Prevalence of infectious diseases, immunity to vaccine-preventable diseases and chronic medical conditions among Ukrainian refugees in Germany - A cross sectional study from the German Network University Medicine (NUM)

BACKGROUND

Vulnerability to infectious diseases in refugees is dependent on country of origin, flight routes, and conditions. Information on specific medical needs of different groups of refugees is lacking. We assessed the prevalence of infectious diseases, immunity to vaccine-preventable diseases, and chronic medical conditions in children, adolescents, and adult refugees from Ukraine who arrived in Germany in 2022.

METHODS

Using different media, we recruited Ukrainian refugees at 13 sites between 9-12/2022. An antigen test for acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) infection, serologies for a range of vaccine-preventable diseases, as well as interferon gamma release assays (IGRAs) for tuberculosis (TB), and SARS-CoV-2 were performed. We assessed personal and family history of chronic medical conditions, infectious diseases, vaccination status, and conditions during migration.

RESULTS

Overall, 1793 refugees (1401 adults and 392 children/adolescents) were included. Most participants were females (n = 1307; 72·3%) and from Eastern or Southern Ukraine. TB IGRA was positive in 13% (n = 184) of the adults and in 2% (n = 7) of the children. Serology-based immunological response was insufficient in approximately 21% (360/1793) of the participants for measles, 32% (572/1793) for diphtheria, and 74% (1289/1793) for hepatitis B.

CONCLUSIONS

We show evidence of low serological response to vaccine-preventable infections and increased LTBI prevalence in Ukrainian refugees. These findings should be integrated into guidelines for screening and treatment of infectious diseases in migrants and refugees in Germany and Europe. Furthermore, low immunity for vaccine-preventable diseases in Ukrainians independent of their refugee status, calls for tailor-made communication efforts.

Standardization of a CT Protocol for Imaging Patients with Suspected COVID-19-A RACOON Project

CT protocols that diagnose COVID-19 vary in regard to the associated radiation exposure and the desired image quality (IQ). This study aims to evaluate CT protocols of hospitals participating in the RACOON (Radiological Cooperative Network) project, consolidating CT protocols to provide recommendations and strategies for future pandemics. In this retrospective study, CT acquisitions of COVID-19 patients scanned between March 2020 and October 2020 (RACOON phase 1) were included, and all non-contrast protocols were evaluated. For this purpose, CT protocol parameters, IQ ratings, radiation exposure (CTDIvol), and central patient diameters were sampled. Eventually, the data from 14 sites and 534 CT acquisitions were analyzed. IQ was rated good for 81% of the evaluated examinations. Motion, beam-hardening artefacts, or image noise were reasons for a suboptimal IQ. The tube potential ranged between 80 and 140 kVp, with the majority between 100 and 120 kVp. CTDIvol was 3.7 ± 3.4 mGy. Most healthcare facilities included did not have a specific non-contrast CT protocol. Furthermore, CT protocols for chest imaging varied in their settings and radiation exposure. In future, it will be necessary to make recommendations regarding the required IQ and protocol parameters for the majority of CT scanners to enable comparable IQ as well as radiation exposure for different sites but identical diagnostic questions.

Ultra-short echo time (UTE) MR imaging: A brief review on technical considerations and clinical applications

BACKGROUND

 With the availability of MRI sequences with ultrashort echo times (UTE sequences), a signal can be gained from tissue, which was formerly only indirectly accessible. While already extensively employed in various research settings, the widespread transition of UTE imaging to clinical practice is just starting.

METHODS

 Based on a systematic literature search as well as knowledge gained through annual participation in conferences dedicated to advances in MRI, this review aims to give a brief overview of technical considerations and challenges of UTE imaging and summarizes the major areas of application of UTE imaging.

RESULTS

 UTE is already employed in clinical practice for structural lung imaging as well as the characterization of tissue composition and its alterations in selected musculoskeletal, cardiovascular, or neurodegenerative diseases. In specific contexts it can replace CT examinations with ionizing radiation and is especially attractive for pediatric patients and longitudinal monitoring of disease progression and treatment.

CONCLUSION

 UTE imaging provides an interesting and very valuable tool for various clinical purposes and promises a multitude of new insights into tissue properties. While some challenges remain, ongoing adoption in the clinical routine can be expected, as UTE approaches provide a new contrast and capture a signal in tissue formerly invisible on MR imaging.

KEY POINTS

  · UTE imaging gains relevance in clinical settings. · UTE imaging is employed for the characterization of tissue composition and its alterations in selected musculoskeletal, cardiovascular, or neurodegenerative diseases. · UTE imaging is employed in the clinical routine for structural lung imaging. · UTE imaging promises a multitude of new insights into tissue properties.

Age-related differences of cerebellar cortex and nuclei: MRI findings in healthy controls and its application to spinocerebellar ataxia (SCA6) patients

Understanding cerebellar alterations due to healthy aging provides a reference point against which pathological findings in late-onset disease, for example spinocerebellar ataxia type 6 (SCA6), can be contrasted. In the present study, we investigated the impact of aging on the cerebellar nuclei and cerebellar cortex in 109 healthy controls (age range: 16 - 78 years) using 3 Tesla magnetic resonance imaging (MRI). Findings were compared with 25 SCA6 patients (age range: 38 - 78 years). A subset of 16 SCA6 (included: 14) patients and 50 controls (included: 45) received an additional MRI scan at 7 Tesla and were re-scanned after one year. MRI included T1-weighted, T2-weighted FLAIR, and multi-echo T2*-weighted imaging. The T2*-weighted phase images were converted to quantitative susceptibility maps (QSM). Since the cerebellar nuclei are characterized by elevated iron content with respect to their surroundings, two independent raters manually outlined them on the susceptibility maps. T1-weighted images acquired at 3T were utilized to automatically identify the cerebellar gray matter (GM) volume. Linear correlations revealed significant atrophy of the cerebellum due to tissue loss of cerebellar cortical GM in healthy controls with increasing age. Reduction of the cerebellar GM was substantially stronger in SCA6 patients. The volume of the dentate nuclei did not exhibit a significant relationship with age, at least in the age range between 18 and 78 years, whereas mean susceptibilities of the dentate nuclei increased with age. As previously shown, the dentate nuclei volumes were smaller and magnetic susceptibilities were lower in SCA6 patients compared to age- and sex-matched controls. The significant dentate volume loss in SCA6 patients could also be confirmed with 7T MRI. Linear mixed effects models and individual paired t-tests accounting for multiple comparisons revealed no statistical significant change in volume and susceptibility of the dentate nuclei after one year in neither patients nor controls. Importantly, dentate volumes were more sensitive to differentiate between SCA6 (Cohen's d = 3.02) and matched controls than the cerebellar cortex volume (d = 2.04). In addition to age-related decline of the cerebellar cortex and atrophy in SCA6 patients, age-related increase of susceptibility of the dentate nuclei was found in controls, whereas dentate volume and susceptibility was significantly decreased in SCA6 patients. Because no significant changes of any of these parameters was found at follow-up, these measures do not allow to monitor disease progression at short intervals.

Reorganization and Plasticity of the Language Network in Patients with Cerebral Gliomas

Language is organized in large-scale networks in the human brain that show a strong potential for flexible interactions and adaptation. Neuroplasticity is the central mechanism that allows such dynamic modulation to changing conditions across the life span and is particularly important for network reorganization after brain lesions. Most studies on language reorganization focused on language recovery after stroke. Yet, a strong degree of adaptive neuroplasticity can also be observed in patients with brain tumors in language-eloquent brain areas. This review discusses key mechanisms for neural reorganization in patients with brain tumors. Our main aim is to elucidate the underlying mechanisms for intra- and interhemispheric plasticity in the language network in these patients. The following reorganization patterns are discussed: 1) Persisting function within the tumor; 2) Reorganization in perilesional regions; 3) Reorganization in a distributed network of the affected hemisphere; 4) Reorganization to the contralesional hemisphere. In this context, we shed light on language-related reorganization patterns in frontal and temporo-parietal areas and discuss their functional relevance. We also address tumor-related changes in structural and functional connectivity between eloquent brain regions. Thereby, we aim to expand the general understanding of the plastic potential of the neural language network and facilitate clinical decision-making processes for effective, function-preserving tumor treatment.

Optimized Whole-Body PET MRI Sequence Workflow in Pediatric Hodgkin Lymphoma Patients

¹⁸F-FDG PET/MRI might be the diagnostic method of choice for Hodgkin lymphoma patients, as it combines significant metabolic information from PET with excellent soft-tissue contrast from MRI and avoids radiation exposure from CT. However, a major issue is longer examination times than for PET/CT, especially for younger children needing anesthesia. Thus, a targeted selection of suitable whole-body MRI sequences is important to optimize the PET/MRI workflow. Methods: The initial PET/MRI scans of 84 EuroNet-PHL-C2 study patients from 13 international PET centers were evaluated. In each available MRI sequence, 5 PET-positive lymph nodes were assessed. If extranodal involvement occurred, 2 splenic lesions, 2 skeletal lesions, and 2 lung lesions were also assessed. A detection rate was calculated dividing the number of visible, anatomically assignable, and measurable lesions in the respective MRI sequence by the total number of lesions. Results: Relaxation time-weighted (T2w) transverse sequences with fat saturation (fs) yielded the best result, with detection rates of 95% for nodal lesions, 62% for splenic lesions, 94% for skeletal lesions, and 83% for lung lesions, followed by T2w transverse sequences without fs (86%, 49%, 16%, and 59%, respectively) and longitudinal relaxation time-weighted contrast-enhanced transverse sequences with fs (74%, 35%, 57%, and 55%, respectively). Conclusion: T2w transverse sequences with fs yielded the highest detection rates and are well suited for accurate whole-body PET/MRI in lymphoma patients. There is no evidence to recommend the use of contrast agents.

Neurometabolic patterns of an "at risk for mental disorders" syndrome involve abnormalities in the thalamus and anterior midcingulate cortex

BACKGROUND

The ultra-high risk (UHR) paradigm allows the investigation of individuals at increased risk of developing psychotic or other mental disorders with the aim of making prevention and early intervention as specific as possible in terms of the individual outcome.

METHODS

Single-session ¹H-/³¹P-Chemical Shift Imaging of thalamus, prefrontal (DLPFC) and anterior midcingulate (aMCC) cortices was applied to 69 UHR patients for psychosis and 61 matched healthy controls. N-acetylaspartate (NAA), glutamate/glutamine complex (Glx), energy (PCr, ATP) and phospholipid metabolites were assessed, analysed by ANOVA (or ANCOVA [with covariates]) and correlated with symptomatology (SCL-90R).

RESULTS

The thalamus showed decreased NAA, inversely correlated with self-rated aggressiveness, as well as increased PCr, and altered phospholipid breakdown. While the aMCC showed a pattern of NAA decrease and PCr increase, the DLPFC showed PCr increase only in the close-to-psychosis patient subgroup. There were no specific findings in transition patients.

CONCLUSION

The results do not support the notion of a specific pre-psychotic neurometabolic pattern, but likely reflect correlates of an "at risk for mental disorders syndrome". This includes disturbed neuronal (mitochondrial) metabolism in the thalamus and aMCC, with emphasis on left-sided structures, and altered PL remodeling across structures.

Vascular malformations of the female and male genitalia: type and distribution patterns revealed by magnetic resonance imaging

BACKGROUND

Vascular malformations of the genitalia often go undetected in clinical examination. These vascular malformations can cause a variety of clinical symptoms such as swelling, pain and bleeding.

AIM

To characterize the distribution patterns of genital vascular malformations using magnetic resonance imaging (MRI) and to correlate these patterns with clinical findings in order to guide diagnostic decisions.

METHODS

A retrospective analysis of MRIs of the pelvis and legs in 370 patients with vascular malformation was performed to determine the involvement of the internal and external genitalia.

RESULTS

In 71 patients (19%), genital involvement could be identified by MRI. Of these, 11.3% (8 of 71) presented with internal involvement, 36.6% (26 of 71) with external involvement and 52.1% (37 of 71) with both internal and external involvement. Over half (57.1%) of the 49 patients with visible external genital signs detected during a clinical examination had additional internal genital involvement.

CONCLUSIONS

Genital involvement is a common finding in patients with vascular malformation of the legs and/or pelvis. Based on our data, we recommend MRI of the legs and pelvic region in patients with externally visible signs of a vascular malformation of the external genitalia in order to exclude additional internal involvement.

Classification of first-episode psychosis using cortical thickness: A large multicenter MRI study

Machine learning classifications of first-episode psychosis (FEP) using neuroimaging have predominantly analyzed brain volumes. Some studies examined cortical thickness, but most of them have used parcellation approaches with data from single sites, which limits claims of generalizability. To address these limitations, we conducted a large-scale, multi-site analysis of cortical thickness comparing parcellations and vertex-wise approaches. By leveraging the multi-site nature of the study, we further investigated how different demographical and site-dependent variables affected predictions. Finally, we assessed relationships between predictions and clinical variables. 428 subjects (147 females, mean age 27.14) with FEP and 448 (230 females, mean age 27.06) healthy controls were enrolled in 8 centers by the ClassiFEP group. All subjects underwent a structural MRI and were clinically assessed. Cortical thickness parcellation (68 areas) and full cortical maps (20,484 vertices) were extracted. Linear Support Vector Machine was used for classification within a repeated nested cross-validation framework. Vertex-wise thickness maps outperformed parcellation-based methods with a balanced accuracy of 66.2% and an Area Under the Curve of 72%. By stratifying our sample for MRI scanner, we increased generalizability across sites. Temporal brain areas resulted as the most influential in the classification. The predictive decision scores significantly correlated with age at onset, duration of treatment, and positive symptoms. In conclusion, although far from the threshold of clinical relevance, temporal cortical thickness proved to classify between FEP subjects and healthy individuals. The assessment of site-dependent variables permitted an increase in the across-site generalizability, thus attempting to address an important machine learning limitation.

Alterations of neurometabolism in the dorsolateral prefrontal cortex and thalamus in transition to psychosis patients change under treatment as usual - A two years follow-up 1H/31P-MR-spectroscopy study

BACKGROUND

The ultra-high risk (UHR) paradigm allows early contact with patients developing acute psychosis and the study of treatment effects on the underlying pathology.

METHODS

29 patients with first acute psychosis according to CAARMS criteria (transition patients, TP) (T0) and thereof 22 patients after two-year follow-up (mean 788 d) (T1) underwent ¹H-/³¹P-MR spectroscopy of the prefrontal (DLPFC) and anterior midcingulate (aMCC) cortices and the thalamus. N-acetylaspartate (NAA), glutamate (Glu, Glx), energy (PCr, ATP) and phospholipid metabolites (PME, PDE) were compared to 27 healthy controls by ANCOVA and correlated with patients' symptom ratings (BPRS-E, SCL-90R). For longitudinal analysis, linear mixed model (LMM) and ANCOVA for repeated measures were used.

RESULTS

DLPFC: In patients, NAA and PME were decreased bilaterally and Glu on the left side at T0. Left-sided Glu and NAA (trend) and bilateral Glx increased during follow-up. Thalamus: In TP, bilateral NAA, left-sided Glu and right-sided Glx were decreased at T0; bilateral NAA and left-sided Glx increased during follow-up. aMCC: In TP, bilateral NAA, right-sided Glu, and bilateral PME and PDE were decreased, while left-sided PCr was increased at T0. No changes were observed during follow-up.

CONCLUSION

Regardless of the long-term diagnosis, the psychotic state of illness includes disturbed neuronal function in the DLPFC, thalamus and aMCC. Treatment-as-usual (TAU), including antipsychotic/antidepressant medication and supportive psychotherapy, had an effect on the thalamo-frontal area but not or less pronounced on the neurometabolic deficits of the aMCC.

Energy Expenditure of Dynamic Submaximal Human Plantarflexion Movements: Model Prediction and Validation by in-vivo Magnetic Resonance Spectroscopy

To understand the organization and efficiency of biological movement, it is important to evaluate the energy requirements on the level of individual muscles. To this end, predicting energy expenditure with musculoskeletal models in forward-dynamic computer simulations is currently the most promising approach. However, it is challenging to validate muscle models in-vivo in humans, because access to the energy expenditure of single muscles is difficult. Previous approaches focused on whole body energy expenditure, e.g., oxygen consumption (VO2), or on thermal measurements of individual muscles by tracking blood flow and heat release (through measurements of the skin temperature). This study proposes to validate models of muscular energy expenditure by using functional phosphorus magnetic resonance spectroscopy (³¹P-MRS). ³¹P-MRS allows to measure phosphocreatine (PCr) concentration which changes in relation to energy expenditure. In the first 25 s of an exercise, PCr breakdown rate reflects ATP hydrolysis, and is therefore a direct measure of muscular enthalpy rate. This method was applied to the gastrocnemius medialis muscle of one healthy subject during repetitive dynamic plantarflexion movements at submaximal contraction, i.e., 20% of the maximum plantarflexion force using a MR compatible ergometer. Furthermore, muscle activity was measured by surface electromyography (EMG). A model (provided as open source) that combines previous models for muscle contraction dynamics and energy expenditure was used to reproduce the experiment in simulation. All parameters (e.g., muscle length and volume, pennation angle) in the model were determined from magnetic resonance imaging or literature (e.g., fiber composition), leaving no free parameters to fit the experimental data. Model prediction and experimental data on the energy supply rates are in good agreement with the validation phase (<25 s) of the dynamic movements. After 25 s, the experimental data differs from the model prediction as the change in PCr does not reflect all metabolic contributions to the energy expenditure anymore and therefore underestimates the energy consumption. This shows that this new approach allows to validate models of muscular energy expenditure in dynamic movements in vivo.

Clinical relevance of total choline (tCho) quantification in suspicious lesions on multiparametric breast MRI

Purpose

To assess the additional value of quantitative tCho evaluation to diagnose malignancy and lymph node metastases in suspicious lesions on multiparametric breast MRI (mpMRI, BI-RADS 4, and BI-RADS 5).

Methods

One hundred twenty-one patients that demonstrated suspicious multiparametric breast MRI lesions using DCE, T2w, and diffusion-weighted (DW) images were prospectively enrolled in this IRB-approved study. All underwent single-voxel proton MR spectroscopy (¹H-MRS, point-resolved spectroscopy sequence, TR 2000 ms, TE 272 ms) with and without water suppression. The total choline (tCho) amplitude was measured and normalized to millimoles/liter according to established methodology by two independent readers (R1, R2). ROC-analysis was employed to predict malignancy and lymph node status by tCho results.

Results

One hundred three patients with 74 malignant and 29 benign lesions had full ¹H-MRS data. The area under the ROC curve (AUC) for prediction of malignancy was 0.816 (R1) and 0.809 (R2). A cutoff of 0.8 mmol/l tCho could diagnose malignancy with a sensitivity of > 95%. For prediction of lymph node metastases, tCho measurements achieved an AUC of 0.760 (R1) and 0.788 (R2). At tCho levels < 2.4 mmol/l, no metastatic lymph nodes were found.

Conclusion

Quantitative tCho evaluation from ¹H-MRS allowed diagnose malignancy and lymph node status in breast lesions suspicious on multiparametric breast MRI. tCho therefore demonstrated the potential to downgrade suspicious mpMRI lesions and stratify the risk of lymph node metastases for improved patient management.

Key Points

• Quantitative tCho evaluation can distinguish benign from malignant breast lesions suspicious after multiparametric MRI assessment.

• Quantitative tCho levels are associated with lymph node status in breast cancer.

• Quantitative tCho levels are higher in hormonal receptor positive compared to hormonal receptor negative lesions.

Electronic supplementary material

The online version of this article (10.1007/s00330-020-06678-z) contains supplementary material, which is available to authorized users.

Disturbed glutathione antioxidative defense is associated with structural brain changes in neuroleptic-naïve first-episode psychosis patients

BACKGROUND

Oxidative stress and impaired antioxidant defense are reported in schizophrenia and are thought to be associated with disturbed neurodevelopment, brain structural alterations, glutamatergic imbalance, negative symptomatology, and cognitive impairment. To test some of these assumptions we investigated the glutathione (GSH) antioxidant defense system (AODS) and brain structural abnormalities in drug-naïve individuals with first acute episode of psychosis (FEP).

METHOD

The study involved 27 drug-naïve FEP patients and 31 healthy controls (HC). GSH AODS markers and TBARS (thiobarbituric acid reactive substances) were measured in blood plasma and erythrocytes. High-resolution T₁-weighted 3T MRI were acquired from all subjects. To investigate brain structural abnormalities and effects of illness on interactions between GSH metabolites or enzyme activities and local grey matter density, voxel-based morphometry (VBM) with the computational anatomy toolbox (CAT12) was used. Symptomatology was assessed using the Positive and Negative Syndrome Scale (PANSS) and the Symptom Checklist 1990 revised (SCL-90-R).

RESULTS

(i) In FEP patients, glutathione reductase activity (GSR) was lower than in the HC group. GSR activity in plasma was inversely correlated with SCL-90-R scores of depression and PANSS scores of the negative symptom subscale. (ii) A reduction of GM was observed in left inferior frontal, bilateral temporal, as well as parietal cortices of FEP patients. (iii) Interaction analyses revealed an influence of illness on GSR/GM associations in the left orbitofrontal cortex (BA 47).

CONCLUSION

Our findings support the notion of altered GSH antioxidative defense in untreated acute psychosis as a potential pathomechanism for localized brain structural abnormalities. This pathology relates to a key brain region of social cognition, affective motivation control and decision making, and is clinically accompanied by depressive and negative symptoms.

Comparison of metabolic adaptations between endurance- and sprint-trained athletes after an exhaustive exercise in two different calf muscles using a multi-slice 31 P-MR spectroscopic sequence

Measurements of exercise-induced metabolic changes, such as oxygen consumption, carbon dioxide exhalation or lactate concentration, are important indicators for assessing the current performance level of athletes in training science. With exercise-limiting metabolic processes occurring in loaded muscles, ³¹ P-MRS represents a particularly powerful modality to identify and analyze corresponding training-induced alterations. Against this background, the current study aimed to analyze metabolic adaptations after an exhaustive exercise in two calf muscles (m. soleus - SOL - and m. gastrocnemius medialis - GM) of sprinters and endurance athletes by using localized dynamic ³¹ P-MRS. In addition, the respiratory parameters VO₂ and VCO₂ , as well as blood lactate concentrations, were monitored simultaneously to assess the effects of local metabolic adjustments in the loaded muscles on global physiological parameters. Besides noting obvious differences between the SOL and the GM muscles, we were also able to identify distinct physiological strategies in dealing with the exhaustive exercise by recruiting two athlete groups with opposing metabolic profiles. Endurance athletes tended to use the aerobic pathway in the metabolism of glucose, whereas sprinters produced a significantly higher peak concentration of lactate. These global findings go along with locally measured differences, especially in the main performer GM, with sprinters revealing a higher degree of acidification at the end of exercise (pH 6.29 ± 0.20 vs. 6.57 ± 0.21). Endurance athletes were able to partially recover their PCr stores during the exhaustive exercise and seemed to distribute their metabolic activity more consistently over both investigated muscles. In contrast, sprinters mainly stressed Type II muscle fibers, which corresponds more to their training orientation preferring the glycolytic energy supply pathway. In conclusion, we were able to analyze the relation between specific local metabolic processes in loaded muscles and typical global adaptation parameters, conventionally used to monitor the training status of athletes, in two cohorts with different sports orientations.

Prefrontal glutamatergic emotion regulation is disturbed in cluster B and C personality disorders - A combined 1H/31P-MR spectroscopic study

BACKGROUND

Personality disorders (PD) belong to the most common and most serious mental disorders as regards social dysfunction, inability to work, occurrence of comorbidity and suicidal risk. PDs also crucially influence the incidence, clinical course and treatment response of mental disorders with high suicidal risk, such as depression or substance abuse. One key issue of PD concerns the regulation of emotions.

METHODS

Both ¹H-/³¹P-Chemical Shift Imaging (CSI) was applied in a single session to assess neurochemical markers of glutamate function (NAA, Glu) and local energy metabolism (PCr, ATP) in two patient cohorts encompassing 22 cluster B (CB) and 21 cluster C (CC) PD patients, whereby 10 patients of each group were on low-dose antidepressants, and in 60 healthy controls (HC). Non-parametric statistical tests and correlation analyses were performed to assess disease effects on the metabolites and their relation to symptomatology as assessed by SCL-90R self-ratings.

RESULTS

Overall comparison including Bonferroni correction revealed significant differences of Glu across all groups in the dorsolateral prefrontal cortex (DLPFC). The following uncorrected results of pairwise tests were obtained: (i) Glu was bilaterally increased in the DLPFC in CB patients, whereas it was - together with NAA - bilaterally decreased in the DLPFC in CC patients and accompanied by increased PCr in the left DLPFC. (ii) NAA and Glu, accompanied by increased PCr, were significantly decreased in the dorsomedial prefrontal cortex (DMPFC) in CC patients. (iii) NAA was decreased in the right anterior cingulate cortex (ACC) in CB patients, and in the left ACC in CC patients with PCr being increased bilaterally. (iv) No associations were observed between metabolites and psychopathology measures.

CONCLUSION

The observations in the DLPFC may reflect a neurobiochemical correlate of disturbed cognitive control function in CB and CC PD. While the alterations in CB patients suggest increased basal activity, the observed patterns in CC patients likely reflect decreased or inhibited activity. The alterations of NAA and Glu levels in the ACC and DMPFC indirectly support the assumption of disturbed neuronal function in regions involved in social cognition and mentalizing abilities in both CB and CC PD. Further studies should include the investigation of metabolites of neuronal inhibition (GABA) and the examination of treatment effects.

Combined spiroergometry and 31 P-MRS of human calf muscle during high-intensity exercise

Simultaneous measurements of pulmonary oxygen consumption (VO₂ ), carbon dioxide exhalation (VCO₂ ) and phosphorus magnetic resonance spectroscopy (³¹ P-MRS) are valuable in physiological studies to evaluate muscle metabolism during specific loads. Therefore, the aim of this study was to adapt a commercially available spirometric device to enable measurements of VO₂ and VCO₂ whilst simultaneously performing ³¹ P-MRS at 3 T. Volunteers performed intense plantar flexion of their right calf muscle inside the MR scanner against a pneumatic MR-compatible pedal ergometer. The use of a non-magnetic pneumotachograph and extension of the sampling line from 3 m to 5 m to place the spirometric device outside the MR scanner room did not affect adversely the measurements of VO₂ and VCO₂ . Response and delay times increased, on average, by at most 0.05 s and 0.79 s, respectively. Overall, we were able to demonstrate a feasible ventilation response (VO₂ = 1.05 ± 0.31 L/min; VCO₂ = 1.11 ± 0.33 L/min) during the exercise of a single calf muscle, as well as a good correlation between local energy metabolism and muscular acidification (τ_{PCr fast} and pH; R² = 0.73, p < 0.005) and global respiration (τ_{PCr fast} and VO₂ ; R²  = 0.55, p = 0.01). This provides improved insights into aerobic and anaerobic energy supply during strong muscular performances.

Difference optimization: Automatic correction of relative frequency and phase for mean non-edited and edited GABA 1H MEGA-PRESS spectra

Phase and frequency corrections of magnetic resonance spectroscopic data are of major importance to obtain reliable and unambiguous metabolite estimates as validated in recent research for single-shot scans with the same spectral fingerprint. However, when using the J-difference editing technique ¹H MEGA-PRESS, misalignment between mean edited (ON‾) and non-edited (OFF‾) spectra that may remain even after correction of the corresponding individual single-shot scans results in subtraction artefacts compromising reliable GABA quantitation. We present a fully automatic routine that iteratively optimizes simultaneously relative frequencies and phases between the mean ON‾ and OFF‾¹H MEGA-PRESS spectra while minimizing the sum of the magnitude of the difference spectrum (L¹ norm). The proposed method was applied to simulated spectra at different SNR levels with deliberately preset frequency and phase errors. Difference optimization proved to be more sensitive to small signal fluctuations, as e.g. arising from subtraction artefacts, and outperformed the alternative spectral registration approach, that, in contrast to our proposed linear approach, uses a nonlinear least squares minimization (L² norm), at all investigated levels of SNR. Moreover, the proposed method was applied to 47 MEGA-PRESS datasets acquired in vivo at 3T. The results of the alignment between the mean OFF‾ and ON‾ spectra were compared by applying (a) no correction, (b) difference optimization or (c) spectral registration. Since the true frequency and phase errors are not known for in vivo data, manually corrected spectra were used as the gold standard reference (d). Automatically corrected data applying both, method (b) or method (c), showed distinct improvements of spectra quality as revealed by the mean Pearson correlation coefficient between corresponding real part mean DIFF‾ spectra of R_bd=0.997±0.003 (method (b) vs. (d)), compared to R_ad=0.764±0.220 (method (a) vs. (d)) with no alignment between OFF‾ and ON‾. Method (c) revealed a slightly lower correlation coefficient of R_cd=0.972±0.028 compared to R_bd, that can be ascribed to small remaining subtraction artefacts in the final DIFF‾ spectrum. In conclusion, difference optimization performs robustly with no restrictions regarding the input data range or user intervention and represents a complementary tool to optimize the final DIFF‾ spectrum following the mandatory frequency and phase corrections of single ON and OFF scans prior to averaging.

The reproducibility of different metabolic markers for muscle fiber type distributions investigated by functional 31P-MRS during dynamic exercise

PURPOSE

The objective of the study was to investigate the reproducibility of exercise induced pH-heterogeneity by splitting of the inorganic phosphate (Pi) signal in the corresponding ³¹P-MRS spectra and to compare results of this approach with other fiber-type related markers, like phosphocreatine/adenosine triphosphate (PCr/ATP) ratio, and PCr-recovery parameters.

MATERIAL AND METHODS

Subjects (N=3) with different sportive background were tested in 10 test sessions separated by at least 3 days. A MR-compatible pedal ergometer was used to perform the exercise and to induce a pH-based splitting of the Pi-signal in ³¹P-MR spectra of the medial gastrocnemius muscle. The PCr recovery was analyzed using a non-negative least square algorithm (NNLS) and multi-exponential regression analysis to estimate the number of non-exponential components as well as their amplitude and time constant. The reproducibility of the estimated metabolic marker and the resulting fiber-type distributions between the 10 test sessions were compared.

RESULTS

The reproducibility (standard deviation between measurements) based on (1) Pi components varied from 2% to 4%, (2) PCr recovery time components varied from 10% to 12% and (3) phosphate concentrations at rest varied from 8% to 11% between test sessions. Due to the sportive activity differences between the 3 subjects were expected in view of fiber type distribution. All estimated markers indicate the highest type I percentage for volunteer 3 medium for volunteer 2 and the lowest for volunteer 1.

CONCLUSIONS

The relative high reproducibility of pH dependent Pi components during exercise indicates a high potential of this method to estimate muscle fiber-type distributions in vivo. To make this method usable not only to detect differences in muscle fiber distributions but also to determine individual fiber-type volume contents it is therefore recommended to validate this marker by histological methods and to reveal the effects of muscle fiber recruitments and fiber-type specific Pi concentrations on the intensity ratios between the splitted Pi-components.

The pH heterogeneity in human calf muscle during neuromuscular electrical stimulation

PURPOSE

The aim of the study was to examine pH heterogeneity during fatigue induced by neuromuscular electrical stimulation (NMES) using phosphorus magnetic resonance spectroscopy (³¹ P-MRS). It is hypothesized that three pH components would occur in the ³¹ P-MRS during fatigue, representing three fiber types.

METHODS

The medial gastrocnemius of eight subjects was stimulated within a 3-Tesla whole body MRI scanner. The maximal force during stimulation (F_stim ) was examined by a pressure sensor. Phosphocreatine (PCr), adenosintriphosphate, inorganic phosphate (Pi), and the corresponding pH were estimated by a nonvolume-selective ³¹ P-MRS using a small loop coil at rest and during fatigue.

RESULTS

During fatigue, F_stim and PCr decreased to 27% and 33% of their initial levels, respectively. In all cases, the Pi peak increased when NMES was started and split into three different peaks. Based on the single Pi peaks during fatigue, an alkaline (6.76 ± 0.08), a medium (6.40 ± 0.06), and an acidic (6.09 ± 0.05) pH component were observed compared to the pH (7.02 ± 0.02) at rest.

CONCLUSION

It is suggested that NMES is able to induce pH heterogeneity in the medial gastrocnemius, and that the single Pi peaks represent the different muscle fiber types of the skeletal muscle. Magn Reson Med 77:2097-2106, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

Hippocampal structure, metabolism, and inflammatory response after a 6-week intense aerobic exercise in healthy young adults: a controlled trial

Interventional studies suggest that changes in physical fitness affect brain function and structure. We studied the influence of high intensity physical exercise on hippocampal volume and metabolism in 17 young healthy male adults during a 6-week exercise program compared with matched controls. We further aimed to relate these changes to hypothesized changes in exercised-induced brain-derived neurotrophic factor (BDNF), interleukin-6 (IL-6), and tumor necrosis factor alpha (TNF-α). We show profound improvement of physical fitness in most subjects and a positive correlation between the degree of fitness improvement and increased BDNF levels. We unexpectedly observed an average volume decrease of about 2%, which was restricted to right hippocampal subfields CA2/3, subiculum, and dentate gyrus and which correlated with fitness improvement and increased BDNF levels negatively. This result indicates that mainly those subjects who did not benefit from the exercise program show decreased hippocampal volume, reduced BDNF levels, and increased TNF-α concentrations. While spectroscopy results do not indicate any neuronal loss (unchanged N-acetylaspartate levels) decreased glutamate-glutamine levels were observed in the right anterior hippocampus in the exercise group only. Responder characteristics need to be studied in more detail. Our results point to an important role of the inflammatory response after exercise on changes in hippocampal structure.

Glutamatergic dysfunction linked to energy and membrane lipid metabolism in frontal and anterior cingulate cortices of never treated first-episode schizophrenia patients

BACKGROUND

Glutamatergic dysfunction and altered membrane lipid and energy metabolism have been repeatedly demonstrated in the frontal/prefrontal and anterior cingulate cortex (ACC) in schizophrenia. Though having been already studied in animals, the presumed link between glutamatergic function and structural plasticity has not been investigated directly in the human brain yet. We measured glutamate (Glu), focal energy metabolism, and membrane phospholipid turnover to investigate main pathologies in those key brain regions of schizophrenia.

METHODS

(1)H- and (31)P-Chemical Shift Imaging (CSI) was combined in a single session to assess Glu and markers of energy (PCr, ATP) and membrane lipid (PME, PDE) metabolism in 31 neuroleptic-naïve first acute onset psychosis patients and 31 matched healthy controls. Multivariate analyses of covariance were used to assess disease effects on Glu and to investigate the impact of Glu alterations on phospholipid and energy metabolites.

RESULTS

Glu levels of patients were increased in the frontal and prefrontal cortex bilaterally and in the ACC. Higher Glu was associated with increased left frontal/prefrontal PME and right frontal/prefrontal PDE in patients, which was not observed in healthy controls. In contrast, higher Glu levels were associated with lower PCr or ATP values in the frontal/prefrontal cortex bilaterally and in the right ACC of controls. This was not observed in the right ACC and left frontal/prefrontal cortex of patients.

CONCLUSION

Frontal glutamatergic hyperactivity is disconnected from physiologically regulated energy metabolism and is associated with increased membrane breakdown in right and increased membrane restoration in left frontal and prefrontal cortical regions. As indicated by previous findings, this pathology is likely dynamic during the course of first acute illness and possibly associated with negative symptoms and cognitive impairment. Our findings underline the importance of further research on neuroprotective treatment options during the early acute or even better for the ultra-high risk state of psychotic illness.

Age-related structural and functional changes of low back muscles

During aging declining maximum force capacity with more or less unchanged fatigability is observed with the underlying mechanisms still not fully understood. Therefore, we compared morphology and function of skeletal muscles between different age groups. Changes in high-energy phosphate turnover (PCr, Pi and pH) and muscle functional MRI (mfMRI) parameters, including proton transverse relaxation time (T2), diffusion (D) and vascular volume fraction (f), were investigated in moderately exercised low back muscles of young and late-middle-aged healthy subjects with (31)P-MR spectroscopy, T2- and diffusion-weighted MRI at 3T. In addition, T1-weighted MRI data were acquired to determine muscle cross-sectional areas (CSA) and to assess fat infiltration into muscle tissue. Except for pH, both age groups showed similar load-induced MR changes and rates of perceived exertion (RPE), which indicates comparable behavior of muscle activation at moderate loads. Changes of mfMRI parameters were significantly associated with RPE in both cohorts. Age-related differences were observed, with lower pH and higher Pi/ATP ratios as well as lower D and f values in the late-middle-aged subjects. These findings are ascribed to age-related changes of fiber type composition, fiber size and vascularity. Interestingly, post exercise f was negatively associated with fat infiltration with the latter being significantly higher in late-middle-aged subjects. CSA of low back muscles remained unchanged, while CSA of inner back muscle as well as mean T2 at rest were associated with maximum force capacity. Overall, applying the proposed MR approach provides evidence of age-related changes in several muscle tissue characteristics and gives new insights into the physiological processes that take place during aging.

Brain structure in people at ultra-high risk of psychosis, patients with first-episode schizophrenia, and healthy controls: a VBM study

Early intervention research in schizophrenia has suggested that brain structural alterations might be present in subjects at high risk of developing psychosis. The heterogeneity of regional effects of these changes, which is established in schizophrenia, however, has not been explored in prodromal or high-risk populations. We used high-resolution MRI and voxel-based morphometry (VBM8) to analyze grey matter differences in 43 ultra high-risk subjects for psychosis (meeting ARMS criteria, identified through CAARMS interviews), 24 antipsychotic-naïve first-episode schizophrenia patients and 49 healthy controls (groups matched for age and gender). Compared to healthy controls, resp., first-episode schizophrenia patients had reduced regional grey matter in left prefrontal, insula, right parietal and left temporal cortices, while the high-risk group showed reductions in right middle temporal and left anterior frontal cortices. When dividing the ultra-high-risk group in those with a genetic risk vs. those with attenuated psychotic symptoms, the former showed left anterior frontal, right caudate, as well as a smaller right hippocampus, and amygdala reduction, while the latter subgroup showed right middle temporal cortical reductions (each compared to healthy controls). Our findings in a clinical psychosis high-risk cohort demonstrate variability of brain structural changes according to subgroup and background of elevated risk, suggesting frontal and possibly also hippocampal/amygdala changes in individuals with genetic susceptibility. Heterogeneity of structural brain changes (as seen in schizophrenia) appears evident even at high-risk stage, prior to potential onset of psychosis.

In vivo detection of acute pain-induced changes of GABA+ and Glx in the human brain by using functional 1H MEGA-PRESS MR spectroscopy

In vivo(1)H MR spectroscopic detection of pain associated metabolic changes in the human brain may allow for an objective evaluation of the perceived pain intensity and assessment of the involved neurotransmitters. Ultimately, it may lead to a deeper understanding of the mechanisms that underlie neuronal pain processing. The present study reports results of time-resolved measurements of acute heat pain induced changes of the excitatory (Glx) and inhibitory (GABA+) neurotransmitter turnover in the anterior cingulate cortex (ACC) and occipital cortex (OC) by using (1)H MEGA-PRESS spectroscopy. In ACC and OC, the ratio Glx/tCr increased by median values of 21.5% (p < 0.001) and 15.7% (p < 0.001), respectively. At the same time, GABA+/tCr decreased by median values of 15.1% (p = 0.114) in ACC and 12.7% (p < 0.001) in OC. To our knowledge, this study demonstrates for the first time the possibility of quantifying pain-induced neurotransmitter changes in the brain by using functional (1)H MEGA-PRESS. The increase of Glx/tCr may be ascribed to an elevated glutamatergic turnover, while the decrease of GABA+/tCr may reflect reduced activity of the inhibitory system in ACC and OC during pain processing.

Interrelations of muscle functional MRI, diffusion-weighted MRI and (31) P-MRS in exercised lower back muscles

Exercise-induced changes of transverse proton relaxation time (T2 ), tissue perfusion and metabolic turnover were investigated in the lower back muscles of volunteers by applying muscle functional MRI (mfMRI) and diffusion-weighted imaging (DWI) before and after as well as dynamic (31) P-MRS during the exercise. Inner (M. multifidus, MF) and outer lower back muscles (M. erector spinae, ES) were examined in 14 healthy young men performing a sustained isometric trunk-extension. Significant phosphocreatine (PCr) depletions ranging from 30% (ES) to 34% (MF) and Pi accumulations between 95% (left ES) and 120%-140% (MF muscles and right ES) were observed during the exercise, which were accompanied by significantly decreased pH values in all muscles (∆pH ≈ -0.05). Baseline T2 values were similar across all investigated muscles (approximately 27 ms at 3 T), but revealed right-left asymmetric increases (T2 ,inc ) after the exercise (right ES/MF: T2 ,inc  = 11.8/9.7%; left ES/MF: T2 ,inc  = 4.6/8.9%). Analyzed muscles also showed load-induced increases in molecular diffusion D (p = .007) and perfusion fraction f (p = .002). The latter parameter was significantly higher in the MF than in the ES muscles both at rest and post exercise. Changes in PCr (p = .03), diffusion (p < .01) and perfusion (p = .03) were strongly associated with T2,inc , and linear mixed model analysis revealed that changes in PCr and perfusion both affect T2,inc (p < .001). These findings support previous assumptions that T2 changes are not only an intra-cellular phenomenon resulting from metabolic stress but are also affected by increased perfusion in loaded muscles.

MR-compatible pedal ergometer for reproducible exercising of the human calf muscle

A pneumatic MR-compatible pedal ergometer was designed to perform dynamic contraction exercises of the human calf muscle in a whole-body 3T MR scanner. The set-up includes sensors for monitoring mechanical parameters, such as pedal angle, cadence as well as applied force and power. Actual parameter values during the exercise were presented to the volunteer as a visual feedback to enable real-time self-adjustment of pedal deflection and cadence to the target reference value. Time-resolved dynamic (31)P-MR spectroscopic measurements of phosphocreatine (PCr), inorganic phosphate (Pi) and pH were performed in a pilot experiment before, during, and after the exercise by a single volunteer. Two different load strengths were applied in these experiments (15% and 25% of the maximum voluntary contraction, MVC). As expected, mechanical and metabolic parameters differed for the two load levels. Small variations of the cadence, power and metabolic changes (time constants of PCr depletion and Pi accumulation) during the experiments demonstrate a highly reproducible mechanical output by the volunteer mediated by the ergometer.

Superior temporal metabolic changes related to auditory hallucinations: a (31)P-MR spectroscopy study in antipsychotic-free schizophrenia patients

Structural deficits in the superior temporal cortex and transverse temporal gyri appear to be related to auditory hallucinations in schizophrenia, which are a key symptom of this disorder. However, the cellular and neurochemical underpinnings are poorly understood and hardly studied in vivo. We used (31)P-MRS (magnetic resonance spectroscopy) with chemical shift imaging to assess the association between left superior temporal cortex metabolism and severity of auditory hallucinations in 29 schizophrenia patients off antipsychotics. Hallucinations scores derived from the Scale for the Assessment of Positive Symptoms showed significant positive correlations with both measures of phospholipids (phosphomonoesters and phosphodiesters), and energy (inorganic phosphate and phosphocreatine, but not adenosine tri-phosphate) metabolism in left superior temporal gyrus/Heschl gyrus voxels. There was no correlation of metabolites in these regions with formal thought disorder, a symptom also linked to superior temporal pathology, thus suggesting symptom specificity. Our findings provide a link between established structural deficits and neurochemical pathology related to membrane pathology and markers of general metabolic turnover.

Effects of olanzapine on 31P MRS metabolic markers in schizophrenia

Antipsychotic drug action might include mechanisms related to normalising phospholipid and high-energy metabolism. We applied brain metabolic imaging with (31)P magnetic resonance spectroscopy ((31)P MRS) and two-dimensional chemical shift imaging to assess changes of metabolism of phospholipids and high-energy phosphates in schizophrenia patients at baseline (four antipsychotic-naïve and three off antipsychotics) and at follow-up, after 6 weeks of treatment with olanzapine. Results indicate a significant increase of adenosine-triphosphate (ATP) in the right inferior temporal cortex and a trend towards ATP decrease in the left cerebellum. This suggests a shift in high-energy phosphates (rather than phospholipids), possibly related to normalisation of functioning in these areas.

Antipsychotic drug effects on left prefrontal phospholipid metabolism: a follow-up 31P-2D-CSI study of haloperidol and risperidone in acutely ill chronic schizophrenia patients

INTRODUCTION

³¹Phosphorous magnetic resonance spectroscopy (2D chemical shift imaging, CSI) allows multiregional study of membrane phospholipids and high-energy phosphates in vivo. Increased membrane lipid turnover and impaired energy supply have repeatedly been shown in first-episode schizophrenia patients, and might be a target of drug actions other than dopamine receptors. Here, we explored differential metabolic effects of a typical vs. an atypical antipsychotic on brain phospholipids.

METHODS

We applied 2D-CSI MR spectroscopy in 17 recurrent-episode schizophrenia patients off antipsychotics at baseline and at follow-up after 6 weeks, during which 7 patients were treated with haloperidol (10-16 mg/d) and 10 with risperidone (4-6 mg/d). Psychopathology changes were assessed using PANSS, BPRS and CGI scores.

RESULTS

Follow-up analysis using repeated measure ANOVA revealed different effects of both antipsychotic agents: while risperidone generally increased metabolite levels, haloperidol showed a tendency to decrease them. This diverging effect was significant for ATP levels in the left lateral frontal cortex. Furthermore, risperidone increased ATP in the left dorsolateral prefrontal cortex, left anterior temporal cortex and left insular cortex, basal ganglia, and anterior cerebellum, along with left frontal and prefrontal increase of PCr, PDE and PME in these brain regions.

CONCLUSION

Risperidone seems to stimulate neuronal and synaptic phospholipid remodeling in left frontal and prefrontal regions, and to a lesser extent also in temporal and insular cortices. We discuss these effects with respect to clinical effects on negative and cognitive symptoms, as well as interaction of phospholipid metabolism with glutamatergic neurotransmission.

Effect of contrast agent on the results of in vivo ¹H MRS of breast tumors - is it clinically significant?

Choline (Cho) signal identification and quantification in (1)H MRS are used in breast cancer diagnosis. However, an influence of the gadolinium-based contrast agent on the Cho amplitude has been reported experimentally. This study aims to identify the impact of gadolinium-based contrast agents on Cho detection and quantification in postcontrast breast MRS. Consecutive patients were recruited prospectively and randomly allocated to two groups. Group A received a neutral (gadolinium diethylenetriaminepentaacetic acid bis-methylamide) and group B an ionic (gadolinium diethylenetriaminepentaacetic acid) contrast agent, each at a dosage of 0.1 mmol/kg. First, the presence of Cho was identified visually. Then, the normalized Cho intensity in malignant lesions was quantified. Multivariate analysis was applied to identify independent influencing factors on Cho. Sixty-three lesions were investigated [A, n = 34; B, n = 29; 43 malignant (one bilaterally malignant), 20 benign]. Cho was identified visually in 14 of 20 malignant tumors in group A and 12 of 22 malignant tumors in group B (p = 0.477). Normalized Cho differed significantly (p = 0.001) between groups A (mean, 26.8 ± 6.0 AU) and B (mean, 18.2 ± 12.5 AU). No linewidth differences were identified (p > 0.05). Multivariate analysis revealed only group membership (A versus B) as an independent predictor of Cho (p = 0.017). The results suggest stronger negative effects of an ionic relative to a neutral gadolinium-based contrast agent on breast tumor MRS in vivo. These results should be considered when conducting and comparing quantitative Cho measurements in the breast.

31P-MR spectroscopy in monozygotic twins discordant for schizophrenia / schizoaffective disorders

Introduction

Magnetic resonance spectroscopy (MRS) using 2D-chemical shift imaging (CSI) allows the quantification of brain metabolites in vivo across several brain regions. Previous studies using 31Phosphorus MRS have shown alterations of phospholipid compounds and high-energy phosphates like ATP in prefrontal and temporal regions in schizophrenia.

Aim

We used a monozygotic (MZ) co-twin study design to examine whether metabolic alterations are due to genetic effects or the expression of disease phenotype.

Methods

31P-MRS with 2D-CSI was applied at 1.5 T in 8 MZ twin pairs (3 male, 5 female; mean age 33.8, SD 13.1) discordant for a DSM-IV and ICD-10 diagnosis of either schizophrenia (4 pairs), acute schizophreniform psychosis (1 pair), or schizoaffective disorder (3 pairs)) and 8 age- and gender-matched healthy control MZ twins (mean age: 32.9, SD 14.3). Metabolic profiles were compared using oneway ANOVAs.

Results

Voxel-wise comparisons between affected twins and healthy control twins revealed increased PDE concentrations in right cerebellum and increased ATP concentrations in right frontal cortex, insular cortex and bilateral cerebellum. Alterations in energy metabolism were shown in healthy co-twins compared to healthy control twins with an increase in PDE concentrations in right posterior lateral cerebellum, an increase in ATP concentration in left lateral prefrontal cortex as well as left anterior/ lateral temporal cortex and an increase in PCr in left lateral prefrontal cortex.

Conclusions

Our findings suggest that metabolic alterations in schizophrenia result from a combination of both genetic effects and disease manifestation, which can be further explored in larger twin samples.

WITHDRAWN: Erratum to "1H-MR spectroscopic detection of metabolic changes in pain processing brain regions in the presence of non-specific chronic low back pain" [NeuroImage 54/2 (2011) 1315-1323]

The Publisher regrets that this article is an accidental duplication of an article that has already been published, http://dx.doi.org/10.1016/j.neuroimage.2010.11.069. The duplicate article has therefore been withdrawn.

1H-MR spectroscopic detection of metabolic changes in pain processing brain regions in the presence of non-specific chronic low back pain

Reliable detection of metabolic changes in the brain in vivo induced by chronic low back pain may provide improved understanding of neurophysiological mechanisms underlying the manifestation of chronic pain. In the present study, absolute concentrations of N-acetyl-aspartate (NAA), creatine (Cr), total choline (tCho), myo-inositol (mI), glutamate (Glu) and glutamine (Gln) were measured in three different pain processing cortical regions (anterior insula, anterior cingulate cortex, and thalamus) of ten patients with non-specific chronic low back pain by means of proton MR spectroscopy ((1)H-MRS) and compared to matched healthy controls. Significant decrease of Glu was observed in the anterior cingulate cortex of patients. Patients also revealed a trend of decreasing Gln concentrations in all investigated brain areas. Reductions of NAA were observed in the patient group in anterior insula and in anterior cingulated cortex, whereas mI was reduced in anterior cingulated cortex and in thalamus of patients. Reduced concentrations of Glu and Gln may indicate disordered glutamatergic neurotransmission due to prolonged pain perception, whereas decrease of NAA and mI may be ascribed to neuron and glial cell loss. No significant changes were found for Cr. The morphological evaluation of anatomic brain data revealed a significantly decreased WM volume of 17% (p<0.05) as well as a non significant trend for GM volume increase in the anterior insula of patients.

Time-resolved functional 1H MR spectroscopic detection of glutamate concentration changes in the brain during acute heat pain stimulation

Non-invasive in vivo detection of cortical neurotransmitter concentrations and their changes in the presence of pain may help to better understand the biochemical principles of pain processing in the brain. In the present study acute heat pain related changes of the excitatory neurotransmitter glutamate were investigated in the anterior insular cortex of healthy volunteers by means of time-resolved functional proton magnetic resonance spectroscopy ((1)H-MRS). Dynamic metabolite changes were estimated with a temporal resolution of five seconds by triggering data acquisition to the time course of the cyclic stimulus application. An overall increase of glutamate concentration up to 18% relative to the reference non-stimulus condition was observed during the application of short pain stimuli.

[Quantitation of glutamate in the brain by using MR proton spectroscopy at 1.5 T and 3 T]

PURPOSE

The influence of different magnetic field strengths on the quantification of glutamate was experimentally investigated by means of IN VITRO and IN VIVO (1)H-MR spectroscopic measurements at 1.5 T and 3 T.

MATERIALS AND METHODS

In vitro (1)H-MR measurements of aqueous solutions of NAA, glutamate, glutamine and GABA were performed on two clinical MR scanners at 1.5 T and 3 T using a single voxel PRESS sequence (TR/TE = 10 000 / 30 ms). IN VITRO brain measurements were also performed at both field strengths using a PRESS 2D- (1)H-CSI-sequence (TR/TE = 5000 / 30 ms) in 6 volunteers. Spectra at 1.5 T and 3 T were compared with respect to the overlap of the single compound spectra and the deviations between estimated and nominally adjusted concentrations. In vivo spectra at both field strengths were compared with respect to SNR (Glu), line width and Cramer-Rao values of the estimated glutamate intensities by using the LCModel. For the thalamus, insular and parietal cortex mean Glu/tCr ratios were estimated and compared between 1.5 T and 3 T as well as with corresponding values in the literature.

RESULTS

In general, an improved separation of signal maxima was observed in the IN VITRO spectra at 3 T. Except for GABA, all IN VITRO concentrations estimated at 3 T revealed lower deviations from their adjusted nominal concentration compared to 1.5 T: NAA (1.5 T: -5.5 %, 3 T: 0.7 %), glutamate (1.5 T: -18.1 %, 3 T: 12.3 %), glutamine (1.5 T: 44.8 %, 3 T: 9.2 %), GABA (1.5 T: - 24.8 %, 3 T: 33.8 %). The SNR of IN VIVO spectra at 3 T was nearly doubled compared to 1.5 T. The mean number of voxels with %SD (Glu)< 20 was distinctly lower at 1.5 T (53 %) than at 3 T (80 %). Estimated Glu/tCr ratios for thalamus, insular and parietal cortex lay in the upper range of the literature values.

CONCLUSION

The results indicate that the advantageous distribution of signal maxima at 3 T allows an improved separation of the individual spectra. Both the higher initial magnetization at 3 T and the improved sensitivity of the phased array matrix coil used in the 3 T study result in an increased SNR, which leads to better reliability of the individual detection as well as a more accurate quantification of glutamate.