processing (NOCISCAN-LS®; Aclarion Inc.) calculated disc-specific NOCISCORES® that reflect relative differences in degenerative pain biomarkers for diagnosing chemically painful discs. Outcomes in 78 patients were evaluated using Oswestry Disability Index (ODI) scores. Surgical success (≥ 15-point ODI improvement) was compared between surgeries that were "Concordant" (Group C) versus "Discordant" (Group D) with NOCISCORE-based diagnosis for painful discs.

RESULTS

Success rates were higher for Group C versus Group D: 6 months (88% vs. 62%; p = 0.01), 12 months (91% vs. 56%; p < 0.001), and 24 months (85% vs. 63%; p = 0.07). Success rates for Group C surgeries were also higher than Group D surgeries in a variety of sub-group comparisons. Group C had a greater reduction in ODI from pre-operative to follow-up than Group D [absolute change (% change), (p)]: 6 months: - 35 (- 61%) versus - 23 (- 39%), (p < 0.05); 12 months: - 39 (- 69%) versus - 22 (- 39%), (p < 0.01); and 24 months:  - 38 (- 66%) versus - 26 (- 48%), (p < 0.05).

CONCLUSION

More successful, sustained outcomes were obtained when surgically treating chemically painful discs identified by NOCISCAN-LS post-processed disc MRS exams. Results suggest that NOCISCAN-LS provides a valuable new diagnostic tool to help clinicians better select treatment levels.

Cross-sectional Exploration of the Relationship Between Glutamate Abnormalities and Tic Disorder Severity Using Proton Magnetic Resonance Spectroscopy

Glutamate (Glu) has been reported to be closely related to the pathophysiology of Tic Disorders (TD). By using proton magnetic resonance spectroscopy (1H-MRS), we aimed to investigate the relationship between in vivo Glu levels and the severity of TD. We performed a cross-sectional study in medication-free patients with TD and healthy controls aged between 5 and 13 years using 1H-MRS at 3 T. First, we measured the Glu levels in both patients and controls and observed the difference in subgroups, including mild TD patients and moderate TD patients. We then examined the correlations between the Glu levels and clinical features of the patients. Finally, we assessed the diagnostic value of 1H-MRS and the influencing factors. Our results show that the Glu levels in the striatum of all patients with TD were not significantly different from those of the healthy controls. Subgroup analysis revealed that the Glu levels in the moderate TD group were higher than those in the mild TD group and healthy controls. The correlation analysis showed that Glu levels are strongly positive correlated with TD severity. The optimal cutoff value of Glu levels to differentiate mild tics from moderate tics was 1.244, with a sensitivity of 88.2% and a specificity of 94.7%. Multiple linear regression models revealed that the severity of TD is one of the important factors that affect Glu levels. We conclude that Glu levels are mainly associated with the severity of tics, thus it could serve as a key biomarker for TD classification.

J-difference GABA-edited MRS reveals altered cerebello-thalamo-cortical metabolism in patients with hepatic encephalopathy

Hepatic encephalopathy (HE) is a common neurological manifestation of liver cirrhosis and is characterized by an increase of ammonia in the brain accompanied by a disrupted neurotransmitter balance, including the GABAergic and glutamatergic systems. The aim of this study is to investigate metabolic abnormalities in the cerebello-thalamo-cortical system of HE patients using GABA-edited MRS and links between metabolite levels, disease severity, critical flicker frequency (CFF), motor performance scores, and blood ammonia levels. GABA-edited MRS was performed in 35 participants (16 controls, 19 HE patients) on a clinical 3 T MRI system. MRS voxels were placed in the right cerebellum, left thalamus, and left motor cortex. Levels of GABA+ and of other metabolites of interest (glutamine, glutamate, myo-inositol, glutathione, total choline, total NAA, and total creatine) were assessed. Group differences in metabolite levels and associations with clinical metrics were tested. GABA+ levels were significantly increased in the cerebellum of patients with HE. GABA+ levels in the motor cortex were significantly decreased in HE patients, and correlated with the CFF (r = 0.73; p < .05) and motor performance scores (r = -0.65; p < .05). Well-established HE-typical metabolite patterns (increased glutamine, decreased myo-inositol and total choline) were confirmed in all three regions and were closely linked to clinical metrics. In summary, our findings provide further evidence for alterations in the GABAergic system in the cerebellum and motor cortex in HE. These changes were accompanied by characteristic patterns of osmolytes and oxidative stress markers in the cerebello-thalamo-cortical system. These metabolic disturbances are a likely contributor to HE motor symptoms in HE. In patients with hepatic encephalopathy, GABA+ levels in the cerebello-thalamo-cortical loop are significantly increased in the cerebellum and significantly decreased in the motor cortex. GABA+ levels in the motor cortex strongly correlate with critical flicker frequency (CFF) and motor performance score (pegboard test tPEG), but not blood ammonia levels (NH3).

Development and validation of a novel non-invasive test for diagnosing nonalcoholic fatty liver disease in Chinese children

BACKGROUND

With the exploding prevalence of obesity, many children are at risk of developing nonalcoholic fatty liver disease. Using anthropometric and laboratory parameters, our study aimed to develop a model to quantitatively evaluate liver fat content (LFC) in children with obesity.

METHODS

A well-characterized cohort of 181 children between 5 and 16 years of age were recruited to the study in the Endocrinology Department as the derivation cohort. The external validation cohort comprised 77 children. The assessment of liver fat content was performed using proton magnetic resonance spectroscopy. Anthropometry and laboratory metrics were measured in all subjects. B-ultrasound examination was carried out in the external validation cohort. The Kruskal-Wallis test, Spearman bivariate correlation analyses, univariable linear regressions and multivariable linear regression were used to build the optimal predictive model.

RESULTS

The model was based on indicators including alanine aminotransferase, homeostasis model assessment of insulin resistance, triglycerides, waist circumference and Tanner stage. The adjusted R² of the model was 0.589, which presented high sensitivity and specificity both in internal [sensitivity of 0.824, specificity of 0.900, area under curve (AUC) of 0.900 with a 95% confidence interval: 0.783-1.000] and external validation (sensitivity of 0.918 and specificity of 0.821, AUC of 0.901 with a 95% confidence interval: 0.818-0.984).

CONCLUSIONS

Our model based on five clinical indicators was simple, non-invasive, and inexpensive; it had high sensitivity and specificity in predicting LFC in children. Thus, it may be useful for identifying children with obesity who are at risk for developing nonalcoholic fatty liver disease.