Contact
Biomedical Research Center251 Bayview Boulevard
Baltimore, MD 21224
Email: honggu@mail.nih.gov
Education
B.S. - Electronic Engineering, Hefei University of Technology
M.S. - Electronic Engineering, University of Science and Technology of China
Ph.D. - Biomedical Engineering, Shanghai Jiao Tong University
Research Interests
Dr. Gu received her B.S. (1993) and M.S. (1996) in Electronic Engineering at Hefei University of Technology and University of Science and Technology of China, respectively. She received her Ph.D. in Biomedical Engineering from Shanghai Jiao Tong University, China in 2000. She then went on to postdoctoral associate position from 2000 to 2003 in the Functional Neuroimaging Laboratory at Weill Medical College of Cornell University in New York City. In 2003, she joined the Neuroimaging Research Branch at the National Institute on Drug Abuse (NIDA) as a research associate. Her research interests focus on the development and application of functional magnetic resonance imaging (fMRI) and functional connectivity MRI methodologies.
Projects:
- Development of reesting-state functional connectivity analysis methods
- Development of simultaneous VASO, perfusion, and BOLD imaging techniques
- Development of efficient fMRI imaging techniques to reduce susceptibility artifacts
- Application of novel data analysis methods to fMRI data
Publications
Selected Publications
2015
Hu, Yuzheng; Salmeron, Betty Jo; Gu, Hong; Stein, Elliot A; Yang, Yihong
In: JAMA Psychiatry, vol. 72, no. 6, pp. 584–592, 2015, ISSN: 2168-6238 (Electronic); 2168-622X (Linking).
@article{Hu2015,
title = {Impaired functional connectivity within and between frontostriatal circuits and its association with compulsive drug use and trait impulsivity in cocaine addiction.},
author = {Yuzheng Hu and Betty Jo Salmeron and Hong Gu and Elliot A Stein and Yihong Yang},
url = {https://www.ncbi.nlm.nih.gov/pubmed/25853901},
doi = {10.1001/jamapsychiatry.2015.1},
issn = {2168-6238 (Electronic); 2168-622X (Linking)},
year = {2015},
date = {2015-06-01},
journal = {JAMA Psychiatry},
volume = {72},
number = {6},
pages = {584--592},
address = {Neuroimaging Research Branch, Intramural Research Program National Institute on Drug Abuse, Baltimore, Maryland.},
abstract = {IMPORTANCE: Converging evidence has long identified both impulsivity and compulsivity as key psychological constructs in drug addiction. Although dysregulated striatal-cortical network interactions have been identified in cocaine addiction, the association between these brain networks and addiction is poorly understood. OBJECTIVES: To test the hypothesis that cocaine addiction is associated with disturbances in striatal-cortical communication as captured by resting-state functional connectivity (rsFC), measured from coherent spontaneous fluctuations in the blood oxygenation level-dependent functional magnetic resonance imaging signal, and to explore the relationships between striatal rsFC, trait impulsivity, and uncontrolled drug use in cocaine addiction. DESIGN, SETTING, AND PARTICIPANTS: A case-control, cross-sectional study was conducted at the National Institute on Drug Abuse Intramural Research Program outpatient magnetic resonance imaging facility. Data used in the present study were collected between December 8, 2005, and September 30, 2011. Participants included 56 non-treatment-seeking cocaine users (CUs) (52 with cocaine dependence and 3 with cocaine abuse) and 56 healthy individuals serving as controls (HCs) matched on age, sex, years of education, race, estimated intelligence, and smoking status. MAIN OUTCOMES AND MEASURES: Voxelwise statistical parametric analysis testing the rsFC strength differences between CUs and HCs in brain regions functionally connected to 6 striatal subregions defined a priori. RESULTS: Increased rsFC strength was observed predominantly in striatal-frontal circuits; decreased rsFC was found between the striatum and cingulate, striatal, temporal, hippocampal/amygdalar, and insular regions in the CU group compared with the HCs. Increased striatal-dorsal lateral prefrontal cortex connectivity strength was positively correlated with the amount of recent cocaine use (uncorrected P < .046) and elevated trait impulsivity in the CUs (uncorrected P < .012), and an index reflecting the balance between striatal-dorsal anterior cingulate cortex and striatal-anterior prefrontal/orbitofrontal cortex circuits was significantly associated with loss of control over cocaine use (corrected P < .012). CONCLUSIONS AND RELEVANCE: Cocaine addiction is associated with disturbed rsFC in several specific striatal-cortical circuits. Specifically, compulsive cocaine use, a defining characteristic of dependence, was associated with a balance of increased striatal-anterior prefrontal/orbitofrontal and decreased striatal-dorsal anterior cingulate connectivity; trait impulsivity, both a risk factor for and a consequence of cocaine use, was associated with increased dorsal striatal-dorsal lateral prefrontal cortex connectivity uniquely in CUs. These findings provide new insights toward the neurobiological mechanisms of addiction and suggest potential novel therapeutic targets for treatment.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
IMPORTANCE: Converging evidence has long identified both impulsivity and compulsivity as key psychological constructs in drug addiction. Although dysregulated striatal-cortical network interactions have been identified in cocaine addiction, the association between these brain networks and addiction is poorly understood. OBJECTIVES: To test the hypothesis that cocaine addiction is associated with disturbances in striatal-cortical communication as captured by resting-state functional connectivity (rsFC), measured from coherent spontaneous fluctuations in the blood oxygenation level-dependent functional magnetic resonance imaging signal, and to explore the relationships between striatal rsFC, trait impulsivity, and uncontrolled drug use in cocaine addiction. DESIGN, SETTING, AND PARTICIPANTS: A case-control, cross-sectional study was conducted at the National Institute on Drug Abuse Intramural Research Program outpatient magnetic resonance imaging facility. Data used in the present study were collected between December 8, 2005, and September 30, 2011. Participants included 56 non-treatment-seeking cocaine users (CUs) (52 with cocaine dependence and 3 with cocaine abuse) and 56 healthy individuals serving as controls (HCs) matched on age, sex, years of education, race, estimated intelligence, and smoking status. MAIN OUTCOMES AND MEASURES: Voxelwise statistical parametric analysis testing the rsFC strength differences between CUs and HCs in brain regions functionally connected to 6 striatal subregions defined a priori. RESULTS: Increased rsFC strength was observed predominantly in striatal-frontal circuits; decreased rsFC was found between the striatum and cingulate, striatal, temporal, hippocampal/amygdalar, and insular regions in the CU group compared with the HCs. Increased striatal-dorsal lateral prefrontal cortex connectivity strength was positively correlated with the amount of recent cocaine use (uncorrected P < .046) and elevated trait impulsivity in the CUs (uncorrected P < .012), and an index reflecting the balance between striatal-dorsal anterior cingulate cortex and striatal-anterior prefrontal/orbitofrontal cortex circuits was significantly associated with loss of control over cocaine use (corrected P < .012). CONCLUSIONS AND RELEVANCE: Cocaine addiction is associated with disturbed rsFC in several specific striatal-cortical circuits. Specifically, compulsive cocaine use, a defining characteristic of dependence, was associated with a balance of increased striatal-anterior prefrontal/orbitofrontal and decreased striatal-dorsal anterior cingulate connectivity; trait impulsivity, both a risk factor for and a consequence of cocaine use, was associated with increased dorsal striatal-dorsal lateral prefrontal cortex connectivity uniquely in CUs. These findings provide new insights toward the neurobiological mechanisms of addiction and suggest potential novel therapeutic targets for treatment.
Adinoff, Bryon; Gu, Hong; Merrick, Carmen; McHugh, Meredith; Jeon-Slaughter, Haekyung; Lu, Hanzhang; Yang, Yihong; Stein, Elliot A
Basal Hippocampal Activity and Its Functional Connectivity Predicts Cocaine Relapse. Journal Article
In: Biol Psychiatry, vol. 78, no. 7, pp. 496–504, 2015, ISSN: 1873-2402 (Electronic); 0006-3223 (Linking).
@article{Adinoff2015,
title = {Basal Hippocampal Activity and Its Functional Connectivity Predicts Cocaine Relapse.},
author = {Bryon Adinoff and Hong Gu and Carmen Merrick and Meredith McHugh and Haekyung Jeon-Slaughter and Hanzhang Lu and Yihong Yang and Elliot A Stein},
url = {https://www.ncbi.nlm.nih.gov/pubmed/25749098},
doi = {10.1016/j.biopsych.2014.12.027},
issn = {1873-2402 (Electronic); 0006-3223 (Linking)},
year = {2015},
date = {2015-01-30},
journal = {Biol Psychiatry},
volume = {78},
number = {7},
pages = {496--504},
address = {Veterans Affairs North Texas Health Care System, University of Texas Southwestern Medical Center, Dallas, Texas; Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas. Electronic address: Bryon.adinoff@utsouthwestern.edu.},
abstract = {BACKGROUND: Cocaine-induced neuroplastic changes may result in a heightened propensity for relapse. Using regional cerebral blood flow (rCBF) as a marker of basal neuronal activity, this study assessed alterations in rCBF and related resting state functional connectivity (rsFC) to prospectively predict relapse in patients following treatment for cocaine use disorder (CUD). METHODS: Pseudocontinuous arterial spin labeling functional magnetic resonance imaging and resting blood oxygen level-dependent functional magnetic resonance imaging data were acquired in the same scan session in abstinent participants with CUD before residential treatment discharge and in 20 healthy matched control subjects. Substance use was assessed twice weekly following discharge. Relapsed participants were defined as those who used stimulants within 30 days following treatment discharge (n = 22); early remission participants (n = 18) did not. RESULTS: Voxel-wise, whole-brain analysis revealed enhanced rCBF only in the left posterior hippocampus (pHp) in the relapsed group compared with the early remission and control groups. Using this pHp as a seed, increased rsFC strength with the posterior cingulate cortex (PCC)/precuneus was seen in the relapsed versus early remission subgroups. Together, both increased pHp rCBF and strengthened pHp-PCC rsFC predicted relapse with 75% accuracy at 30, 60, and 90 days following treatment. CONCLUSIONS: In CUD participants at risk of early relapse, increased pHp basal activity and pHp-PCC circuit strength may reflect the propensity for heightened reactivity to cocaine cues and persistent cocaine-related ruminations. Mechanisms to mute hyperactivated brain regions and delink dysregulated neural circuits may prove useful to prevent relapse in patients with CUD.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
BACKGROUND: Cocaine-induced neuroplastic changes may result in a heightened propensity for relapse. Using regional cerebral blood flow (rCBF) as a marker of basal neuronal activity, this study assessed alterations in rCBF and related resting state functional connectivity (rsFC) to prospectively predict relapse in patients following treatment for cocaine use disorder (CUD). METHODS: Pseudocontinuous arterial spin labeling functional magnetic resonance imaging and resting blood oxygen level-dependent functional magnetic resonance imaging data were acquired in the same scan session in abstinent participants with CUD before residential treatment discharge and in 20 healthy matched control subjects. Substance use was assessed twice weekly following discharge. Relapsed participants were defined as those who used stimulants within 30 days following treatment discharge (n = 22); early remission participants (n = 18) did not. RESULTS: Voxel-wise, whole-brain analysis revealed enhanced rCBF only in the left posterior hippocampus (pHp) in the relapsed group compared with the early remission and control groups. Using this pHp as a seed, increased rsFC strength with the posterior cingulate cortex (PCC)/precuneus was seen in the relapsed versus early remission subgroups. Together, both increased pHp rCBF and strengthened pHp-PCC rsFC predicted relapse with 75% accuracy at 30, 60, and 90 days following treatment. CONCLUSIONS: In CUD participants at risk of early relapse, increased pHp basal activity and pHp-PCC circuit strength may reflect the propensity for heightened reactivity to cocaine cues and persistent cocaine-related ruminations. Mechanisms to mute hyperactivated brain regions and delink dysregulated neural circuits may prove useful to prevent relapse in patients with CUD.
2014
Lerman, Caryn; Gu, Hong; Loughead, James; Ruparel, Kosha; Yang, Yihong; Stein, Elliot A
Large-scale brain network coupling predicts acute nicotine abstinence effects on craving and cognitive function. Journal Article
In: JAMA Psychiatry, vol. 71, no. 5, pp. 523–530, 2014, ISSN: 2168-6238 (Electronic); 2168-622X (Linking).
@article{Lerman2014,
title = {Large-scale brain network coupling predicts acute nicotine abstinence effects on craving and cognitive function.},
author = {Caryn Lerman and Hong Gu and James Loughead and Kosha Ruparel and Yihong Yang and Elliot A Stein},
url = {https://www.ncbi.nlm.nih.gov/pubmed/24622915},
doi = {10.1001/jamapsychiatry.2013.4091},
issn = {2168-6238 (Electronic); 2168-622X (Linking)},
year = {2014},
date = {2014-05-01},
journal = {JAMA Psychiatry},
volume = {71},
number = {5},
pages = {523--530},
address = {Center for Interdisciplinary Research on Nicotine Addiction, Department of Psychiatry, University of Pennsylvania, Philadelphia.},
abstract = {IMPORTANCE: Interactions of large-scale brain networks may underlie cognitive dysfunctions in psychiatric and addictive disorders. OBJECTIVES: To test the hypothesis that the strength of coupling among 3 large-scale brain networks--salience, executive control, and default mode--will reflect the state of nicotine withdrawal (vs smoking satiety) and will predict abstinence-induced craving and cognitive deficits and to develop a resource allocation index (RAI) that reflects the combined strength of interactions among the 3 large-scale networks. DESIGN, SETTING, AND PARTICIPANTS: A within-subject functional magnetic resonance imaging study in an academic medical center compared resting-state functional connectivity coherence strength after 24 hours of abstinence and after smoking satiety. We examined the relationship of abstinence-induced changes in the RAI with alterations in subjective, behavioral, and neural functions. We included 37 healthy smoking volunteers, aged 19 to 61 years, for analyses. INTERVENTIONS: Twenty-four hours of abstinence vs smoking satiety. MAIN OUTCOMES AND MEASURES: Inter-network connectivity strength (primary) and the relationship with subjective, behavioral, and neural measures of nicotine withdrawal during abstinence vs smoking satiety states (secondary). RESULTS: The RAI was significantly lower in the abstinent compared with the smoking satiety states (left RAI},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
IMPORTANCE: Interactions of large-scale brain networks may underlie cognitive dysfunctions in psychiatric and addictive disorders. OBJECTIVES: To test the hypothesis that the strength of coupling among 3 large-scale brain networks--salience, executive control, and default mode--will reflect the state of nicotine withdrawal (vs smoking satiety) and will predict abstinence-induced craving and cognitive deficits and to develop a resource allocation index (RAI) that reflects the combined strength of interactions among the 3 large-scale networks. DESIGN, SETTING, AND PARTICIPANTS: A within-subject functional magnetic resonance imaging study in an academic medical center compared resting-state functional connectivity coherence strength after 24 hours of abstinence and after smoking satiety. We examined the relationship of abstinence-induced changes in the RAI with alterations in subjective, behavioral, and neural functions. We included 37 healthy smoking volunteers, aged 19 to 61 years, for analyses. INTERVENTIONS: Twenty-four hours of abstinence vs smoking satiety. MAIN OUTCOMES AND MEASURES: Inter-network connectivity strength (primary) and the relationship with subjective, behavioral, and neural measures of nicotine withdrawal during abstinence vs smoking satiety states (secondary). RESULTS: The RAI was significantly lower in the abstinent compared with the smoking satiety states (left RAI
2013
Hu, Yuzheng; Chen, Xi; Gu, Hong; Yang, Yihong
Resting-state glutamate and GABA concentrations predict task-induced deactivation in the default mode network. Journal Article
In: J Neurosci, vol. 33, no. 47, pp. 18566–18573, 2013, ISSN: 1529-2401 (Electronic); 0270-6474 (Linking).
@article{Hu2013,
title = {Resting-state glutamate and GABA concentrations predict task-induced deactivation in the default mode network.},
author = {Yuzheng Hu and Xi Chen and Hong Gu and Yihong Yang},
url = {https://www.ncbi.nlm.nih.gov/pubmed/24259578},
doi = {10.1523/JNEUROSCI.1973-13.2013},
issn = {1529-2401 (Electronic); 0270-6474 (Linking)},
year = {2013},
date = {2013-11-20},
journal = {J Neurosci},
volume = {33},
number = {47},
pages = {18566--18573},
address = {Neuroimaging Research Branch, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland 21224.},
abstract = {Deactivation of the human brain's default mode network (DMN) is regarded as suppression of endogenous activity to support exogenous task-related processes. This phenomenon has important functional relevance and insufficient DMN deactivation has been implicated in several neuropsychiatric disorders. However, the neurochemical mechanism of the DMN's deactivation remains largely unknown. In the present study, we test the hypothesis that the major excitatory and inhibitory neurotransmitters, glutamate and GABA, respectively, are associated with DMN deactivation. We used magnetic resonance spectroscopy to measure neurotransmitter concentrations in the posterior cingulate cortex/precuneus (PCC/PCu), a key component of the DMN, and functional magnetic resonance imaging to evaluate DMN deactivation induced by an n-back working memory task. Our results demonstrate significant associations of glutamate and GABA with DMN deactivation. Specifically, high regional GABA concentration in the PCC/PCu area is associated with enhanced deactivation induced by the task in the same region, whereas high glutamate concentration is associated with reduced deactivation. Furthermore, the association between GABA and DMN deactivation increases with the cognitive loads. These neurochemical characteristics of DMN deactivation may provide novel insights toward better understanding of the DMN's functions under normal physiological conditions and dysfunctions in neuropsychiatric disorders.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Deactivation of the human brain's default mode network (DMN) is regarded as suppression of endogenous activity to support exogenous task-related processes. This phenomenon has important functional relevance and insufficient DMN deactivation has been implicated in several neuropsychiatric disorders. However, the neurochemical mechanism of the DMN's deactivation remains largely unknown. In the present study, we test the hypothesis that the major excitatory and inhibitory neurotransmitters, glutamate and GABA, respectively, are associated with DMN deactivation. We used magnetic resonance spectroscopy to measure neurotransmitter concentrations in the posterior cingulate cortex/precuneus (PCC/PCu), a key component of the DMN, and functional magnetic resonance imaging to evaluate DMN deactivation induced by an n-back working memory task. Our results demonstrate significant associations of glutamate and GABA with DMN deactivation. Specifically, high regional GABA concentration in the PCC/PCu area is associated with enhanced deactivation induced by the task in the same region, whereas high glutamate concentration is associated with reduced deactivation. Furthermore, the association between GABA and DMN deactivation increases with the cognitive loads. These neurochemical characteristics of DMN deactivation may provide novel insights toward better understanding of the DMN's functions under normal physiological conditions and dysfunctions in neuropsychiatric disorders.
2012
Lu, Hanbing; Zou, Qihong; Gu, Hong; Raichle, Marcus E; Stein, Elliot A; Yang, Yihong
Rat brains also have a default mode network. Journal Article
In: Proc Natl Acad Sci U S A, vol. 109, no. 10, pp. 3979–3984, 2012, ISSN: 1091-6490 (Electronic); 0027-8424 (Linking).
@article{Lu2012,
title = {Rat brains also have a default mode network.},
author = {Hanbing Lu and Qihong Zou and Hong Gu and Marcus E Raichle and Elliot A Stein and Yihong Yang},
url = {https://www.ncbi.nlm.nih.gov/pubmed/22355129},
doi = {10.1073/pnas.1200506109},
issn = {1091-6490 (Electronic); 0027-8424 (Linking)},
year = {2012},
date = {2012-03-06},
journal = {Proc Natl Acad Sci U S A},
volume = {109},
number = {10},
pages = {3979--3984},
address = {Neuroimaging Research Branch, National Institute on Drug Abuse, Intramural Research Programs, National Institutes of Health, Baltimore, MD 21224, USA.},
abstract = {The default mode network (DMN) in humans has been suggested to support a variety of cognitive functions and has been implicated in an array of neuropsychological disorders. However, its function(s) remains poorly understood. We show that rats possess a DMN that is broadly similar to the DMNs of nonhuman primates and humans. Our data suggest that, despite the distinct evolutionary paths between rodent and primate brain, a well-organized, intrinsically coherent DMN appears to be a fundamental feature in the mammalian brain whose primary functions might be to integrate multimodal sensory and affective information to guide behavior in anticipation of changing environmental contingencies.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The default mode network (DMN) in humans has been suggested to support a variety of cognitive functions and has been implicated in an array of neuropsychological disorders. However, its function(s) remains poorly understood. We show that rats possess a DMN that is broadly similar to the DMNs of nonhuman primates and humans. Our data suggest that, despite the distinct evolutionary paths between rodent and primate brain, a well-organized, intrinsically coherent DMN appears to be a fundamental feature in the mammalian brain whose primary functions might be to integrate multimodal sensory and affective information to guide behavior in anticipation of changing environmental contingencies.
2010
Gu, Hong; Salmeron, Betty Jo; Ross, Thomas J; Geng, Xiujuan; Zhan, Wang; Stein, Elliot A; Yang, Yihong
Mesocorticolimbic circuits are impaired in chronic cocaine users as demonstrated by resting-state functional connectivity. Journal Article
In: Neuroimage, vol. 53, no. 2, pp. 593–601, 2010, ISSN: 1095-9572 (Electronic); 1053-8119 (Linking).
@article{Gu2010,
title = {Mesocorticolimbic circuits are impaired in chronic cocaine users as demonstrated by resting-state functional connectivity.},
author = {Hong Gu and Betty Jo Salmeron and Thomas J Ross and Xiujuan Geng and Wang Zhan and Elliot A Stein and Yihong Yang},
url = {https://www.ncbi.nlm.nih.gov/pubmed/20603217},
doi = {10.1016/j.neuroimage.2010.06.066},
issn = {1095-9572 (Electronic); 1053-8119 (Linking)},
year = {2010},
date = {2010-11-01},
journal = {Neuroimage},
volume = {53},
number = {2},
pages = {593--601},
address = {Neuroimaging Research Branch, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA.},
abstract = {Preclinical models have consistently demonstrated the importance of the mesocorticolimbic (MCL) brain reward system in drug dependence, with critical molecular and cellular neuroadaptations identified within these structures following chronic cocaine administration. Cocaine dependent individuals manifest alterations in reward functioning that may relate to changes induced by cocaine or to pre-existing differences related to vulnerability to addiction. The circuit level manifestations of these drug-induced plastic changes and predispositions to drug dependence are poorly understood in preclinical models and virtually unknown in human drug dependence. Using whole-brain resting-state fMRI connectivity analysis with 'seed voxels' placed within individual nodes of the MCL system, we report network-specific functional connectivity strength decreases in cocaine users within distinct circuits of the system, including between ventral tegmental area (VTA) and a region encompassing thalamus/lentiform nucleus/nucleus accumbens, between amygdala and medial prefrontal cortex (mPFC), and between hippocampus and dorsal mPFC. Further, regression analysis on regions showing significant functional connectivity decrease in chronic cocaine users revealed that the circuit strength between VTA and thalamus/lentiform nucleus/nucleus accumbens was negatively correlated with years of cocaine use. This is the first evidence of circuit-related changes in human cocaine dependence and is consistent with the range of cognitive and behavioral disruptions seen in cocaine dependence. As potential circuit level biomarkers of cocaine dependence, these circuit alterations may be usefully applied in treatment development and monitoring treatment outcome.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Preclinical models have consistently demonstrated the importance of the mesocorticolimbic (MCL) brain reward system in drug dependence, with critical molecular and cellular neuroadaptations identified within these structures following chronic cocaine administration. Cocaine dependent individuals manifest alterations in reward functioning that may relate to changes induced by cocaine or to pre-existing differences related to vulnerability to addiction. The circuit level manifestations of these drug-induced plastic changes and predispositions to drug dependence are poorly understood in preclinical models and virtually unknown in human drug dependence. Using whole-brain resting-state fMRI connectivity analysis with 'seed voxels' placed within individual nodes of the MCL system, we report network-specific functional connectivity strength decreases in cocaine users within distinct circuits of the system, including between ventral tegmental area (VTA) and a region encompassing thalamus/lentiform nucleus/nucleus accumbens, between amygdala and medial prefrontal cortex (mPFC), and between hippocampus and dorsal mPFC. Further, regression analysis on regions showing significant functional connectivity decrease in chronic cocaine users revealed that the circuit strength between VTA and thalamus/lentiform nucleus/nucleus accumbens was negatively correlated with years of cocaine use. This is the first evidence of circuit-related changes in human cocaine dependence and is consistent with the range of cognitive and behavioral disruptions seen in cocaine dependence. As potential circuit level biomarkers of cocaine dependence, these circuit alterations may be usefully applied in treatment development and monitoring treatment outcome.
2009
Shin, Wanyong; Gu, Hong; Yang, Yihong
Incidental magnetization transfer contrast by fat saturation preparation pulses in multislice Look-Locker echo planar imaging. Journal Article
In: Magn Reson Med, vol. 62, no. 2, pp. 520–526, 2009, ISSN: 1522-2594 (Electronic); 0740-3194 (Linking).
@article{Shin2009b,
title = {Incidental magnetization transfer contrast by fat saturation preparation pulses in multislice Look-Locker echo planar imaging.},
author = {Wanyong Shin and Hong Gu and Yihong Yang},
url = {https://www.ncbi.nlm.nih.gov/pubmed/19526506},
doi = {10.1002/mrm.22034},
issn = {1522-2594 (Electronic); 0740-3194 (Linking)},
year = {2009},
date = {2009-08-01},
journal = {Magn Reson Med},
volume = {62},
number = {2},
pages = {520--526},
address = {Neuroimaging Research Branch, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA. shinwa@nida.nih.gov},
abstract = {In this study, it is demonstrated that fat saturation (FS) preparation (prep) pulses generate incidental magnetization transfer contrast (MTC) in multislice Look-Locker (LL) imaging. It is shown that frequency-selective FS prep pulses can invoke MTC through the exchange between free and motion-restricted protons. Simulation reveals that the fractional signal loss by these MTC effects is more severe for smaller flip angles (FAs), shorter repetition times (TRs), and greater number of slices (SN). These incidental MTC effects result in a signal attenuation at a steady state (up to 30%) and a T(1) measurement bias (up to 20%) when using inversion recovery (IR) LL echo-planar imaging (EPI) sequences. Furthermore, it is shown that water-selective MRI using binomial pulses has the potential to minimize the signal attenuation and provide unbiased T(1) measurement without fat artifacts in MR images.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
In this study, it is demonstrated that fat saturation (FS) preparation (prep) pulses generate incidental magnetization transfer contrast (MTC) in multislice Look-Locker (LL) imaging. It is shown that frequency-selective FS prep pulses can invoke MTC through the exchange between free and motion-restricted protons. Simulation reveals that the fractional signal loss by these MTC effects is more severe for smaller flip angles (FAs), shorter repetition times (TRs), and greater number of slices (SN). These incidental MTC effects result in a signal attenuation at a steady state (up to 30%) and a T(1) measurement bias (up to 20%) when using inversion recovery (IR) LL echo-planar imaging (EPI) sequences. Furthermore, it is shown that water-selective MRI using binomial pulses has the potential to minimize the signal attenuation and provide unbiased T(1) measurement without fat artifacts in MR images.
Wu, Changwei W; Gu, Hong; Lu, Hanbing; Stein, Elliot A; Chen, Jyh-Horng; Yang, Yihong
Mapping functional connectivity based on synchronized CMRO2 fluctuations during the resting state. Journal Article
In: Neuroimage, vol. 45, no. 3, pp. 694–701, 2009, ISSN: 1095-9572 (Electronic); 1053-8119 (Linking).
@article{Wu:2009aa,
title = {Mapping functional connectivity based on synchronized CMRO2 fluctuations during the resting state.},
author = {Changwei W Wu and Hong Gu and Hanbing Lu and Elliot A Stein and Jyh-Horng Chen and Yihong Yang},
url = {https://www.ncbi.nlm.nih.gov/pubmed/19280693},
issn = {1095-9572 (Electronic); 1053-8119 (Linking)},
year = {2009},
date = {2009-04-15},
journal = {Neuroimage},
volume = {45},
number = {3},
pages = {694--701},
address = {Neuroimaging Research Branch, National Institute on Drug Abuse, NIH, Baltimore, MD 21224, USA.},
abstract = {Synchronized low-frequency fluctuations in the resting state functional MRI (fMRI) signal have been suggested to be associated with functional connectivity in brain networks. However, the underlying mechanism of this connectivity is still poorly understood, with the synchronized fluctuations could either originate from hemodynamic oscillations or represent true neuronal signaling. To better interpret the resting signal, in the current work, we examined spontaneous fluctuations at the level of cerebral metabolic rate of oxygenation (CMRO2), an index reflecting regional oxygen consumption and metabolism, and thus less sensitive to vascular dynamics. The CMRO2 signal was obtained based on a biophysical model with data acquired from simultaneous blood oxygenation level dependent (BOLD) and perfusion signals. CMRO2-based functional connectivity maps were generated in three brain networks: visual, default-mode, and hippocampus. Experiments were performed on twelve healthy participants during 'resting state' and as a comparison, with a visual task. CMRO2 signals in each of the above mentioned brain networks showed significant correlations. Functional connectivity maps from the CMRO2 signal are, in general, similar to those from BOLD and perfusion. In addition, we demonstrated that the three parameters (M, alpha and beta) in the biophysical model for calculating CMRO2 have negligible effects on the determination of the CMRO2-based connectivity strength. This study provides evidence that the spontaneous fluctuations in fMRI at rest likely originate from dynamic changes of cerebral metabolism reflecting neuronal activity.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Synchronized low-frequency fluctuations in the resting state functional MRI (fMRI) signal have been suggested to be associated with functional connectivity in brain networks. However, the underlying mechanism of this connectivity is still poorly understood, with the synchronized fluctuations could either originate from hemodynamic oscillations or represent true neuronal signaling. To better interpret the resting signal, in the current work, we examined spontaneous fluctuations at the level of cerebral metabolic rate of oxygenation (CMRO2), an index reflecting regional oxygen consumption and metabolism, and thus less sensitive to vascular dynamics. The CMRO2 signal was obtained based on a biophysical model with data acquired from simultaneous blood oxygenation level dependent (BOLD) and perfusion signals. CMRO2-based functional connectivity maps were generated in three brain networks: visual, default-mode, and hippocampus. Experiments were performed on twelve healthy participants during 'resting state' and as a comparison, with a visual task. CMRO2 signals in each of the above mentioned brain networks showed significant correlations. Functional connectivity maps from the CMRO2 signal are, in general, similar to those from BOLD and perfusion. In addition, we demonstrated that the three parameters (M, alpha and beta) in the biophysical model for calculating CMRO2 have negligible effects on the determination of the CMRO2-based connectivity strength. This study provides evidence that the spontaneous fluctuations in fMRI at rest likely originate from dynamic changes of cerebral metabolism reflecting neuronal activity.
Geng, Xiujuan; Christensen, Gary E; Gu, Hong; Ross, Thomas J; Yang, Yihong
Implicit reference-based group-wise image registration and its application to structural and functional MRI. Journal Article
In: Neuroimage, vol. 47, no. 4, pp. 1341–1351, 2009, ISSN: 1095-9572 (Electronic); 1053-8119 (Linking).
@article{Geng2009,
title = {Implicit reference-based group-wise image registration and its application to structural and functional MRI.},
author = {Xiujuan Geng and Gary E Christensen and Hong Gu and Thomas J Ross and Yihong Yang},
url = {https://www.ncbi.nlm.nih.gov/pubmed/19371788},
doi = {10.1016/j.neuroimage.2009.04.024},
issn = {1095-9572 (Electronic); 1053-8119 (Linking)},
year = {2009},
date = {2009-04-14},
urldate = {2009-04-14},
journal = {Neuroimage},
volume = {47},
number = {4},
pages = {1341--1351},
address = {Neuroimaging Research Branch, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA. gengx@nida.nih.gov},
abstract = {In this study, an implicit reference group-wise (IRG) registration with a small deformation, linear elastic model was used to jointly estimate correspondences between a set of MRI images. The performance of pair-wise and group-wise registration algorithms was evaluated for spatial normalization of structural and functional MRI data. Traditional spatial normalization is accomplished by group-to-reference (G2R) registration in which a group of images are registered pair-wise to a reference image. G2R registration is limited due to bias associated with selecting a reference image. In contrast, implicit reference group-wise (IRG) registration estimates correspondences between a group of images by jointly registering the images to an implicit reference corresponding to the group average. The implicit reference is estimated during IRG registration eliminating the bias associated with selecting a specific reference image. Registration performance was evaluated using segmented T1-weighted magnetic resonance images from the Nonrigid Image Registration Evaluation Project (NIREP), DTI and fMRI images. Implicit reference pair-wise (IRP) registration-a special case of IRG registration for two images-is shown to produce better relative overlap than IRG for pair-wise registration using the same small deformation, linear elastic registration model. However, IRP-G2R registration is shown to have significant transitivity error, i.e., significant inconsistencies between correspondences defined by different pair-wise transformations. In contrast, IRG registration produces consistent correspondence between images in a group at the cost of slightly reduced pair-wise RO accuracy compared to IRP-G2R. IRG spatial normalization of the fractional anisotropy (FA) maps of DTI is shown to have smaller FA variance compared with G2R methods using the same elastic registration model. Analyses of fMRI data sets with sensorimotor and visual tasks show that IRG registration, on average, increases the statistical detectability of brain activation compared to G2R registration.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
In this study, an implicit reference group-wise (IRG) registration with a small deformation, linear elastic model was used to jointly estimate correspondences between a set of MRI images. The performance of pair-wise and group-wise registration algorithms was evaluated for spatial normalization of structural and functional MRI data. Traditional spatial normalization is accomplished by group-to-reference (G2R) registration in which a group of images are registered pair-wise to a reference image. G2R registration is limited due to bias associated with selecting a reference image. In contrast, implicit reference group-wise (IRG) registration estimates correspondences between a group of images by jointly registering the images to an implicit reference corresponding to the group average. The implicit reference is estimated during IRG registration eliminating the bias associated with selecting a specific reference image. Registration performance was evaluated using segmented T1-weighted magnetic resonance images from the Nonrigid Image Registration Evaluation Project (NIREP), DTI and fMRI images. Implicit reference pair-wise (IRP) registration-a special case of IRG registration for two images-is shown to produce better relative overlap than IRG for pair-wise registration using the same small deformation, linear elastic registration model. However, IRP-G2R registration is shown to have significant transitivity error, i.e., significant inconsistencies between correspondences defined by different pair-wise transformations. In contrast, IRG registration produces consistent correspondence between images in a group at the cost of slightly reduced pair-wise RO accuracy compared to IRP-G2R. IRG spatial normalization of the fractional anisotropy (FA) maps of DTI is shown to have smaller FA variance compared with G2R methods using the same elastic registration model. Analyses of fMRI data sets with sensorimotor and visual tasks show that IRG registration, on average, increases the statistical detectability of brain activation compared to G2R registration.
Shin, Wanyong; Gu, Hong; Yang, Yihong
In: Magn Reson Med, vol. 61, no. 4, pp. 899–906, 2009, ISSN: 1522-2594 (Electronic); 0740-3194 (Linking).
@article{Shin2009,
title = {Fast high-resolution T1 mapping using inversion-recovery Look-Locker echo-planar imaging at steady state: optimization for accuracy and reliability.},
author = {Wanyong Shin and Hong Gu and Yihong Yang},
url = {https://www.ncbi.nlm.nih.gov/pubmed/19195021},
doi = {10.1002/mrm.21836},
issn = {1522-2594 (Electronic); 0740-3194 (Linking)},
year = {2009},
date = {2009-04-01},
journal = {Magn Reson Med},
volume = {61},
number = {4},
pages = {899--906},
address = {Neuroimaging Research Branch, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland 21224, USA. shinwa@mail.nih.gov},
abstract = {A fast T(1) measurement sequence using inversion recovery Look-Locker echo-planar imaging at steady state (IR LL-EPI SS) is presented. Delay time for a full magnetization recovery is not required in the sequence, saving acquisition time significantly for high-resolution T(1) mapping. Imaging parameters of the IR LL-EPI SS sequence were optimized to minimize the bias from the excitation pulses imperfection and to maximize the accuracy and reliability of T(1) measurements, which are critical for its applications. Compared with the conventional inversion recovery Look-Locker echo-planar imaging (IR LL-EPI) sequence, IR LL-EPI SS method preserves similar accuracy and reliability, while saving 20% in acquisition time. Optimized IR LL-EPI SS provided quantitative T(1) mapping with 1 x 1 x 4 mm(3) resolution and whole-brain coverage (28 slices) in approximately 4 min.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
A fast T(1) measurement sequence using inversion recovery Look-Locker echo-planar imaging at steady state (IR LL-EPI SS) is presented. Delay time for a full magnetization recovery is not required in the sequence, saving acquisition time significantly for high-resolution T(1) mapping. Imaging parameters of the IR LL-EPI SS sequence were optimized to minimize the bias from the excitation pulses imperfection and to maximize the accuracy and reliability of T(1) measurements, which are critical for its applications. Compared with the conventional inversion recovery Look-Locker echo-planar imaging (IR LL-EPI) sequence, IR LL-EPI SS method preserves similar accuracy and reliability, while saving 20% in acquisition time. Optimized IR LL-EPI SS provided quantitative T(1) mapping with 1 x 1 x 4 mm(3) resolution and whole-brain coverage (28 slices) in approximately 4 min.
Hong, Elliot L; Gu, Hong; Yang, Yihong; Ross, Thomas J; Salmeron, Betty Jo; Buchholz, Brittany; Thaker, Gunvant K; Stein, Elliot A
Association of nicotine addiction and nicotine's actions with separate cingulate cortex functional circuits. Journal Article
In: Arch Gen Psychiatry, vol. 66, no. 4, pp. 431–441, 2009, ISSN: 1538-3636 (Electronic); 0003-990X (Linking).
@article{Hong2009,
title = {Association of nicotine addiction and nicotine's actions with separate cingulate cortex functional circuits.},
author = {Elliot L Hong and Hong Gu and Yihong Yang and Thomas J Ross and Betty Jo Salmeron and Brittany Buchholz and Gunvant K Thaker and Elliot A Stein},
url = {https://www.ncbi.nlm.nih.gov/pubmed/19349313},
doi = {10.1001/archgenpsychiatry.2009.2},
issn = {1538-3636 (Electronic); 0003-990X (Linking)},
year = {2009},
date = {2009-04-01},
urldate = {2009-04-01},
journal = {Arch Gen Psychiatry},
volume = {66},
number = {4},
pages = {431--441},
address = {Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, PO Box 21247, Baltimore, MD 21228, USA. ehong@mprc.umaryland.edu},
abstract = {CONTEXT: Understanding the mechanisms underlying nicotine addiction to develop more effective treatment is a public health priority. Research consistently shows that nicotine transiently improves multiple cognitive functions. However, using nicotine replacement to treat nicotine addiction yields generally inconsistent results. Although this dichotomy is well known, the reasons are unclear. Imaging studies showed that nicotine challenges almost always involve the cingulate cortex, suggesting that this locus may be a key region associated with nicotine addiction and its treatment. OBJECTIVE: To identify cingulate functional circuits that are associated with the severity of nicotine addiction and study how nicotine affects them by means of region-specific resting-state functional magnetic resonance imaging. DESIGN: Double-blind, placebo-controlled study. SETTING: Outpatient clinics. PARTICIPANTS: Nineteen healthy smokers. INTERVENTION: Single-dose (21- or 35-mg) nicotine patch. MAIN OUTCOME MEASURES: Correlation of nicotine addiction severity and cingulate resting-state functional connectivity, and effects of short-term nicotine administration on connectivity strength. RESULTS: Clearly separated pathways that correlated with nicotine addiction vs nicotine's action were found. The severity of nicotine addiction was associated with the strength of dorsal anterior cingulate cortex (dACC)-striatal circuits, which were not modified by nicotine patch administration. In contrast, short-term nicotine administration enhanced cingulate-neocortical functional connectivity patterns, which may play a role in nicotine's cognition-enhancing properties. CONCLUSIONS: Resting-state dACC-striatum functional connectivity may serve as a circuit-level biomarker for nicotine addiction, and the development of new therapeutic agents aiming to enhance the dACC-striatum functional pathways may be effective for nicotine addiction treatment.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
CONTEXT: Understanding the mechanisms underlying nicotine addiction to develop more effective treatment is a public health priority. Research consistently shows that nicotine transiently improves multiple cognitive functions. However, using nicotine replacement to treat nicotine addiction yields generally inconsistent results. Although this dichotomy is well known, the reasons are unclear. Imaging studies showed that nicotine challenges almost always involve the cingulate cortex, suggesting that this locus may be a key region associated with nicotine addiction and its treatment. OBJECTIVE: To identify cingulate functional circuits that are associated with the severity of nicotine addiction and study how nicotine affects them by means of region-specific resting-state functional magnetic resonance imaging. DESIGN: Double-blind, placebo-controlled study. SETTING: Outpatient clinics. PARTICIPANTS: Nineteen healthy smokers. INTERVENTION: Single-dose (21- or 35-mg) nicotine patch. MAIN OUTCOME MEASURES: Correlation of nicotine addiction severity and cingulate resting-state functional connectivity, and effects of short-term nicotine administration on connectivity strength. RESULTS: Clearly separated pathways that correlated with nicotine addiction vs nicotine's action were found. The severity of nicotine addiction was associated with the strength of dorsal anterior cingulate cortex (dACC)-striatal circuits, which were not modified by nicotine patch administration. In contrast, short-term nicotine administration enhanced cingulate-neocortical functional connectivity patterns, which may play a role in nicotine's cognition-enhancing properties. CONCLUSIONS: Resting-state dACC-striatum functional connectivity may serve as a circuit-level biomarker for nicotine addiction, and the development of new therapeutic agents aiming to enhance the dACC-striatum functional pathways may be effective for nicotine addiction treatment.
2008
Wu, Changwei W; Gu, Hong; Lu, Hanbing; Stein, Elliot A; Chen, Jyh-Horng; Yang, Yihong
Frequency specificity of functional connectivity in brain networks. Journal Article
In: Neuroimage, vol. 42, no. 3, pp. 1047–1055, 2008, ISSN: 1095-9572 (Electronic); 1053-8119 (Linking).
@article{Wu2008,
title = {Frequency specificity of functional connectivity in brain networks.},
author = {Changwei W Wu and Hong Gu and Hanbing Lu and Elliot A Stein and Jyh-Horng Chen and Yihong Yang},
url = {https://www.ncbi.nlm.nih.gov/pubmed/18632288},
doi = {10.1016/j.neuroimage.2008.05.035},
issn = {1095-9572 (Electronic); 1053-8119 (Linking)},
year = {2008},
date = {2008-07-15},
journal = {Neuroimage},
volume = {42},
number = {3},
pages = {1047--1055},
address = {Neuroimaging Research Branch, National Institute on Drug Abuse, NIH, Baltimore, MD 21224, USA.},
abstract = {Synchronized low-frequency spontaneous fluctuations of the functional MRI (fMRI) signal have been shown to be associated with electroencephalography (EEG) power fluctuations in multiple brain networks within predefined frequency bands. However, it remains unclear whether frequency-specific characteristics exist in the resting-state fMRI signal. In this study, fMRI signals in five functional brain networks (sensorimotor, 'default mode', visual, amygdala, and hippocampus) were decomposed into various frequency bands within a low-frequency range (0-0.24 Hz). Results show that the correlations in cortical networks concentrate within ultra-low frequencies (0.01-0.06 Hz) while connections within limbic networks distribute over a wider frequency range (0.01-0.14 Hz), suggesting distinct frequency-specific features in the resting-state fMRI signal within these functional networks. Moreover, the connectivity decay rates along the frequency bands are positively correlated with the physical distances between connected brain regions and seed points. This distance-frequency relationship might be attributed to a larger attenuation of synchrony of brain regions separated with longer distance and/or connected with more synaptic steps.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Synchronized low-frequency spontaneous fluctuations of the functional MRI (fMRI) signal have been shown to be associated with electroencephalography (EEG) power fluctuations in multiple brain networks within predefined frequency bands. However, it remains unclear whether frequency-specific characteristics exist in the resting-state fMRI signal. In this study, fMRI signals in five functional brain networks (sensorimotor, 'default mode', visual, amygdala, and hippocampus) were decomposed into various frequency bands within a low-frequency range (0-0.24 Hz). Results show that the correlations in cortical networks concentrate within ultra-low frequencies (0.01-0.06 Hz) while connections within limbic networks distribute over a wider frequency range (0.01-0.14 Hz), suggesting distinct frequency-specific features in the resting-state fMRI signal within these functional networks. Moreover, the connectivity decay rates along the frequency bands are positively correlated with the physical distances between connected brain regions and seed points. This distance-frequency relationship might be attributed to a larger attenuation of synchrony of brain regions separated with longer distance and/or connected with more synaptic steps.
2007
Lu, Hanbing; Zuo, Yantao; Gu, Hong; Waltz, James A; Zhan, Wang; Scholl, Clara A; Rea, William; Yang, Yihong; Stein, Elliot A
Synchronized delta oscillations correlate with the resting-state functional MRI signal. Journal Article
In: Proc Natl Acad Sci U S A, vol. 104, no. 46, pp. 18265–18269, 2007, ISSN: 1091-6490 (Electronic); 0027-8424 (Linking).
@article{Lu2007,
title = {Synchronized delta oscillations correlate with the resting-state functional MRI signal.},
author = {Hanbing Lu and Yantao Zuo and Hong Gu and James A Waltz and Wang Zhan and Clara A Scholl and William Rea and Yihong Yang and Elliot A Stein},
url = {https://www.ncbi.nlm.nih.gov/pubmed/17991778},
doi = {10.1073/pnas.0705791104},
issn = {1091-6490 (Electronic); 0027-8424 (Linking)},
year = {2007},
date = {2007-11-08},
journal = {Proc Natl Acad Sci U S A},
volume = {104},
number = {46},
pages = {18265--18269},
address = {Neuroimaging Research Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA.},
abstract = {Synchronized low-frequency spontaneous fluctuations of the functional MRI (fMRI) signal have recently been applied to investigate large-scale neuronal networks of the brain in the absence of specific task instructions. However, the underlying neural mechanisms of these fluctuations remain largely unknown. To this end, electrophysiological recordings and resting-state fMRI measurements were conducted in alpha-chloralose-anesthetized rats. Using a seed-voxel analysis strategy, region-specific, anesthetic dose-dependent fMRI resting-state functional connectivity was detected in bilateral primary somatosensory cortex (S1FL) of the resting brain. Cortical electroencephalographic signals were also recorded from bilateral S1FL; a visual cortex locus served as a control site. Results demonstrate that, unlike the evoked fMRI response that correlates with power changes in the gamma bands, the resting-state fMRI signal correlates with the power coherence in low-frequency bands, particularly the delta band. These data indicate that hemodynamic fMRI signal differentially registers specific electrical oscillatory frequency band activity, suggesting that fMRI may be able to distinguish the ongoing from the evoked activity of the brain.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Synchronized low-frequency spontaneous fluctuations of the functional MRI (fMRI) signal have recently been applied to investigate large-scale neuronal networks of the brain in the absence of specific task instructions. However, the underlying neural mechanisms of these fluctuations remain largely unknown. To this end, electrophysiological recordings and resting-state fMRI measurements were conducted in alpha-chloralose-anesthetized rats. Using a seed-voxel analysis strategy, region-specific, anesthetic dose-dependent fMRI resting-state functional connectivity was detected in bilateral primary somatosensory cortex (S1FL) of the resting brain. Cortical electroencephalographic signals were also recorded from bilateral S1FL; a visual cortex locus served as a control site. Results demonstrate that, unlike the evoked fMRI response that correlates with power changes in the gamma bands, the resting-state fMRI signal correlates with the power coherence in low-frequency bands, particularly the delta band. These data indicate that hemodynamic fMRI signal differentially registers specific electrical oscillatory frequency band activity, suggesting that fMRI may be able to distinguish the ongoing from the evoked activity of the brain.
2005
Gu, Hong; Lu, Hanzhang; Ye, Frank Q; Stein, Elliot A; Yang, Yihong
Noninvasive quantification of cerebral blood volume in humans during functional activation. Journal Article
In: Neuroimage, vol. 30, no. 2, pp. 377–387, 2005, ISSN: 1053-8119 (Print); 1053-8119 (Linking).
@article{Gu2005b,
title = {Noninvasive quantification of cerebral blood volume in humans during functional activation.},
author = {Hong Gu and Hanzhang Lu and Frank Q Ye and Elliot A Stein and Yihong Yang},
url = {https://www.ncbi.nlm.nih.gov/pubmed/16278086},
doi = {10.1016/j.neuroimage.2005.09.057},
issn = {1053-8119 (Print); 1053-8119 (Linking)},
year = {2005},
date = {2005-11-07},
journal = {Neuroimage},
volume = {30},
number = {2},
pages = {377--387},
address = {Neuroimaging Research Branch, National Institute on Drug Abuse, National Institutes of Health, 5500 Nathan Shock Dr., Building C, Room 383, Baltimore, MD 21042, USA.},
abstract = {Like cerebral blood flow (CBF), cerebral blood volume (CBV) is an important physiological parameter closely associated with brain activity and thus, noninvasive quantification of CBV during brain activation provides another opportunity to investigate the relationship between neuronal activity and hemodynamic changes. In this paper, a new method is presented that is able to quantify CBV at rest and during activation. Specifically, using an inversion recovery pulse sequence, a set of brain images was collected at various inversion times (TIs). At each TI, functional images were acquired with a block-design visual stimulation paradigm. A biophysical model comprised of multiple tissue components was developed and was utilized for the determination of CBV using the visual stimulation data. MRI experiments on five healthy volunteers showed that CBV was 5.0 +/- 1.5 ml blood/100 ml brain during rest and increased to 6.6 +/- 1.8 ml blood/100 ml brain following visual stimulation. Furthermore, experiments with visual stimulation at two frequencies (2 and 8 Hz) showed that the increases in CBV correlated with the strength of stimulation. This technique, with its ability to measure quantitative CBV values noninvasively, provides a valuable tool for quantifying hemodynamic signals associated with brain activation.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Like cerebral blood flow (CBF), cerebral blood volume (CBV) is an important physiological parameter closely associated with brain activity and thus, noninvasive quantification of CBV during brain activation provides another opportunity to investigate the relationship between neuronal activity and hemodynamic changes. In this paper, a new method is presented that is able to quantify CBV at rest and during activation. Specifically, using an inversion recovery pulse sequence, a set of brain images was collected at various inversion times (TIs). At each TI, functional images were acquired with a block-design visual stimulation paradigm. A biophysical model comprised of multiple tissue components was developed and was utilized for the determination of CBV using the visual stimulation data. MRI experiments on five healthy volunteers showed that CBV was 5.0 +/- 1.5 ml blood/100 ml brain during rest and increased to 6.6 +/- 1.8 ml blood/100 ml brain following visual stimulation. Furthermore, experiments with visual stimulation at two frequencies (2 and 8 Hz) showed that the increases in CBV correlated with the strength of stimulation. This technique, with its ability to measure quantitative CBV values noninvasively, provides a valuable tool for quantifying hemodynamic signals associated with brain activation.
Gu, Hong; Stein, Elliot A; Yang, Yihong
Nonlinear responses of cerebral blood volume, blood flow and blood oxygenation signals during visual stimulation. Journal Article
In: Magn Reson Imaging, vol. 23, no. 9, pp. 921–928, 2005, ISSN: 0730-725X (Print); 0730-725X (Linking).
@article{Gu2005,
title = {Nonlinear responses of cerebral blood volume, blood flow and blood oxygenation signals during visual stimulation.},
author = {Hong Gu and Elliot A Stein and Yihong Yang},
url = {https://www.ncbi.nlm.nih.gov/pubmed/16310107},
doi = {10.1016/j.mri.2005.09.007},
issn = {0730-725X (Print); 0730-725X (Linking)},
year = {2005},
date = {2005-11-03},
journal = {Magn Reson Imaging},
volume = {23},
number = {9},
pages = {921--928},
address = {Neuroimaging Research Branch, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA.},
abstract = {Hemodynamic-based functional magnetic resonance imaging (fMRI) techniques provide a great utility for noninvasive functional brain mapping. However, because the hemodynamic signals reflect underlying neural activity indirectly, characterization of these signals following brain activation is essential for experimental design and data interpretation. In this report, the linear (or nonlinear) responses to neuronal activation of three hemodynamic parameters based primarily on changes of cerebral blood volume, blood flow and blood oxygenation were investigated by testing these hemodynamic responses' additivity property. Using a recently developed fMRI technique that acquires vascular space occupancy (VASO), arterial spin labeling (ASL) perfusion and blood oxygenation level-dependent (BOLD) signals simultaneously, the additivity property of the three hemodynamic responses in human visual cortex was assessed using various visual stimulus durations. Experiments on healthy volunteers showed that all three hemodynamic-weighted signals responded nonlinearly to stimulus durations less than 4 s, with the degree of nonlinearity becoming more severe as the stimulus duration decreased. Vascular space occupancy and ASL perfusion signals showed similar nonlinearity properties, whereas the BOLD signal was the most nonlinear. These data suggest that caution should be taken in the interpretation of hemodynamic-based signals in fMRI.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Hemodynamic-based functional magnetic resonance imaging (fMRI) techniques provide a great utility for noninvasive functional brain mapping. However, because the hemodynamic signals reflect underlying neural activity indirectly, characterization of these signals following brain activation is essential for experimental design and data interpretation. In this report, the linear (or nonlinear) responses to neuronal activation of three hemodynamic parameters based primarily on changes of cerebral blood volume, blood flow and blood oxygenation were investigated by testing these hemodynamic responses' additivity property. Using a recently developed fMRI technique that acquires vascular space occupancy (VASO), arterial spin labeling (ASL) perfusion and blood oxygenation level-dependent (BOLD) signals simultaneously, the additivity property of the three hemodynamic responses in human visual cortex was assessed using various visual stimulus durations. Experiments on healthy volunteers showed that all three hemodynamic-weighted signals responded nonlinearly to stimulus durations less than 4 s, with the degree of nonlinearity becoming more severe as the stimulus duration decreased. Vascular space occupancy and ASL perfusion signals showed similar nonlinearity properties, whereas the BOLD signal was the most nonlinear. These data suggest that caution should be taken in the interpretation of hemodynamic-based signals in fMRI.
Yang, Yihong; Gu, Hong; Silbersweig, David A; Stern, Emily
Simultaneous perfusion and blood-oxygenation-level-dependent measurements using single-shot interleaved z-shim echo-planar imaging. Journal Article
In: Magn Reson Med, vol. 53, no. 5, pp. 1207–1211, 2005, ISSN: 0740-3194 (Print); 0740-3194 (Linking).
@article{Yang2005,
title = {Simultaneous perfusion and blood-oxygenation-level-dependent measurements using single-shot interleaved z-shim echo-planar imaging.},
author = {Yihong Yang and Hong Gu and David A Silbersweig and Emily Stern},
url = {https://www.ncbi.nlm.nih.gov/pubmed/15844153},
doi = {10.1002/mrm.20431},
issn = {0740-3194 (Print); 0740-3194 (Linking)},
year = {2005},
date = {2005-05-01},
journal = {Magn Reson Med},
volume = {53},
number = {5},
pages = {1207--1211},
address = {Functional Neuroimaging Laboratory, Department of Psychiatry, Weill Medical College of Cornell University, New York, New York, USA. yihongyang@intra.nida.nih.gov},
abstract = {Single-shot interleaved z-shim EPI (SSIZS-EPI) was extended to a simultaneous perfusion and blood-oxygenation-level-dependent (BOLD) imaging technique that reduces susceptibility-induced signal loss while preserving rapid image acquisition. Experiments on human brains showed that images acquired with this technique had improved signal-to-noise ratio in the inferior prefrontal, meso-, and lateral-temporal lobes compared with a conventional EPI. Perfusion maps obtained from the SSIZS-EPI images at resting state illustrated substantial signal recovery in these brain areas. Perfusion and BOLD images collected with a sensorimotor paradigm demonstrated the feasibility of the technique to simultaneously measure cerebral blood flow and blood oxygenation signals associated with brain activation. Functional experiments with a neuropsychiatric paradigm showed increased brain activities in the periamygdalar regions in both perfusion and BOLD maps, consistent with a previous H(2) (15)O PET study. The proposed technique, with its advantages of reducing susceptibility artifacts and fast scanning speed, would be useful for obtaining more reliable measurements of functional signals, particularly in the brain regions with field inhomogeneities.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Single-shot interleaved z-shim EPI (SSIZS-EPI) was extended to a simultaneous perfusion and blood-oxygenation-level-dependent (BOLD) imaging technique that reduces susceptibility-induced signal loss while preserving rapid image acquisition. Experiments on human brains showed that images acquired with this technique had improved signal-to-noise ratio in the inferior prefrontal, meso-, and lateral-temporal lobes compared with a conventional EPI. Perfusion maps obtained from the SSIZS-EPI images at resting state illustrated substantial signal recovery in these brain areas. Perfusion and BOLD images collected with a sensorimotor paradigm demonstrated the feasibility of the technique to simultaneously measure cerebral blood flow and blood oxygenation signals associated with brain activation. Functional experiments with a neuropsychiatric paradigm showed increased brain activities in the periamygdalar regions in both perfusion and BOLD maps, consistent with a previous H(2) (15)O PET study. The proposed technique, with its advantages of reducing susceptibility artifacts and fast scanning speed, would be useful for obtaining more reliable measurements of functional signals, particularly in the brain regions with field inhomogeneities.
2004
Yang, Yihong; Gu, Hong; Stein, Elliot A
Simultaneous MRI acquisition of blood volume, blood flow, and blood oxygenation information during brain activation. Journal Article
In: Magn Reson Med, vol. 52, no. 6, pp. 1407–1417, 2004, ISSN: 0740-3194 (Print); 0740-3194 (Linking).
@article{Yang2004,
title = {Simultaneous MRI acquisition of blood volume, blood flow, and blood oxygenation information during brain activation.},
author = {Yihong Yang and Hong Gu and Elliot A Stein},
url = {https://www.ncbi.nlm.nih.gov/pubmed/15562477},
doi = {10.1002/mrm.20302},
issn = {0740-3194 (Print); 0740-3194 (Linking)},
year = {2004},
date = {2004-12-01},
journal = {Magn Reson Med},
volume = {52},
number = {6},
pages = {1407--1417},
address = {Neuroimaging Research Branch, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21042, USA. yihongyang@intra.nida.nih.gov},
abstract = {Simultaneous acquisition of complementary functional hemodynamic indices reflecting different aspects of brain activity would be a valuable tool for functional brain-imaging studies offering enhanced detection power and improved data interpretation. As such, a new MRI technique is presented that is able to achieve concurrent acquisition of three hemodynamic images based primarily on the changes of cerebral blood volume, blood flow, and blood oxygenation, respectively, associated with brain activation. Specifically, an inversion recovery pulse sequence has been designed to measure VASO (vascular space occupancy), ASL (arterial spin labeling) perfusion, and BOLD (blood-oxygenation-level-dependent) signals in a single scan. The MR signal characteristics in this sequence were analyzed, and image parameters were optimized for the simultaneous acquisition of these functional images. The feasibility and efficacy of the new technique were assessed by brain activation experiments with visual stimulation paradigms. Experiments on healthy volunteers showed that this technique provided efficient image acquisition, and thus higher contrast-to-noise ratio per unit time, compared with conventional techniques collecting these functional images separately. In addition, it was demonstrated that the proposed technique was able to be utilized in event-related functional MRI experiments, with potential advantages of obtaining accurate transient information of the activation-induced hemodynamic responses.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Simultaneous acquisition of complementary functional hemodynamic indices reflecting different aspects of brain activity would be a valuable tool for functional brain-imaging studies offering enhanced detection power and improved data interpretation. As such, a new MRI technique is presented that is able to achieve concurrent acquisition of three hemodynamic images based primarily on the changes of cerebral blood volume, blood flow, and blood oxygenation, respectively, associated with brain activation. Specifically, an inversion recovery pulse sequence has been designed to measure VASO (vascular space occupancy), ASL (arterial spin labeling) perfusion, and BOLD (blood-oxygenation-level-dependent) signals in a single scan. The MR signal characteristics in this sequence were analyzed, and image parameters were optimized for the simultaneous acquisition of these functional images. The feasibility and efficacy of the new technique were assessed by brain activation experiments with visual stimulation paradigms. Experiments on healthy volunteers showed that this technique provided efficient image acquisition, and thus higher contrast-to-noise ratio per unit time, compared with conventional techniques collecting these functional images separately. In addition, it was demonstrated that the proposed technique was able to be utilized in event-related functional MRI experiments, with potential advantages of obtaining accurate transient information of the activation-induced hemodynamic responses.
2003
Feng, Hanhua; Gu, Hong; Silbersweig, David; Stern, Emily; Yang, Yihong
Single-shot MR imaging using trapezoidal-gradient-based Lissajous trajectories. Journal Article
In: IEEE Trans Med Imaging, vol. 22, no. 8, pp. 925–932, 2003, ISSN: 0278-0062 (Print); 0278-0062 (Linking).
@article{Feng2003,
title = {Single-shot MR imaging using trapezoidal-gradient-based Lissajous trajectories.},
author = {Hanhua Feng and Hong Gu and David Silbersweig and Emily Stern and Yihong Yang},
url = {https://www.ncbi.nlm.nih.gov/pubmed/12906246},
doi = {10.1109/TMI.2003.815902},
issn = {0278-0062 (Print); 0278-0062 (Linking)},
year = {2003},
date = {2003-08-01},
journal = {IEEE Trans Med Imaging},
volume = {22},
number = {8},
pages = {925--932},
address = {Department of Psychiatry, Weill Medical College of Cornell University, New York, NY 10021, USA.},
abstract = {A novel single-shot trapezoidal-gradient-based Lissajous trajectory is described and implemented on a 3-tesla magnetic resonance (MR) scanner. A feature of this trajectory is that its sampling points are located on a nonequidistant rectangular grid, which permits the usage of one-dimensional optimal algorithms to increase the robustness and speed of image reconstruction. Another advantage of the trajectory is that two images with different effective echo times can be obtained within a single excitation, which might be used for fast T2* mapping, in functional MR imaging scanning of brain activity associated with mental processes. Potential artifacts in reconstructed images were investigated and methods for suppressing these artifacts were developed. Experiments on normal subjects at rest and during brain activation were performed to demonstrate the feasibility of the new sequence.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
A novel single-shot trapezoidal-gradient-based Lissajous trajectory is described and implemented on a 3-tesla magnetic resonance (MR) scanner. A feature of this trajectory is that its sampling points are located on a nonequidistant rectangular grid, which permits the usage of one-dimensional optimal algorithms to increase the robustness and speed of image reconstruction. Another advantage of the trajectory is that two images with different effective echo times can be obtained within a single excitation, which might be used for fast T2* mapping, in functional MR imaging scanning of brain activity associated with mental processes. Potential artifacts in reconstructed images were investigated and methods for suppressing these artifacts were developed. Experiments on normal subjects at rest and during brain activation were performed to demonstrate the feasibility of the new sequence.
Zhan, Wang; Gu, Hong; Xu, Su; Silbersweig, David A; Stern, Emily; Yang, Yihong
Circular spectrum mapping for intravoxel fiber structures based on high angular resolution apparent diffusion coefficients. Journal Article
In: Magn Reson Med, vol. 49, no. 6, pp. 1077–1088, 2003, ISSN: 0740-3194 (Print); 0740-3194 (Linking).
@article{Zhan2003,
title = {Circular spectrum mapping for intravoxel fiber structures based on high angular resolution apparent diffusion coefficients.},
author = {Wang Zhan and Hong Gu and Su Xu and David A Silbersweig and Emily Stern and Yihong Yang},
url = {https://www.ncbi.nlm.nih.gov/pubmed/12768586},
doi = {10.1002/mrm.10484},
issn = {0740-3194 (Print); 0740-3194 (Linking)},
year = {2003},
date = {2003-06-01},
journal = {Magn Reson Med},
volume = {49},
number = {6},
pages = {1077--1088},
address = {Functional Neuroimaging Laboratory, Department of Psychiatry, Weill Medical College of Cornell University, New York, New York, USA.},
abstract = {A method is presented for mapping intravoxel fiber structures using spectral decomposition onto a circular distribution of measured apparent diffusion coefficients (ADCs). The zeroth-, second-, and fourth-order harmonic components of the ADC distribution on the circle spanned by the major and median eigenvectors of the diffusion tensor can be used to provide quantitative indices for isotropic, linear, and fiber-crossing diffusion, respectively. A diffusion-weighted MRI technique with 90 encoding orientations was implemented to estimate the circular ADC distribution and calculate the circular spectrum. A digital phantom was used to simulate various diffusion patterns. Comparisons were made between the circular spectrum and regular DTI-based index maps. The results indicated that the zeroth- and second-order circular spectrum maps exhibited a strong consistency with the DTI-based mean diffusivity and linear indices, respectively, and the fourth-order circular spectrum map was able to identify the fiber crossings. MRI experiments were performed on seven healthy human brains using a 3T scanner. The in vivo fourth-order maps showed significantly higher densities in several brain regions, including the corpus callosum, cingulum bundle, superior longitudinal fasciculus, corticospinal tract, and middle cerebellar peduncle, which indicated the existence of fiber crossings in these regions.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
A method is presented for mapping intravoxel fiber structures using spectral decomposition onto a circular distribution of measured apparent diffusion coefficients (ADCs). The zeroth-, second-, and fourth-order harmonic components of the ADC distribution on the circle spanned by the major and median eigenvectors of the diffusion tensor can be used to provide quantitative indices for isotropic, linear, and fiber-crossing diffusion, respectively. A diffusion-weighted MRI technique with 90 encoding orientations was implemented to estimate the circular ADC distribution and calculate the circular spectrum. A digital phantom was used to simulate various diffusion patterns. Comparisons were made between the circular spectrum and regular DTI-based index maps. The results indicated that the zeroth- and second-order circular spectrum maps exhibited a strong consistency with the DTI-based mean diffusivity and linear indices, respectively, and the fourth-order circular spectrum map was able to identify the fiber crossings. MRI experiments were performed on seven healthy human brains using a 3T scanner. The in vivo fourth-order maps showed significantly higher densities in several brain regions, including the corpus callosum, cingulum bundle, superior longitudinal fasciculus, corticospinal tract, and middle cerebellar peduncle, which indicated the existence of fiber crossings in these regions.
2002
Gu, Hong; Feng, Hanhua; Zhan, Wang; Xu, Su; Silbersweig, David A; Stern, Emily; Yang, Yihong
Single-shot interleaved z-shim EPI with optimized compensation for signal losses due to susceptibility-induced field inhomogeneity at 3 T. Journal Article
In: Neuroimage, vol. 17, no. 3, pp. 1358–1364, 2002, ISSN: 1053-8119 (Print); 1053-8119 (Linking).
@article{Gu2002,
title = {Single-shot interleaved z-shim EPI with optimized compensation for signal losses due to susceptibility-induced field inhomogeneity at 3 T.},
author = {Hong Gu and Hanhua Feng and Wang Zhan and Su Xu and David A Silbersweig and Emily Stern and Yihong Yang},
url = {https://www.ncbi.nlm.nih.gov/pubmed/12414275},
issn = {1053-8119 (Print); 1053-8119 (Linking)},
year = {2002},
date = {2002-11-01},
journal = {Neuroimage},
volume = {17},
number = {3},
pages = {1358--1364},
address = {Functional Neuroimaging Laboratory, Department of Psychiatry, Weill Medical College of Cornell University, New York, New York 10021, USA.},
abstract = {A new single-shot echo-planar imaging (EPI) sequence with interleaved z-shim and optimized compensation for susceptibility-induced signal loss is proposed in this paper. Experiments on human brain demonstrated that the new method is able to regain signal dropout in brain areas with severe susceptibility-induced local gradients, while its image acquisition speed is comparable to that of conventional single-shot EPI techniques. Significant signal-to-noise ratio improvements were demonstrated in the ventral prefrontal and lateral temporal lobes with the new technique compared to a conventional EPI. Brain activation experiments with a bilateral finger-tapping task were performed with intentionally introduced local gradients near the left sensorimotor cortex, by a small gadolinium (Gd)-doped bottle placed on the left side of the head. The results of the functional experiments showed that the interleaved z-shim EPI sequence effectively recovered the signal loss caused by the Gd-doped bottle and reliably detected activation signals in bilateral sensorimotor regions, while the activation signals on the left side diminished considerably in a conventional EPI technique. The new technique, with the capability of reducing susceptibility artifacts and rapid scanning speed, may be particularly useful for event-related functional MRI experiments in the base of the brain, which are of great importance in neuropsychiatric studies.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
A new single-shot echo-planar imaging (EPI) sequence with interleaved z-shim and optimized compensation for susceptibility-induced signal loss is proposed in this paper. Experiments on human brain demonstrated that the new method is able to regain signal dropout in brain areas with severe susceptibility-induced local gradients, while its image acquisition speed is comparable to that of conventional single-shot EPI techniques. Significant signal-to-noise ratio improvements were demonstrated in the ventral prefrontal and lateral temporal lobes with the new technique compared to a conventional EPI. Brain activation experiments with a bilateral finger-tapping task were performed with intentionally introduced local gradients near the left sensorimotor cortex, by a small gadolinium (Gd)-doped bottle placed on the left side of the head. The results of the functional experiments showed that the interleaved z-shim EPI sequence effectively recovered the signal loss caused by the Gd-doped bottle and reliably detected activation signals in bilateral sensorimotor regions, while the activation signals on the left side diminished considerably in a conventional EPI technique. The new technique, with the capability of reducing susceptibility artifacts and rapid scanning speed, may be particularly useful for event-related functional MRI experiments in the base of the brain, which are of great importance in neuropsychiatric studies.
Yang, Yihong; Gu, Hong; Zhan, Wang; Xu, Su; Silbersweig, David A; Stern, Emily
In: Magn Reson Med, vol. 48, no. 2, pp. 278–289, 2002, ISSN: 0740-3194 (Print); 0740-3194 (Linking).
@article{Yang2002,
title = {Simultaneous perfusion and BOLD imaging using reverse spiral scanning at 3T: characterization of functional contrast and susceptibility artifacts.},
author = {Yihong Yang and Hong Gu and Wang Zhan and Su Xu and David A Silbersweig and Emily Stern},
url = {https://www.ncbi.nlm.nih.gov/pubmed/12210936},
doi = {10.1002/mrm.10196},
issn = {0740-3194 (Print); 0740-3194 (Linking)},
year = {2002},
date = {2002-08-01},
journal = {Magn Reson Med},
volume = {48},
number = {2},
pages = {278--289},
address = {Functional Neuroimaging Laboratory, Department of Psychiatry, Weill Medical College of Cornell University, New York, New York 10021, USA. yihong@hanazono.med.cornell.edu},
abstract = {Reverse spiral scanning with arterial spin-labeling was developed at 3T to simultaneously detect perfusion and BOLD signals in the brain by subtracting or adding the control and labeled images, respectively, in the same dataset. BOLD contrast was improved with the longer effective echo time achieved in the reverse spiral scan compared to conventional forward spiral scans. Susceptibility artifacts near air-tissue interfaces in the brain were substantially reduced in the reverse spiral images due to their early data acquisition time and, hence, less signal attenuation. Brain activation experiments with the reverse spiral scan were performed on normal subjects and were compared to forward spiral imaging in the same subjects. The experiments demonstrated that reverse spiral imaging was able to detect perfusion and BOLD signals simultaneously and reliably, even in the brain regions with severe susceptibility-induced local gradients, while forward spiral scans were either not optimal for detecting the two functional signals at the same time or were vulnerable to susceptibility artifacts.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Reverse spiral scanning with arterial spin-labeling was developed at 3T to simultaneously detect perfusion and BOLD signals in the brain by subtracting or adding the control and labeled images, respectively, in the same dataset. BOLD contrast was improved with the longer effective echo time achieved in the reverse spiral scan compared to conventional forward spiral scans. Susceptibility artifacts near air-tissue interfaces in the brain were substantially reduced in the reverse spiral images due to their early data acquisition time and, hence, less signal attenuation. Brain activation experiments with the reverse spiral scan were performed on normal subjects and were compared to forward spiral imaging in the same subjects. The experiments demonstrated that reverse spiral imaging was able to detect perfusion and BOLD signals simultaneously and reliably, even in the brain regions with severe susceptibility-induced local gradients, while forward spiral scans were either not optimal for detecting the two functional signals at the same time or were vulnerable to susceptibility artifacts.
Zhan, Wang; Gu, Hong; Silbersweig, David A; Stern, Emily; Yang, Yihong
In: Magn Reson Imaging, vol. 20, no. 6, pp. 487–494, 2002, ISSN: 0730-725X (Print); 0730-725X (Linking).
@article{Zhan2002,
title = {Inversion profiles of adiabatic inversion pulses for flowing spins: the effects on labeling efficiency and labeling accuracy in perfusion imaging with pulsed arterial spin-labeling.},
author = {Wang Zhan and Hong Gu and David A Silbersweig and Emily Stern and Yihong Yang},
url = {https://www.ncbi.nlm.nih.gov/pubmed/12361796},
issn = {0730-725X (Print); 0730-725X (Linking)},
year = {2002},
date = {2002-07-01},
journal = {Magn Reson Imaging},
volume = {20},
number = {6},
pages = {487--494},
address = {Functional Neuroimaging Laboratory, Department of Psychiatry, Weill Medical College of Cornell University, New York, NY 10021, USA.},
abstract = {The inversion profile of adiabatic inversion pulses is essential to the accuracy of perfusion measurement with pulsed arterial spin-labeling (ASL). In this paper, the inversion profiles for flowing spins were investigated using a numerical solution of the modified Bloch equations including a term for moving spins. Inversion profiles for spins flowing at a constant or varying velocity were examined for hyperbolic secant (HS) and frequency-offset corrected inversion (FOCI) pulses. Distortions of the inversion profiles were found for both pulses with spins flowing within physiological velocity range. The effects of the distorted profiles on labeling efficiency and labeling accuracy in the application of pulsed ASL perfusion imaging were analyzed. These effects should be taken into account in ASL techniques, in order to obtain robust and accurate perfusion measurements.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The inversion profile of adiabatic inversion pulses is essential to the accuracy of perfusion measurement with pulsed arterial spin-labeling (ASL). In this paper, the inversion profiles for flowing spins were investigated using a numerical solution of the modified Bloch equations including a term for moving spins. Inversion profiles for spins flowing at a constant or varying velocity were examined for hyperbolic secant (HS) and frequency-offset corrected inversion (FOCI) pulses. Distortions of the inversion profiles were found for both pulses with spins flowing within physiological velocity range. The effects of the distorted profiles on labeling efficiency and labeling accuracy in the application of pulsed ASL perfusion imaging were analyzed. These effects should be taken into account in ASL techniques, in order to obtain robust and accurate perfusion measurements.
2001
Gu, H; Engelien, W; Feng, H; Silbersweig, D A; Stern, E; Yang, Y
Mapping transient, randomly occurring neuropsychological events using independent component analysis. Journal Article
In: Neuroimage, vol. 14, no. 6, pp. 1432–1443, 2001, ISSN: 1053-8119 (Print); 1053-8119 (Linking).
@article{Gu2001,
title = {Mapping transient, randomly occurring neuropsychological events using independent component analysis.},
author = {H Gu and W Engelien and H Feng and D A Silbersweig and E Stern and Y Yang},
url = {https://www.ncbi.nlm.nih.gov/pubmed/11707099},
doi = {10.1006/nimg.2001.0914},
issn = {1053-8119 (Print); 1053-8119 (Linking)},
year = {2001},
date = {2001-12-01},
journal = {Neuroimage},
volume = {14},
number = {6},
pages = {1432--1443},
address = {Functional Neuroimaging Laboratory, Department of Psychiatry, Weill Medical College, Cornell University, New York, New York 10021, USA.},
abstract = {The feasibility of mapping transient, randomly occurring neuropsychological events using independent component analysis (ICA) was evaluated in an auditory sentence-monitoring fMRI experiment, in which prerecorded short sentences of random content were presented in varying temporal patterns. The efficacy of ICA on fMRI data with such temporal characteristics was assessed by a series of simulation studies, as well as by human activation studies. The effects of contrast-to-noise ratio level, spatially varied hemodynamic response within a brain region, time lags of the responses among brain regions, and different simulated activation locations on the ICA were investigated in the simulations. Component maps obtained from the auditory sentence-monitoring experiments in each subject using ICA showed distinct activation in bilateral auditory and language cortices, as well as in superior sensorimotor cortices, consistent with previous PET studies. The associated time courses in the activated brain regions matched well to the timing of the sentence presentation, as evidenced by the recorded button-press response signals. Methods for ICA component ordering that may rank highly the components of primary interest in such experiments were developed. The simulation results characterized the performance of ICA under various conditions and may provide useful information for experimental design and data interpretation.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The feasibility of mapping transient, randomly occurring neuropsychological events using independent component analysis (ICA) was evaluated in an auditory sentence-monitoring fMRI experiment, in which prerecorded short sentences of random content were presented in varying temporal patterns. The efficacy of ICA on fMRI data with such temporal characteristics was assessed by a series of simulation studies, as well as by human activation studies. The effects of contrast-to-noise ratio level, spatially varied hemodynamic response within a brain region, time lags of the responses among brain regions, and different simulated activation locations on the ICA were investigated in the simulations. Component maps obtained from the auditory sentence-monitoring experiments in each subject using ICA showed distinct activation in bilateral auditory and language cortices, as well as in superior sensorimotor cortices, consistent with previous PET studies. The associated time courses in the activated brain regions matched well to the timing of the sentence presentation, as evidenced by the recorded button-press response signals. Methods for ICA component ordering that may rank highly the components of primary interest in such experiments were developed. The simulation results characterized the performance of ICA under various conditions and may provide useful information for experimental design and data interpretation.
2000
Yang, Y; Engelien, W; Xu, S; Gu, H; Silbersweig, D A; Stern, E
In: Magn Reson Med, vol. 44, no. 5, pp. 680–685, 2000, ISSN: 0740-3194 (Print); 0740-3194 (Linking).
@article{Yang2000,
title = {Transit time, trailing time, and cerebral blood flow during brain activation: measurement using multislice, pulsed spin-labeling perfusion imaging.},
author = {Y Yang and W Engelien and S Xu and H Gu and D A Silbersweig and E Stern},
url = {https://www.ncbi.nlm.nih.gov/pubmed/11064401},
issn = {0740-3194 (Print); 0740-3194 (Linking)},
year = {2000},
date = {2000-11-01},
journal = {Magn Reson Med},
volume = {44},
number = {5},
pages = {680--685},
address = {Functional Neuroimaging Laboratory, Department of Psychiatry, Weill Medical College of Cornell University, New York, New York 10021, USA. yihong@hanazono.med.cornell.edu},
abstract = {Transit time and trailing time in pulsed spin-labeling perfusion imaging are likely to be modulated by local blood flow changes, such as those accompanying brain activation. The majority of transit/trailing time is due to the passage of the tagged blood bolus through the arteriole/capillary regions, because of lower blood flow velocity in these regions. Changes of transit/trailing time during activation could affect the quantification of CBF in functional neuroimaging studies, and are therefore important to characterize. In this work, the measurement of transit and trailing times and CBF during sensorimotor activation using multislice perfusion imaging with pulsed arterial spin-labeling is described. While CBF elevated dramatically ( thick similar80.7%) during the sensorimotor activation, sizable reductions of transit time ( thick similar0.11 sec) and trailing time ( thick similar0.26 sec) were observed. Transit and trailing times were dependent on the distances from the leading and trailing edges of the tagged blood bolus to the location of the imaging slices. The effects of transit/trailing time changes on CBF quantification during brain activation were analyzed by simulation studies. Significant errors can be caused in the estimation of CBF if such changes of transit/trailing time are not taken into account.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Transit time and trailing time in pulsed spin-labeling perfusion imaging are likely to be modulated by local blood flow changes, such as those accompanying brain activation. The majority of transit/trailing time is due to the passage of the tagged blood bolus through the arteriole/capillary regions, because of lower blood flow velocity in these regions. Changes of transit/trailing time during activation could affect the quantification of CBF in functional neuroimaging studies, and are therefore important to characterize. In this work, the measurement of transit and trailing times and CBF during sensorimotor activation using multislice perfusion imaging with pulsed arterial spin-labeling is described. While CBF elevated dramatically ( thick similar80.7%) during the sensorimotor activation, sizable reductions of transit time ( thick similar0.11 sec) and trailing time ( thick similar0.26 sec) were observed. Transit and trailing times were dependent on the distances from the leading and trailing edges of the tagged blood bolus to the location of the imaging slices. The effects of transit/trailing time changes on CBF quantification during brain activation were analyzed by simulation studies. Significant errors can be caused in the estimation of CBF if such changes of transit/trailing time are not taken into account.
