Quantitative cerebral blood flow in dynamic susceptibility contrast MRI using total cerebral flow from phase contrast magnetic resonance angiography.

Dynamic susceptibility contrast magnetic resonance imaging during bolus injection of gadolinium contrast agent is commonly used to investigate cerebral hemodynamics. The large majority of clinical applications of dynamic susceptibility contrast magnetic resonance imaging to date have reported relative cerebral blood flow values because of dependence of the result on the accuracy of determining the arterial input function, the robustness of the singular value decomposition algorithm, and others. We propose a calibration approach that directly measures the total (i.

Exploring the relationship of macrophage colony-stimulating factor levels on neuroaxonal metabolism and cognition during chronic human immunodeficiency virus infection.

Macrophage colony-stimulating factor (M-CSF) promotes macrophage differentiation, increases susceptibility of macrophages to viral infection, and enhances human immunodeficiency virus (HIV) replication in infected macrophages. Given the current model of HIV neuropathogenesis, which involves monocyte trafficking into the central nervous system, immune factors linked with macrophage maturation and survival may be associated with cognitive decline (measured by neuropsychological z-score [NPZ-8] or Memorial Sloan-Kettering [MSK] score) and alterations in a marker of neuronal integrity, N-acetylaspartate (NAA). Fifty-four chronically infected HIV+ subjects underwent neuropsychological assessment, magnetic resonance spectroscopic imaging, and quantification of M-CSF in plasma and cerebrospinal fluid (CSF) at baseline.

Diffusion tensor imaging in children and adolescents: reproducibility, hemispheric, and age-related differences.

Unlabelled: We evaluated intra-rater, inter-rater, and between-scan reproducibility, hemispheric differences, and the effect of age on apparent diffusion coefficient (ADC) and fractional anisotropy (FA) in healthy children (age range 5.5-19.1 years) examined with a clinical diffusion tensor imaging (DTI) protocol at 1.

Evidence for cortical dysfunction and widespread manganese accumulation in the nonhuman primate brain following chronic manganese exposure: a 1H-MRS and MRI study.

Exposure to high levels of manganese (Mn) is known to produce a complex neurological syndrome with psychiatric disturbances, cognitive impairment, and parkinsonian features. However, the neurobiological basis of chronic low-level Mn exposure is not well defined. We now provide evidence that exposure to levels of Mn that results in blood Mn concentrations in the upper range of environmental and occupational exposures and in certain medical conditions produces widespread Mn accumulation in the nonhuman primate brain as visualized by T1-weighted magnetic resonance imaging.

Childhood obstructive sleep apnea associates with neuropsychological deficits and neuronal brain injury.

Background: Childhood obstructive sleep apnea (OSA) is associated with neuropsychological deficits of memory, learning, and executive function. There is no evidence of neuronal brain injury in children with OSA. We hypothesized that childhood OSA is associated with neuropsychological performance dysfunction, and with neuronal metabolite alterations in the brain, indicative of neuronal injury in areas corresponding to neuropsychological function.

Noninvasive assessment of brain injury in a canine model of hypothermic circulatory arrest using magnetic resonance spectroscopy.

Background: Studies have confirmed the neuroprotective effect of diazoxide in canines undergoing hypothermic circulatory arrest (HCA). A decreased N-acetyl-asparate:choline (NAA:Cho) ratio is believed to reflect the severity of neurologic injury. We demonstrated that noninvasive measurement of NAA:Cho with magnetic resonance spectroscopy facilitates assessment of neuronal injury after HCA and allows for evaluation of neuroprotective strategies.

Quantitative proton magnetic resonance spectroscopic imaging: regional variations in the corpus callosum and cortical gray matter.

Purpose: To evaluate regional variations of metabolite concentrations in normal adult brain cortical gray matter regions, and the genu and splenium of the corpus callosum, using proton magnetic resonance spectroscopic imaging (MRSI).

Materials And Methods: Quantitative, multislice proton MRSI (TR/TE = 2000/280 msec) was performed in 12 normal human volunteers (age = 39 +/- 6 years, 7 male). Metabolite concentrations in selected cortical gray matter regions and the corpus callosum were estimated using the phantom replacement methodology.

Anatomy of spatial attention: insights from perfusion imaging and hemispatial neglect in acute stroke.

The site of lesion responsible for left hemispatial neglect after stroke has been intensely debated recently. Some studies provide evidence that right angular lesions are most likely to cause left neglect, whereas others indicate that right superior temporal lesions are most likely to cause neglect. We examine two potential accounts of the conflicting results: (1) neglect could result from cortical dysfunction beyond the structural lesion in some studies; and (2) different forms of neglect with separate neural correlates have been included in different proportions in separate studies.

Determination of relaxation characteristics during preacute stage of lysophosphatidyl choline-induced demyelinating lesion in rat brain: an animal model of multiple sclerosis.

Relaxation time measurements were carried out during the preacute stage of lesion progression in an animal model of demyelination created in the internal capsule (ic) area of the rat brain using lysophosphatidyl choline (LPC). T1 and T2 were determined both before and after 36 h of lesion creation. Histology carried out on the rats after MR measurements showed focal demyelinating lesion and surrounding edema with prominent infiltration of inflammatory cells.

The roles of the "visual word form area" in reading.

Activation of the left midfusiform gyrus in response to reading words and pseudowords is such a reliable finding in functional imaging that this region has been called "the visual word form area" (VWFA). However, this label has recently been challenged, because activation in VWFA is also observed in other lexical tasks. We evaluated whether VWFA is necessary, sufficient, or specialized for reading by examining how frequently acute lesions in VWFA disrupt tasks that require access to written word forms versus other lexical tasks.

Metabolites in ventricular cerebrospinal fluid detected by proton magnetic resonance spectroscopic imaging.

Normally, ventricular cerebrospinal fluid (CSF) contains low levels of all metabolite signals on proton magnetic resonance spectroscopic imaging (MRSI). We present here three cases (two with seizure disorders, one with a central nervous system lymphoma) who presented with unusually elevated CSF signals on MRSI. Based on chemical shifts and in vitro studies (in one case), the signals were assigned to propan-1,2-diol (PD), acetone, and lactate, respectively.

Evaluation of skin tumors by magnetic resonance imaging.

In vivo magnetic resonance imaging (MRI) is a powerful noninvasive technique in medical diagnosis; however, its application to analyze skin disorders is still at initial stages. To check whether MRI can be used as a noninvasive tool to analyze skin tumors, we carried out MRI of mice after treatment with benzo[a]pyrene (BP), a well known carcinogen. MRI was done on whole mice and was particularly focused on various layers and regions of interest of the skin: dermis, epidermis, and tumor.

Protective role of cyclosporine in experimental unilateral blunt testicular trauma: evaluation by 31P MR spectroscopy.

Magnetic resonance (MR) imaging is a useful tool to study the anatomy of the testis while 31P magnetic resonance spectroscopy (MRS) provides a non-invasive alternative method to demonstrate the metabolic status of testes. This study was designed to test whether the protective role of cyclosporine in experimental unilateral blunt testicular trauma (UBTT) could be assessed by 31P MRS. Male Wistar rats (n = 30) aged 20 days were randomised into group I (sham surgery), group II (UBTT) and group III (UBTT and cyclosporine for 7 days).

Sequential diffusion-weighted magnetic resonance imaging study of lysophosphatidyl choline-induced experimental demyelinating lesion: an animal model of multiple sclerosis.

Purpose: To differentiate the surrounding edema from the focal demyelinating lesion during the early phase of the lesion using an apparent diffusion coefficient (ADC), and to monitor the changes in ADCs during the complete progression of a lysophosphatidyl choline (LPC)-induced experimental demyelinating lesion, an animal model of multiple sclerosis (MS).

Material And Methods: Eighteen rats divided into two groups-demyelinating lesion (group I, N = 12) and vehicle group (saline injected; group II, N = 6)-were studied. A 0.