Amygdalar nuclei and hippocampal subfields on MRI: Test-retest reliability of automated volumetry across different MRI sites and vendors.

BACKGROUND: The amygdala and the hippocampus are two limbic structures that play a critical role in cognition and behavior, however their manual segmentation and that of their smaller nuclei/subfields in multicenter datasets is time consuming and difficult due to the low contrast of standard MRI. Here, we assessed the reliability of the automated segmentation of amygdalar nuclei and hippocampal subfields across sites and vendors using FreeSurfer in two independent cohorts of older and younger healthy adults. METHODS: Sixty-five healthy older (cohort 1) and 68 younger subjects (cohort 2), from the PharmaCog and CoRR consortia, underwent repeated 3D-T1 MRI (interval 1-90 days). Segmentation was performed using FreeSurfer v6.0. Reliability was assessed using volume reproducibility error (ε) and spatial overlapping coefficient (DICE) between test and retest session. RESULTS: Significant MRI site and vendor effects (p â€‹< â€‹.05) were found in a few subfields/nuclei for the ε, while extensive effects were found for the DICE score of most subfields/nuclei. Reliability was strongly influenced by volume, as ε correlated negatively and DICE correlated positively with volume size of structures (absolute value of Spearman's r correlations >0.43, p â€‹< â€‹1.39E-36). In particular, volumes larger than 200 â€‹mm3 (for amygdalar nuclei) and 300 â€‹mm3 (for hippocampal subfields, except for molecular layer) had the best test-retest reproducibility (ε â€‹< â€‹5% and DICE â€‹> â€‹0.80). CONCLUSION: Our results support the use of volumetric measures of larger amygdalar nuclei and hippocampal subfields in multisite MRI studies. These measures could be useful for disease tracking and assessment of efficacy in drug trials.

Cognitive correlates of α4ß2 nicotinic acetylcholine receptors in mild Alzheimer's dementia.

In early Alzheimer's dementia, there is a need for PET biomarkers of disease progression with close associations to cognitive dysfunction that may aid to predict further cognitive decline and neurodegeneration. Amyloid biomarkers are not suitable for that purpose. The α4ß2 nicotinic acetylcholine receptors (α4ß2-nAChRs) are widely abundant in the human brain. As neuromodulators they play an important role in cognitive functions such as attention, learning and memory. Post-mortem studies reported lower expression of α4ß2-nAChRs in more advanced Alzheimer's dementia. However, there is ongoing controversy whether α4ß2-nAChRs are reduced in early Alzheimer's dementia. Therefore, using the recently developed α4ß2-nAChR-specific radioligand (-)-18F-flubatine and PET, we aimed to quantify the α4ß2-nAChR availability and its relationship to specific cognitive dysfunction in mild Alzheimer's dementia. Fourteen non-smoking patients with mild Alzheimer's dementia, drug-naïve for cholinesterase therapy, were compared with 15 non-smoking healthy controls matched for age, sex and education by applying (-)-18F-flubatine PET together with a neuropsychological test battery. The one-tissue compartment model and Logan plot method with arterial input function were used for kinetic analysis to obtain the total distribution volume (VT) as the primary, and the specific binding part of the distribution volume (VS) as the secondary quantitative outcome measure of α4ß2-nAChR availability. VS was determined by using a pseudo-reference region. Correlations between VT within relevant brain regions and Z-scores of five cognitive functions (episodic memory, executive function/working memory, attention, language, visuospatial function) were calculated. VT (and VS) were applied for between-group comparisons. Volume of interest and statistical parametric mapping analyses were carried out. Analyses revealed that in patients with mild Alzheimer's dementia compared to healthy controls, there was significantly lower VT, especially within the hippocampus, fronto-temporal cortices, and basal forebrain, which was similar to comparisons of VS. VT decline in Alzheimer's dementia was associated with distinct domains of impaired cognitive functioning, especially episodic memory and executive function/working memory. Using (-)-18F-flubatine PET in patients with mild Alzheimer's dementia, we show for the first time a cholinergic α4ß2-nAChR deficiency mainly present within the basal forebrain-cortical and septohippocampal cholinergic projections and a relationship between lower α4ß2-nAChR availability and impairment of distinct cognitive domains, notably episodic memory and executive function/working memory. This shows the potential of (-)-18F-flubatine as PET biomarker of cholinergic α4ß2-nAChR dysfunction and specific cognitive decline. Thus, if validated by longitudinal PET studies, (-)-18F-flubatine might become a PET biomarker of progression of neurodegeneration in Alzheimer's dementia.

Habenula volume increases with disease severity in unmedicated major depressive disorder as revealed by 7T MRI.

The habenula is a paired epithalamic structure involved in the pathogenesis of major depressive disorder (MDD). Evidence comes from its impact on the regulation of serotonergic and dopaminergic neurons, the role in emotional processing and studies on animal models of depression. The present study investigated habenula volumes in 20 unmedicated and 20 medicated MDD patients and 20 healthy controls for the first time by applying a triplanar segmentation algorithm on 7 Tesla magnetic resonance (MR) whole-brain T1 maps. The hypothesis of a right-side decrease of habenula volumes in the MDD patients was tested, and the relationship between volumetric abnormalities and disease severity was exploratively investigated. Absolute and relative total and hemispheric habenula volumes did not differ significantly between the three groups. In the patients with short duration of disease for which medication effects could be ruled out, significant correlations were found between bilateral habenula volumes and HAMD-17- and BDI-II-related severities. In the medicated patients, this positive relationship disappeared. Our findings suggest an involvement of habenula pathology in the beginning of MDD, while general effects independent of severity or stage of disease did not occur. Our findings warrant future combined tractographic and functional investigation using ultra-high-resolution in vivo MR imaging.

Longitudinal reproducibility of default-mode network connectivity in healthy elderly participants: A multicentric resting-state fMRI study.

To date, limited data are available regarding the inter-site consistency of test-retest reproducibility of functional connectivity measurements, in particular with regard to integrity of the Default Mode Network (DMN) in elderly participants. We implemented a harmonized resting-state fMRI protocol on 13 clinical scanners at 3.0T using vendor-provided sequences. Each site scanned a group of 5 healthy elderly participants twice, at least a week apart. We evaluated inter-site differences and test-retest reproducibility of both temporal signal-to-noise ratio (tSNR) and functional connectivity measurements derived from: i) seed-based analysis (SBA) with seed in the posterior cingulate cortex (PCC), ii) group independent component analysis (ICA) separately for each site (site ICA), and iii) consortium ICA, with group ICA across the whole consortium. Despite protocol harmonization, significant and quantitatively important inter-site differences remained in the tSNR of resting-state fMRI data; these were plausibly driven by hardware and pulse sequence differences across scanners which could not be harmonized. Nevertheless, the tSNR test-retest reproducibility in the consortium was high (ICC=0.81). The DMN was consistently extracted across all sites and analysis methods. While significant inter-site differences in connectivity scores were found, there were no differences in the associated test-retest error. Overall, ICA measurements were more reliable than PCC-SBA, with site ICA showing higher reproducibility than consortium ICA. Across the DMN nodes, the PCC yielded the most reliable measurements (≈4% test-retest error, ICC=0.85), the medial frontal cortex the least reliable (≈12%, ICC=0.82) and the lateral parietal cortices were in between (site ICA). Altogether these findings support usage of harmonized multisite studies of resting-state functional connectivity to characterize longitudinal effects in studies that assess disease progression and treatment response.

Test-retest reliability of the default mode network in a multi-centric fMRI study of healthy elderly: Effects of data-driven physiological noise correction techniques.

Understanding how to reduce the influence of physiological noise in resting state fMRI data is important for the interpretation of functional brain connectivity. Limited data is currently available to assess the performance of physiological noise correction techniques, in particular when evaluating longitudinal changes in the default mode network (DMN) of healthy elderly participants. In this 3T harmonized multisite fMRI study, we investigated how different retrospective physiological noise correction (rPNC) methods influence the within-site test-retest reliability and the across-site reproducibility consistency of DMN-derived measurements across 13 MRI sites. Elderly participants were scanned twice at least a week apart (five participants per site). The rPNC methods were: none (NPC), Tissue-based regression, PESTICA and FSL-FIX. The DMN at the single subject level was robustly identified using ICA methods in all rPNC conditions. The methods significantly affected the mean z-scores and, albeit less markedly, the cluster-size in the DMN; in particular, FSL-FIX tended to increase the DMN z-scores compared to others. Within-site test-retest reliability was consistent across sites, with no differences across rPNC methods. The absolute percent errors were in the range of 5-11% for DMN z-scores and cluster-size reliability. DMN pattern overlap was in the range 60-65%. In particular, no rPNC method showed a significant reliability improvement relative to NPC. However, FSL-FIX and Tissue-based physiological correction methods showed both similar and significant improvements of reproducibility consistency across the consortium (ICC = 0.67) for the DMN z-scores relative to NPC. Overall these findings support the use of rPNC methods like tissue-based or FSL-FIX to characterize multisite longitudinal changes of intrinsic functional connectivity. Hum Brain Mapp 37:2114-2132, 2016. © 2016 Wiley Periodicals, Inc.

The COMTp.Val158Met Polymorphism and Cognitive Performance in Adult Development, Healthy Aging and Mild Cognitive Impairment.

BACKGROUND: The impact of genetic polymorphisms on cognition is assumed to increase with age as losses of brain resources have to be compensated for. We investigate the relation of catechol-O-methyltransferase (COMT)p.Val158Met polymorphism and cognitive capacity in the course of adult development, healthy aging and the development of mild cognitive impairment (MCI) in two birth cohorts of subjects born between 1930 and 1932 or between 1950 and 1952. METHODS: Thorough neuropsychological assessment was conducted in a total of 587 participants across three examination waves between 1993 and 2008. The COMT genotype was determined as a restriction fragment length polymorphism after PCR amplification and digestion with NlaIII. RESULTS: Significant effects of the COMTp.Val158Met polymorphism were identified for attention and cognitive flexibility in the younger but not the older cohort. CONCLUSION: These results confirm the importance of the COMTp.Val158Met genotype on tasks assessing attention and cognitive flexibility in midlife but not in healthy aging and the development of MCI. Our findings suggest that the influence of COMT changes as a function of age, decreasing from midlife to aging.

First-in-human PET quantification study of cerebral α4ß2* nicotinic acetylcholine receptors using the novel specific radioligand (-)-[(18)F]Flubatine.

α4ß2* nicotinic receptors (α4ß2* nAChRs) could provide a biomarker in neuropsychiatric disorders (e.g., Alzheimer's and Parkinson's diseases, depressive disorders, and nicotine addiction). However, there is a lack of α4ß2* nAChR specific PET radioligands with kinetics fast enough to enable quantification of nAChR within a reasonable time frame. Following on from promising preclinical results, the aim of the present study was to evaluate for the first time in humans the novel PET radioligand (-)-[(18)F]Flubatine, formerly known as (-)-[(18)F]NCFHEB, as a tool for α4ß2* nAChR imaging and in vivo quantification. Dynamic PET emission recordings lasting 270min were acquired on an ECAT EXACT HR+ scanner in 12 healthy male non-smoking subjects (71.0±5.0years) following the intravenous injection of 353.7±9.4MBq of (-)-[(18)F]Flubatine. Individual magnetic resonance imaging (MRI) was performed for co-registration. PET frames were motion-corrected, before the kinetics in 29 brain regions were characterized using 1- and 2-tissue compartment models (1TCM, 2TCM). Given the low amounts of metabolite present in plasma, we tested arterial input functions with and without metabolite corrections. In addition, pixel-based graphical analysis (Logan plot) was used. The model's goodness of fit, with and without metabolite correction was assessed by Akaike's information criterion. Model parameters of interest were the total distribution volume VT (mL/cm(3)), and the binding potential BPND relative to the corpus callosum, which served as a reference region. The tracer proved to have high stability in vivo, with 90% of the plasma radioactivity remaining as untransformed parent compound at 90min, fast brain kinetics with rapid uptake and equilibration between free and receptor-bound tracer. Adequate fits of brain TACs were obtained with the 1TCM. VT could be reliably estimated within 90min for all regions investigated, and within 30min for low-binding regions such as the cerebral cortex. The rank order of VT by region corresponded well with the known distribution of α4ß2* receptors (VT [thalamus] 27.4±3.8, VT [putamen] 12.7±0.9, VT [frontal cortex] 10.0±0.8, and VT [corpus callosum] 6.3±0.8). The BPND, which is a parameter of α4ß2* nAChR availability, was 3.41±0.79 for the thalamus, 1.04±0.25 for the putamen and 0.61±0.23 for the frontal cortex, indicating high specific tracer binding. Use of the arterial input function without metabolite correction resulted in a 10% underestimation in VT, and was without important biasing effects on BPND. Altogether, kinetics and imaging properties of (-)-[(18)F]Flubatine appear favorable and suggest that (-)-[(18)F]Flubatine is a very suitable and clinically applicable PET tracer for in vivo imaging of α4ß2* nAChRs in neuropsychiatric disorders.

Longitudinal reproducibility of automatically segmented hippocampal subfields: A multisite European 3T study on healthy elderly.

Recently, there has been an increased interest in the use of automatically segmented subfields of the human hippocampal formation derived from magnetic resonance imaging (MRI). However, little is known about the test-retest reproducibility of such measures, particularly in the context of multisite studies. Here, we report the reproducibility of automated Freesurfer hippocampal subfields segmentations in 65 healthy elderly enrolled in a consortium of 13 3T MRI sites (five subjects per site). Participants were scanned in two sessions (test and retest) at least one week apart. Each session included two anatomical 3D T1 MRI acquisitions harmonized in the consortium. We evaluated the test-retest reproducibility of subfields segmentation (i) to assess the effects of averaging two within-session T1 images and (ii) to compare subfields with whole hippocampus volume and spatial reliability. We found that within-session averaging of two T1 images significantly improved the reproducibility of all hippocampal subfields but not that of the whole hippocampus. Volumetric and spatial reproducibility across MRI sites were very good for the whole hippocampus, CA2-3, CA4-dentate gyrus (DG), subiculum (reproducibility error∼2% and DICE > 0.90), good for CA1 and presubiculum (reproducibility error ∼ 5% and DICE ∼ 0.90), and poorer for fimbria and hippocampal fissure (reproducibility error ∼ 15% and DICE < 0.80). Spearman's correlations confirmed that test-retest reproducibility improved with volume size. Despite considerable differences of MRI scanner configurations, we found consistent hippocampal subfields volumes estimation. CA2-3, CA4-DG, and sub-CA1 (subiculum, presubiculum, and CA1 pooled together) gave test-retest reproducibility similar to the whole hippocampus. Our findings suggest that the larger hippocampal subfields volume may be reliable longitudinal markers in multisite studies.

The LIFE-Adult-Study: objectives and design of a population-based cohort study with 10,000 deeply phenotyped adults in Germany.

BACKGROUND: The LIFE-Adult-Study is a population-based cohort study, which has recently completed the baseline examination of 10,000 randomly selected participants from Leipzig, a major city with 550,000 inhabitants in the east of Germany. It is the first study of this kind and size in an urban population in the eastern part of Germany. The study is conducted by the Leipzig Research Centre for Civilization Diseases (LIFE). Our objective is to investigate prevalences, early onset markers, genetic predispositions, and the role of lifestyle factors of major civilization diseases, with primary focus on metabolic and vascular diseases, heart function, cognitive impairment, brain function, depression, sleep disorders and vigilance dysregulation, retinal and optic nerve degeneration, and allergies. METHODS/DESIGN: The study covers a main age range from 40-79 years with particular deep phenotyping in elderly participants above the age of 60. The baseline examination was conducted from August 2011 to November 2014. All participants underwent an extensive core assessment programme (5-6 h) including structured interviews, questionnaires, physical examinations, and biospecimen collection. Participants over 60 underwent two additional assessment programmes (3-4 h each) on two separate visits including deeper cognitive testing, brain magnetic resonance imaging, diagnostic interviews for depression, and electroencephalography. DISCUSSION: The participation rate was 33 %. The assessment programme was accepted well and completely passed by almost all participants. Biomarker analyses have already been performed in all participants. Genotype, transcriptome and metabolome analyses have been conducted in subgroups. The first follow-up examination will commence in 2016.

Association of speed of onset and speed of recovery of depressive episodes in patients with major depression.

BACKGROUND: Depressive episodes show large interindividual differences concerning their speed of onset and speed of recovery, which might suggest differences in underlying pathophysiological processes. The aim of the present study was to assess whether there is a relationship between the speed of onset and the speed of recovery from depressive episodes. METHODS: The speed of onset and the speed of recovery from depression were assessed using a structured patient interview, the Onset of Depression Inventory (ODI). In total, 28 patients with bipolar depression and 91 patients with unipolar depression were included. RESULTS: The mean speed of onset of depression was significantly faster than the mean speed of recovery from depression (35.25, range 0-360 days vs. 59.60, range 0.13-720 days; Z = -3.40; p = 0.001). The correlation between these variables was positive, but numerically low (ρ = 0.22; p = 0.016). The speed of onset of the previous episode and that of the present episode were significantly correlated (ρ = 0.45; p < 0.001). LIMITATIONS: Data are based on retrospective patient reports within a naturalistic study. CONCLUSIONS: While the speed of onset of depressive episodes has been found to show large interindividual variability and some intraindividual stability, the data of this study do not indicate that the neurobiological processes involved in the onset of and in the recovery from depressive episodes are closely linked.

"Onset of Depression Inventory"--comparison between the data of depressed patients and their relatives.

BACKGROUND: The "Onset of Depression Inventory" (ODI) represents a patient interview which aims to register the speed of onset of depression systematically. The purpose of this study was to evaluate the patient-relative agreement regarding the speed of onset of depression in the patients. METHODS: The ODI was investigated in 31 patients with a depressive episode. Moreover, 31 patients' relatives participated in an interview for which a modified version of the ODI (for relatives of depressed patients; ODI-A) was applied. RESULTS: There was a significant association between patients' estimation of the speed of onset of the depressive episode and relatives' estimation of this parameter in the case of patients and relatives living in a common household (rho = 0.68; p = 0.006). CONCLUSIONS: There was an agreement between patients and their relatives regarding the speed of onset of the current depressive episodes, however only if they lived in a common household.

Diffusion tensor imaging in Alzheimer's disease and affective disorders.

The functional organization of the brain in segregated neuronal networks has become a leading paradigm in the study of brain diseases. Diffusion tensor imaging (DTI) allows testing the validity and clinical utility of this paradigm on the structural connectivity level. DTI in Alzheimer's disease (AD) suggests a selective impairment of intracortical projecting fiber tracts underlying the functional disorganization of neuronal networks supporting memory and other cognitive functions. These findings have already been tested for their utility as clinical markers of AD in large multicenter studies. Affective disorders, including major depressive disorder (MDD) and bipolar disorder (BP), show a high comorbidity with AD in geriatric populations and may even have a pathogenetic overlap with AD. DTI studies in MDD and BP are still limited to small-scale monocenter studies, revealing subtle abnormalities in cortico-subcortial networks associated with affect regulation and reward/aversion control. The clinical utility of these findings remains to be further explored. The present paper presents the methodological background of diffusion imaging, including DTI and diffusion spectrum imaging, and discusses key findings in AD and affective disorders. The results of our review strongly point toward the necessity of large-scale multicenter multimodal transnosological networks to study the structural and functional basis of neuronal disconnection underlying different neuropsychiatric diseases.

Test-retest stability of the Onset of Depression Inventory.

BACKGROUND: The 'Onset of Depression Inventory' (ODI) is a patient interview developed for systematically registering the speed of onset of depression. The ODI might contribute to the detection of hidden bipolarity because in previous studies a more rapid depression onset was found in patients with bipolar compared to unipolar depression. The aim of this study was to evaluate the test-retest stability of the ODI. Patients were asked concerning the speed of onset at the time of hospitalization and again before discharge. SAMPLING AND METHODS: Test-retest stability of the ODI was investigated in 37 patients with a depressive episode. Each patient was interviewed concerning his present depressive episode by the same person at two different time points. Severity of depression at the different time points was assessed using the Hamilton Depression Rating Scale (HAMD-17) and the Inventory of Depressive Symptomatology (IDS-C). RESULTS: The speed of onset as assessed with the ODI showed good test-retest stability (rho = 0.83, p < 0.001). This parameter was not influenced by changes in depression severity. CONCLUSIONS: The ODI allows reliable assessment of the speed of onset of depressive episodes. The instrument might be useful for the detection of hidden bipolarity.

Highfield imaging of the subgenual anterior cingulate cortex in uni- and bipolar depression.

Background: The subgenual Anterior Cingulate Cortex (sgACC), as a part of the Anterior Cingulate Cortex and the limbic system plays a crucial role in mood regulation. Previous structural and functional brain imaging studies of the sgACC have revealed alterations of Gray Matter (GM) volumes and Blood Oxygenation Level Dependent signals (BOLD) in patients with Major Depressive Disorder (MDD) and Bipolar Disorder (BD), suggesting potential biomarker traits for affective disorders. Method: In this study we investigated the gray matter volume of the sgACC in 3 different patient groups: 40 MDD patients, of which 20 were medicated (MDDm) and 20 were unmedicated (MDDu), and 21 medicated BD patients, and compared them with 23 healthy volunteers. We examined GM volume alteration using high-resolution 7T Magnetic Resonance Imaging (MRI) which produced quantitative maps of the spin-lattice relaxation time (T1). T1 maps provide high contrast between gray and white matter, and at 7 Tesla voxels with submillimeter resolution can be acquired in a reasonable scan time. We developed a semi-automatic segmentation protocol based on refined landmarks derived from previous volumetric studies using quantitative T1 maps as raw input data for automatic tissue segmentation of GM, WM and CSF (cerebrospinal fluid) tissue. The sgACC ROI was then superimposed on these tissue probability maps and traced manually by two independent raters (F.B., M.M.) following our semi-automatic segmentation protocol. Interrater reliability was calculated on a subset of 10 brain scans for each hemisphere, showing an Intra-Class Correlation coefficient (ICC) r = 0.96 for left sgACC and r = 0.84 for right sgACC respectively. In summary, we have developed a reproducible and reliable semi-automatic segmentation protocol to measure gray matter volume in the sgACC. Based on previous findings from meta-analyses on morphometric studies of the sgACC, we hypothesized that patients with MDD would have lower gray matter sgACC volumes compared to healthy subjects. Results: Post-hoc analysis revealed smaller subgenual volumes for the left hemisphere in both the medicated (MDDm) and non-medicated (MDDu) group versus healthy controls (p = .001, p = .008) respectively. For the right hemisphere, the (MDDu) and BD group exhibited significantly lower subgenual volumes than healthy controls (p < .001, p = .004) respectively. Conclusion: To our knowledge, this is the first morphometric MRI study using T1 maps obtained in high-resolution 7 Tesla MRI to compare MDD and BD patients with healthy controls.

Hypothalamic atrophy and structural covariance in amnestic mild cognitive impairment and Alzheimer's dementia.

BACKGROUND: Alzheimer's disease (AD) is characterized by progressive cognitive decline and specific brain atrophy patterns, primarily involving the medial temporal lobes. A number of studies have discussed hypothalamic involvement in AD with consecutive metabolic and/or autonomic disturbances yet only few studies have investigated hypothalamic atrophy in AD and its early stages in particular. METHODS: We applied semi-automated volumetry of the hypothalamus (HTH) in 3 T MRI in a sample N = 175 participants [age 74.9 ± 7.22; gender 85 m/90f; cognitively normal controls (CN; N = 56); amnestic mild cognitive impairment (MCI; N = 78); AD (N = 41)] from the Alzheimer's Disease Neuroimaging Initiative (ADNI). In addition, we used voxel-based morphometry (VBM), cortical thickness (CTH) analyses and source-based morphometry (SBM) derived networks of structural covariance to investigate brain structural covariance patterns of the HTH under consideration of diagnostic groups, ß-amyloid (AB) positivity and apolipoprotein E (APOE) ε4 status. RESULTS: Hypothalamic atrophy was observed in both early and advanced disease stages (i.e. hypothalamic volume CN > MCI > AD). VBM, CTH analysis and SBM revealed positive associations between hypothalamic volume (HV) and AD-vulnerable regions, largely corresponding to the Papez circuit and brain regions implicated in autonomic regulation, however, group differences regarding HTH structural covariance were not observed. Similar observations were made in carriers and non-carriers of the ε4 allele, yet more pronounced in ε4 carriers. Although not reaching significance, comparisons of AB positive vs. negative subjects indicated stronger HTH atrophy in biomarker positive participants. HV was not associated with body mass index or longitudinal weight change. CONCLUSIONS: Our findings support early structural changes of the HTH in AD. HV covaries with regional volumes of AD-vulnerable regions. This could point to secondary atrophy of the HTH following atrophy of the hippocampus and other structures of the Papez circuit in AD.

Brain morphometry reproducibility in multi-center 3T MRI studies: a comparison of cross-sectional and longitudinal segmentations.

Large-scale longitudinal multi-site MRI brain morphometry studies are becoming increasingly crucial to characterize both normal and clinical population groups using fully automated segmentation tools. The test-retest reproducibility of morphometry data acquired across multiple scanning sessions, and for different MR vendors, is an important reliability indicator since it defines the sensitivity of a protocol to detect longitudinal effects in a consortium. There is very limited knowledge about how across-session reliability of morphometry estimates might be affected by different 3T MRI systems. Moreover, there is a need for optimal acquisition and analysis protocols in order to reduce sample sizes. A recent study has shown that the longitudinal FreeSurfer segmentation offers improved within session test-retest reproducibility relative to the cross-sectional segmentation at one 3T site using a nonstandard multi-echo MPRAGE sequence. In this study we implement a multi-site 3T MRI morphometry protocol based on vendor provided T1 structural sequences from different vendors (3D MPRAGE on Siemens and Philips, 3D IR-SPGR on GE) implemented in 8 sites located in 4 European countries. The protocols used mild acceleration factors (1.5-2) when possible. We acquired across-session test-retest structural data of a group of healthy elderly subjects (5 subjects per site) and compared the across-session reproducibility of two full-brain automated segmentation methods based on either longitudinal or cross-sectional FreeSurfer processing. The segmentations include cortical thickness, intracranial, ventricle and subcortical volumes. Reproducibility is evaluated as absolute changes relative to the mean (%), Dice coefficient for volume overlap and intraclass correlation coefficients across two sessions. We found that this acquisition and analysis protocol gives comparable reproducibility results to previous studies that used longer acquisitions without acceleration. We also show that the longitudinal processing is systematically more reliable across sites regardless of MRI system differences. The reproducibility errors of the longitudinal segmentations are on average approximately half of those obtained with the cross sectional analysis for all volume segmentations and for entorhinal cortical thickness. No significant differences in reliability are found between the segmentation methods for the other cortical thickness estimates. The average of two MPRAGE volumes acquired within each test-retest session did not systematically improve the across-session reproducibility of morphometry estimates. Our results extend those from previous studies that showed improved reliability of the longitudinal analysis at single sites and/or with non-standard acquisition methods. The multi-site acquisition and analysis protocol presented here is promising for clinical applications since it allows for smaller sample sizes per MRI site or shorter trials in studies evaluating the role of potential biomarkers to predict disease progression or treatment effects.

Diffusion imaging-based subdivision of the human hypothalamus: a magnetic resonance study with clinical implications.

The hypothalamus and its subdivisions are involved in many neuropsychiatric conditions such as affective disorders, schizophrenia, or narcolepsy, but parcellations of hypothalamic subnuclei have hitherto been feasible only with histological techniques in postmortem brains. In an attempt to map subdivisions of the hypothalamus in vivo, we analyzed the directionality information from high-resolution diffusion-weighted magnetic resonance images of healthy volunteers. We acquired T1-weighted and diffusion-weighted scans in ten healthy subjects at 3 T. In the T1-weighted images, we manually delineated an individual mask of the hypothalamus in each subject and computed in the co-registered diffusion-weighted images the similarity of the principal diffusion direction for each pair of mask voxels. By clustering the similarity matrix into three regions with a k-means algorithm, we obtained an anatomically coherent arrangement of subdivisions across hemispheres and subjects. In each hypothalamus mask, we found an anterior region with dorsoventral principal diffusion direction, a posteromedial region with rostro-caudal direction, and a lateral region with mediolateral direction. A comparative analysis with microstructural hypothalamus parcellations from the literature reveals that each of these regions corresponds to a specific group of hypothalamic subnuclei as defined in postmortem brains. This is to our best knowledge the first in vivo study that attempts a delineation of hypothalamic subdivisions by clustering diffusion-weighted magnetic resonance imaging data. When applied in a larger sample of neuropsychiatric patients, a structural analysis of hypothalamic subnuclei should contribute to a better understanding of the pathogenesis of neuropsychiatric conditions such as affective disorders.

Indeterminacy of translation and impaired intersubjectivity in schizophrenia.

Impaired intersubjectivity in schizophrenia has been subject to debate in clinical psychiatry and psychotherapy. In this paper, we will discuss recent perspectives on disordered intersubjectivity among the core symptoms of schizophrenic psychoses. Based on symptoms crucial for communication deficits in schizophrenia, we address indeterminacy of translation as a potential default in the therapeutic setting. The concept of indeterminacy of translation reviewed here assumes that no reference for translation of languages is given, but principles to substitute this non-referring space of unknown terms are to be demonstrated: firstly, a maxim of indulgence which requires that as many true considerations as possible have to be achieved by the final interpretation of a proposition, and secondly, a coherence which is given when the considerations are deductable and not contradictory. Indulgence and coherence are hypothesized as reflecting an approximation process of reconstructing intersubjectivity in conditions where it is severely disturbed such as schizophrenia.

Mammillary body and hypothalamic volumes in mood disorders.

We have previously reported an in vivo enlargement of the left hypothalamus in mood disorders using 7 T magnetic resonance imaging. The aim of this follow-up study was to find out whether the hypothalamic volume difference may be located in the mammillary bodies (MB) rather than being widespread across the hypothalamus. We developed and evaluated a detailed segmentation algorithm that allowed a reliable segmentation of the MBs, and applied it to 20 unmedicated (MDDu) and 20 medicated patients with major depressive disorder, 21 medicated patients with bipolar disorder, and 23 controls. 20 out of 23 healthy controls were matched to the MDDu. We tested for group differences in MB and hypothalamus without MB (HTh) volumes using analyses of covariance. Associations between both volumes of interest were analysed using bivariate and partial correlations. In contrast to postmortem findings, we found no statistically significant differences of the MB volumes between the study groups. Left HTh volumes differed significantly across the study groups after correction for intracranial volume (ICV) and for ICV and sex. Our result of an HTh enlargement in mood disorders was confirmed by a paired t-test between the matched pairs of MDDu and healthy controls using the native MB and HTh volumes. In the whole sample, MB volumes correlated significantly with the ipsilateral HTh volumes. Our results indicate a structural relationship between both volumes, and that our previous in vivo finding of a hypothalamus enlargement does not extend to the MB, but is limited to the HTh. The enlargement is more likely related to the dysregulation of the HPA axis than to cognitive dysfunctions accompanying mood disorders.

E-mental health in Germany - what is the current use and what are experiences of different types of health care providers for patients with mental illnesses?

BACKGROUND: As a new and effective support option, e-mental health interventions can be useful in complementing treatment in mental health care. To date, little is known about how health care providers use these programs to treat patients with mental illnesses in Germany. The present study aims to examine the use of and experiences with e-mental health interventions from the point of view of different types of health care providers for patients with mental illnesses. METHODS: Data from a cross-sectional survey of routine care health care providers in Germany in 2021 were analysed. In this survey, data were collected from n = 107 general practitioners (GPs), n = 114 specialist doctors, n = 102 psychotherapists, and n = 102 inpatient clinicians. Assessments included professional use of digital media, as well as knowledge, use and experiences regarding e-mental health interventions in care of people with mental illness. RESULTS: In the total sample of n = 425, 65.6% (n = 279) were female. The study participants had an average age of 47.7 years (SD = 11.0) and their average work experience was 20.0 years (SD = 11.1). Overall, the majority (83.8%, n = 353) had heard of e-mental health interventions, but few felt well informed. Only 28.5% (n = 121) had already used e-mental health interventions for treatment support. The most commonly recommended e-mental health interventions in the sample were deprexis (39.7%, n = 48), moodgym (24.8%, n = 30), and iFightDepression (22.3%, n = 27). The use was predominantly considered to be helpful and satisfactory. Insufficient knowledge about e-mental health interventions and lack of informational materials for patients were reported as relevant barriers to the use of e-mental health interventions. CONCLUSIONS: E-mental health interventions can be a useful support option, but they are rarely used in the treatment of patients with mental illnesses. There is a need to disseminate information specific to the various types of health care providers. Tailored implementation strategies need to be developed in order to capitalize on the potential of effective e-mental health interventions and to improve health care for patients with mental illnesses.