Yonker Wang - Academia.edu (original) (raw)

Papers by Yonker Wang

Research paper thumbnail of Clinical and MRI features of neurological complications after influenza A (H1N1) infection in critically ill children

Pediatric Radiology, 2013

Influenza A (H1N1) can cause severe neurological complications. The purpose of this study was to ... more Influenza A (H1N1) can cause severe neurological complications. The purpose of this study was to analyze clinical and MRI features of neurological complications after H1N1 infection in critically ill children. We retrospectively analyzed clinical and neuroimaging findings in 17 children who were hospitalized in an intensive care unit with severe neurological complications after H1N1 infection in South China between September 2009 and December 2011. All children underwent pre- and post-contrast-enhanced brain MRI. Postmortem studies were performed in two children. Six children died, five because of acute necrotizing encephalopathy (ANE) and one because of intracranial fungal infection. Eleven recovered; their manifestations of H1N1 were meningitis (3), encephalitis (1) and influenza encephalopathy (7). MRI features of ANE included multiple symmetrical brain lesions demonstrating prolonged T1 and T2 signal in the thalami, internal capsule, lenticular nucleus and pontine tegmentum. Postmortem MRI in two children with acute necrotizing encephalopathy showed diffuse prolonged T1 and T2 signal in the bilateral thalami, brainstem deformation and tonsillar herniation. Fatal neurological complications in children after H1N1 infection include ANE and opportunistic fungal infection. MRI is essential for identification of neurological complications and for clinical evaluation.

Research paper thumbnail of Clinical and MRI features of neurological complications after influenza A (H1N1) infection in critically ill children

Pediatric Radiology

BACKGROUND: Influenza A (H1N1) can cause severe neurological complications. OBJECTIVE: The purpos... more BACKGROUND: Influenza A (H1N1) can cause severe neurological complications. OBJECTIVE: The purpose of this study was to analyze clinical and MRI features of neurological complications after H1N1 infection in critically ill children. MATERIALS AND METHODS: We retrospectively analyzed clinical and neuroimaging findings in 17 children who were hospitalized in an intensive care unit with severe neurological complications after H1N1 infection in South China between September 2009 and December 2011. All children underwent pre- and post-contrast-enhanced brain MRI. Postmortem studies were performed in two children. RESULTS: Six children died, five because of acute necrotizing encephalopathy (ANE) and one because of intracranial fungal infection. Eleven recovered; their manifestations of H1N1 were meningitis (3), encephalitis (1) and influenza encephalopathy (7). MRI features of ANE included multiple symmetrical brain lesions demonstrating prolonged T1 and T2 signal in the thalami, internal...

Research paper thumbnail of New Findings, Classification and Long-Term Follow-Up Study Based on MRI Characterization of Brainstem Encephalitis Induced by Enterovirus 71

PLOS ONE, 2016

To report the diversity of MRI features of brainstem encephalitis (BE) induced by Enterovirus 71.... more To report the diversity of MRI features of brainstem encephalitis (BE) induced by Enterovirus 71. This is supported by implementation and testing of our new classification scheme in order to improve the diagnostic level on this specific disease. Neuroimaging of 91 pediatric patients who got EV71 related BE were hospitalized between March, 2010 to October, 2012, were analyzed retrospectively. All patients underwent pre- and post-contrast MRI scan. Thereafter, 31 patients were randomly called back for follow-up MRI study during December 2013 to August 2014. The MRI signal patterns of BE primary lesion were analyzed and classified according to MR signal alteration at various disease stages. Findings in fatal and non-fatal cases were compared, and according to the MRI scan time point during the course of this disease, the patients' conditions were classified as 1) acute stage, 2) convalescence stage, 3) post mortem stage, and 4) long term follow-up study. 103 patients were identified. 11 patients did not undergo MRI, as they died within 48 hours. One patient died on 14th day without MR imaging. 2 patients had postmortem MRI. Medical records and imaging were reviewed in the 91 patients, aged 4 months to 12 years, and two cadavers who have had MRI scan. At acute stage: the most frequent pattern (40 patients) was foci of prolonged T1 and T2 signal, with (15) or without (25) contrast enhancement. We observed a novel pattern in 4 patients having foci of low signal intensity on T2WI, with contrast enhancement. Another pattern in 10 patients having foci of contrast enhancement without abnormalities in T1WI or T2WI weighted images. Based on 2 cases, the entire medulla and pons had prolonged T1 and T2 signal, and 2 of our postmortem cases demonstrated the same pattern. At convalescence stage, the pattern observed in 4 patients was foci of prolonged T1 and T2 signal without contrast enhancement. Follow-up MR study of 31 cases showed normal in 26 cases, and demonstrated foci of prolonged T1 and T2 signal with hyper-intensity on FLAIR in 3 cases, or of prolonged T1 and T2 signal with hypo-intensity on FLAIR in 2 cases. Most importantly, MR findings of each case were thoroughly investigated and classified according to phases and MRI signal alteration. This study has provided enhanced and useful information for the MRI features of BE induced by EV71, apart from common practice established by previous reports. In addition, a classification scheme that summarizes all types of features based on the MRI signal at the four different stages of the disease would be helpful to improve the diagnostic level.

Research paper thumbnail of Neurochemical adaptation to cocaine abuse: reduction of N-acetyl aspartate in thalamus of human cocaine abusers

Biological Psychiatry, Jun 1, 1999

The aim of this study was to determine the existence of, and possible mechanisms for, chronic coc... more The aim of this study was to determine the existence of, and possible mechanisms for, chronic cocaine use-induced neurotoxicity in the human brain. Because in vivo magnetic resonance spectroscopy (MRS) provides a noninvasive way to detect biochemical and physiological changes in the brain, we sought to specifically determine the neurochemical adaptations in chronic cocaine-dependent subjects. Methods: Twenty-one cocaine users and 13 non-drugusing, age-matched normal volunteers were recruited for an in vivo proton MRS study. Following screening that included physical examination, histories, and blood testing, cocaine group subjects received a spectral scan on a 1.5-T GE Signa scanner. Spectra were obtained from the left basal ganglia and/or the left thalamus from subjects in both groups using an rf bird-cage type head coil with single-voxel localization. Results: The level of N-acetyl aspartate in the region of left thalamus was lower (17%) in the chronic cocaine user group but not in the region of left basal ganglia, compared with the control group. Conclusions: These results suggest that chronic cocaine use may induce abnormal neurochemical activity and a state of neuronal dysregulation and/or neurotoxicity. It will now be important to determine if these alterations are reversible during withdrawal and what the functional implications of this observation are with respect to cognitive function and drug relapse.

Research paper thumbnail of MRI signal intensity differentiation of brainstem encephalitis induced by Enterovirus 71: a classification approach for acute and convalescence stages

Biomedical engineering online, Jan 25, 2016

The objective of this study is to assess standardized histograms of signal intensities of T1 sign... more The objective of this study is to assess standardized histograms of signal intensities of T1 signal and T2 signal on sagittal view without enhancement during (1) acute stage, and (2) convalescence stage of pediatric patients with Enterovirus 71 related brainstem encephalitis (BE), and with respect to (3) healthy normal. Our subjects were hospitalized between March 2010 and October 2012, and underwent pre- and post-contrast MRI studies. The research question to be answered is whether the comparison of the MRI image intensity histograms and relevant statistical quantification can add new knowledge to the diagnosis of BE patients. So, both 25 cases in acute stage with prolonged T1 and T2 signal, without enhancement, and 13 cases in convalescence stage were introduced. In additional, a healthy group with 25 cases was recruited for comparison. MRI signal intensity histogram changes of the lesions were compared at the acute and convalescence stages of the disease. Our preliminary results ...

Research paper thumbnail of Differentiation of metabolic concentrations between gray matter and white matter of human brain by invivo1H magnetic resonance spectroscopy

Magn Reson Med, 1998

Differentiation of absolute metabolite concentrations between gray and white matter in the occipi... more Differentiation of absolute metabolite concentrations between gray and white matter in the occipital region of normal human brain was performed by in vivo localized single-voxel 'H magnetic resonance spectroscopy at 1.5 Testa with long echo time (136 ms). With the combination of image segmentation between white and gray matter and cerebrospinal fluid, signal compensation of T, and T2 effects, tissue water signal as the internal concentration reference, as well as compensation by different water contents in gray and white matters, it was determined that the levels of N-acetylaspartate (NAA), creatine and/or phosphocreatine (Cr), and choline-containing compounds (Cho) in gray matter were significantly higher than in white matter. The averaged NAA, Cr, and Cho concentrations in gray matter were 11 .O, 9.7, and 1.9 mM/liter, respectively, in comparison with 7.5, 5.2, and 1.6 mM/liter in white matter. These results suggest that precise composition of white and gray matter and cerebrospinal fluid is necessary to avoid partial voluming effect in a single voxel and to accurately quantify the metabolite concentrations.

Research paper thumbnail of Decreased glutamate + glutamine in Alzheimer's disease detected in vivo with 1H-MRS at 0.5 T

Neurology, 2001

To determine whether glutamate + glutamine (GLX) levels in the brain as measured in vivo with pro... more To determine whether glutamate + glutamine (GLX) levels in the brain as measured in vivo with proton MRS at 0.5 tesla (T) distinguish between probable Alzheimer's disease and normal aging. Glutamatergic markers had been measured previously in postmortem brain tissue. Conventional proton MRS at 1.5 T cannot reliably detect the GLX resonance in vivo. The authors developed a technique at 0.5 T that is sensitive to the GLX resonance. Metabolite ratios using creatine and phosphocreatine resonance as an internal standard were acquired from the cingulate region of 18 patients with AD and 12 healthy controls. The major resonances in the spectrum were examined: N-acetylaspartate (NAA), choline-containing compounds, myo-inositol, and GLX. The Mini-Mental State Examination (MMSE) was used to assess cognitive status. The Instrumental Activities of Daily Living Scale (Instrumental ADL) was used to assess functional status. Reduced ratios of GLX (-10%, p = 0.001) and NAA (-12%, p = 0.000) were found in patients with AD. Increased ratios of myo-inositol in patients with AD approached significance (+14%). GLX ratios of patients with AD were correlated with MMSE (r = 0.61, p = 0.007) and Instrumental ADL (r = 0.59, p = 0.01) scores. The combined sensitivity of NAA and myo-inositol in correctly diagnosing AD was 78%. The addition of GLX to NAA and myo-inositol increased the sensitivity to 89%. Overall diagnostic accuracy improved from 80 to 83% with the addition of GLX. Glutamate + glutamine reduction may be a biologic marker for AD and may be a potential aid in the early clinical diagnosis of AD.

Research paper thumbnail of Differentiation of metabolic concentrations between gray matter and white matter of human brain by invivo1H magnetic resonance spectroscopy

Magnetic Resonance in Medicine, 1998

Differentiation of absolute metabolite concentrations between gray and white matter in the occipi... more Differentiation of absolute metabolite concentrations between gray and white matter in the occipital region of normal human brain was performed by in vivo localized single-voxel 'H magnetic resonance spectroscopy at 1.5 Testa with long echo time (136 ms). With the combination of image segmentation between white and gray matter and cerebrospinal fluid, signal compensation of T, and T2 effects, tissue water signal as the internal concentration reference, as well as compensation by different water contents in gray and white matters, it was determined that the levels of N-acetylaspartate (NAA), creatine and/or phosphocreatine (Cr), and choline-containing compounds (Cho) in gray matter were significantly higher than in white matter. The averaged NAA, Cr, and Cho concentrations in gray matter were 11 .O, 9.7, and 1.9 mM/liter, respectively, in comparison with 7.5, 5.2, and 1.6 mM/liter in white matter. These results suggest that precise composition of white and gray matter and cerebrospinal fluid is necessary to avoid partial voluming effect in a single voxel and to accurately quantify the metabolite concentrations.

Research paper thumbnail of Neurochemical adaptation to cocaine abuse: reduction of N-acetyl aspartate in thalamus of human cocaine abusers

Biological Psychiatry, 1999

The aim of this study was to determine the existence of, and possible mechanisms for, chronic coc... more The aim of this study was to determine the existence of, and possible mechanisms for, chronic cocaine use-induced neurotoxicity in the human brain. Because in vivo magnetic resonance spectroscopy (MRS) provides a noninvasive way to detect biochemical and physiological changes in the brain, we sought to specifically determine the neurochemical adaptations in chronic cocaine-dependent subjects. Methods: Twenty-one cocaine users and 13 non-drugusing, age-matched normal volunteers were recruited for an in vivo proton MRS study. Following screening that included physical examination, histories, and blood testing, cocaine group subjects received a spectral scan on a 1.5-T GE Signa scanner. Spectra were obtained from the left basal ganglia and/or the left thalamus from subjects in both groups using an rf bird-cage type head coil with single-voxel localization. Results: The level of N-acetyl aspartate in the region of left thalamus was lower (17%) in the chronic cocaine user group but not in the region of left basal ganglia, compared with the control group. Conclusions: These results suggest that chronic cocaine use may induce abnormal neurochemical activity and a state of neuronal dysregulation and/or neurotoxicity. It will now be important to determine if these alterations are reversible during withdrawal and what the functional implications of this observation are with respect to cognitive function and drug relapse.

Research paper thumbnail of Clinical and MRI features of neurological complications after influenza A (H1N1) infection in critically ill children

Pediatric Radiology, 2013

Influenza A (H1N1) can cause severe neurological complications. The purpose of this study was to ... more Influenza A (H1N1) can cause severe neurological complications. The purpose of this study was to analyze clinical and MRI features of neurological complications after H1N1 infection in critically ill children. We retrospectively analyzed clinical and neuroimaging findings in 17 children who were hospitalized in an intensive care unit with severe neurological complications after H1N1 infection in South China between September 2009 and December 2011. All children underwent pre- and post-contrast-enhanced brain MRI. Postmortem studies were performed in two children. Six children died, five because of acute necrotizing encephalopathy (ANE) and one because of intracranial fungal infection. Eleven recovered; their manifestations of H1N1 were meningitis (3), encephalitis (1) and influenza encephalopathy (7). MRI features of ANE included multiple symmetrical brain lesions demonstrating prolonged T1 and T2 signal in the thalami, internal capsule, lenticular nucleus and pontine tegmentum. Postmortem MRI in two children with acute necrotizing encephalopathy showed diffuse prolonged T1 and T2 signal in the bilateral thalami, brainstem deformation and tonsillar herniation. Fatal neurological complications in children after H1N1 infection include ANE and opportunistic fungal infection. MRI is essential for identification of neurological complications and for clinical evaluation.

Research paper thumbnail of Clinical and MRI features of neurological complications after influenza A (H1N1) infection in critically ill children

Pediatric Radiology, 2013

Influenza A (H1N1) can cause severe neurological complications. The purpose of this study was to ... more Influenza A (H1N1) can cause severe neurological complications. The purpose of this study was to analyze clinical and MRI features of neurological complications after H1N1 infection in critically ill children. We retrospectively analyzed clinical and neuroimaging findings in 17 children who were hospitalized in an intensive care unit with severe neurological complications after H1N1 infection in South China between September 2009 and December 2011. All children underwent pre- and post-contrast-enhanced brain MRI. Postmortem studies were performed in two children. Six children died, five because of acute necrotizing encephalopathy (ANE) and one because of intracranial fungal infection. Eleven recovered; their manifestations of H1N1 were meningitis (3), encephalitis (1) and influenza encephalopathy (7). MRI features of ANE included multiple symmetrical brain lesions demonstrating prolonged T1 and T2 signal in the thalami, internal capsule, lenticular nucleus and pontine tegmentum. Postmortem MRI in two children with acute necrotizing encephalopathy showed diffuse prolonged T1 and T2 signal in the bilateral thalami, brainstem deformation and tonsillar herniation. Fatal neurological complications in children after H1N1 infection include ANE and opportunistic fungal infection. MRI is essential for identification of neurological complications and for clinical evaluation.

Research paper thumbnail of Clinical and MRI features of neurological complications after influenza A (H1N1) infection in critically ill children

Pediatric Radiology

BACKGROUND: Influenza A (H1N1) can cause severe neurological complications. OBJECTIVE: The purpos... more BACKGROUND: Influenza A (H1N1) can cause severe neurological complications. OBJECTIVE: The purpose of this study was to analyze clinical and MRI features of neurological complications after H1N1 infection in critically ill children. MATERIALS AND METHODS: We retrospectively analyzed clinical and neuroimaging findings in 17 children who were hospitalized in an intensive care unit with severe neurological complications after H1N1 infection in South China between September 2009 and December 2011. All children underwent pre- and post-contrast-enhanced brain MRI. Postmortem studies were performed in two children. RESULTS: Six children died, five because of acute necrotizing encephalopathy (ANE) and one because of intracranial fungal infection. Eleven recovered; their manifestations of H1N1 were meningitis (3), encephalitis (1) and influenza encephalopathy (7). MRI features of ANE included multiple symmetrical brain lesions demonstrating prolonged T1 and T2 signal in the thalami, internal...

Research paper thumbnail of New Findings, Classification and Long-Term Follow-Up Study Based on MRI Characterization of Brainstem Encephalitis Induced by Enterovirus 71

PLOS ONE, 2016

To report the diversity of MRI features of brainstem encephalitis (BE) induced by Enterovirus 71.... more To report the diversity of MRI features of brainstem encephalitis (BE) induced by Enterovirus 71. This is supported by implementation and testing of our new classification scheme in order to improve the diagnostic level on this specific disease. Neuroimaging of 91 pediatric patients who got EV71 related BE were hospitalized between March, 2010 to October, 2012, were analyzed retrospectively. All patients underwent pre- and post-contrast MRI scan. Thereafter, 31 patients were randomly called back for follow-up MRI study during December 2013 to August 2014. The MRI signal patterns of BE primary lesion were analyzed and classified according to MR signal alteration at various disease stages. Findings in fatal and non-fatal cases were compared, and according to the MRI scan time point during the course of this disease, the patients' conditions were classified as 1) acute stage, 2) convalescence stage, 3) post mortem stage, and 4) long term follow-up study. 103 patients were identified. 11 patients did not undergo MRI, as they died within 48 hours. One patient died on 14th day without MR imaging. 2 patients had postmortem MRI. Medical records and imaging were reviewed in the 91 patients, aged 4 months to 12 years, and two cadavers who have had MRI scan. At acute stage: the most frequent pattern (40 patients) was foci of prolonged T1 and T2 signal, with (15) or without (25) contrast enhancement. We observed a novel pattern in 4 patients having foci of low signal intensity on T2WI, with contrast enhancement. Another pattern in 10 patients having foci of contrast enhancement without abnormalities in T1WI or T2WI weighted images. Based on 2 cases, the entire medulla and pons had prolonged T1 and T2 signal, and 2 of our postmortem cases demonstrated the same pattern. At convalescence stage, the pattern observed in 4 patients was foci of prolonged T1 and T2 signal without contrast enhancement. Follow-up MR study of 31 cases showed normal in 26 cases, and demonstrated foci of prolonged T1 and T2 signal with hyper-intensity on FLAIR in 3 cases, or of prolonged T1 and T2 signal with hypo-intensity on FLAIR in 2 cases. Most importantly, MR findings of each case were thoroughly investigated and classified according to phases and MRI signal alteration. This study has provided enhanced and useful information for the MRI features of BE induced by EV71, apart from common practice established by previous reports. In addition, a classification scheme that summarizes all types of features based on the MRI signal at the four different stages of the disease would be helpful to improve the diagnostic level.

Research paper thumbnail of Neurochemical adaptation to cocaine abuse: reduction of N-acetyl aspartate in thalamus of human cocaine abusers

Biological Psychiatry, Jun 1, 1999

The aim of this study was to determine the existence of, and possible mechanisms for, chronic coc... more The aim of this study was to determine the existence of, and possible mechanisms for, chronic cocaine use-induced neurotoxicity in the human brain. Because in vivo magnetic resonance spectroscopy (MRS) provides a noninvasive way to detect biochemical and physiological changes in the brain, we sought to specifically determine the neurochemical adaptations in chronic cocaine-dependent subjects. Methods: Twenty-one cocaine users and 13 non-drugusing, age-matched normal volunteers were recruited for an in vivo proton MRS study. Following screening that included physical examination, histories, and blood testing, cocaine group subjects received a spectral scan on a 1.5-T GE Signa scanner. Spectra were obtained from the left basal ganglia and/or the left thalamus from subjects in both groups using an rf bird-cage type head coil with single-voxel localization. Results: The level of N-acetyl aspartate in the region of left thalamus was lower (17%) in the chronic cocaine user group but not in the region of left basal ganglia, compared with the control group. Conclusions: These results suggest that chronic cocaine use may induce abnormal neurochemical activity and a state of neuronal dysregulation and/or neurotoxicity. It will now be important to determine if these alterations are reversible during withdrawal and what the functional implications of this observation are with respect to cognitive function and drug relapse.

Research paper thumbnail of MRI signal intensity differentiation of brainstem encephalitis induced by Enterovirus 71: a classification approach for acute and convalescence stages

Biomedical engineering online, Jan 25, 2016

The objective of this study is to assess standardized histograms of signal intensities of T1 sign... more The objective of this study is to assess standardized histograms of signal intensities of T1 signal and T2 signal on sagittal view without enhancement during (1) acute stage, and (2) convalescence stage of pediatric patients with Enterovirus 71 related brainstem encephalitis (BE), and with respect to (3) healthy normal. Our subjects were hospitalized between March 2010 and October 2012, and underwent pre- and post-contrast MRI studies. The research question to be answered is whether the comparison of the MRI image intensity histograms and relevant statistical quantification can add new knowledge to the diagnosis of BE patients. So, both 25 cases in acute stage with prolonged T1 and T2 signal, without enhancement, and 13 cases in convalescence stage were introduced. In additional, a healthy group with 25 cases was recruited for comparison. MRI signal intensity histogram changes of the lesions were compared at the acute and convalescence stages of the disease. Our preliminary results ...

Research paper thumbnail of Differentiation of metabolic concentrations between gray matter and white matter of human brain by invivo1H magnetic resonance spectroscopy

Magn Reson Med, 1998

Differentiation of absolute metabolite concentrations between gray and white matter in the occipi... more Differentiation of absolute metabolite concentrations between gray and white matter in the occipital region of normal human brain was performed by in vivo localized single-voxel 'H magnetic resonance spectroscopy at 1.5 Testa with long echo time (136 ms). With the combination of image segmentation between white and gray matter and cerebrospinal fluid, signal compensation of T, and T2 effects, tissue water signal as the internal concentration reference, as well as compensation by different water contents in gray and white matters, it was determined that the levels of N-acetylaspartate (NAA), creatine and/or phosphocreatine (Cr), and choline-containing compounds (Cho) in gray matter were significantly higher than in white matter. The averaged NAA, Cr, and Cho concentrations in gray matter were 11 .O, 9.7, and 1.9 mM/liter, respectively, in comparison with 7.5, 5.2, and 1.6 mM/liter in white matter. These results suggest that precise composition of white and gray matter and cerebrospinal fluid is necessary to avoid partial voluming effect in a single voxel and to accurately quantify the metabolite concentrations.

Research paper thumbnail of Decreased glutamate + glutamine in Alzheimer's disease detected in vivo with 1H-MRS at 0.5 T

Neurology, 2001

To determine whether glutamate + glutamine (GLX) levels in the brain as measured in vivo with pro... more To determine whether glutamate + glutamine (GLX) levels in the brain as measured in vivo with proton MRS at 0.5 tesla (T) distinguish between probable Alzheimer's disease and normal aging. Glutamatergic markers had been measured previously in postmortem brain tissue. Conventional proton MRS at 1.5 T cannot reliably detect the GLX resonance in vivo. The authors developed a technique at 0.5 T that is sensitive to the GLX resonance. Metabolite ratios using creatine and phosphocreatine resonance as an internal standard were acquired from the cingulate region of 18 patients with AD and 12 healthy controls. The major resonances in the spectrum were examined: N-acetylaspartate (NAA), choline-containing compounds, myo-inositol, and GLX. The Mini-Mental State Examination (MMSE) was used to assess cognitive status. The Instrumental Activities of Daily Living Scale (Instrumental ADL) was used to assess functional status. Reduced ratios of GLX (-10%, p = 0.001) and NAA (-12%, p = 0.000) were found in patients with AD. Increased ratios of myo-inositol in patients with AD approached significance (+14%). GLX ratios of patients with AD were correlated with MMSE (r = 0.61, p = 0.007) and Instrumental ADL (r = 0.59, p = 0.01) scores. The combined sensitivity of NAA and myo-inositol in correctly diagnosing AD was 78%. The addition of GLX to NAA and myo-inositol increased the sensitivity to 89%. Overall diagnostic accuracy improved from 80 to 83% with the addition of GLX. Glutamate + glutamine reduction may be a biologic marker for AD and may be a potential aid in the early clinical diagnosis of AD.

Research paper thumbnail of Differentiation of metabolic concentrations between gray matter and white matter of human brain by invivo1H magnetic resonance spectroscopy

Magnetic Resonance in Medicine, 1998

Differentiation of absolute metabolite concentrations between gray and white matter in the occipi... more Differentiation of absolute metabolite concentrations between gray and white matter in the occipital region of normal human brain was performed by in vivo localized single-voxel 'H magnetic resonance spectroscopy at 1.5 Testa with long echo time (136 ms). With the combination of image segmentation between white and gray matter and cerebrospinal fluid, signal compensation of T, and T2 effects, tissue water signal as the internal concentration reference, as well as compensation by different water contents in gray and white matters, it was determined that the levels of N-acetylaspartate (NAA), creatine and/or phosphocreatine (Cr), and choline-containing compounds (Cho) in gray matter were significantly higher than in white matter. The averaged NAA, Cr, and Cho concentrations in gray matter were 11 .O, 9.7, and 1.9 mM/liter, respectively, in comparison with 7.5, 5.2, and 1.6 mM/liter in white matter. These results suggest that precise composition of white and gray matter and cerebrospinal fluid is necessary to avoid partial voluming effect in a single voxel and to accurately quantify the metabolite concentrations.

Research paper thumbnail of Neurochemical adaptation to cocaine abuse: reduction of N-acetyl aspartate in thalamus of human cocaine abusers

Biological Psychiatry, 1999

The aim of this study was to determine the existence of, and possible mechanisms for, chronic coc... more The aim of this study was to determine the existence of, and possible mechanisms for, chronic cocaine use-induced neurotoxicity in the human brain. Because in vivo magnetic resonance spectroscopy (MRS) provides a noninvasive way to detect biochemical and physiological changes in the brain, we sought to specifically determine the neurochemical adaptations in chronic cocaine-dependent subjects. Methods: Twenty-one cocaine users and 13 non-drugusing, age-matched normal volunteers were recruited for an in vivo proton MRS study. Following screening that included physical examination, histories, and blood testing, cocaine group subjects received a spectral scan on a 1.5-T GE Signa scanner. Spectra were obtained from the left basal ganglia and/or the left thalamus from subjects in both groups using an rf bird-cage type head coil with single-voxel localization. Results: The level of N-acetyl aspartate in the region of left thalamus was lower (17%) in the chronic cocaine user group but not in the region of left basal ganglia, compared with the control group. Conclusions: These results suggest that chronic cocaine use may induce abnormal neurochemical activity and a state of neuronal dysregulation and/or neurotoxicity. It will now be important to determine if these alterations are reversible during withdrawal and what the functional implications of this observation are with respect to cognitive function and drug relapse.

Research paper thumbnail of Clinical and MRI features of neurological complications after influenza A (H1N1) infection in critically ill children

Pediatric Radiology, 2013

Influenza A (H1N1) can cause severe neurological complications. The purpose of this study was to ... more Influenza A (H1N1) can cause severe neurological complications. The purpose of this study was to analyze clinical and MRI features of neurological complications after H1N1 infection in critically ill children. We retrospectively analyzed clinical and neuroimaging findings in 17 children who were hospitalized in an intensive care unit with severe neurological complications after H1N1 infection in South China between September 2009 and December 2011. All children underwent pre- and post-contrast-enhanced brain MRI. Postmortem studies were performed in two children. Six children died, five because of acute necrotizing encephalopathy (ANE) and one because of intracranial fungal infection. Eleven recovered; their manifestations of H1N1 were meningitis (3), encephalitis (1) and influenza encephalopathy (7). MRI features of ANE included multiple symmetrical brain lesions demonstrating prolonged T1 and T2 signal in the thalami, internal capsule, lenticular nucleus and pontine tegmentum. Postmortem MRI in two children with acute necrotizing encephalopathy showed diffuse prolonged T1 and T2 signal in the bilateral thalami, brainstem deformation and tonsillar herniation. Fatal neurological complications in children after H1N1 infection include ANE and opportunistic fungal infection. MRI is essential for identification of neurological complications and for clinical evaluation.