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Ren J, Yu F, Greenberg BM. ATP line splitting in association with reduced intracellular magnesium and pH: a brain 31 P MR spectroscopic imaging (MRSI) study of pediatric patients with myelin oligodendrocyte glycoprotein antibody-associated disorders (MOGADs). NMR IN BIOMEDICINE 2023; 36:e4836. [PMID: 36150743 DOI: 10.1002/nbm.4836] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2022] [Revised: 09/06/2022] [Accepted: 09/18/2022] [Indexed: 06/16/2023]
Abstract
Over the past four decades, ATP, the obligatory energy molecule for keeping all cells alive and functioning, has been thought to contribute only one set of signals in brain 31 P MR spectra. Here we report for the first time the observation of two separate β-ATP peaks in brain spectra acquired from patients with myelin oligodendrocyte glycoprotein antibody-associated disorders (MOGADs) using 3D MRSI at 7 T. In voxel spectra with β-ATP line splitting, these two peaks are separated by 0.46 ± 0.18 ppm (n = 6). Spectral lineshape analysis indicates that the upper field β-ATP peak is smaller in relative intensity (24 ± 11% versus 76 ± 11%), and narrower in linewidth (56.8 ± 10.3 versus 41.2 ± 10.3 Hz) than the downfield one. Data analysis also reveals a similar line splitting for the intracellular inorganic phosphate (Pi ) signal, which is characterized by two components with a smaller separation (0.16 ± 0.09 ppm) and an intensity ratio (26 ± 7%:74 ± 7%) comparable to that of β-ATP. While the major components of Pi and β-ATP correspond to a neutral intracellular pH (6.99 ± 0.01) and a free Mg2+ level (0.18 ± 0.02 mM, by Iotti's conversion formula) as found in healthy subjects, their minor counterparts relate to a slightly acidic pH (6.86 ± 0.07) and a 50% lower [Mg2+ ] (0.09 ± 0.02 mM), respectively. Data correlation between β-ATP and Pi signals appears to suggest an association between an increased [H+ ] and a reduced [Mg2+ ] in MOGAD patients.
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Affiliation(s)
- Jimin Ren
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX, USA
- Department of Radiology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Fang Yu
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX, USA
- Department of Radiology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Benjamin M Greenberg
- Department of Neurology, University of Texas Southwestern Medical Center, Dallas, TX, USA
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Zhang Y, Du W, Yin Y, Li H, Liu Z, Yang Y, Han Y, Gao JH. Impaired cerebral vascular and metabolic responses to parametric N-back tasks in subjective cognitive decline. J Cereb Blood Flow Metab 2021; 41:2743-2755. [PMID: 33951945 PMCID: PMC8504959 DOI: 10.1177/0271678x211012153] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Previous studies reported abnormally increased and/or decreased blood oxygen level-dependent (BOLD) activations during functional tasks in subjective cognitive decline (SCD). The neurophysiological basis underlying these functional aberrations remains debated. This study aims to investigate vascular and metabolic responses and their dependence on cognitive processing loads during functional tasks in SCD. Twenty-one SCD and 18 control subjects performed parametric N-back working-memory tasks during MRI scans. Task-evoked percentage changes (denoted as δ) in cerebral blood volume (δCBV), cerebral blood flow (δCBF), BOLD signal (δBOLD) and cerebral metabolic rate of oxygen (δCMRO2) were evaluated. In the frontal lobe, trends of decreased δCBV, δCBF and δCMRO2 and increased δBOLD were observed in SCD compared with control subjects under lower loads, and these trends increased to significant differences under the 3-back load. δCBF was significantly correlated with δCMRO2 in controls, but not in SCD subjects. As N-back loads increased, the differences between SCD and control subjects in δCBF and δCMRO2 tended to enlarge. In the parietal lobe, no significant between-group difference was observed. Our findings suggested that impaired vascular and metabolic responses to functional tasks occurred in the frontal lobe of SCD, which contributed to unusual BOLD hyperactivation and was modulated by cognitive processing loads.
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Affiliation(s)
- Yaoyu Zhang
- Institute for Medical Imaging Technology, School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China.,Center for MRI Research, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China
| | - Wenying Du
- Department of Neurology, Xuanwu Hospital of Capital Medical University, Beijing, China
| | - Yayan Yin
- Department of Radiology, Xuanwu Hospital of Capital Medical University, Beijing, China
| | - Huanjie Li
- School of Biomedical Engineering, Dalian University of Technology, Dalian, China
| | - Zhaowei Liu
- Center for Excellence in Brain Science and Intelligence Technology (Institute of Neuroscience), Chinese Academy of Sciences, Shanghai, China
| | - Yang Yang
- Center for MRI Research, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China
| | - Ying Han
- Department of Neurology, Xuanwu Hospital of Capital Medical University, Beijing, China.,Biomedical Engineering Institute, Hainan University, Haikou, China.,Center of Alzheimer's Disease, Beijing Institute for Brain Disorders, Beijing, China.,National Clinical Research Center for Geriatric Disorders, Beijing, China
| | - Jia-Hong Gao
- Center for MRI Research, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China.,Beijing City Key Lab for Medical Physics and Engineering, Institute of Heavy Ion Physics, School of Physics, Peking University, Beijing, China.,McGovern Institute for Brain Research, Peking University, Beijing, China
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Zhang Y, Yin Y, Li H, Gao JH. Measurement of CMRO 2 and its relationship with CBF in hypoxia with an extended calibrated BOLD method. J Cereb Blood Flow Metab 2020; 40:2066-2080. [PMID: 31665954 PMCID: PMC7786846 DOI: 10.1177/0271678x19885124] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMRO2) are physiological parameters that not only reflect brain health and disease but also jointly contribute to blood oxygen level-dependent (BOLD) signals. Nevertheless, unsolved issues remain concerning the CBF-CMRO2 relationship in the working brain under various oxygen conditions. In particular, the CMRO2 responses to functional tasks in hypoxia are less studied. We extended the calibrated BOLD model to incorporate CMRO2 measurements in hypoxia. The extended model, which was cross-validated with a multicompartment BOLD model, considers the influences of the reduced arterial saturation level and increased baseline cerebral blood volume (CBV) and deoxyhemoglobin concentration on the changes of BOLD signals in hypoxia. By implementing a pulse sequence to simultaneously acquire the CBV-, CBF- and BOLD-weighted signals, we investigated the effects of mild hypoxia on the CBF and CMRO2 responses to graded visual stimuli. Compared with normoxia, mild hypoxia caused significant alterations in both the amplitude and the trend of the CMRO2 responses but did not impact the corresponding CBF responses. Our observations suggested that the flow-metabolism coupling strategies in the brain during mild hypoxia were different from those during normoxia.
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Affiliation(s)
- Yaoyu Zhang
- Center for MRI Research, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China.,Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China
| | - Yayan Yin
- Center for MRI Research, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China.,Beijing City Key Lab for Medical Physics and Engineering, Institute of Heavy Ion Physics, School of Physics, Peking University, Beijing, China
| | - Huanjie Li
- School of Biomedical Engineering, Dalian University of Technology, Dalian, China
| | - Jia-Hong Gao
- Center for MRI Research, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China.,Beijing City Key Lab for Medical Physics and Engineering, Institute of Heavy Ion Physics, School of Physics, Peking University, Beijing, China.,McGovern Institute for Brain Research, Peking University, Beijing, China
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Huber L, Ivanov D, Handwerker DA, Marrett S, Guidi M, Uludağ K, Bandettini PA, Poser BA. Techniques for blood volume fMRI with VASO: From low-resolution mapping towards sub-millimeter layer-dependent applications. Neuroimage 2018; 164:131-143. [PMID: 27867088 PMCID: PMC5436958 DOI: 10.1016/j.neuroimage.2016.11.039] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Revised: 10/24/2016] [Accepted: 11/14/2016] [Indexed: 12/24/2022] Open
Abstract
Quantitative cerebral blood volume (CBV) fMRI has the potential to overcome several specific limitations of BOLD fMRI. It provides direct physiological interpretability and promises superior localization specificity in applications of sub-millimeter resolution fMRI applications at ultra-high magnetic fields (7T and higher). Non-invasive CBV fMRI using VASO (vascular space occupancy), however, is inherently limited with respect to its data acquisition efficiency, restricting its imaging coverage and achievable spatial and temporal resolution. This limitation may be reduced with recent advanced acceleration and reconstruction strategies that allow two-dimensional acceleration, such as in simultaneous multi-slice (SMS) 2D-EPI or 3D-EPI in combination with CAIPIRINHA field-of-view shifting. In this study, we sought to determine the functional sensitivity and specificity of these readout strategies with VASO over a broad range of spatial resolutions; spanning from low spatial resolution (3mm) whole-cortex to sub-millimeter (0.75mm) slab-of-cortex (for cortical layer-dependent applications). In the thermal-noise-dominated regime of sub-millimeter resolutions, 3D-EPI-VASO provides higher temporal stability and sensitivity to detect changes in CBV compared to 2D-EPI-VASO. In this regime, 3D-EPI-VASO unveils task activation located in the cortical laminae with little contamination from surface veins, in contrast to the cortical surface weighting of GE-BOLD fMRI. In the physiological-noise-dominated regime of lower resolutions, however, 2D-SMS-VASO shows superior performance compared to 3D-EPI-VASO. Due to its superior sensitivity at a layer-dependent level, 3D-EPI VASO promises to play an important role in future neuroscientific applications of layer-dependent fMRI.
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Affiliation(s)
- Laurentius Huber
- Section on Functional Imaging Methods, Laboratory of Brain and Cognition, NIMH, NIH, Bethesda, MD, USA.
| | - Dimo Ivanov
- Maastricht Brain Imaging Centre, Faculty of Psychology and Neurosciencve, Maastricht University, Maastricht, The Netherlands
| | - Daniel A Handwerker
- Section on Functional Imaging Methods, Laboratory of Brain and Cognition, NIMH, NIH, Bethesda, MD, USA
| | | | - Maria Guidi
- Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | - Kâmil Uludağ
- Maastricht Brain Imaging Centre, Faculty of Psychology and Neurosciencve, Maastricht University, Maastricht, The Netherlands
| | - Peter A Bandettini
- Section on Functional Imaging Methods, Laboratory of Brain and Cognition, NIMH, NIH, Bethesda, MD, USA; FMRIF, NIMH, NIH, Bethesda, MD, USA
| | - Benedikt A Poser
- Maastricht Brain Imaging Centre, Faculty of Psychology and Neurosciencve, Maastricht University, Maastricht, The Netherlands
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Ciris PA, Qiu M, Constable RT. Non-invasive quantification of absolute cerebral blood volume during functional activation applicable to the whole human brain. Magn Reson Med 2016; 71:580-90. [PMID: 23475774 DOI: 10.1002/mrm.24694] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
PURPOSE Cerebral blood volume (CBV) changes in many diverse pathologic conditions, and in response to functional challenges along with changes in blood flow, blood oxygenation, and the cerebral metabolic rate of oxygen. The feasibility of a new method for non-invasive quantification of absolute cerebral blood volume that can be applicable to the whole human brain was investigated. METHODS Multi-slice data were acquired at 3 T using a novel inversion recovery echo planar imaging (IR-EPI) pulse sequence with varying contrast weightings and an efficient rotating slice acquisition order, at rest and during visual activation. A biophysical model was used to estimate absolute cerebral blood volume at rest and during activation, and oxygenation during activation, on data from 13 normal human subjects. RESULTS Cerebral blood volume increased by 21.7% from 6.6 ± 0.8 mL/100 mL of brain parenchyma at rest to 8.0 ± 1.3 mL/100 mL of brain parenchyma in the occipital cortex during visual activation, with average blood oxygenation of 84 ± 2.1% during activation, comparing well with literature. CONCLUSION The method is feasible, and could foster improved understanding of the fundamental physiological relationship between neuronal activity, hemodynamic changes, and metabolism underlying brain activation; complement existing methods for estimating compartmental changes; and potentially find utility in evaluating vascular health.
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Affiliation(s)
- Pelin Aksit Ciris
- Department of Biomedical Engineering, Yale University, School of Medicine, Magnetic Resonance Research Center, New Haven, Connecticut, USA
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Krieger SN, Huber L, Poser BA, Turner R, Egan GF. Simultaneous acquisition of cerebral blood volume-, blood flow-, and blood oxygenation-weighted MRI signals at ultra-high magnetic field. Magn Reson Med 2014; 74:513-7. [DOI: 10.1002/mrm.25431] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Revised: 08/05/2014] [Accepted: 08/07/2014] [Indexed: 11/05/2022]
Affiliation(s)
- Steffen N. Krieger
- Max Plank Institute for Human Cognitive and Brain Sciences; Leipzig Germany
- Monash Biomedical Imaging, Monash University; Melbourne Australia
| | - Laurentius Huber
- Max Plank Institute for Human Cognitive and Brain Sciences; Leipzig Germany
| | - Benedikt A. Poser
- Maastricht Brain Imaging Centre, Maastricht University; Maastricht The Netherlands
| | - Robert Turner
- Max Plank Institute for Human Cognitive and Brain Sciences; Leipzig Germany
| | - Gary F. Egan
- Monash Biomedical Imaging, Monash University; Melbourne Australia
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Ciris PA, Qiu M, Constable RT. Noninvasive MRI measurement of the absolute cerebral blood volume-cerebral blood flow relationship during visual stimulation in healthy humans. Magn Reson Med 2013; 72:864-75. [PMID: 24151246 DOI: 10.1002/mrm.24984] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Revised: 08/12/2013] [Accepted: 09/13/2013] [Indexed: 01/02/2023]
Abstract
PURPOSE The relationship between cerebral blood volume (CBV) and cerebral blood flow (CBF) underlies blood oxygenation level-dependent functional MRI signal. This study investigates the potential for improved characterization of the CBV-CBF relationship in humans, and examines sex effects as well as spatial variations in the CBV-CBF relationship. METHODS Healthy subjects were imaged noninvasively at rest and during visual stimulation, constituting the first MRI measurement of the absolute CBV-CBF relationship in humans with complete coverage of the functional areas of interest. RESULTS CBV and CBF estimates were consistent with the literature, and their relationship varied both spatially and with sex. In a region of interest with stimulus-induced activation in CBV and CBF at a significance level of the P < 0.05, a power function fit resulted in CBV = 2.1 CBF(0.32) across all subjects, CBV = 0.8 CBF(0.51) in females and CBV = 4.4 CBF(0.15) in males. Exponents decreased in both sexes as ROIs were expanded to include less significantly activated regions. CONCLUSION Consideration for potential sex-related differences, as well as regional variations under a range of physiological states, may reconcile some of the variation across literature and advance our understanding of the underlying cerebrovascular physiology.
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Affiliation(s)
- Pelin Aksit Ciris
- Department of Biomedical Engineering, Yale University, School of Medicine, Magnetic Resonance Research Center, New Haven, Connecticut, USA
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Lu H, Hua J, van Zijl PCM. Noninvasive functional imaging of cerebral blood volume with vascular-space-occupancy (VASO) MRI. NMR IN BIOMEDICINE 2013; 26:932-948. [PMID: 23355392 PMCID: PMC3659207 DOI: 10.1002/nbm.2905] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Revised: 10/29/2012] [Accepted: 11/18/2012] [Indexed: 06/01/2023]
Abstract
Functional MRI (fMRI) based on changes in cerebral blood volume (CBV) can probe directly vasodilatation and vasoconstriction during brain activation or physiologic challenges, and can provide important insights into the mechanism of blood oxygenation level-dependent (BOLD) signal changes. At present, the most widely used CBV fMRI technique in humans is called vascular-space-occupancy (VASO) MRI, and this article provides a technical review of this method. VASO MRI utilizes T1 differences between blood and tissue to distinguish between these two compartments within a voxel, and employs a blood-nulling inversion recovery sequence to yield an MR signal proportional to 1 - CBV. As such, vasodilatation will result in a VASO signal decrease and vasoconstriction will have the reverse effect. The VASO technique can be performed dynamically with a temporal resolution comparable with several other fMRI methods, such as BOLD or arterial spin labeling (ASL), and is particularly powerful when conducted in conjunction with these complementary techniques. The pulse sequence and imaging parameters of VASO can be optimized such that the signal change is predominantly of CBV origin, but careful considerations should be taken to minimize other contributions, such as those from the BOLD effect, cerebral blood flow (CBF) and cerebrospinal fluid (CSF). The sensitivity of the VASO technique is the primary disadvantage when compared with BOLD, but this technique is increasingly demonstrating its utility in neuroscientific and clinical applications.
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Affiliation(s)
- Hanzhang Lu
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX, USA.
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Hua J, Jones CK, Qin Q, van Zijl PCM. Implementation of vascular-space-occupancy MRI at 7T. Magn Reson Med 2012; 69:1003-13. [PMID: 22585570 DOI: 10.1002/mrm.24334] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Revised: 04/11/2012] [Accepted: 04/22/2012] [Indexed: 11/07/2022]
Abstract
Vascular-space-occupancy (VASO) MRI exploits the difference between blood and tissue T1 to null blood signal and measure cerebral blood volume changes using the residual tissue signal. VASO imaging is more difficult at higher field because of sensitivity loss due to the convergence of tissue and blood T1 values and increased contamination from blood-oxygenation-level-dependent (BOLD) effects. In addition, compared to 3T, 7T MRI suffers from increased geometrical distortions, e.g., when using echo-planar-imaging, and from increased power deposition, the latter especially problematic for the spin-echo-train sequences commonly used for VASO MRI. Third, non-steady-state blood spin effects become substantial at 7T when only a head coil is available for radiofrequency transmit. In this study, the magnetization-transfer-enhanced-VASO approach was applied to maximize tissue-blood signal difference, which boosted signal-to-noise ratio by 149% ± 13% (n = 7) compared to VASO. Second, a 3D fast gradient-echo sequence with low flip-angle (7°) and short echo-time (1.8 ms) was used to minimize the BOLD effect and to reduce image distortion and power deposition. Finally, a magnetization-reset technique was combined with a motion-sensitized-driven-equilibrium approach to suppress three types of non-steady-state spins. Our initial functional MRI results in normal human brains at 7T with this optimized VASO sequence showed better signal-to-noise ratio than at 3T.
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Affiliation(s)
- Jun Hua
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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Lu H, van Zijl PCM. A review of the development of Vascular-Space-Occupancy (VASO) fMRI. Neuroimage 2012; 62:736-42. [PMID: 22245650 DOI: 10.1016/j.neuroimage.2012.01.013] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2011] [Revised: 12/19/2011] [Accepted: 01/01/2012] [Indexed: 12/26/2022] Open
Abstract
Vascular-Space-Occupancy (VASO) fMRI is a non-invasive technique to detect brain activation based on changes in Cerebral Blood Volume (CBV), as opposed to conventional BOLD fMRI, which is based on changes in blood oxygenation. This technique takes advantage of the T1 difference between blood and surrounding tissue, and uses an inversion recovery pulse sequence to null blood signal while maintaining part of the tissue signal. The VASO signal intensity can thus be considered proportional to 1-CBV. When neural activation causes CBV to increase, the VASO signal will show a decrease, allowing the detection of activated regions in the brain. Activation-induced changes in VASO signal, ∆S/S, are in the order of -1%. Absolute quantification of ∆CBV requires additional assumptions on baseline CBV and water contents of the parenchyma and blood. The first VASO experiment was conducted approximately 10 years ago. The original goal of nulling the blood signal was to isolate and measure extravascular BOLD effects, thus a long TE of 50 ms was used in the inversion recovery experiment. Instead of a positive signal change, a slight decrease in signal was observed, which became more pronounced when TE was shortened to 10 ms. These findings led to the hypothesis of a CBV signal mechanism and the development of VASO fMRI. Since its discovery, VASO has been validated by comparison with MION-CBV studies in animals and has been used in humans and animals to understand metabolic and hemodynamic changes during brain activation and physiologic challenges. With recent development of more sensitive VASO acquisitions, the availability of arterial-based VASO sequences, and improvement in spatial coverage, this technique is finding its place in neuroscience and clinical studies.
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Affiliation(s)
- Hanzhang Lu
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
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Hua J, Qin Q, Donahue MJ, Zhou J, Pekar JJ, van Zijl PCM. Inflow-based vascular-space-occupancy (iVASO) MRI. Magn Reson Med 2011; 66:40-56. [PMID: 21695719 DOI: 10.1002/mrm.22775] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2010] [Revised: 11/03/2010] [Accepted: 11/24/2010] [Indexed: 01/24/2023]
Abstract
Vascular-space-occupancy (VASO) MRI, a blood nulling approach for assessing changes in cerebral blood volume (CBV), is hampered by low signal-to-noise ratio (SNR) because only 10-20% of tissue signal is recovered when using nonselective inversion for blood nulling. A new approach, called inflow-VASO (iVASO), is introduced in which only blood flowing into the slice has experienced inversion, thereby keeping tissue and cerebrospinal fluid (CSF) signal in the slice maximal and reducing CSF partial volume effects. SNR increases of 198% ± 12% and 334% ± 9% (mean ± SD, n = 7) with respect to VASO were found at TR values of 5 s and 2 s, respectively. When using inflow approaches, data interpretation is complicated by the fact that signal changes are affected by vascular transit times. An optimal TR-range (1.5-2.5 s) was derived in which the iVASO response during activation predominantly reflects arterial/arteriolar CBV (CBV(a)) changes. In this TR-range, perfusion contributions to the signal change are negligible because arterial label has not yet undergone capillary exchange, and arterial and precapillary blood signals are nulled. For TR = 2 s, the iVASO signal change upon visual stimulation corresponded to a CBV(a) increase of 58% ± 7%, in agreement with arteriolar CBV changes previously reported. The onset of the hemodynamic response for iVASO occurred 1.2 ± 0.5 s (n = 7) faster than for conventional VASO.
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Affiliation(s)
- Jun Hua
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
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Hoshimaru M. Neuropsychological improvement in patients with cervical spondylotic myelopathy after posterior decompression surgery. Neurol Med Chir (Tokyo) 2010; 50:554-9. [PMID: 20671380 DOI: 10.2176/nmc.50.554] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Patients with cervical spondylotic myelopathy sometimes complain of cognitive dysfunction, which may be coincidence. However, cognitive dysfunction may be related to disorders of the cervical spine and/or spinal cord. This study investigated cognitive dysfunction in patients with cervical spinal disorders. A total of 79 patients with cervical spondylotic myelopathy (40 women and 39 men, mean age 61.2 years) underwent cervical laminoplasty between January 2006 and July 2007. Ten of these 79 patients (7 women and 3 men, mean age 65.2 years) complained of moderate to severe memory disturbances. These 10 patients underwent neuroimaging studies and a battery of neuropsychological tests consisting of the mini-mental state examination, Kohs Block Design Test, Miyake Memory Test, Benton Visual Retention Test (BVRT), and "kana-hiroi" test before and 3 months after surgery. Brain magnetic resonance imaging showed no organic brain lesions in the 10 patients, but single photon emission computed tomography demonstrated reduced regional cerebral blood flow in the posterior cortical areas in eight patients before surgery. Neuropsychological test scores showed statistically significant improvement after surgery in the Kohs Block Design Test and the BVRT, which measure visuospatial perception and reflect the function of the parietal and/or occipital lobes (p < 0.05). The practice effect may have contributed to the neuropsychological improvements, but this study suggests that cervical spinal disorders may affect cognitive functions and that surgical treatment can ameliorate such effects.
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Affiliation(s)
- Minoru Hoshimaru
- Department of Neurosurgery, Ohtsu Municipal Hospital, Ohtsu, Shiga, Japan.
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