Quantitative <sup>1</sup>H spectroscopic imaging of human brain at 4.1 T using image segmentation

Hetherington, Hoby P.; Pan, Jullie W.; Mason, Graeme F.; Adams, David S.; Vaughn, Michael J.; Twieg, Donald B.; Pohost, Gerald M.

doi:10.1002/mrm.1910360106

Cited by 197 publications

(213 citation statements)

References 29 publications

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“…Quantitative large single voxel measurements from occipital gray matter and parietal white matter (24,25) demonstrated tissue differences between white and gray matter contents of creatine (Cr) (6.3, 8.3 mM), N-acetyl aspartate (NAA) (10.3, 10.7 mM), and choline (1.8, 1.5 mM). This was subsequently confirmed in spectroscopic imaging studies using 0.5 mL volumes at 4T and image segmentation (26), reporting values for Cr (6.1, 8.2), NAA (10.5, 9.7 mM), and choline (1.5, 1.5 mM). Based upon these observations, it became clear that tissue heterogeneity could be a limiting factor in the identification of metabolically altered regions.…”

Section: H Spectroscopic Lateralization Of Epileptogenic Regions and mentioning

confidence: 56%

“…Although these methods are most commonly used in global pathologies to identify gray or white matter specific alterations in comparison to control subjects (27,28), they can also be employed on a voxel-by-voxel basis within subjects (26,29). Using segmented anatomical images, the gray and white matter content of each spectroscopic imaging voxel can be determined.…”

Section: H Spectroscopic Lateralization Of Epileptogenic Regions and mentioning

confidence: 99%

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¹H and ³¹P spectroscopy and bioenergetics in the lateralization of seizures in temporal lobe epilepsy

Hetherington

Pan

Spencer

2002

Magnetic Resonance Imaging

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Over the past decade, 1 H and 31 P spectroscopy measurements have demonstrated that significant metabolic alterations occur in temporal lobe epilepsy. However, to most accurately interpret these changes, metabolic heterogeneity and differences between gray and white matter must be accounted for. These alterations, decreased NAA and the ratio of phosphocreatine/inorganic phosphate, can be reversed with successful treatment of seizures. The reversibility of these two measures is consistent with the localization of NAA synthesis to neuronal mitochondria and the important role for bioenergetics in the pathophysiology of temporal lobe epilepsy.

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Section: H Spectroscopic Lateralization Of Epileptogenic Regions and mentioning

confidence: 56%

Section: H Spectroscopic Lateralization Of Epileptogenic Regions and mentioning

confidence: 99%

¹H and ³¹P spectroscopy and bioenergetics in the lateralization of seizures in temporal lobe epilepsy

Hetherington

Pan

Spencer

2002

Magnetic Resonance Imaging

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“…The reported white vs. gray matter metabolite concentrations, in various brain regions, differ by 5-47% (mean ϭ 18.6%) for NAA, 10 -86% (mean ϭ 39.7%) for Cr, and 0 -35% (mean ϭ 16.3%) for Cho (11,15,22,23). Therefore, if a 30% change in common volume altered a voxel's white/gray-matter fractions proportionally, its metabolite levels could vary by up to 14% for NAA, 26% for Cr, and 11% for Cho.…”

Section: Probable Source Of the In Vivo Variationsmentioning

confidence: 97%

Reproducibility of 3D proton spectroscopy in the human brain

Babb

Soher

et al. 2002

Magnetic Resonance in Med

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The inter-and intrasubject reproducibility of the metabolite levels of N-acetylaspartate (NAA), creatine (Cr), and choline (Cho), obtained with three-dimensional (3D) multivoxel proton spectroscopy ( 1 H-MRS), was analyzed in eight healthy volunteers. Serial, back-to-back measurements on a phantom showed the methodology and instrumentation to be highly reproducible, with a median coefficient of variation (CV) of 3.8%. In the human brain, the metabolite levels' variability was larger, with intrasubject median CVs for a total of 1876 signal voxels of 13.8%, 18.5%, and 20.1% for NAA, Cr, and Cho, respectively. These variations possibly arise from small, unavoidable, ؎1-2 mm volume-of-interest (VOI) repositioning uncertainties, which vary each 0.75-cm 3 voxel's partial fluid/gray/white-matter fractions. Comparing the CVs between eight subjects in a total of 324 selected voxels gave total interindividual CVs of 15.6%, 23.3%, and 24.4%, compared with intraindividual CVs in the same voxels of 14.4%, 14.8%, and 15.3%, for NAA, Cr, and Cho, respectively. Replacing the signal(s) from each voxel by the average of itself with its six canonical neighbors reduces the intrasubject median CVs to 8.3%, 9.5%, and 9.7%. The measurement uncertainties can be reduced at a cost of either spatial resolution (by using larger voxels Key words: absolute quantification; brain; multivoxel localization; proton spectroscopy; reproducibility 1 H-MRS frequently augments MRI in studies of focal as well as diffuse brain pathologies, e.g., for multiple sclerosis (MS), cancer, AIDS, trauma, Alzheimer's disease (AD), and stroke (1). Due to the progressive nature of these disorders, MRS is usually performed serially, over time, to assess the disease's advance or its response to treatment. The evaluation of the MRS data is based primarily on the comparison of either relative or absolute levels of the three major 1 H-MRS-observable metabolites: NAA, Cr, and Cho, in regions of suspected pathology, with corresponding healthy ones. Reported metabolite variations in these diseases range between 10 -20% for HIV infection and focal epilepsy to upwards of 30% in MS and AD (1).However, to objectively evaluate the significance of such changes, it is necessary to establish how reproducible the measured metabolite levels are in normal controls, both cross-sectionally and temporally. Only then, when changes in suspected region(s) in a patient are significant compared with these normal variations, can one be confident that they represent true pathology and not normal biological fluctuations or intrinsic errors of the instrumentation and method(s).To address the reproducibility issues, we conducted a study to identify and quantify the: 1) stability of the machine and the methodology, using back-to-back measurements on a phantom; 2) intraindividual temporal variations in the brain of a volunteer; and 3) interindividual variations across a cohort of healthy subjects. Previous studies on this topic mostly employed single-voxel MRS techniques (2-5), and more recently, s...

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“…The exact tissue composition of each voxel was determined from T 1 -based image segmentation maps according to a previously described protocol (Hetherington et al, 1996). In short, quantitative T 1 relaxation maps were generated for 15 consecutive slices (1.5-mm slice thickness) by nonselectively inverting the longitudinal magnetization and sampling the recovery to thermal equilibrium by slice-selective, low-angle (∼20°) excitation at seven recovery times given by (30 + n.282) millisecond, with 0 Յ n Յ 6.…”

Section: Magnetic Resonance Imaging and Spectroscopymentioning

confidence: 99%

Differentiation of Glucose Transport in Human Brain Gray and White Matter

Graaf

Pan

Telang

et al. 2001

J Cereb Blood Flow Metab

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Summary:Localized 1 H nuclear magnetic resonance spectroscopy has been applied to determine human brain gray matter and white matter glucose transport kinetics by measuring the steady-state glucose concentration under normoglycemia and two levels of hyperglycemia. Nuclear magnetic resonance spectroscopic measurements were simultaneously performed on three 12-mL volumes, containing predominantly gray or white matter. The exact volume compositions were determined from quantitative T 1 relaxation magnetic resonance images. The absolute brain glucose concentration as a function of the plasma glucose level was fitted with two kinetic transport models, based on standard (irreversible) or reversible MichaelisMenten kinetics. The steady-state brain glucose levels were similar for cerebral gray and white matter, although the white matter levels were consistently 15% to 20% higher. The ratio of the maximum glucose transport rate, V max , to the cerebral metabolic utilization rate of glucose, CMR Glc , was 3.2 ± 0.10 and 3.9 ± 0.15 for gray matter and white matter using the standard transport model and 1.8 ± 0.10 and 2.2 ± 0.12 for gray matter and white matter using the reversible transport model. The Michaelis-Menten constant K m was 6.2 ± 0.85 and 7.3 ± 1.1 mmol/L for gray matter and white matter in the standard model and 1.1 ± 0.66 and 1.7 ± 0.88 mmol/L in the reversible model. Taking into account the threefold lower rate of CMR Glc in white matter, this finding suggests that blood-brain barrier glucose transport activity is lower by a similar amount in white matter. The regulation of glucose transport activity at the blood-brain barrier may be an important mechanism for maintaining glucose homeostasis throughout the cerebral cortex.

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Quantitative ¹H spectroscopic imaging of human brain at 4.1 T using image segmentation

Cited by 197 publications

References 29 publications

¹H and ³¹P spectroscopy and bioenergetics in the lateralization of seizures in temporal lobe epilepsy

¹H and ³¹P spectroscopy and bioenergetics in the lateralization of seizures in temporal lobe epilepsy

Reproducibility of 3D proton spectroscopy in the human brain

Differentiation of Glucose Transport in Human Brain Gray and White Matter

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Quantitative 1H spectroscopic imaging of human brain at 4.1 T using image segmentation

Cited by 197 publications

References 29 publications

1H and 31P spectroscopy and bioenergetics in the lateralization of seizures in temporal lobe epilepsy

1H and 31P spectroscopy and bioenergetics in the lateralization of seizures in temporal lobe epilepsy

Reproducibility of 3D proton spectroscopy in the human brain

Differentiation of Glucose Transport in Human Brain Gray and White Matter

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Quantitative ¹H spectroscopic imaging of human brain at 4.1 T using image segmentation

¹H and ³¹P spectroscopy and bioenergetics in the lateralization of seizures in temporal lobe epilepsy

¹H and ³¹P spectroscopy and bioenergetics in the lateralization of seizures in temporal lobe epilepsy