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ABSTRACT: Pyrexia soon after stroke is associated with severe stroke and poor functional outcome. Few studies have assessed brain temperature after stroke in patients, so little is known of its associations with body temperature, stroke severity, or outcome. We measured temperatures in ischemic and normal-appearing brain using (1)H-magnetic resonance spectroscopy and its correlations with body (tympanic) temperature measured four-hourly, infarct growth by 5 days, early neurologic (National Institute of Health Stroke Scale, NIHSS) and late functional outcome (death or dependency). Among 40 patients (mean age 73 years, median NIHSS 7, imaged at median 17 hours), temperature in ischemic brain was higher than in normal-appearing brain on admission (38.6°C-core, 37.9°C-contralateral hemisphere, P=0.03) but both were equally elevated by 5 days; both were higher than tympanic temperature. Ischemic lesion temperature was not associated with NIHSS or 3-month functional outcome; in contrast, higher contralateral normal-appearing brain temperature was associated with worse NIHSS, infarct expansion and poor functional outcome, similar to associations for tympanic temperature. We conclude that brain temperature is higher than body temperature; that elevated temperature in ischemic brain reflects a local tissue response to ischemia, whereas pyrexia reflects the systemic response to stroke, occurs later, and is associated with adverse outcomes.Journal of Cerebral Blood Flow & Metabolism advance online publication, 10 April 2013; doi:10.1038/jcbfm.2013.52.
Journal of cerebral blood flow and metabolism: official journal of the International Society of Cerebral Blood Flow and Metabolism 04/2013; · 5.46 Impact Factor
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Osamu Kano,
Ken Ikeda,
Yasuo Iwasaki,
Joanna M Wardlaw,
William N Whiteley,
Ralph Thomas,
Gordon Lowe,
Ann Rumley,
Bartosz Karaszewski,
Paul Armitage, Ian Marshall,
Katherine Lymer,
Martin Dennis
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ABSTRACT: Whiteley et al.(1) reported that higher level of circulating markers of the acute inflammatory response in acute stroke were associated with higher temperatures in normal brain. They found no association between blood markers of inflammation and brain temperature in different regions of brain. The authors measured 3 markers of inflammation: C-reactive protein, interleukin-6, and fibrinogen. Higher temperature in diffusion-weighted imaging-abnormal brain was not associated with higher body temperature at the time of the first scan, but was associated with higher contemporaneous body temperature at the second scan. Was there any correlation between ischemic lesions and markers of inflammation? For example, did ischemic lesions in the infratentorial lesions correlate with one of these measurements? Body temperature is related to brain lesion in the hypothalamus and direct or indirect damage to the hypothalamus could contribute to the findings. In addition to brain cooling, elevating these biomarkers should be explored further.
Neurology 02/2013; 80(8):777-8. · 8.31 Impact Factor
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Neurology 02/2013; 80(8):778. · 8.31 Impact Factor
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ABSTRACT: BACKGROUND: Bipolar disorder is associated with both white matter abnormalities and hypothalamo-pituitary-adrenal axis dysfunction. In a post-hoc analysis of diffusion tensor data, the relationship between cortisol levels and white matter structural integrity was explored in healthy controls and in euthymic patients with bipolar disorder. METHODS: Healthy control subjects and patients with bipolar disorder, prospectively verified as euthymic, underwent diffusion tensor MRI: fractional anisotropy and mean diffusivity data in fifteen regions of interest were obtained. Morning and evening salivary cortisol levels (SCLs) were measured. RESULTS: Significant negative partial correlations were found between fractional anisotropy and evening SCLs in control subjects in four periventricular regions. This pattern was absent in bipolar patients, possibly due to the presence of an excess of extracellular fluid manifested as a significant increase in mean diffusivity in those regions. LIMITATIONS: This is an exploratory, post-hoc analysis of data with relatively small sample sizes. Lithium treatment and past substance abuse in the bipolar group are potentially confounding factors in this study. CONCLUSIONS: These preliminary data show an inverse relationship between evening cortisol levels and a measure of periventricular white matter integrity in healthy controls. This relationship appears disrupted in bipolar patients, possibly due to periventricular osmoregulatory dysfunction, the effects of medication or past substance use. Future research should further investigate the influences of cortisol on oligodendrocyte function, white matter integrity and brain osmoregulation in bipolar disorder.
Journal of affective disorders 02/2013; · 3.76 Impact Factor
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Nichola M Brydges,
Heather C Whalley,
Maurits A Jansen,
Gavin D Merrifield,
Emma R Wood,
Stephen M Lawrie,
Sara-Madge Wynne,
Mark Day,
Sue Fleetwood-Walker,
Douglas Steele, Ian Marshall,
Jeremy Hall,
Megan C Holmes
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ABSTRACT: Functional magnetic resonance imaging (fMRI) is a powerful method for exploring emotional and cognitive brain responses in humans. However rodent fMRI has not previously been applied to the analysis of learned behaviour in awake animals, limiting its use as a translational tool. Here we have developed a novel paradigm for studying brain activation in awake rats responding to conditioned stimuli using fMRI. Using this method we show activation of the amygdala and related fear circuitry in response to a fear-conditioned stimulus and demonstrate that the magnitude of fear circuitry activation is increased following early life stress, a rodent model of affective disorders. This technique provides a new translatable method for testing environmental, genetic and pharmacological manipulations on emotional and cognitive processes in awake rodent models.
PLoS ONE 01/2013; 8(1):e54197. · 4.09 Impact Factor
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ABSTRACT: Both brain and body temperature rise after stroke but the cause of each is uncertain. We investigated the relationship between circulating markers of inflammation with brain and body temperature after stroke.
We recruited patients with acute ischemic stroke and measured brain temperature at hospital admission and 5 days after stroke with multivoxel magnetic resonance spectroscopic imaging in normal brain and the acute ischemic lesion (defined by diffusion-weighted imaging [DWI]). We measured body temperature with digital aural thermometers 4-hourly and drew blood daily to measure interleukin-6, C-reactive protein, and fibrinogen, for 5 days after stroke.
In 44 stroke patients, the mean temperature in DWI-ischemic brain soon after admission was 38.4° C (95% confidence interval [CI] 38.2-38.6), in DWI-normal brain was 37.7° C (95% CI 37.6-37.7), and mean body temperature was 36.6° C (95% CI 36.3-37.0). Higher mean levels of interleukin-6, C-reactive protein, and fibrinogen were associated with higher temperature in DWI-normal brain at admission and 5 days, and higher overall mean body temperature, but only with higher temperature in DWI-ischemic brain on admission.
Systemic inflammation after stroke is associated with elevated temperature in normal brain and the body but not with later ischemic brain temperature. Elevated brain temperature is a potential mechanism for the poorer outcome observed in stroke patients with higher levels of circulating inflammatory markers.
Neurology 06/2012; 79(2):152-8. · 8.31 Impact Factor
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Michael J Thrippleton,
Mark E Bastin,
Kirsty I Munro,
Alistair R Williams,
Anca Oniscu,
Maurits A Jansen,
Gavin D Merrifield,
Graham McKillop,
David E Newby,
Scott I Semple, Ian Marshall,
Hilary O Critchley
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ABSTRACT: To investigate the water diffusion tensor properties of ex vivo tissue in the fibroid uterus, including the influence of degeneration, and the relevance of the principal eigenvector orientation to the underlying tissue structure.
Following hysterectomy, high-resolution structural T(2) -weighted and diffusion tensor magnetic resonance imaging (DT-MRI) were performed on nine uteri at 7 T. Mean diffusivity (MD), fractional anisotropy (FA), and principal eigenvector orientation were measured in myometrium and in myxoid and dense tissue in fibroids. Imaging data and measurements of water diffusion parameters were compared with histopathology findings.
The nine uteri yielded 23 fibroids. MD was 50% higher in regions of myxoid degeneration compared to dense fibroid tissue (P = 0.001), while myometrium was intermediate in value (dense fibroid tissue, P = 0.15; myxoid degeneration, P = 0.23). FA was lower in dense fibroid tissue than in myometrium (P = 3 × 10(-5) ), but higher than in myxoid tissue (P = 0.003). Principal eigenvector orientation corresponded qualitatively with that of uterine smooth muscle fibers.
The water diffusion tensor measured ex vivo in the fibroid uterus is a sensitive probe of tissue type, myxoid degeneration, and morphology.
Journal of Magnetic Resonance Imaging 09/2011; 34(6):1445-51. · 2.70 Impact Factor
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ABSTRACT: Manganese (Mn(2+))-enhanced magnetic resonance (MR) imaging (MEMRI) in rodents offers unique opportunities for the longitudinal study of hippocampal structure and function in parallel with cognitive testing. However, Mn(2+) is a potent toxin and there is evidence that it can interfere with neuronal function. Thus, apart from causing adverse peripheral side effects, Mn(2+) may disrupt the function of brain areas where it accumulates to produce signal enhancement and, thereby, Mn(2+) administration may confound cognitive testing. Here, we examined in male adult Lister hooded rats if a moderate systemic dose of MnCl₂ (200 μmol/kg; two intraperitoneal injections of 100 μmol/kg separated by 1 h) that produces hippocampal MR signal enhancement would disrupt hippocampal function. To this end, we used a delayed-matching-to-place (DMP) watermaze task, which requires rapid allocentric place learning and is highly sensitive to interference with hippocampal function. Tested on the DMP task 1 h and 24 h after MnCl₂ injection, rats did not show any impairment in indices of memory performance (latencies, search preference) or any sensorimotor effects. However, MnCl₂ injection caused acute peripheral effects (severe ataxia and erythema, i.e. redness of paws, ears, and nose) which subsided over 30 min. Additionally, rats injected with MnCl₂ showed reduced weight 1 day after injection and failed to reach the normal weight-growth curve of control rats within the 16 days monitored. Our results indicate that 200 μmol/kg MnCl₂ produces hippocampal MR signal enhancement without disrupting hippocampus-dependent behavior on a rapid place learning task, even though attention must be paid to peripheral side effects.
Behavioural brain research 01/2011; 216(1):293-300. · 3.22 Impact Factor
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Philip R Holland,
Mark E Bastin,
Maurits A Jansen,
Gavin D Merrifield,
Robin B Coltman,
Fiona Scott,
Hanna Nowers,
Karim Khallout, Ian Marshall,
Joanna M Wardlaw,
Ian J Deary,
James McCulloch,
Karen Horsburgh
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ABSTRACT: White matter (WM) abnormalities, possibly resulting from hypoperfusion, are key features of the aging human brain. It is unclear, however, whether in vivo magnetic resonance imaging (MRI) approaches, such as diffusion tensor and magnetization transfer MRI are sufficiently sensitive to detect subtle alterations to WM integrity in mouse models developed to study the aging brain. We therefore investigated the use of diffusion tensor and magnetization transfer MRI to measure structural changes in 4 WM tracts following 1 month of moderate hypoperfusion, which results in diffuse WM pathology in C57Bl/6J mice. Following MRI, brains were processed for evaluation of white and gray matter pathology. Significant reductions in fractional anisotropy were observed in the corpus callosum (p = 0.001) and internal capsule (p = 0.016), and significant decreases in magnetization transfer ratio were observed in the corpus callosum (p = 0.023), fimbria (p = 0.032), internal capsule (p = 0.046) and optic tract (p = 0.047) following hypoperfusion. Hypoperfused mice demonstrated diffuse axonal and myelin pathology which was essentially absent in control mice. Both fractional anisotropy and magnetization transfer ratio correlate with markers of myelin integrity/degradation and not axonal pathology. The study demonstrates that in vivo MRI is a sensitive measure of diffuse, subtle WM changes in the murine brain.
Neurobiology of aging 12/2010; 32(12):2325.e1-6. · 5.94 Impact Factor
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Victoria Gradin,
Viktoria-Eleni Gountouna,
Gordon Waiter,
Trevor S Ahearn,
David Brennan,
Barrie Condon, Ian Marshall,
David J McGonigle,
Alison D Murray,
Heather Whalley,
Jonathan Cavanagh,
Donald Hadley,
Katherine Lymer,
Andrew McIntosh,
Thomas William Moorhead,
Dominic Job,
Joanna Wardlaw,
Stephen M Lawrie,
John Douglas Steele
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ABSTRACT: Psychiatric neuroimaging techniques are likely to improve understanding of the brain in health and disease, but studies tend to be small, based in one imaging centre and of unclear generalisability. Multicentre studies have great appeal but face problems if functional magnetic resonance imaging (fMRI) data from different centres are to be combined. Fourteen healthy volunteers had two brain scans on different days at three scanners. Considerable effort was first made to use similar scanning sequences and standardise task implementation across centres. The n-back cognitive task was used to investigate between- and within-scanner reproducibility and reliability. Both the functional imaging and behavioural results were in good accord with the existing literature. We found no significant differences in the activation/deactivation maps between scanners, or between repeat visits to the same scanners. Between- and within-scanner reproducibility and reliability was very similar. However, the smoothness of images from the scanners differed, suggesting that smoothness equalization might further reduce inter-scanner variability. Our results for the n-back task suggest it is possible to acquire fMRI data from different scanners which allows pooling across centres, when the same field strength scanners are used and scanning sequences and paradigm implementations are standardised.
Psychiatry Research 09/2010; 184(2):86-95. · 2.52 Impact Factor
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Ian Marshall
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ABSTRACT: To evaluate the use of computational fluid dynamic (CFD)-based magnetic resonance imaging (MRI) simulations to predict the image appearance and velocity measurement of fluid flow in human carotid bifurcation geometries, and to compare the results with images from experimental MRI studies.
Simulated particle paths were calculated from available CFD datasets of normal and moderately stenosed carotid bifurcation geometries. An MRI simulator based on the spin isochromat method was used to generate images corresponding to a 3D phase-contrast sequence with velocity encoding in three orthogonal directions. The resulting images were compared qualitatively with experimental MRI scans of the corresponding physical models.
The simulations predicted the main features observed in experimental studies, such as the low image intensity in regions of complex flow and the position and bright appearance of the jet in the stenosed bifurcation. Simulated velocity images also agreed well with experimental results. The effects of sequence parameters such as repetition time (TR) and echo time (TE) were readily demonstrated by the simulations.
CFD-based MRI simulations can be used to predict the appearance of MRI images of regions of physiological flow, and may be useful in the development of improved pulse sequences for flow measurement.
Journal of Magnetic Resonance Imaging 04/2010; 31(4):928-34. · 2.70 Impact Factor
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Karine A N Macritchie,
Adrian J Lloyd,
Mark E Bastin,
Kamini Vasudev,
Peter Gallagher,
Rachel Eyre, Ian Marshall,
Joanna M Wardlaw,
I Nicol Ferrier,
P Brian Moore,
Allan H Young
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ABSTRACT: Abnormal diffusion parameters are reported in specific brain regions and white matter tracts in bipolar disorder.
To investigate whether these abnormalities are generalised, and thus evident in large regions of white matter.
Diffusion parameters were measured at several regions in the corpus callosum and in deep/periventricular white matter in 28 currently euthymic patients with bipolar disorder and controls. White matter hyperintensity loads were assessed.
Comparing the whole data-sets using the sign test, in the group with bipolar disorder, mean diffusivity was greater at all 15 sites (P<0.001) and fractional anisotropy was reduced at 13 (P<0.01). The effect of diagnosis was significant for callosal mean diffusivity and fractional anisotropy and for deep/periventricular mean diffusivity (MANCOVA). Comparing individual regions (Mann-Whitney U-test), prefrontal and periventricular mean diffusivity were significantly increased; callosal and occipital fractional anisotropy were significantly reduced. Former substance use and lithium were possible confounding factors. Periventricular white matter hyperintensities were associated with significantly increased periventricular mean diffusivity in individuals with bipolar disorder.
Generalised white matter microstructural abnormalities may exist in bipolar disorder, possibly exacerbated by past substance use and ameliorated by lithium.
The British journal of psychiatry: the journal of mental science 01/2010; 196(1):52-8. · 6.62 Impact Factor
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Viktoria-Eleni Gountouna,
Dominic E Job,
Andrew M McIntosh,
T William J Moorhead,
G Katherine L Lymer,
Heather C Whalley,
Jeremy Hall,
Gordon D Waiter,
David Brennan,
David J McGonigle,
Trevor S Ahearn,
Jonathan Cavanagh,
Barrie Condon,
Donald M Hadley, Ian Marshall,
Alison D Murray,
J Douglas Steele,
Joanna M Wardlaw,
Stephen M Lawrie
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ABSTRACT: Multicentre MRI studies offer great potential to increase study power and flexibility, but it is not yet clear how reproducible the results from multiple centres may be. Here we present results from the multicentre study 'CaliBrain', examining the reproducibility of fMRI data within and between three sites. Fourteen subjects were scanned twice on three 1.5 T GE scanners using an identical scanning protocol. We present data from a motor task with three conditions, sequential and random finger tapping and rest. Similar activation maps were obtained for each site and visit; brain areas consistently activated during the task included the premotor, primary motor and supplementary motor areas, the striatum and cerebellum. Reproducibility was evaluated within and between sites by comparing the extent and spatial agreement of activation maps at both the subject and group levels. The results were within the range previously reported for similar tasks on single scanners and both measures were found to be comparable within and between sites, with between site reproducibility similar to the within site measures. A variance components analysis was used to examine the effects of site, subject and visit. The contributions of site and visit were small and reproducibility was similar between and within sites, whereas the variance between subjects, and unexplained variance was large. These findings suggest that we can have confidence in combined results from multicentre fMRI studies, at least when a consistent protocol is followed on similar machines in all participating scanning sites and care is taken to select homogeneous subject groups.
NeuroImage 08/2009; 49(1):552-60. · 5.89 Impact Factor
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ABSTRACT: Magnetic resonance (MR) diffusion and perfusion imaging are used to identify ischaemic penumbra, but there are few comparisons with neuronal loss and ischaemia in vivo. The authors compared N-acetyl aspartate (NAA, found in intact neurons) and lactate (anaerobic metabolism) with diffusion/perfusion parameters.
The authors prospectively recruited patients with acute ischaemic stroke and performed MR diffusion tensor, perfusion (PWI) and proton chemical shift spectroscopic imaging (CSI). We superimposed a 0.5 cm voxel grid on the diffusion-weighted images (DWI) and classified voxels as 'definitely abnormal,' 'possibly abnormal' or normal on DWI appearance, and 'mismatch' for voxels in DWI/PWI mismatch areas. The authors compared metabolite (NAA, lactate), perfusion and apparent diffusion coefficient (ADC) values in each voxel type.
NAA differentiated 'definitely' from 'possibly abnormal,' and 'possibly abnormal' from 'mismatch' (both comparisons p<0.01) voxels, but not 'mismatch' from 'normal' voxels. Lactate was highest in 'definitely abnormal,' and progressively lower in 'possibly abnormal,' 'mismatch,' than 'normal' voxels (all differences p<0.01). There was no correlation between NAA and ADC or PWI values, but high lactate correlated with low ADC (Spearman r=-0.41, p=0.02) and prolonged mean transit time (Spearman r=0.42, p=0.02).
ADC and mean transit time indicate the presence of ischaemia (lactate) but not cumulative total neuronal damage (NAA) in acute ischaemic stroke, suggesting that caution is required if using ADC and PWI parameters to differentiate salvageable from non-salvageable tissue. Further refinement of the DWI/PWI concept is required prior to more widespread use.
Journal of neurology, neurosurgery, and psychiatry 08/2009; 81(2):185-91. · 4.87 Impact Factor
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ABSTRACT: Early after acute ischaemic stroke, elevation of brain temperature might augment tissue metabolic rate and conversion of ischaemic but viable tissue to infarction. This might explain the observed link between pyrexia, severe stroke and poor outcome. We tested this hypothesis by measuring brain temperature and lactate concentration with multi-voxel magnetic resonance spectroscopic imaging across the acute ischaemic stroke lesion and normal brain as determined on diffusion imaging. We compared patterns of lactate concentration (reported in 'institutional units') and temperature elevation in diffusion lesion core, potential penumbra, ipsilateral and contralateral normal brain and with stroke severity. Amongst 40 patients with moderate to severe acute stroke imaged up to 26 h after onset, lactate concentration was highest in the ischaemic lesion core (42 versus 26 units in potential penumbra, P < 0.05), whereas temperature was highest in the potential penumbra (37.7 versus 37.3 degrees C in lesion core, P < 0.05). Neither sub-regional temperature nor lactate concentration correlated with stroke severity. With increasing time after stroke, ipsilateral brain temperature did not change, but contralateral hemisphere temperature was higher in patients scanned at later times; lactate remained elevated in the lesion core, but declined in potential penumbral and ipsilateral normal tissue at later times. We conclude that early brain temperature elevation after stroke is not directly related to lactate concentration, therefore augmented metabolism is unlikely to explain the relationship between early pyrexia, severe stroke and poor outcome. Early brain temperature elevation may result from different mechanisms to those which raise body temperature after stroke. Further studies are required to determine why early brain temperature elevation is highest in potential penumbral tissue.
Brain 04/2009; 132(Pt 4):955-64. · 9.46 Impact Factor
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ABSTRACT: In acute ischemic stroke, the amount of neuronal damage in hyperintense areas on MR diffusion imaging (DWI) is unclear. We used spectroscopic imaging to measure N-acetyl aspartate (NAA, a marker of normal neurons) and lactate (a marker of ischemia) to compare with diffusion and perfusion values in the diffusion lesion in acute ischemic stroke.
We recruited patients with acute ischemic stroke prospectively and performed MR diffusion weighted (DWI), perfusion, and spectroscopic imaging. We coregistered the images, outlined the visible diffusion lesion, and extracted metabolite, perfusion, and apparent diffusion coefficient (ADC) values from the diffusion lesion.
42 patients were imaged, from 1.5 to 24 hours after stroke. In the DWI lesion, although NAA was reduced, there was no correlation between NAA and ADC or perfusion values. However, raised lactate correlated with reduced ADC (Spearman rho=0.32, P=0.04) and prolonged mean transit time (MTT, rho=0.31, P=0.04). Increasing DWI lesion size was associated with lower NAA and higher lactate (rho=-0.44, P=0.003; rho=0.49, P=0.001 respectively); NAA fell with increasing times to imaging (rho=-0.3, P=0.03), but lactate did not change.
Although larger confirmatory studies are needed, the correlation of ADC and MTT with lactate but not NAA suggests that ADC and MTT are better markers of the presence of ischemia than of cumulative neuronal loss. Further studies should define more precisely the rate of neuronal loss and relationship to diffusion and perfusion parameters with respect to the depth and duration of ischemia.
Stroke 02/2009; 40(3):767-72. · 5.73 Impact Factor
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ABSTRACT: Choline and creatine are commonly used as denominators for other metabolites in ischemic stroke spectroscopy, assuming that they do not change. We investigated their concentration variation over time after stroke.
Choline and creatine concentrations were measured by proton MR spectroscopic imaging in 51 patients at 5 times up to 3 months after stroke.
Choline and creatine levels changed significantly in the ischemic region. Choline was significantly reduced during the first 2 weeks after stroke onset (P=0.034). Creatine was significantly reduced during the whole period of the study (P=0.011).
Choline and creatine concentrations are not reliable denominators for metabolite ratios in acute stroke because their levels vary significantly in ischemic brain regions.
Stroke 08/2008; 39(9):2467-9. · 5.73 Impact Factor
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ABSTRACT: We determined the reproducibility of GABA (gamma-aminobutyric acid) measurements using 2D J-resolved magnetic resonance spectroscopy (MRS) on a clinical 1.5-T MR imaging scanner. Two-dimensional J-resolved spectra were acquired in vitro across five GABA concentrations using a volume head coil and a 5-in. surface coil. Additional spectra using a sixth GABA phantom with a very low concentration and from a healthy volunteer were recorded in the 5-in. surface coil only. In each case, the 3.01-ppm GABA resonance was quantified; for comparison, the peak integrals of choline (3.2 ppm) and creatine (3.03 ppm) were recorded. At a physiological concentration (1.2 mM), in vitro GABA measurement was significantly more reproducible in the surface coil than in the volume coil (P=.005), with coefficients of variation (CVs) being less than 16% with the surface coil and up to 68% with the volume head coil. At the smallest concentration of in vivo GABA reported using other spectroscopy techniques (0.8 mM) and detected only using the surface coil, the CV for GABA was 23% and was less than 10% for choline and creatine, which compare favorably with results from published studies. In vivo, the CV for GABA measurement was 26%, suggesting that 2D J-resolved MRS would be suitable for detecting physiological changes in GABA, similar to those reported using other methods.
Magnetic Resonance Imaging 07/2007; 25(5):634-40. · 1.99 Impact Factor
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ABSTRACT: Pyrexia is associated with poor outcome after stroke, but the temperature changes in the brain after stroke are poorly understood. We used magnetic resonance spectroscopic imaging (water-to-N-acetylaspartate frequency shift) to measure cerebral temperature noninvasively in stroke patients.
We performed magnetic resonance diffusion, perfusion (diffusion- and perfusion-weighted imaging), and magnetic resonance spectroscopic imaging, compared temperatures in tissues as defined by the diffusion-weighted imaging appearance (definitely abnormal, possibly abnormal and immediately adjacent normal-appearing brain, and normal brain), and tested associations with lesion and patient characteristics.
Among 40 patients, temperature was higher in possibly abnormal (37.63 degrees C) than in definitely abnormal tissue (37.30 degrees C; p < 0.001) or in normal-appearing brain (ipsilateral, 37.16 degrees C; contralateral, 37.22 degrees C; both p < 0.001). Ischemic lesion temperature increased before normal brain temperature. Higher temperatures occurred in lesions that were large, had diffusion/perfusion-weighted imaging mismatch, had reduced cerebral blood flow, and in clinically severe strokes. Only 1 of 25 patients with ischemic lesion temperature greater than 37.5 degrees C was pyrexial.
Temperature is elevated in acutely ischemic brain. More work is required to determine whether raised temperature results from ischemic metabolic reactions, impaired heat exchange from reduced cerebral blood flow, or early inflammatory cell activity (or a combination of these), but magnetic resonance spectroscopic imaging could be used in studies of temperature after brain injury and to monitor interventions.
Annals of Neurology 11/2006; 60(4):438-46. · 11.09 Impact Factor
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ABSTRACT: Verbal declarative memory is a core deficit in schizophrenia patients, seen to a lesser extent in unaffected biological relatives. Neuroimaging studies suggest volumetric differences and aberrant function in prefrontal and temporal regions in schizophrenia patients compared to controls. These deficits are also reflected in the small number of similar investigations in unaffected biological relatives. However, it is unclear the extent to which dysfunction is genetically mediated or a feature of the established illness.
Event-related blood-oxygen-level-dependent (BOLD) functional magnetic resonance imaging (fMRI) was used to measure brain activation in 68 biological relatives of schizophrenia patients (of whom 27 experienced transient or isolated psychotic symptoms) and 21 controls during verbal classification and recognition.
During word classification, the high-risk group showed a greater response relative to controls in the right inferior frontal gyrus. During correct recognition (relative to correct rejection), the high-risk group showed significantly greater response relative to controls in the right cerebellum. When the high-risk group was split into those with (HR+) and without (HR-) psychotic symptoms, the increased response in the right inferior frontal gyrus was only seen when the HR+ were compared to controls. The greater cerebellar response was seen when both HR groups were compared to controls.
Activation increases in the right inferior frontal gyrus and cerebellum in high-risk subjects compared to controls during a relatively low-load memory task are likely to represent compensation for genetically mediated abnormalities. This is consistent with a leftward shift of the inverted 'U' load-response model of cognitive function in schizophrenia.
Psychological Medicine 11/2006; 36(10):1427-39. · 6.16 Impact Factor
