E. Ratai | Harvard Medical School (original) (raw)

Papers by E. Ratai

E-M. Ratai, C-G. Joo, J. Bombardier, J. He, L. Annamalai, T. H. Burdo, J. H. Campbell, C. Soulas,... more E-M. Ratai, C-G. Joo, J. Bombardier, J. He, L. Annamalai, T. H. Burdo, J. H. Campbell, C. Soulas, P. Autissier, S. V. Westmoreland, K. Williams, and R. G. Gonzalez Radiology, Massachusetts General Hospital A.A. Martinos Center for Biomedical Imaging, Charlestown, MA, United States, New England Regional Primate Research Center, Southborough, MA, United States, Biology Department, Boston College, Boston, MA, United States

E-M. Ratai, N. Atassi, S. Wallace, J. Bombardier, D. Greenblatt, M. Cudkowicz, and A. Dibernardo ... more E-M. Ratai, N. Atassi, S. Wallace, J. Bombardier, D. Greenblatt, M. Cudkowicz, and A. Dibernardo Department of Radiology, A. A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, United States, Harvard Medical School, Boston, MA, United States, Neurology, Massachusetts General Hospital, Charlestown, MA, United States, Psychiatry, Massachusetts General Hospital, Charlestown, MA, United States, Pharmacology & Experimental Therapeutics, Tufts University School of Medicine, Boston, MA, United States

INTRODUCTION Proton magnetic resonance spectroscopy (H-MRS) is increasingly used in clinical stud... more INTRODUCTION Proton magnetic resonance spectroscopy (H-MRS) is increasingly used in clinical studies of brain tumor to provide information about tissue metabolic profiles. It shows clear differences between the spectral profiles of brain tumor and normal tissues. This study investigated early changes in predominant metabolites for predicting tumor responses to an anti-angiogenic treatment in recurrent malignant glioblastoma (rGBM). PATIENTS and METHODS Thirty-one patients with rGBM treated with daily cycles of cediranib (45mg oral dose) were studied [1]. The patients were scanned using a 3T Siemens MRI scanner at different time points throughout the course of their treatment. In this study, we focused on the metabolic changes at the early post-treatment time points (i.e days 1, 28, 56) because early indications of therapeutic outcome provide a better opportunity to optimize therapeutic intervention and improve survival. Chemical Shift Imaging, multi-voxel MRS, using a PRESS sequence...

H. Kim, C. Catana, E-M. Ratai, W-T. Zhang, P. Yeo, O. C. Andronesi, T. T. Batchelor, R. K. Jain, ... more H. Kim, C. Catana, E-M. Ratai, W-T. Zhang, P. Yeo, O. C. Andronesi, T. T. Batchelor, R. K. Jain, and A. G. Sorensen NSE/HST, Massachusetts Institute of Technology, Cambridge, MA, United States, Radiology, Massachusetts General Hospital, Boston, MA, United States, Neurology, Massachusetts General Hospital, Boston, MA, United States, Radiation Oncology, Massachusetts General Hospital, Boston, MA, United States

E-M. Ratai, S. Pilkenton, J. Bombardier, C-G. Joo, K. W. Turk, M. R. Lentz, J. He, L. Annamalai, ... more E-M. Ratai, S. Pilkenton, J. Bombardier, C-G. Joo, K. W. Turk, M. R. Lentz, J. He, L. Annamalai, S. O' Neil, S. V. Westmoreland, T. H. Burdo, J. H. Campbell, C. Soulas, P. Autissier, W-K. Kim, K. Williams, and R. G. Gonzalez Radiology, Massachusetts General Hospital A.A. Martinos Center for Biomedical Imaging, Charlestown, MA, United States, Harvard Medical School, Boston, MA, United States, New England Regional Primate Research Center, Southborough, MA, United States, Biology Department, Boston College, Boston, MA, United States, Eastern Virginia Medical School, Norfolk, VA, United States

J. P. Bombardier, E-M. Ratai, C. Joo, J. D. Lifson, M. Piatak, Jr, E. Halpern, S. V. Westmoreland... more J. P. Bombardier, E-M. Ratai, C. Joo, J. D. Lifson, M. Piatak, Jr, E. Halpern, S. V. Westmoreland, L. Annamalai, K. Williams, and R. G. Gonzalez Radiology, Massachusetts General Hospital, Charlestown, MA, United States, Radiology, Harvard Medical School, Charlestown, MA, United States, AIDS and Cancer Virus Program, SAIC-Frederick, National Cancer Institute, Frederick, MD, United States, New England regional Primate Research Center, Harvard Medical School, Southborough, MA, United States, Biology, Boston College, Chestnut Hill, MA, United States

E-M. Ratai, J. Bombardier, C-G. Joo, J. He, L. Annamalai, S. V. Westmoreland, T. H. Burdo, J. H. ... more E-M. Ratai, J. Bombardier, C-G. Joo, J. He, L. Annamalai, S. V. Westmoreland, T. H. Burdo, J. H. Campbell, C. Soulas, K. Williams, and R. G. Gonzalez Radiology, Massachusetts General Hospital A.A. Martinos Center for Biomedical Imaging, Charlestown, MA, United States, New England Regional Primate Research Center, Southborough, MA, United States, Biology Department, Boston College, Boston, MA, United States

SummaryBackgroundThe impact of COVID-19 on human health extends beyond the morbidity and death to... more SummaryBackgroundThe impact of COVID-19 on human health extends beyond the morbidity and death toll directly caused by the SARS-CoV-2 virus. In fact, accumulating evidence indicates a global increase in the incidence of fatigue, brain fog and depression, including among non-infected, since the pandemic onset. Motivated by previous evidence linking those symptoms to neuroimmune activation in other pathological contexts, we hypothesized that subjects examined after the enforcement of lockdown/stay-at-home measures would demonstrate increased neuroinflammation.MethodsWe performed simultaneous brain Positron Emission Tomography / Magnetic Resonance Imaging in healthy volunteers either before (n=57) or after (n=15) the 2020 Massachusetts lockdown, using [11C]PBR28, a radioligand for the glial marker 18 kDa translocator protein (TSPO). First, we compared [11C]PBR28 signal across pre- and post-lockdown cohorts. Then, we evaluated the link between neuroinflammatory signals and scores on a q...

Background: Type 2 diabetes mellitus is known to be associated with neurobiological and cognitive... more Background: Type 2 diabetes mellitus is known to be associated with neurobiological and cognitive deficits; however, their extent, overlap with aging effects, and the effectiveness of existing treatments in the context of the brain are currently unknown. Methods: We characterized neurocognitive effects independently associated with T2DM and age in a large cohort of human subjects from the UK Biobank with cross-sectional neuroimaging and cognitive data. We then proceeded to evaluate the extent of overlap between the effects related to T2DM and age by applying correlation measures to the separately characterized neurocognitive changes. Our findings were complemented by meta-analyses of published reports with cognitive or neuroimaging measures for T2DM and healthy controls (HC). We also evaluated in a cohort of T2DM diagnosed individuals using UK Biobank how disease chronicity and metformin treatment interact with the identified neurocognitive effects. Results: The UK Biobank dataset i...

American Journal of Neuroradiology, 2020

Brain multivoxel MR spectroscopic imaging was performed in 3 consecutive patients with coronaviru... more Brain multivoxel MR spectroscopic imaging was performed in 3 consecutive patients with coronavirus disease 2019 (COVID-19). These included 1 patient with COVID-19-associated necrotizing leukoencephalopathy, another patient who had a recent pulseless electrical activity cardiac arrest with subtle white matter changes, and a patient without frank encephalopathy or a recent severe hypoxic episode. The MR spectroscopic imaging findings were compared with those of 2 patients with white matter pathology not related to Severe Acute Respiratory Syndrome coronavirus 2 infection and a healthy control subject. The NAA reduction, choline elevation, and glutamate/glutamine elevation found in the patient with COVID-19-associated necrotizing leukoencephalopathy and, to a lesser degree, the patient with COVID-19 postcardiac arrest, follow a similar pattern as seen with the patient with delayed posthypoxic leukoencephalopathy. Lactate elevation was most pronounced in the patient with COVID-19 necrotizing leukoencephalopathy.

Proceedings of the National Academy of Sciences, 2020

Epidemiological studies suggest that insulin resistance accelerates progression of age-based cogn... more Epidemiological studies suggest that insulin resistance accelerates progression of age-based cognitive impairment, which neuroimaging has linked to brain glucose hypometabolism. As cellular inputs, ketones increase Gibbs free energy change for ATP by 27% compared to glucose. Here we test whether dietary changes are capable of modulating sustained functional communication between brain regions (network stability) by changing their predominant dietary fuel from glucose to ketones. We first established network stability as a biomarker for brain aging using two large-scale ( n = 292, ages 20 to 85 y; n = 636, ages 18 to 88 y) 3 T functional MRI (fMRI) datasets. To determine whether diet can influence brain network stability, we additionally scanned 42 adults, age < 50 y, using ultrahigh-field (7 T) ultrafast (802 ms) fMRI optimized for single-participant-level detection sensitivity. One cohort was scanned under standard diet, overnight fasting, and ketogenic diet conditions. To isola...

Magnetic Resonance Imaging Clinics of North America, 2016

Magnetic resonance spectroscopy (MRS) is a magnetic resonance-based imaging modality that allows ... more Magnetic resonance spectroscopy (MRS) is a magnetic resonance-based imaging modality that allows noninvasive sampling of metabolic changes in normal and abnormal brain parenchyma. MRS is particularly useful in the differentiation of developmental or non-neoplastic disorders from neoplastic processes. MRS is also useful during routine imaging follow-up after radiation treatment or during antiangiogenic treatment and for predicting outcomes and treatment response. The objective of this article is to provide a concise but thorough review of the basic physical principles, important applications of MRS in brain tumor imaging, and future directions.

Physics and Chemistry of Glasses

During the past 40 years, solid state NMR has provided immensely detailed information on the stru... more During the past 40 years, solid state NMR has provided immensely detailed information on the structural organisation of alkali borate glasses. While early wideline NMR work concentrated on the structural speciation of boron in the network, more recent high resolution and double resonance studies have provided more intricate detail on the location and the spatial distribution of the alkali ions. In particular, this work has provided some insights into the structural origins of the mixed alkali effect. The present contribution attempts to summarise the current state of knowledge, including the unresolved issues in the structural description of single and mixed alkali borate glasses.

Background: Growing documentation of metabolic alterations in autism increases the need to charac... more Background: Growing documentation of metabolic alterations in autism increases the need to characterize metabolism in brain tissue. Magnetic Resonance Spectroscopy (MRS) is constrained by the impossibility of performing whole brain acquisitions and the need to place localized voxels, as well as the impact of acquisition protocols on findings. Literature review can contribute to well-targeted choice of future research design. Objectives: To consider the potentiality of MRS for measuring metabolites pertinent to emerging metabolic findings in ASD and from this vantage point to produce a systematic and critical overview of MRS investigations in ASD to date. Methods: PubMed was searched for papers on MRS in ASD as well as brain metabolites. Relevant papers were reviewed and tabulated based upon regions of interest, absolute metabolite concentrations and/or ratios in each region studied, field strength, repetition time (TR) and time to echo (TE), subject characteristics (age, gender, dia...

Background: The tissue nature of brain enlargement in young autistic subjects has not yet been cl... more Background: The tissue nature of brain enlargement in young autistic subjects has not yet been clearly established. Published findings do not support an increase in neuronal density in gray matter or the attribution of white matter enlargement to an increase in myelinated fibers. Given the growing documentation of metabolic findings in autism, these brain changes need to be investigated using techniques sensitive to metabolites. Frontal and prefrontal white matter enlargement is particularly prominent and its metabolic underpinnings need to be targeted using magnetic resonance spectroscopy (MRS) methods. Objectives: To investigate metabolic alterations in ASD brain tissue collected using single voxel spectroscopy and chemical shift imaging. Methods: Proton magnetic resonance spectroscopy was performed with a 3T Siemens scanner on age matched typically developing and children with Autism Spectrum Disorders (6-13 year olds). Single Voxel Spectroscopy (SVS) was acquired with the voxel ...

HIV medicine, Jan 17, 2015

As ∼40% of HIV-infected individuals experience neurocognitive decline, we investigated whether pr... more As ∼40% of HIV-infected individuals experience neurocognitive decline, we investigated whether proton magnetic resonance spectroscopic imaging ((1) H-MRSI) detects early metabolic abnormalities in the cerebral cortex of a simian immunodeficiency virus (SIV)-infected rhesus monkey model of neuroAIDS. The brains of five rhesus monkeys before and 4 or 6 weeks after SIV infection (with CD8(+) T-cell depletion) were assessed with T2 -weighted quantitative magnetic resonance imaging (MRI) and 16×16×4 multivoxel (1) H-MRSI (echo time/repetition time = 33/1440 ms). Grey matter and white matter masks were segmented from the animal MRIs and used to produce cortical masks co-registered to (1) H-MRSI data to yield cortical metabolite concentrations of the glial markers myo-inositol (mI), creatine (Cr) and choline (Cho), and of the neuronal marker N-acetylaspartate (NAA). The cortex volume within the large, 28 cm(3) (∼35% of total monkey brain) volume of interest was also calculated for each ani...

Defect and Diffusion Forum, 2001

Stroke, 2007

Background and Purpose— Recent studies suggest that normobaric oxygen therapy (NBO) is neuroprote... more Background and Purpose— Recent studies suggest that normobaric oxygen therapy (NBO) is neuroprotective in acute ischemic stroke. Methods— We performed multivoxel magnetic resonance spectroscopic imaging and diffusion/perfusion MRI in patients with stroke treated with NBO or room air. Imaging was performed before, during, and after therapy. Results— Voxel-based analysis showed excellent correlation between apparent diffusion coefficient values, lactate, and N -acetyl-aspartate levels at all time points. Lactate decreased during NBO and increased post-NBO. N -acetyl-aspartate decreased in patients receiving room air but not in NBO-treated patients. Conclusion— These data suggest that NBO improves aerobic metabolism and preserves neuronal integrity in the ischemic brain.

Solid State Ionics, 1998

The structural environments and the spatial distributions of the alkali ions in single-and mixed-... more The structural environments and the spatial distributions of the alkali ions in single-and mixed-alkali borate glasses are studied by complementary solid state NMR techniques. Specifically, spin echo decay spectroscopy is used to extract 23 133 homodipolar second moments for Na and Cs in binary sodium and cesium borate glasses. These values are found to be quantitatively most consistent with spatially homogeneous cation distributions, except in sodium borate glasses with cation contents #16 mole %. Complementary isotropic chemical shifts extracted from field-dependent magic-angle spinning (MAS)-NMR depend linearly on alkali ion content, revealing a continuous concomitant change in the oxygen environment of the alkali ions. This effect can be related to structural changes in the network, where trigonal BO units are 3 / 2 2 progressively converted to tetrahedral BO sites as the alkali oxide content is increased. Taken together these data argue 4 / 2 7 2 3 strongly against cation clustering models previously proposed for other types of glass systems. Isotropic Li and Na chemical shift data measured for mixed-alkali Li,Na and K,Na-borate glasses containing 30 mole % alkali oxide indicate universal compositional trends that can be understood in terms of the site-mismatch concept of Bunde's dynamic structure 1 model: Consistent with current semi-empirical predictions, mismatching the cation of interest, e.g. Na to a smaller Li site 23 produces a low-frequency shift, while mismatching to a larger K site produces high-frequency Na isotropic chemical shifts.

Science Translational Medicine, 2010

Magnetic resonance spectroscopy can generate comprehensive maps of metabolites in the prostate th... more Magnetic resonance spectroscopy can generate comprehensive maps of metabolites in the prostate that reveal cancerous regions, potentially guiding biopsies and prognosis.

E-M. Ratai, C-G. Joo, J. Bombardier, J. He, L. Annamalai, T. H. Burdo, J. H. Campbell, C. Soulas,... more E-M. Ratai, C-G. Joo, J. Bombardier, J. He, L. Annamalai, T. H. Burdo, J. H. Campbell, C. Soulas, P. Autissier, S. V. Westmoreland, K. Williams, and R. G. Gonzalez Radiology, Massachusetts General Hospital A.A. Martinos Center for Biomedical Imaging, Charlestown, MA, United States, New England Regional Primate Research Center, Southborough, MA, United States, Biology Department, Boston College, Boston, MA, United States

E-M. Ratai, N. Atassi, S. Wallace, J. Bombardier, D. Greenblatt, M. Cudkowicz, and A. Dibernardo ... more E-M. Ratai, N. Atassi, S. Wallace, J. Bombardier, D. Greenblatt, M. Cudkowicz, and A. Dibernardo Department of Radiology, A. A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, United States, Harvard Medical School, Boston, MA, United States, Neurology, Massachusetts General Hospital, Charlestown, MA, United States, Psychiatry, Massachusetts General Hospital, Charlestown, MA, United States, Pharmacology & Experimental Therapeutics, Tufts University School of Medicine, Boston, MA, United States

INTRODUCTION Proton magnetic resonance spectroscopy (H-MRS) is increasingly used in clinical stud... more INTRODUCTION Proton magnetic resonance spectroscopy (H-MRS) is increasingly used in clinical studies of brain tumor to provide information about tissue metabolic profiles. It shows clear differences between the spectral profiles of brain tumor and normal tissues. This study investigated early changes in predominant metabolites for predicting tumor responses to an anti-angiogenic treatment in recurrent malignant glioblastoma (rGBM). PATIENTS and METHODS Thirty-one patients with rGBM treated with daily cycles of cediranib (45mg oral dose) were studied [1]. The patients were scanned using a 3T Siemens MRI scanner at different time points throughout the course of their treatment. In this study, we focused on the metabolic changes at the early post-treatment time points (i.e days 1, 28, 56) because early indications of therapeutic outcome provide a better opportunity to optimize therapeutic intervention and improve survival. Chemical Shift Imaging, multi-voxel MRS, using a PRESS sequence...

H. Kim, C. Catana, E-M. Ratai, W-T. Zhang, P. Yeo, O. C. Andronesi, T. T. Batchelor, R. K. Jain, ... more H. Kim, C. Catana, E-M. Ratai, W-T. Zhang, P. Yeo, O. C. Andronesi, T. T. Batchelor, R. K. Jain, and A. G. Sorensen NSE/HST, Massachusetts Institute of Technology, Cambridge, MA, United States, Radiology, Massachusetts General Hospital, Boston, MA, United States, Neurology, Massachusetts General Hospital, Boston, MA, United States, Radiation Oncology, Massachusetts General Hospital, Boston, MA, United States

E-M. Ratai, S. Pilkenton, J. Bombardier, C-G. Joo, K. W. Turk, M. R. Lentz, J. He, L. Annamalai, ... more E-M. Ratai, S. Pilkenton, J. Bombardier, C-G. Joo, K. W. Turk, M. R. Lentz, J. He, L. Annamalai, S. O' Neil, S. V. Westmoreland, T. H. Burdo, J. H. Campbell, C. Soulas, P. Autissier, W-K. Kim, K. Williams, and R. G. Gonzalez Radiology, Massachusetts General Hospital A.A. Martinos Center for Biomedical Imaging, Charlestown, MA, United States, Harvard Medical School, Boston, MA, United States, New England Regional Primate Research Center, Southborough, MA, United States, Biology Department, Boston College, Boston, MA, United States, Eastern Virginia Medical School, Norfolk, VA, United States

J. P. Bombardier, E-M. Ratai, C. Joo, J. D. Lifson, M. Piatak, Jr, E. Halpern, S. V. Westmoreland... more J. P. Bombardier, E-M. Ratai, C. Joo, J. D. Lifson, M. Piatak, Jr, E. Halpern, S. V. Westmoreland, L. Annamalai, K. Williams, and R. G. Gonzalez Radiology, Massachusetts General Hospital, Charlestown, MA, United States, Radiology, Harvard Medical School, Charlestown, MA, United States, AIDS and Cancer Virus Program, SAIC-Frederick, National Cancer Institute, Frederick, MD, United States, New England regional Primate Research Center, Harvard Medical School, Southborough, MA, United States, Biology, Boston College, Chestnut Hill, MA, United States

E-M. Ratai, J. Bombardier, C-G. Joo, J. He, L. Annamalai, S. V. Westmoreland, T. H. Burdo, J. H. ... more E-M. Ratai, J. Bombardier, C-G. Joo, J. He, L. Annamalai, S. V. Westmoreland, T. H. Burdo, J. H. Campbell, C. Soulas, K. Williams, and R. G. Gonzalez Radiology, Massachusetts General Hospital A.A. Martinos Center for Biomedical Imaging, Charlestown, MA, United States, New England Regional Primate Research Center, Southborough, MA, United States, Biology Department, Boston College, Boston, MA, United States

SummaryBackgroundThe impact of COVID-19 on human health extends beyond the morbidity and death to... more SummaryBackgroundThe impact of COVID-19 on human health extends beyond the morbidity and death toll directly caused by the SARS-CoV-2 virus. In fact, accumulating evidence indicates a global increase in the incidence of fatigue, brain fog and depression, including among non-infected, since the pandemic onset. Motivated by previous evidence linking those symptoms to neuroimmune activation in other pathological contexts, we hypothesized that subjects examined after the enforcement of lockdown/stay-at-home measures would demonstrate increased neuroinflammation.MethodsWe performed simultaneous brain Positron Emission Tomography / Magnetic Resonance Imaging in healthy volunteers either before (n=57) or after (n=15) the 2020 Massachusetts lockdown, using [11C]PBR28, a radioligand for the glial marker 18 kDa translocator protein (TSPO). First, we compared [11C]PBR28 signal across pre- and post-lockdown cohorts. Then, we evaluated the link between neuroinflammatory signals and scores on a q...

Background: Type 2 diabetes mellitus is known to be associated with neurobiological and cognitive... more Background: Type 2 diabetes mellitus is known to be associated with neurobiological and cognitive deficits; however, their extent, overlap with aging effects, and the effectiveness of existing treatments in the context of the brain are currently unknown. Methods: We characterized neurocognitive effects independently associated with T2DM and age in a large cohort of human subjects from the UK Biobank with cross-sectional neuroimaging and cognitive data. We then proceeded to evaluate the extent of overlap between the effects related to T2DM and age by applying correlation measures to the separately characterized neurocognitive changes. Our findings were complemented by meta-analyses of published reports with cognitive or neuroimaging measures for T2DM and healthy controls (HC). We also evaluated in a cohort of T2DM diagnosed individuals using UK Biobank how disease chronicity and metformin treatment interact with the identified neurocognitive effects. Results: The UK Biobank dataset i...

American Journal of Neuroradiology, 2020

Brain multivoxel MR spectroscopic imaging was performed in 3 consecutive patients with coronaviru... more Brain multivoxel MR spectroscopic imaging was performed in 3 consecutive patients with coronavirus disease 2019 (COVID-19). These included 1 patient with COVID-19-associated necrotizing leukoencephalopathy, another patient who had a recent pulseless electrical activity cardiac arrest with subtle white matter changes, and a patient without frank encephalopathy or a recent severe hypoxic episode. The MR spectroscopic imaging findings were compared with those of 2 patients with white matter pathology not related to Severe Acute Respiratory Syndrome coronavirus 2 infection and a healthy control subject. The NAA reduction, choline elevation, and glutamate/glutamine elevation found in the patient with COVID-19-associated necrotizing leukoencephalopathy and, to a lesser degree, the patient with COVID-19 postcardiac arrest, follow a similar pattern as seen with the patient with delayed posthypoxic leukoencephalopathy. Lactate elevation was most pronounced in the patient with COVID-19 necrotizing leukoencephalopathy.

Proceedings of the National Academy of Sciences, 2020

Epidemiological studies suggest that insulin resistance accelerates progression of age-based cogn... more Epidemiological studies suggest that insulin resistance accelerates progression of age-based cognitive impairment, which neuroimaging has linked to brain glucose hypometabolism. As cellular inputs, ketones increase Gibbs free energy change for ATP by 27% compared to glucose. Here we test whether dietary changes are capable of modulating sustained functional communication between brain regions (network stability) by changing their predominant dietary fuel from glucose to ketones. We first established network stability as a biomarker for brain aging using two large-scale ( n = 292, ages 20 to 85 y; n = 636, ages 18 to 88 y) 3 T functional MRI (fMRI) datasets. To determine whether diet can influence brain network stability, we additionally scanned 42 adults, age < 50 y, using ultrahigh-field (7 T) ultrafast (802 ms) fMRI optimized for single-participant-level detection sensitivity. One cohort was scanned under standard diet, overnight fasting, and ketogenic diet conditions. To isola...

Magnetic Resonance Imaging Clinics of North America, 2016

Magnetic resonance spectroscopy (MRS) is a magnetic resonance-based imaging modality that allows ... more Magnetic resonance spectroscopy (MRS) is a magnetic resonance-based imaging modality that allows noninvasive sampling of metabolic changes in normal and abnormal brain parenchyma. MRS is particularly useful in the differentiation of developmental or non-neoplastic disorders from neoplastic processes. MRS is also useful during routine imaging follow-up after radiation treatment or during antiangiogenic treatment and for predicting outcomes and treatment response. The objective of this article is to provide a concise but thorough review of the basic physical principles, important applications of MRS in brain tumor imaging, and future directions.

Physics and Chemistry of Glasses

During the past 40 years, solid state NMR has provided immensely detailed information on the stru... more During the past 40 years, solid state NMR has provided immensely detailed information on the structural organisation of alkali borate glasses. While early wideline NMR work concentrated on the structural speciation of boron in the network, more recent high resolution and double resonance studies have provided more intricate detail on the location and the spatial distribution of the alkali ions. In particular, this work has provided some insights into the structural origins of the mixed alkali effect. The present contribution attempts to summarise the current state of knowledge, including the unresolved issues in the structural description of single and mixed alkali borate glasses.

Background: Growing documentation of metabolic alterations in autism increases the need to charac... more Background: Growing documentation of metabolic alterations in autism increases the need to characterize metabolism in brain tissue. Magnetic Resonance Spectroscopy (MRS) is constrained by the impossibility of performing whole brain acquisitions and the need to place localized voxels, as well as the impact of acquisition protocols on findings. Literature review can contribute to well-targeted choice of future research design. Objectives: To consider the potentiality of MRS for measuring metabolites pertinent to emerging metabolic findings in ASD and from this vantage point to produce a systematic and critical overview of MRS investigations in ASD to date. Methods: PubMed was searched for papers on MRS in ASD as well as brain metabolites. Relevant papers were reviewed and tabulated based upon regions of interest, absolute metabolite concentrations and/or ratios in each region studied, field strength, repetition time (TR) and time to echo (TE), subject characteristics (age, gender, dia...

Background: The tissue nature of brain enlargement in young autistic subjects has not yet been cl... more Background: The tissue nature of brain enlargement in young autistic subjects has not yet been clearly established. Published findings do not support an increase in neuronal density in gray matter or the attribution of white matter enlargement to an increase in myelinated fibers. Given the growing documentation of metabolic findings in autism, these brain changes need to be investigated using techniques sensitive to metabolites. Frontal and prefrontal white matter enlargement is particularly prominent and its metabolic underpinnings need to be targeted using magnetic resonance spectroscopy (MRS) methods. Objectives: To investigate metabolic alterations in ASD brain tissue collected using single voxel spectroscopy and chemical shift imaging. Methods: Proton magnetic resonance spectroscopy was performed with a 3T Siemens scanner on age matched typically developing and children with Autism Spectrum Disorders (6-13 year olds). Single Voxel Spectroscopy (SVS) was acquired with the voxel ...

HIV medicine, Jan 17, 2015

As ∼40% of HIV-infected individuals experience neurocognitive decline, we investigated whether pr... more As ∼40% of HIV-infected individuals experience neurocognitive decline, we investigated whether proton magnetic resonance spectroscopic imaging ((1) H-MRSI) detects early metabolic abnormalities in the cerebral cortex of a simian immunodeficiency virus (SIV)-infected rhesus monkey model of neuroAIDS. The brains of five rhesus monkeys before and 4 or 6 weeks after SIV infection (with CD8(+) T-cell depletion) were assessed with T2 -weighted quantitative magnetic resonance imaging (MRI) and 16×16×4 multivoxel (1) H-MRSI (echo time/repetition time = 33/1440 ms). Grey matter and white matter masks were segmented from the animal MRIs and used to produce cortical masks co-registered to (1) H-MRSI data to yield cortical metabolite concentrations of the glial markers myo-inositol (mI), creatine (Cr) and choline (Cho), and of the neuronal marker N-acetylaspartate (NAA). The cortex volume within the large, 28 cm(3) (∼35% of total monkey brain) volume of interest was also calculated for each ani...

Defect and Diffusion Forum, 2001

Stroke, 2007

Background and Purpose— Recent studies suggest that normobaric oxygen therapy (NBO) is neuroprote... more Background and Purpose— Recent studies suggest that normobaric oxygen therapy (NBO) is neuroprotective in acute ischemic stroke. Methods— We performed multivoxel magnetic resonance spectroscopic imaging and diffusion/perfusion MRI in patients with stroke treated with NBO or room air. Imaging was performed before, during, and after therapy. Results— Voxel-based analysis showed excellent correlation between apparent diffusion coefficient values, lactate, and N -acetyl-aspartate levels at all time points. Lactate decreased during NBO and increased post-NBO. N -acetyl-aspartate decreased in patients receiving room air but not in NBO-treated patients. Conclusion— These data suggest that NBO improves aerobic metabolism and preserves neuronal integrity in the ischemic brain.

Solid State Ionics, 1998

The structural environments and the spatial distributions of the alkali ions in single-and mixed-... more The structural environments and the spatial distributions of the alkali ions in single-and mixed-alkali borate glasses are studied by complementary solid state NMR techniques. Specifically, spin echo decay spectroscopy is used to extract 23 133 homodipolar second moments for Na and Cs in binary sodium and cesium borate glasses. These values are found to be quantitatively most consistent with spatially homogeneous cation distributions, except in sodium borate glasses with cation contents #16 mole %. Complementary isotropic chemical shifts extracted from field-dependent magic-angle spinning (MAS)-NMR depend linearly on alkali ion content, revealing a continuous concomitant change in the oxygen environment of the alkali ions. This effect can be related to structural changes in the network, where trigonal BO units are 3 / 2 2 progressively converted to tetrahedral BO sites as the alkali oxide content is increased. Taken together these data argue 4 / 2 7 2 3 strongly against cation clustering models previously proposed for other types of glass systems. Isotropic Li and Na chemical shift data measured for mixed-alkali Li,Na and K,Na-borate glasses containing 30 mole % alkali oxide indicate universal compositional trends that can be understood in terms of the site-mismatch concept of Bunde's dynamic structure 1 model: Consistent with current semi-empirical predictions, mismatching the cation of interest, e.g. Na to a smaller Li site 23 produces a low-frequency shift, while mismatching to a larger K site produces high-frequency Na isotropic chemical shifts.

Science Translational Medicine, 2010

Magnetic resonance spectroscopy can generate comprehensive maps of metabolites in the prostate th... more Magnetic resonance spectroscopy can generate comprehensive maps of metabolites in the prostate that reveal cancerous regions, potentially guiding biopsies and prognosis.