Role of O-(2-(18)F-fluoroethyl)-L-tyrosine PET for differentiation of local recurrent brain metastasis from radiation necrosis.

Unlabelled: The aim of this study was to investigate the potential of O-(2-(18)F-fluoroethyl)-L-tyrosine ((18)F-FET) PET for differentiating local recurrent brain metastasis from radiation necrosis after radiation therapy because the use of contrast-enhanced MRI for this issue is often difficult.

Methods: Thirty-one patients (mean age ± SD, 53 ± 11 y) with single or multiple contrast-enhancing brain lesions (n = 40) on MRI after radiation therapy of brain metastases were investigated with dynamic (18)F-FET PET. Maximum and mean tumor-to-brain ratios (TBR(max) and TBR(mean), respectively; 20-40 min after injection) of (18)F-FET uptake were determined.

Deconstructing the architecture of dorsal and ventral attention systems with dynamic causal modeling.

Attentional orientation to a spatial cue and reorientation-after invalid cueing-are mediated by two distinct networks in the human brain. A bilateral dorsal frontoparietal network, comprising the intraparietal sulcus (IPS) and the frontal eye fields (FEF), controls the voluntary deployment of attention and may modulate visual cortex in preparation for upcoming stimulation. In contrast, reorienting attention to invalidly cued targets engages a right-lateralized ventral frontoparietal network comprising the temporoparietal junction (TPJ) and ventral frontal cortex.

Theory of mind and the brain in anorexia nervosa: relation to treatment outcome.

Objective: Converging evidence suggests deficits in theory-of-mind (ToM) processing in patients with anorexia nervosa (AN). The present study aimed at elucidating the neural mechanisms underlying ToM-deficits in AN.

Method: A total of 19 adolescent patients with AN and 21 age-matched controls were investigated using functional magnetic resonance imaging during performance of a ToM-task at two time points (in-patients: admission to hospital and discharge after weight recovery).

Essential tremor and tremor in Parkinson's disease are associated with distinct 'tremor clusters' in the ventral thalamus.

Different tremor entities such as Essential Tremor (ET) or tremor in Parkinson's disease (PD) can be ameliorated by the implantation of electrodes in the ventral thalamus for Deep Brain Stimulation (DBS). The exact neural mechanisms underlying this treatment, as well as the specific pathophysiology of the tremor in both diseases to date remain elusive. Since tremor-related local field potentials (LFP) have been shown to cluster with a somatotopic representation in the subthalamic nucleus, we here investigated the neurophysiological correlates of tremor in the ventral thalamus in ET and PD using power and coherence analysis.

Changes in grey matter development in autism spectrum disorder.

Results on grey matter (GM) structural alterations in autism spectrum disorder (ASD) are inconclusive. Moreover, little is known about age effects on brain-structure abnormalities in ASD beyond childhood. Here, we aimed to examine regional GM volumes in a large sample of children, adolescents, and adults with ASD.

Differential effects of dopaminergic medication on basic motor performance and executive functions in Parkinson's disease.

Background: Patients with Parkinson's disease (PD) often show deficits in the self-initiation and selection of movements, which can be partly compensated for by external cues. We here investigated impairments in the initiation and selection of self-initiated or externally cued movements in PD. Specifically, we assessed how behavioral changes relate to medication, disease severity, and basic motor or cognitive deficits.

Imagined tool-use in near and far space modulates the extra-striate body area.

Active tool-use can result in the incorporation of the tool into the body schema, e.g., the representation of the arm is enlarged according to tool length.

Effects of the DRD4 genotype on neural networks associated with executive functions in children and adolescents.

Genetic variants within the dopamine D4 receptor gene (DRD4) are among the strongest and most consistently replicated molecular genetic findings in attentional functioning as well as attention deficit hyperactivity disorder (ADHD). Functionally, the 7-repeat allele of the DRD4-48 base pair repeat gene leads to a sub-sensitive postsynaptic D4 receptor, which is expressed at a particularly high density in the frontal lobes. We used fMRI to investigate the influence of the 7-repeat allele on BOLD (Blood Oxygen Level Dependency) responses in 26 healthy children and adolescents while they performed a combined stimulus-response Incompatibility Task (IC) and a Time Discrimination Task (TT).

Neural interaction between spatial domain and spatial reference frame in parietal-occipital junction.

On the basis of double dissociations in clinical symptoms of patients with unilateral visuospatial neglect, neuropsychological research distinguishes between different spatial domains (near vs. far) and different spatial reference frames (egocentric vs. allocentric).

Ventral and dorsal stream interactions during the perception of the Müller-Lyer illusion: evidence derived from fMRI and dynamic causal modeling.

The human visual system converts identically sized retinal stimuli into different-sized perceptions. For instance, the Müller-Lyer illusion alters the perceived length of a line via arrows attached to its end. The strength of this illusion can be expressed as the difference between physical and perceived line length.

Impaired self-awareness of motor deficits in Parkinson's disease: association with motor asymmetry and motor phenotypes.

Background: This study investigated impaired self-awareness of motor deficits in nondemented, nondepressed Parkinson's disease (PD) patients during a defined clinical on state.

Methods: Twenty-eight PD patients were examined. Patients' self-ratings and experts' ratings of patients' motor performance were compared.

Intrinsic network connectivity reflects consistency of synesthetic experiences.

Studying cognitive processes underlying synesthesia, a condition in which stimulation of one sensory modality automatically leads to abnormal additional sensory perception, allows insights into the neural mechanisms of normal and abnormal cross-modal sensory processing. Consistent with the notion that synesthesia results from hyperconnectivity, functional connectivity analysis (adopting independent component analysis and seed-based correlation analysis) of resting-state functional magnetic resonance imaging data of 12 grapheme-color synesthetes and 12 nonsynesthetic control subjects revealed, in addition to increased intranetwork connectivity, both a global and a specific (medial and lateral visual networks to a right frontoparietal network) increase of intrinsic internetwork connectivity in grapheme-color synesthesia. Moreover, this increased intrinsic network connectivity reflected the strength of synesthetic experiences.

Assessment of treatment response in patients with glioblastoma using O-(2-18F-fluoroethyl)-L-tyrosine PET in comparison to MRI.

Unlabelled: The assessment of treatment response in glioblastoma is difficult with MRI because reactive blood-brain barrier alterations with contrast enhancement can mimic tumor progression. In this study, we investigated the predictive value of PET using O-(2-(18)F-fluoroethyl)-l-tyrosine ((18)F-FET PET) during treatment.

Methods: In a prospective study, 25 patients with glioblastoma were investigated by MRI and (18)F-FET PET after surgery (MRI-/FET-1), early (7-10 d) after completion of radiochemotherapy with temozolomide (RCX) (MRI-/FET-2), and 6-8 wk later (MRI-/FET-3).

NG2 and NG2-positive cells delineate focal cerebral infarct demarcation in rats.

Focal cerebral ischemia induces cellular responses that may result in secondary tissue damage. We recently demonstrated multi-facetted spatial and temporal patterns of neuroinflammation by multimodal imaging. In the present study, we especially focus on the separation of vital and necrotic tissue, which enabled us to define a demarcation zone.

The neural basis of anosognosia for spatial neglect after stroke.

Background And Purpose: The present study investigated the lesion anatomy of anosognosia for visuospatial neglect resulting from right hemispheric stroke.

Methods: In 63 patients, self-ratings of performance in paper-and-pencil tests were contrasted with external performance ratings. Lesion analysis was conducted on patient subgroups with different degrees of anosognosia but comparable visuospatial impairment.

Prognostic value of electroencephalography and evoked potentials in the early course of malignant middle cerebral artery infarction.

Space-occupying brain edema may lead to a malignant course in patients with large middle cerebral artery infarction. Decompressive hemicraniectomy has to be initiated early to prevent further tissue damage. In this retrospective study, we analyzed electroencephalography (EEG) and evoked potentials (EPs), obtained within 24 h after onset of stroke, in 22 patients suffering from a large middle cerebral artery infarction.

Structural brain abnormalities in adolescent anorexia nervosa before and after weight recovery and associated hormonal changes.

Objective: The neurobiological mechanisms of structural brain abnormalities in patients with anorexia nervosa (AN) remain poorly understood. In particular, little is known about the changes in and the recovery of gray matter (GM) volumes after weight gain and the relation to hormonal normalization in adolescent patients with AN.

Methods: Nineteen female patients aged 12 to 17 years were assessed using magnetic resonance imaging at the time of admission to the hospital (T1) and after weight recovery (T2).

Differential roles of inferior frontal and inferior parietal cortex in task switching: evidence from stimulus-categorization switching and response-modality switching.

We used fMRI to investigate both common and differential neural mechanisms underlying two distinct types of switching requirements, namely switching between stimulus categorizations (color vs. form) and switching between response modalities (hand vs. foot responses).

Reward system dysfunction in autism spectrum disorders.

Although it has been suggested that social deficits of autism spectrum disorders (ASDs) are related to reward circuitry dysfunction, very little is known about the neural reward mechanisms in ASD. In the current functional magnetic resonance imaging study, we investigated brain activations in response to both social and monetary reward in a group of children with ASD, relative to matched controls. Participants with ASD showed the expected hypoactivation in the mesocorticolimbic circuitry in response to both reward types.

Disentangling self- and fairness-related neural mechanisms involved in the ultimatum game: an fMRI study.

Rejections of unfair offers in the ultimatum game (UG) are commonly assumed to reflect negative emotional arousal mediated by the anterior insula and medial prefrontal cortex. We aimed to disentangle those neural mechanisms associated with direct personal involvement ('I have been treated unfairly') from those associated with fairness considerations, such as the wish to discourage unfair behavior or social norm violations ('this person has been treated unfairly'). For this purpose, we used fMRI and asked participants to play the UG as responders either for themselves (myself) or on behalf of another person (third party).

Imaging of non- or very subtle contrast-enhancing malignant gliomas with [¹¹C]-methionine positron emission tomography.

In patients with World Health Organization (WHO) grade III glioma with a lack of or minimal (< 1 cm3) magnetic resonance imaging (MRI) contrast enhancement, the volume of the metabolically active part of the tumor was assessed by [¹¹C]-methionine positron emission tomography (MET-PET). Eleven patients with WHO grade III gliomas underwent MET-PET and MRI (contrast-enhanced T1- and T2-weighted images). To calculate the volumes in cubic centimeters, threshold-based volume of interest analyses of the metabolically active tumor (MET uptake index ≥ 1.

Potential of early [(18)F]-2-fluoro-2-deoxy-D-glucose positron emission tomography for identifying hypoperfusion and predicting fate of tissue in a rat embolic stroke model.

Background And Purpose: Experimental stroke models are essential to study in vivo pathophysiological processes of focal cerebral ischemia. In this study, an embolic stroke model in rats was applied (1) to characterize early development of regional cerebral blood flow and metabolism with positron emission tomography (PET) using [(15)O]H(2)O and [(18)F]-2-fluoro-2-deoxy-D-glucose (FDG); and (2) to identify potential parameters for predicting tissue fate.

Methods: Remote occlusion of the middle cerebral artery was induced in 10 Wistar rats by injection of 4 TiO(2) macrospheres.