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Several proton magnetic resonance spectroscopy (1H MRS) studies in schizophrenia have found reduced N-acetyl aspartate (NAA) concentrations in pre-frontal and temporal regions of the brain. Reductions in NAA may reflect abnormalities of neuronal structure (e.g. reduced neuronal density or viability) or abnormalities of neuronal function. Diffusion tensor(More)
Low myo-inositol and high glutamine levels in brain are associated with neuropsychological deterioration after induced hyper-ammonemia.—The neuropsychological effect of hyperammonemia is variable. This study tests the hypothesis that the effect of ammonia on the neuropsychological function in patients with cirrhosis is determined by the ability of the brain(More)
Schizophrenia is a highly heritable disorder that typically develops in early adult life. Structural imaging studies have indicated that patients with the illness, and to some extent their unaffected relatives, have subtle deficits in several brain regions, including prefrontal and temporal lobes. It is, however, not known how this inherited vulnerability(More)
Diffusion tensor imaging (DTI) is a modality known to be highly sensitive to the detrimental effects of experimental noise. Here, using Monte Carlo simulations, we compare and contrast how noise complicates the measurement of diffusion anisotropy in diffusion tensor and conventional diffusion-weighted imaging (DWI). As the signal-to-noise ratio (SNR)(More)
OBJECTIVES Patients with type II diabetes are at increased risk of cognitive impairment. The retinal and renal complications of diabetes follow microvascular damage permitting small arterioles to leak, hence the cerebral damage might also follow loss of blood-brain barrier (BBB) integrity. Magnetic resonance (MR) brain imaging with intravenous gadolinium(More)
Around 50% of patients with the sleep apnea/hypopnea syndrome (SAHS) are not obese: body mass index (BMI) < 30 kg/m2. We hypothesized that local fat deposition around the upper airway may be different in nonobese patients with SAHS from that in normal subjects with the same body mass. We therefore examined the relationship between indices of general(More)
Quantification of MRS spectra is a challenging problem when a large baseline is present along with a low signal to noise ratio. This work investigates a robust fitting technique that yields accurate peak areas under these conditions. Using simulated long echo time (1)H MRS spectra with low signal to noise ratio and a large baseline component, both the(More)
Volume-selective lactate editing has been performed successfully in vitro and in vivo in the brain on a clinical scanner using a PRESS-based single voxel 1H spectroscopy and a 1H spectroscopic imaging sequence. The PRESS sequence was made sensitive to homonuclear polarisation by replacing the standard 180 degree refocusing pulses with 90 degree pulses. Two(More)
The use of Lorentzian model lineshapes leads to systematic errors in the quantification of in vivo (1)H NMR spectra. Experimental lineshapes are better modeled by the Voigt (mixed Lorentzian-Gaussian) function, leading to more accurate fits (reduced chi(2)). In this work, results from a group of 41 subjects are presented. It is shown that not only are the(More)
OBJECTIVE Although much tissue damage may occur within the first few hours of ischemic stroke, the duration of tissue injury is not well defined. We assessed the temporal pattern of neuronal loss and ischemia after ischemic stroke using magnetic resonance spectroscopic imaging (MRSI) and diffusion-weighted imaging (DWI). METHODS We measured(More)