The Age-Related Perfusion Pattern Measured With Arterial Spin Labeling MRI in Healthy Subjects.

To analyze age-related cerebral blood flow (CBF) using arterial spin labeling (ASL) MRI in healthy subjects with multivariate principal component analysis (PCA). 50 healthy subjects (mean age 45.8 ± 18.

Frontal lobe functioning during a simple response conflict task in first-episode psychosis and its relationship to treatment response.

Prior functional magnetic resonance imaging (fMRI) studies have investigated the neural mechanisms underlying cognitive control in patients with psychosis with findings of both hypo- and hyperfrontality. One factor that may contribute to inconsistent findings is the use of complex and polyfactorial tasks to investigate frontal lobe functioning. In the current study we employed a simple response conflict task during fMRI to examine differences in brain activation between patients experiencing their first-episode of psychosis (n = 33) and age- and sex-matched healthy volunteers (n = 33).

Integration of routine QA data into mega-analysis may improve quality and sensitivity of multisite diffusion tensor imaging studies.

A novel mega-analytical approach that reduced methodological variance was evaluated using a multisite diffusion tensor imaging (DTI) fractional anisotropy (FA) data by comparing white matter integrity in people with schizophrenia to controls. Methodological variance was reduced through regression of variance captured from quality assurance (QA) and by using Marchenko-Pastur Principal Component Analysis (MP-PCA) denoising. N = 192 (119 patients/73 controls) data sets were collected at three sites equipped with 3T MRI systems: GE MR750, GE HDx, and Siemens Trio.

Investigation of superior longitudinal fasciculus fiber complexity in recent onset psychosis.

Background: Standard diffusion tensor imaging measures (e.g., fractional anisotropy; FA) are difficult to interpret in brain regions with crossing white-matter (WM) fibers.

A novel DTI-QA tool: Automated metric extraction exploiting the sphericity of an agar filled phantom.

Purpose: To develop a quality assurance (QA) tool (acquisition guidelines and automated processing) for diffusion tensor imaging (DTI) data using a common agar-based phantom used for fMRI QA. The goal is to produce a comprehensive set of automated, sensitive and robust QA metrics.

Methods: A readily available agar phantom was scanned with and without parallel imaging reconstruction.

Subcortical modulation in auditory processing and auditory hallucinations.

Hearing perception in individuals with auditory hallucinations has not been well studied. Auditory hallucinations have previously been shown to involve primary auditory cortex activation. This activation suggests that auditory hallucinations activate the terminal of the auditory pathway as if auditory signals are submitted from the cochlea, and that a hallucinatory event is therefore perceived as hearing.

Abnormal resting state FMRI activity predicts processing speed deficits in first-episode psychosis.

Little is known regarding the neuropsychological significance of resting state functional magnetic resonance imaging (rs-fMRI) activity early in the course of psychosis. Moreover, no studies have used different approaches for analysis of rs-fMRI activity and examined gray matter thickness in the same cohort. In this study, 41 patients experiencing a first-episode of psychosis (including N=17 who were antipsychotic drug-naive at the time of scanning) and 41 individually age- and sex-matched healthy volunteers completed rs-fMRI and structural MRI exams and neuropsychological assessments.

Seeing scenes: topographic visual hallucinations evoked by direct electrical stimulation of the parahippocampal place area.

In recent years, functional neuroimaging has disclosed a network of cortical areas in the basal temporal lobe that selectively respond to visual scenes, including the parahippocampal place area (PPA). Beyond the observation that lesions involving the PPA cause topographic disorientation, there is little causal evidence linking neural activity in that area to the perception of places. Here, we combined functional magnetic resonance imaging (fMRI) and intracranial EEG (iEEG) recordings to delineate place-selective cortex in a patient implanted with stereo-EEG electrodes for presurgical evaluation of drug-resistant epilepsy.

Resting-state fMRI connectivity impairment in schizophrenia and bipolar disorder.

Background: Schizophrenia and bipolar disorder share aspects of phenomenology and neurobiology and thus may represent a continuum of disease. Few studies have compared connectivity across the brain in these disorders or investigated their functional correlates.

Methods: We used resting-state functional magnetic resonance imaging to evaluate global and regional connectivity in 32 healthy controls, 19 patients with bipolar disorder, and 18 schizophrenia patients.

APOE genotype modulates proton magnetic resonance spectroscopy metabolites in the aging brain.

Background: Proton magnetic resonance spectroscopy ((1)H-MRS) studies on healthy aging have reported inconsistent findings and have not systematically taken into account the possible modulatory effect of APOE genotype. We aimed to quantify brain metabolite changes in healthy subjects in relation to age and the presence of the APOE E4 genetic risk factor for Alzheimer's disease. Additionally, we examined these measures in relation to cognition.

An Open-Label Exploratory Study with Memantine: Correlation between Proton Magnetic Resonance Spectroscopy and Cognition in Patients with Mild to Moderate Alzheimer's Disease.

Aim: To characterize progression of Alzheimer's disease (AD) using proton magnetic resonance spectroscopy ((1)H MRS).

Methods: Eleven subjects with mild to moderate AD underwent neurocognitive testing and single-voxel (1)H MRS from the precuneus and posterior cingulate region at baseline, after 24 weeks of monotherapy with a cholinesterase inhibitor, and after another 24 weeks of combination therapy with open-label memantine and a cholinesterase inhibitor. Baseline metabolites [N-acetylaspartate (NAA), myo-inositol (mI), choline (Cho), and creatine (Cr)] and their ratios in AD subjects were compared with those of an age-matched control group of 28 cognitively normal subjects.

Feature-based interpolation of diffusion tensor fields and application to human cardiac DT-MRI.

Diffusion tensor interpolation is an important issue in the application of diffusion tensor magnetic resonance imaging (DT-MRI) to the human heart, all the more as the points representing the myocardium of the heart are often sparse. We propose a feature-based interpolation framework for the tensor fields from cardiac DT-MRI, by taking into account inherent relationships between tensor components. In this framework, the interpolation consists in representing a diffusion tensor in terms of two tensor features, eigenvalues and orientation, interpolating the Euler angles or the quaternion relative to tensor orientation and the logarithmically transformed eigenvalues, and reconstructing the tensor to be interpolated from the interpolated eigenvalues and tensor orientations.

Thalamo-striatal diffusion reductions precede disease onset in prion mutation carriers.

Human prion diseases present substantial scientific and public health challenges. They are unique in being sporadic, infectious and inherited, and their pathogen is distinct from all other pathogens in lacking nucleic acids. Despite progress in understanding the molecular structure of prions, their initial cerebral pathophysiology and the loci of cerebral injury are poorly understood.

Cerebral glucose metabolism and D2/D3 receptor availability in young adults with cannabis dependence measured with positron emission tomography.

Introduction: Cannabis users have been reported to have decreased regional cerebral glucose metabolism after short periods of abstinence. The purpose of this study was to measure striatal dopamine receptor (D2/D3) availability and cerebral glucose metabolism with positron emission tomography (PET) in young adults who had a prolonged exposure to cannabis and who had been abstinent for a period of at least 12 weeks.

Materials And Methods: Six 18-21-year-old male subjects with cannabis dependence in early full remission and six age- and sex-matched healthy subjects underwent PET scans for D2/D3 receptor availability measured with [C11]-raclopride and glucose metabolism measured with [18F]-FDG.

Microstructural white matter changes in primary torsion dystonia.

Primary torsion dystonia (PTD) has been conceptualized as a disorder of the basal ganglia. However, recent data suggest a widespread pathology involving motor control pathways. In this report, we explored whether PTD is associated with abnormal anatomical connectivity within motor control pathways.

The imaging appearance of Creutzfeldt-Jakob disease caused by the E200K mutation.

The E200K mutation on chromosome 20 can cause familial Creutzfeldt-Jakob disease (CJD). Patients with this mutation are clinically similar to those with sporadic CJD, but their imaging features are not well documented. We report here the quantitative and qualitative evaluation of the magnetic resonance (MR) imaging characteristics of this unique group of patients using three-dimensional spoiled gradient recalled (SPGR) echo images, diffusion-weighted imaging (DWI) with apparent diffusion coefficient (ADC) measurements, MR spectroscopy and a fluid-attenuated inversion recovery (FLAIR) sequence.

Identification of diffuse and focal brain lesions by clinical magnetic resonance spectroscopy.

The purpose of this paper is to facilitate the comparison of magnetic resonance (MR) spectra acquired from unknown brain lesions with published spectra in order to help identify unknown lesions in clinical settings. The paper includes lists of references for published MR spectra of various brain diseases, including pyogenic abscesses, encephalitis (herpes simplex, Rasmussen's and subacute sclerosing panencephalitis), neurocysticercosis, tuberculoma, cysts (arachnoid, epidermoid and hydatid), acute disseminated encephalomyelitis (ADEM), adrenoleukodystrophy (ALD), Alexander disease, Canavan's disease, Krabbe disease (globoid cell leukodystrophy), Leigh's disease, megalencephalic leukoencephalopathy with cysts, metachromatic leukodystrophy (MLD), Pelizaeus-Merzbacher disease, Zellweger syndrome, HIV-associated lesions [cryptococcus, lymphoma, toxoplasmosis and progressive multifocal leukoencephalopathy (PML)], hydrocephalus and tuberous sclerosis. Each list includes information on the echo time(s) (TE) of the published spectra, whether a control spectrum is shown, whether the corresponding image and voxel position are shown and the patient ages if known.

Contrast-to-noise ratios of diffusion anisotropy indices.

The degree of diffusion anisotropy in different brain regions is usually measured by a diffusion anisotropy index (DAI) such as relative anisotropy (RA) and fractional anisotropy (FA). FA has been reported to have a higher contrast-to-noise ratio (CNR) than RA. The present work compares the CNRs of seven DAIs in theoretical propagation-of-error calculations, in simulations, and in human brain measurements over small and large anisotropy differences.

Microstructural white matter changes in carriers of the DYT1 gene mutation.

We tested the hypothesis that the DYT1 genotype is associated with a disorder of anatomical connectivity involving primarily the sensorimotor cortex. We used diffusion tensor magnetic resonance imaging (DTI) to assess the microstructure of white matter pathways in mutation carriers and control subjects. Fractional anisotropy (FA), a measure of axonal integrity and coherence, was reduced (p < 0.

Newborn brain infarction: clinical aspects and magnetic resonance imaging.

Objective: We describe the clinical and imaging studies of 11 full-term babies with neonatal stroke. We classify the neonatal non-hemorrhagic strokes as thrombotic, embolic, or global vascular insufficiency and determine if this classification is improved by adding magnetic resonance spectroscopy (MRS) and diffusion-weighted imaging (DWI) to conventional magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA).

Methods: Clinically, eight of the 11 babies presented with seizures, one with apnea, and two with lethargy.

Selection of the optimum b factor for diffusion-weighted magnetic resonance imaging assessment of ischemic stroke.

The purpose of this study was to determine the diffusion sensitivity factor b that optimizes the contrast-to-noise ratio (CNR) for both diffusion-weighted signal intensity and the apparent diffusion coefficient (ADCNR) when evaluating ischemic stroke by diffusion-weighted MRI. The relative contrast, noise levels, CNR, and ADCNR were calculated for typical ADC values in human brain, 780 microm(2)/s in adults and 1200 microm(2)/s in neonates in normal tissue, 20-40% less in acute and subacute stroke, and 50% more in chronic stroke. The optimum b factor depends strongly on the ADC, whether TE is fixed or varies with the b factor, whether CNR or ADCNR is measured, and anisotropy.

Optimized precision of inversion-recovery T1 measurements for constrained scan time.

Optimization of inversion-recovery (IR) measurements of T1 relaxation times has focused on the efficiency of T1 estimation (precision per unit time), without explicit consideration of the total experimental time. With the modified fast IR method, the repetition time (TR) is constant and each inversion time (TI) must be less than TR. For a fixed total experimental time in the absence of signal averaging, TR and the longest TI time must decrease as more TI times are added.

Correlation of diffusion-weighted magnetic resonance imaging with neuropathology in Creutzfeldt-Jakob disease.

Background: Although the diagnosis of Creutzfeld-Jakob disease (CJD) is straightforward in fully developed cases, a definitive diagnosis can be difficult early in the course of the illness. T2-weighted magnetic resonance imaging (MRI) signal abnormalities, and recently, diffusion-weighted MRI abnormalities, have been described in patients with CJD, suggesting the utility of MRI in the early recognition of CJD.

Objective: To correlate diffusion-weighted MRI signal abnormalities with neuropathologic changes in CJD.