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Introduction: Aging negatively influences the structure of the human brain including the white matter. The objective of our study was to identify, using fixel-based morphometry, the age induced changes in the pathways connecting several regions of the central auditory system (inferior colliculus, Heschl's gyrus, planumtemporale) and the pathways connecting these structures with parts of the limbic system (anterior insula, hippocampus and amygdala). In addition, we were interested in the extent to which the integrity of these pathways is influenced by hearing loss and tinnitus. Methods: Tractographic data were acquired using a 3 T MRI in 79 volunteers. The participants were categorized into multiple groups in accordance with their age, auditory thresholds and tinnitus status. Fixel-based analysis was utilized to identify alterations in the subsequent three parameters: logarithm of fiber cross-section, fiber density, fiber density and cross-section. Two modes of analysis were used: whole brain analysis and targeted analysis using fixel mask, corresponding to the pathways connecting the aforementioned structures. Results: A significantly negative effect of aging was present for all fixel-based metrics, namely the logarithm of the fiber cross-section, (7 % fixels in whole-brain, 14% fixels in fixel mask), fiber density (5 % fixels in whole-brain, 15% fixels in fixel mask), fiber density and cross section (7 % fixels in whole-brain, 19% fixels in fixel mask). Expressed age-related losses, exceeding 30% fixels, were particularly present in pathways connecting the auditory structures with limbic structures. The effect of hearing loss and/or tinnitus did not reach significance. Conclusions: Our results show that although an age-related reduction of fibers is present in pathways connecting several auditory regions, the connections of these structures with limbic structures are even more reduced. To what extent this fact influences the symptoms of presbycusis, such as decreased speech comprehension, especially in noise conditions, remains to be elucidated. [ABSTRACT FROM AUTHOR]

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Objectives: To compare brain responses to peroneal electrical transcutaneous neuromodulation (peroneal eTNM®) and transcutaneous tibial nerve stimulation (TTNS), two methods for treating overactive bladder (OAB), using functional magnetic resonance imaging (fMRI). The present study was not designed to compare their clinical efficacy. Materials and Methods: This study included 32 healthy adult female volunteers (average age 38.3 years (range 22−73)). Brain MRI using 3 T scanner was performed during three 8‐min blocks of alternating sequences. During each 8‐min block, the protocol alternated between sham stimulation (30 s) and rest (30 s) for 8 repeats; then peroneal eTNM® stimulation (30 s) and rest (30 s) for 8 repeats; then, TTNS stimulation (30 s) and rest (30 s) for 8 repeats. Statistical analysis was performed at the individual level with a threshold of p = 0.05, family‐wise error (FWE)‐corrected. The resulting individual statistical maps were analyzed in group statistics using a one‐sample t‐test, p = 0.05 threshold, false discovery rate (FDR)‐corrected. Results: During peroneal eTNM®, TTNS, and sham stimulations, we recorded activation in the brainstem, bilateral posterior insula, bilateral precentral gyrus, bilateral postcentral gyrus, left transverse temporal gyrus, and right supramarginal gyrus. During both peroneal eTNM® and TTNS stimulations, but not sham stimulations, we recorded activation in the left cerebellum, right transverse temporal gyrus, right middle frontal gyrus, and right inferior frontal gyrus. Exclusively during peroneal eTNM® stimulation, we observed activation in the right cerebellum, right thalamus, bilateral basal ganglia, bilateral cingulate gyrus, right anterior insula, right central operculum, bilateral supplementary motor cortex, bilateral superior temporal gyrus, and left inferior frontal gyrus. Conclusions: Peroneal eTNM®, but not TTNS, induces the activation of brain structures that were previously implicated in neural control of the of bladder filling and play an important role in the ability to cope with urgency. The therapeutic effect of peroneal eTNM® could be exerted, at least in part, at the supraspinal level of neural control. [ABSTRACT FROM AUTHOR]

The volume reduction of the gray matter structures in patients with Alzheimer's disease is often accompanied by an asymmetric increase in the number of white matter fibers located close to these structures. The present study aims to investigate the white matter structure changes in the motor basal ganglia in Alzheimer's disease patients compared to healthy controls using diffusion tensor imaging. The amounts of tracts, tract length, tract volume, quantitative anisotropy, and general fractional anisotropy were measured in ten patients with Alzheimer's disease and ten healthy controls. A significant decrease in the number of tracts and general fractional anisotropy was found in patients with Alzheimer's disease compared to controls in the right caudate nucleus, while an increase was found in the left and the right putamen. Further, a significant decrease in the structural volume of the left and the right putamen was observed. An increase in the white matter diffusion tensor imaging parameters in patients with Alzheimer's disease was observed only in the putamen bilaterally. The right caudate showed a decrease in both the diffusion tensor imaging parameters and the volume in Alzheimer's disease patients. The right pallidum showed an increase in the diffusion tensor imaging parameters but a decrease in volume in Alzheimer's disease patients. [ABSTRACT FROM AUTHOR]

Motor disability is a dominant and restricting symptom in multiple sclerosis, yet its neuroimaging correlates are not fully understood. We apply statistical and machine learning techniques on multimodal neuroimaging data to discriminate between multiple sclerosis patients and healthy controls and to predict motor disability scores in the patients. We examine the data of sixty-four multiple sclerosis patients and sixty-five controls, who underwent the MRI examination and the evaluation of motor disability scales. The modalities used comprised regional fractional anisotropy, regional grey matter volumes, and functional connectivity. For analysis, we employ two approaches: high-dimensional support vector machines run on features selected by Fisher Score (aiming for maximal classification accuracy), and low-dimensional logistic regression on the principal components of data (aiming for increased interpretability). We apply analogous regression methods to predict symptom severity. While fractional anisotropy provides the classification accuracy of 96.1% and 89.9% with both approaches respectively, including other modalities did not bring further improvement. Concerning the prediction of motor impairment, the low-dimensional approach performed more reliably. The first grey matter volume component was significantly correlated (R = 0.28-0.46, p < 0.05) with most clinical scales. In summary, we identified the relationship between both white and grey matter changes and motor impairment in multiple sclerosis. Furthermore, we were able to achieve the highest classification accuracy based on quantitative MRI measures of tissue integrity between patients and controls yet reported, while also providing a low-dimensional classification approach with comparable results, paving the way to interpretable machine learning models of brain changes in multiple sclerosis. [ABSTRACT FROM AUTHOR]

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Functional connectivity analysis is a common approach to the characterization of brain function. While studies of functional connectivity have predominantly focused on resting‐state fMRI, naturalistic paradigms, such as movie watching, are increasingly being used. This ecologically valid, yet relatively unconstrained acquisition state has been shown to improve subject compliance and, potentially, enhance individual differences. However, unlike the reliability of resting‐state functional connectivity, the reliability of functional connectivity during naturalistic viewing has not yet been fully established. The current study investigates the intra‐session reliability of functional connectivity during naturalistic viewing sessions to extend its understanding. Using fMRI data of 24 subjects measured at rest as well as during six naturalistic viewing conditions, we quantified the split‐half reliability of each condition, as well as cross‐condition reliabilities. We find that intra‐session reliability is relatively high for all conditions. While cross‐condition reliabilities are higher for pairings of two naturalistic viewing conditions, split‐half reliability is highest for the resting state. Potential sources of variability across the conditions, as well as the strengths and limitations of using intra‐session reliability as a measure in naturalistic viewing, are discussed. By enhancing the understanding of the reliability of naturalistic fMRI, our study supports future research that relates data measured during this increasingly popular experimental condition to behavioral or clinical characteristics. It demonstrates that the intra‐session reliability of functional connectivity is comparably high during six naturalistic viewing conditions and rest, includes a discussion of potential sources of variability, and a comparison across four anatomical atlases. [ABSTRACT FROM AUTHOR]

The human brain represents a complex computational system, the function and structure of which may be measured using various neuroimaging techniques focusing on separate properties of the brain tissue and activity. We capture the organization of white matter fibers acquired by diffusion-weighted imaging using probabilistic diffusion tractography. By segmenting the results of tractography into larger anatomical units, it is possible to draw inferences about the structural relationships between these parts of the system. This pipeline results in a structural connectivity matrix, which contains an estimate of connection strength among all regions. However, raw data processing is complex, computationally intensive, and requires expert quality control, which may be discouraging for researchers with less experience in the field. We thus provide brain structural connectivity matrices in a form ready for modelling and analysis and thus usable by a wide community of scientists. The presented dataset contains brain structural connectivity matrices together with the underlying raw diffusion and structural data, as well as basic demographic data of 88 healthy subjects. Measurement(s) Diffusion Weighted Imaging Technology Type(s) Magnetic Resonance Imaging Sample Characteristic - Organism Homo sapiens Sample Characteristic - Location Czech Republic [ABSTRACT FROM AUTHOR]

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Neuroplasticity and brain reorganization associated with positive outcomes of multidisciplinary rehabilitation in progressive multiple sclerosis: a fMRI study. Keywords: fMRI; multiple sclerosis; open access; data report; neurorehabilitation EN fMRI multiple sclerosis open access data report neurorehabilitation 1 6 6 06/05/21 20210528 NES 210528 1. Open Access: The Effect of Neurorehabilitation on Multiple Sclerosis - Unlocking the Resting-State fMRI Data FMRI, multiple sclerosis, open access, data report, neurorehabilitation. [Extracted from the article]

In this paper we propose a method for locally adjusted optical flow-based registration of multimodal images, which uses the segmentation of object of interest and its representation by the signed-distance function (OF method). We deal with non-rigid registration of the image series acquired by the Modiffied Look-Locker Inversion Recovery (MOLLI) magnetic resonance imaging sequence, which is used for a pixel-wise estimation of relaxation time. The spatial registration of the images within the series is necessary to compensate the patient's imperfect breath-holding. The evolution of intensities and a large variation of image contrast within the MOLLI image series, together with the myocardium of left ventricle (the object of interest) typically not being the most distinct object in the scene, makes the registration challenging. The paper describes all components of the proposed OF method and their implementation. The method is then compared to the performance of a standard mutual information maximization-based registration method, applied either to the original image (MIM) or to the signed-distance function (MIM). Several experiments with synthetic and real MOLLI images are carried out. On synthetic image with a single object, MIM performed the best, while OF and MIM provided better results on synthetic images with more than one object and on real images. When applied to signed-distance function of two objects of interest, MIM provided a larger registration error, but more homogeneously distributed, compared to OF. For the real MOLLI image series with left ventricle pre-segmented using a level-set method, the proposed OF registration performed the best, as is demonstrated visually and by measuring the increase of mutual information in the object of interest and its neighborhood. [ABSTRACT FROM AUTHOR]

Functional connectivity analysis of resting‐state fMRI data has recently become one of the most common approaches to characterizing individual brain function. It has been widely suggested that the functional connectivity matrix is a useful approximate representation of the brain's connectivity, potentially providing behaviorally or clinically relevant markers. However, functional connectivity estimates are known to be detrimentally affected by various artifacts, including those due to in‐scanner head motion. Moreover, as individual functional connections generally covary only very weakly with head motion estimates, motion influence is difficult to quantify robustly, and prone to be neglected in practice. Although the use of individual estimates of head motion, or group‐level correlation of motion and functional connectivity has been suggested, a sufficiently sensitive measure of individual functional connectivity quality has not yet been established. We propose a new intuitive summary index, Typicality of Functional Connectivity, to capture deviations from standard brain functional connectivity patterns. In a resting‐state fMRI dataset of 245 healthy subjects, this measure was significantly correlated with individual head motion metrics. The results were further robustly reproduced across atlas granularity, preprocessing options, and other datasets, including 1,081 subjects from the Human Connectome Project. In principle, Typicality of Functional Connectivity should be sensitive also to other types of artifacts, processing errors, and possibly also brain pathology, allowing extensive use in data quality screening and quantification in functional connectivity studies as well as methodological investigations. [ABSTRACT FROM AUTHOR]

Age related hearing loss (presbycusis) is a natural process represented by elevated auditory thresholds and decreased speech intelligibility, especially in noisy conditions. Tinnitus is a phantom sound that also potentially leads to cortical changes, with its highest occurrence coinciding with the clinical onset of presbycusis. The aim of our project was to identify age, hearing loss and tinnitus related structural changes, within the auditory system and associated structures. Groups of subjects with presbycusis and tinnitus (22 subjects), with only presbycusis (24 subjects), young tinnitus patients with normal hearing (10 subjects) and young controls (17 subjects), underwent an audiological examination to characterize hearing loss and tinnitus. In addition, MRI (3T MR system, analysis in Freesurfer software) scans were used to identify changes in the cortical and subcortical structures. The following areas of the brain were analyzed: Heschl gyrus (HG), planum temporale (PT), primary visual cortex (V1), gyrus parahippocampus (PH), anterior insula (Ins), amygdala (Amg), and hippocampus (HP). A statistical analysis was performed in R framework using linear mixed-effects models with explanatory variables: age, tinnitus, laterality and hearing. In all of the cortical structures, the gray matter thickness decreased significantly with aging without having an effect on laterality (differences between the left and right hemispheres). The decrease in the gray matter thickness was faster in the HG, PT and Ins in comparison with the PH and V1. Aging did not influence the surface of the cortical areas, however there were differences between the surface size of the reported regions in the left and right hemispheres. Hearing loss caused only a borderline decrease of the cortical surface in the HG. Tinnitus was accompanied by a borderline decrease of the Ins surface and led to an increase in the volume of Amy and HP. In summary, aging is accompanied by a decrease in the cortical gray matter thickness; hearing loss only has a limited effect on the structure of the investigated cortical areas and tinnitus causes structural changes which are predominantly within the limbic system and insula, with the structure of the auditory system only being minimally affected. [ABSTRACT FROM AUTHOR]

Copyright of Czech Radiology / Ceska Radiologie is the property of Czech Medical Association of JE Purkyne and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Czech Radiology / Ceska Radiologie is the property of Czech Medical Association of JE Purkyne and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Objective: The accuracy of phase-contrast magnetic resonance imaging (PC-MRI) measurement is investigated using a computational fluid dynamics (CFD) model with the objective to determine the magnitude of the flow underestimation due to turbulence behind a narrowed valve in a phantom experiment. Materials and methods: An acrylic stationary flow phantom is used with three insertable plates mimicking aortic valvular stenoses of varying degrees. Positive and negative horizontal fluxes are measured at equidistant slices using standard PC-MRI sequences by 1.5T and 3T systems. The CFD model is based on the 3D lattice Boltzmann method (LBM). The experimental and simulated data are compared using the Bland-Altman-derived limits of agreement. Based on the LBM results, the turbulence is quantified and confronted with the level of flow underestimation. Results: LBM gives comparable results to PC-MRI for valves up to moderate stenosis on both field strengths. The flow magnitude through a severely stenotic valve was underestimated due to signal void in the regions of turbulent flow behind the valve, consistently with the level of quantified turbulence intensity. Discussion: Flow measured by PC-MRI is affected by noise and turbulence. LBM can simulate turbulent flow efficiently and accurately, it has therefore the potential to improve clinical interpretation of PC-MRI. [ABSTRACT FROM AUTHOR]

This study analyzes how people's attitudes to the European refugee crisis (ERC) correspond to selected psychological state and trait measures and impact the neural processing of media images of refugees. From a large pool of respondents, who filled in an online xenophobia questionnaire, we selected two groups (total N = 38) with the same socio-demographic background, but with opposite attitudes toward refugees. We found that a negative attitude toward refugees (high xenophobia - HX) was associated with a significantly higher conscientiousness score and with a higher trait aggression and hostility, but there was no group effect connected with empathy, fear, and anxiety measures. At the neural level we found that brain activity during the presentation of ERC stimuli is affected by xenophobic attitudes—with more xenophobic subjects exhibiting a higher BOLD response in the left fusiform gyrus. However, while the fMRI results demonstrate increased attention and vigilance toward ERC-related stimuli in the HX group, they do not show differentiated patterns of brain activity associated with perception of dehumanized outgroup. [ABSTRACT FROM AUTHOR]

In the last years, there has been a considerable increase of research into the neuroimaging correlates of inter-individual temperament and character variability—an endeavour for which the term 'personality neuroscience' was coined. Among other neuroimaging modalities and approaches, substantial work focuses on functional connectivity in resting state (rs-FC) functional magnetic resonance imaging data. In the current paper, we set out to independently query the questions asked in a highly cited study that reported a range of functional connectivity correlates of personality dimensions assessed by the widely used 'Big Five' Personality Inventory. Using a larger sample (84 subjects) and an equivalent data analysis pipeline, we obtained widely disagreeing results compared to the original study. Overall, the results were in line with the hypotheses of no relation between functional connectivity and personality, when more precise permutation-based multiple testing procedures were applied. The results demonstrate that as with other neuroimaging studies, great caution should be applied when interpreting the findings, among other reasons due to multiple testing problem involved at several levels in many neuroimaging studies. Of course, the current study results can not ultimately disprove the existence of some link between personality and brain's intrinsic functional architecture, but clearly shows that its form is very likely different and much more subtle and elusive than was previously reported. [ABSTRACT FROM AUTHOR]

Background: Cannabis, and specifically one of its active compounds delta-9-tetrahydrocannabinol in recreational doses, has a variety of effects on cognitive processes. Most studies employ resting state functional magnetic resonance imaging techniques to assess the stationary effects of cannabis and to-date one report addressed the impact of delta-9-tetrahydrocannabinol on the dynamics of whole-brain functional connectivity.Methods: Using a repeated-measures, within-subjects design, 19 healthy occasional cannabis users (smoking cannabis ⩽2 per week) underwent resting state functional magnetic resonance imaging scans. Each subject underwent two scans: in the intoxicated condition, shortly after smoking a cannabis cigarette, and in the non-intoxicated condition, with the subject being free from cannabinoids for at least one week before. All sessions were randomized and performed in a four-week interval. Data were analysed employing a standard independent component analysis approach with subsequent tracking of the functional connectivity dynamics, which allowed six connectivity clusters (states) to be individuated.Results: Using standard independent component analysis in resting state functional connectivity, a group effect was found in the precuneus connectivity. With a dynamic independent component analysis approach, we identified one transient connectivity state, characterized by high connectivity within and between auditory and somato-motor cortices and anti-correlation with subcortical structures and the cerebellum that was only found during the intoxicated condition. Behavioural measures of the subjective experiences of changed perceptions and tetrahydrocannabinol plasma levels during intoxication were associated with this state.Conclusions: With the help of the dynamic connectivity approach we could elucidate neural correlates of the transitory perceptual changes induced by delta-9-tetrahydrocannabinol in cannabis users, and possibly identify a biomarker of cannabis intoxication. [ABSTRACT FROM AUTHOR]

Copyright of Czech Radiology / Ceska Radiologie is the property of Czech Medical Association of JE Purkyne and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Czech Radiology / Ceska Radiologie is the property of Czech Medical Association of JE Purkyne and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Czech Radiology / Ceska Radiologie is the property of Czech Medical Association of JE Purkyne and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Czech Radiology / Ceska Radiologie is the property of Czech Medical Association of JE Purkyne and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Czech Radiology / Ceska Radiologie is the property of Czech Medical Association of JE Purkyne and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Czech Radiology / Ceska Radiologie is the property of Czech Medical Association of JE Purkyne and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Complex systems are commonly characterized by the properties of their graph representation. Dynamical complex systems are then typically represented by a graph of temporal dependencies between time series of state variables of their subunits. It has been shown recently that graphs constructed in this way tend to have relatively clustered structure, potentially leading to spurious detection of small-world properties even in the case of systems with no or randomly distributed true interactions. However, the strength of this bias depends heavily on a range of parameters and its relevance for real-world data has not yet been established. In this work, we assess the relevance of the bias using two examples of multivariate time series recorded in natural complex systems. The first is the time series of local brain activity as measured by functional magnetic resonance imaging in resting healthy human subjects, and the second is the time series of average monthly surface air temperature coming from a large reanalysis of climatological data over the period 1948-2012. In both cases, the clustering in the thresholded correlation graph is substantially higher compared with a realization of a density-matched random graph, while the shortest paths are relatively short, showing thus distinguishing features of small-world structure. However, comparable or even stronger small-world properties were reproduced in correlation graphs of model processes with randomly scrambled interconnections. This suggests that the small-world properties of the correlation matrices of these real-world systems indeed do not reflect genuinely the properties of the underlying interaction structure, but rather result from the inherent properties of correlation matrix. [ABSTRACT FROM AUTHOR]

Hearing loss, presbycusis, is one of the most common sensory declines in the ageing population. Presbycusis is characterised by a deterioration in the processing of temporal sound features as well as a decline in speech perception, thus indicating a possible central component. With the aim to explore the central component of presbycusis, we studied the function of the auditory cortex by functional MRI in two groups of elderly subjects (>65 years) and compared the results with young subjects (

Purpose To characterize the relationship between superparamagnetic ferritin-bound iron and diffusion tensor scalars in vitro, and validate the results in vivo. Materials and Methods The in vitro model consisted of a series of 40-mL 1.1% agarose gels doped with ferritin covering and exceeding those concentrations normally found within healthy human gray matter. Additionally, regions of interest were placed in the caudate, putamen, and globus pallidus of 29 healthy volunteer subjects 19-80 years of age. Carr-Purcell-Meiboom-Gill sequence (CPMG) and diffusion tensor imaging (DTI) data were collected at 1.5 Tesla (T) and 3T in vitro, and at 1.5T in vivo. Results In vitro, linear relationships were observed between ferritin-bound iron concentration, R2 (1/T2) and 1/SNR. Eigenvalue repulsion with increasing R2 (decreasing SNR) was reflected in an artifactual increase of fractional anisotropy. In vivo, similar relationships were observed, with mean diffusivity also decreasing linearly with increasing R2. Lambda 3 showed the strongest correlation with R2 both in vitro and in vivo. Conclusion The observation that DTI metrics correlate with ferritin-bound iron is an important consideration in the design and interpretation of studies exploring the diffusion characteristics of gray matter regions, especially in studies focused on adolescence as well as diseases associated with altered brain-iron load such as pantothenate kinase-associated neurodegeneration, Huntington disease and multiple system atrophy. J. Magn. Reson. Imaging 2013;38:1103-1110. © 2013 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

The study is designed to determine the relationship between the progress of the wet form of age-related macular degeneration and the activity of the visual cortex examined using functional magnetic resonance imaging. Ten patients with the wet form of age-related macular degeneration (9 female and 1 male) with a mean age of 74.7 years (58-85 years) at various stages of bilateral involvement of the disease were included. Patients did not suffer from any other ocular nor neurological disease. All the patients underwent functional magnetic resonance imaging examinations with stimulation of both eyes using a black-and-white checkerboard of size 25.8 × 16.2 degrees. The group was compared with a group of healthy subjects with an average age of 54.1 years (45-65 years). For statistical evaluation, the Mann-Whitney U test was used. Comparing the extent of visual cortex activations we found a statistically significant difference between both the groups ( p = 0.0247). However, the dependence of functional magnetic resonance imaging activity on visual acuity was not statistically significant ( p = 0.223). We conclude that in patients with the wet form of age-related macular degeneration, lower functional magnetic resonance imaging activity of the visual cortex was found compared with the control group of healthy subjects. Dependence of functional magnetic resonance imaging activity on visual acuity was not statistically significant. [ABSTRACT FROM AUTHOR]

The present report presents a rare case in which a patient with pituitary apoplexy (PA) without compression of the optic chiasm experienced diagnosable visual impairment in the ensuing months. Endocrinologically, the condition was a prolactinoma followed by bleeding into the pituitary gland. Due to the unexplained functional changes in the patient, an electrophysiological examination (pattern electroretinogram and pattern visual evoked potentials) was performed, which verified a bilateral non-inflammatory neurogenic lesion. This finding was confirmed by functional magnetic resonance imaging (fMRI) examination. Structural MRI did not reveal chiasm compression in the time sequence or alteration of the optic nerves (the diameter of the optic nerve at different distances from the eye and the diameter of the optic nerve sheath at different distances from the eye). Similarly, neither the retinal nerve fiber layer (RNFL) nor the vessel density was altered. The present report suggests that changes in visual fields may be due to ischemia in the area of the chiasm and optic nerves, similar to PA. [ABSTRACT FROM AUTHOR]

Abstract: Spinal cord stimulation (SCS) consisting of electrical stimulation of the dorsal spinal cord using epidural electrodes has been shown to relieve chronic neuropathic pain. To analyze the cerebral activation patterns related to SCS, and to evaluate the effects of SCS on the processing of acute experimental pain, we performed functional magnetic resonance imaging (fMRI) on eight patients suffering from failed back surgery syndrome who were also being treated with SCS for severe pain in their legs and lower back. Three types of stimulation were used, each lasting 36s: (i) SCS, (ii) heat pain (HP) applied to the leg affected by neuropathic pain, and (iii) simultaneous HP and SCS. During SCS, we found increased activation of the medial primary sensorimotor cortex somatotopically corresponding to the foot and/or perineal region, contralateral posterior insula, and the ipsilateral secondary somatosensory cortex (S2). Decreased activation was seen in the bilateral primary motor cortices and the ipsilateral primary somatosensory cortex corresponding to the shoulder, elbow and hand. Compared to separately presented HP and SCS, simultaneous HP and SCS showed statistically significant activation of the bilateral inferior temporal cortex and the ipsilateral cerebellar cortex. The activation of the primary motor cortex, insula and S2 during SCS may directly interfere with the processing of neuropathic pain. When SCS is associated with heat pain, the paralimbic association cortex and cerebellum show activation exceeding the sum of activations resulting from separate SCS and heat pain stimulation. The explanation of this could possibly rest with the continuous comparisons of simultaneous pain and somatosensory sensations occurring in a single dermatome. [Copyright &y& Elsevier]

One of the recognised complications of catheter ablation is pulmonary venous stenosis. The aim of this study was to compare two methods of evaluation of pulmonary venous diameter for follow-up assessment of the above complication: (1) a linear approach evaluating two main diameters of the vein, (2) semiautomatically measured cross-sectional area (CSA). The study population consists of 29 patients. All subjects underwent contrast-enhanced magnetic resonance angiography (CeMRA) of the pulmonary veins (PVs) before and after the ablation; 14 patients were also scanned 3 months later. PV diameter was evaluated from two-dimensional multiplanar reconstructions by measuring either the linear diameter or CSA. A comparison between pulmonary venous CSA and linear measurements revealed a systematic difference in absolute values. This difference was not significant when comparing the relative change CSA and quadratic approximation using linear extents (linear approach). However, a trend towards over-estimation of calibre reduction was documented for the linear approach. Using CSA assessment, significant PV stenosis was found in ten PVs (8%) shortly after ablation. Less significant PV stenosis, ranging from 20 to 50% was documented in other 18 PVs (15%). CeMRA with CSA assessment of the PVs is suitable method for evaluation of PV diameters. [ABSTRACT FROM AUTHOR]

Introduction: Catheter ablation of atrial fibrillation (AF) requires exact anatomical information about pulmonary venous (PV) ostia. In this study, anatomy of pulmonary veins (PVs) was assessed using three-dimensional (3D) reconstructions of magnetic resonance angiography (MRA). Methods and Results: Contrast-enhanced MRA of the PVs was performed in 40 patients (mean age 53 ± 9 years) with paroxysmal (30 patients) or persistent (10 patients) AF, scheduled for circumferential ablation around PV ostia. PV ostial anatomy and diameters were evaluated from multiplanar reconstructions and compared with 3D reconstructions. Thirty (75%) patients presented with a common left-sided antrum (21 short and 9 long trunk), while additional PVs were found on right side in 23%. PV ostia were oblong in shape (mean diameters 17.0 ± 4.3 vs 10.5 ± 2.5 mm by two-dimensional (2D) measurements, and 20.8 ± 7.6 mm vs 12.9 ± 3.3 mm by 3D reconstruction, in long and short axis, respectively). There was a correlation between measurements obtained from 2D and 3D images, although 3D imaging provided slightly larger diameters. Conclusions: MRA with 3D reconstructions is an important technique for preprocedural assessment of PVs that allows full understanding of their anatomy and size. This information may be important for selection of appropriate tools. [ABSTRACT FROM AUTHOR]

Presents a letter to the editor about percutaneous shunt creation for hemodialysis using uncovered metallic stents.