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Zhang W, Liu N, Zhao Y, Yao C, Yang D, Yang C, Sun H, Wei X, Sweeney JA, Liang H, Zhang M, Gong Q, Lui S. The acute effects of repetitive transcranial magnetic stimulation on laminar diffusion anisotropy of neocortical gray matter. MedComm (Beijing) 2023; 4:e335. [PMID: 37560755 PMCID: PMC10407029 DOI: 10.1002/mco2.335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Revised: 06/19/2023] [Accepted: 06/26/2023] [Indexed: 08/11/2023] Open
Abstract
Repetitive transcranial magnetic stimulation (rTMS) is increasingly used to treat neuropsychiatric disorders. Inhibitory and excitatory regimens have been both adopted but the exact mechanism of action remains unclear, and investigating their differential effects on laminar diffusion profiles of neocortex may add important evidence. Twenty healthy participants were randomly assigned to receive a low-frequency/inhibitory or high-frequency/excitatory rTMS targeting the left dorsolateral prefrontal cortex (DLPFC). With the brand-new submillimeter diffusion tensor imaging of whole brain and specialized surface-based laminar analysis, fractional anisotropy (FA) and mean diffusion (MD) profiles of cortical layers at different cortical depths were characterized before/after rTMS. Inhibitory and excitatory rTMS both showed impacts on diffusion metrics of somatosensory, limbic, and sensory regions, but different patterns of changes were observed-increased FA with inhibitory rTMS, whereas decreased FA with excitatory rTMS. More importantly, laminar analysis indicated laminar specificity of changes in somatosensory regions during different rTMS patterns-inhibitory rTMS affected the superficial layers contralateral to the DLPFC, while excitatory rTMS led to changes in the intermediate/deep layers bilateral to the DLPFC. These findings provide novel insights into acute neurobiological effects on diffusion profiles of rTMS that may add critical evidence relevant to different protocols of rTMS on neocortex.
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Affiliation(s)
- Wenjing Zhang
- Department of Radiologyand Functional and Molecular Imaging Key Laboratory of Sichuan ProvinceWest China Hospital of Sichuan UniversityChengduChina
- Huaxi MR Research Center (HMRRC)West China Hospital of Sichuan UniversityChengduChina
- Research Unit of PsychoradiologyChinese Academy of Medical SciencesChengduChina
| | - Naici Liu
- Department of Radiologyand Functional and Molecular Imaging Key Laboratory of Sichuan ProvinceWest China Hospital of Sichuan UniversityChengduChina
- Huaxi MR Research Center (HMRRC)West China Hospital of Sichuan UniversityChengduChina
- Research Unit of PsychoradiologyChinese Academy of Medical SciencesChengduChina
| | - Youjin Zhao
- Department of Radiologyand Functional and Molecular Imaging Key Laboratory of Sichuan ProvinceWest China Hospital of Sichuan UniversityChengduChina
- Huaxi MR Research Center (HMRRC)West China Hospital of Sichuan UniversityChengduChina
- Research Unit of PsychoradiologyChinese Academy of Medical SciencesChengduChina
| | - Chenyang Yao
- Department of Radiologyand Functional and Molecular Imaging Key Laboratory of Sichuan ProvinceWest China Hospital of Sichuan UniversityChengduChina
- Huaxi MR Research Center (HMRRC)West China Hospital of Sichuan UniversityChengduChina
- Research Unit of PsychoradiologyChinese Academy of Medical SciencesChengduChina
| | - Dan Yang
- Department of Radiologyand Functional and Molecular Imaging Key Laboratory of Sichuan ProvinceWest China Hospital of Sichuan UniversityChengduChina
| | - Chengmin Yang
- Department of Radiologyand Functional and Molecular Imaging Key Laboratory of Sichuan ProvinceWest China Hospital of Sichuan UniversityChengduChina
- Huaxi MR Research Center (HMRRC)West China Hospital of Sichuan UniversityChengduChina
- Research Unit of PsychoradiologyChinese Academy of Medical SciencesChengduChina
| | - Hui Sun
- Department of Radiologyand Functional and Molecular Imaging Key Laboratory of Sichuan ProvinceWest China Hospital of Sichuan UniversityChengduChina
- Huaxi MR Research Center (HMRRC)West China Hospital of Sichuan UniversityChengduChina
- Research Unit of PsychoradiologyChinese Academy of Medical SciencesChengduChina
| | - Xia Wei
- Department of Radiologyand Functional and Molecular Imaging Key Laboratory of Sichuan ProvinceWest China Hospital of Sichuan UniversityChengduChina
- Huaxi MR Research Center (HMRRC)West China Hospital of Sichuan UniversityChengduChina
- Research Unit of PsychoradiologyChinese Academy of Medical SciencesChengduChina
| | - John A. Sweeney
- Huaxi MR Research Center (HMRRC)West China Hospital of Sichuan UniversityChengduChina
- Department of Psychiatry and Behavioral NeuroscienceUniversity of Cincinnati College of MedicineCincinnatiOhioUSA
| | | | | | - Qiyong Gong
- Department of Radiologyand Functional and Molecular Imaging Key Laboratory of Sichuan ProvinceWest China Hospital of Sichuan UniversityChengduChina
- Huaxi MR Research Center (HMRRC)West China Hospital of Sichuan UniversityChengduChina
- Research Unit of PsychoradiologyChinese Academy of Medical SciencesChengduChina
- Department of RadiologyWest China Xiamen Hospital of Sichuan UniversityXiamenFujianChina
| | - Su Lui
- Department of Radiologyand Functional and Molecular Imaging Key Laboratory of Sichuan ProvinceWest China Hospital of Sichuan UniversityChengduChina
- Huaxi MR Research Center (HMRRC)West China Hospital of Sichuan UniversityChengduChina
- Research Unit of PsychoradiologyChinese Academy of Medical SciencesChengduChina
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Farrher E, Chiang CW, Cho KH, Grinberg F, Buschbeck RP, Chen MJ, Wu KJ, Wang Y, Huang SM, Abbas Z, Choi CH, Shah NJ, Kuo LW. Spatiotemporal characterisation of ischaemic lesions in transient stroke animal models using diffusion free water elimination and mapping MRI with echo time dependence. Neuroimage 2021; 244:118605. [PMID: 34592438 DOI: 10.1016/j.neuroimage.2021.118605] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 09/14/2021] [Accepted: 09/19/2021] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND AND PURPOSE The excess fluid as a result of vasogenic oedema and the subsequent tissue cavitation obscure the microstructural characterisation of ischaemic tissue by conventional diffusion and relaxometry MRI. They lead to a pseudo-normalisation of the water diffusivity and transverse relaxation time maps in the subacute and chronic phases of stroke. Within the context of diffusion MRI, the free water elimination and mapping method (FWE) with echo time dependence has been proposed as a promising approach to measure the amount of free fluid in brain tissue robustly and to eliminate its biasing effect on other biomarkers. In this longitudinal study of transient middle cerebral artery occlusion (MCAo) in the rat brain, we investigated the use of FWE MRI with echo time dependence for the characterisation of the tissue microstructure and explored the potential of the free water fraction as a novel biomarker of ischaemic tissue condition. METHODS Adult rats received a transient MCAo. Diffusion- and transverse relaxation-weighted MRI experiments were performed longitudinally, pre-occlusion and on days 1, 3, 4, 5, 6, 7 and 10 after MCAo on four rats. Histology was performed for non-stroke and 1, 3 and 10 days after MCAo on three different rats at each time point. RESULTS The free water fraction was homogeneously increased in the ischaemic cortex one day after stroke. Between three and ten days after stroke, the core of the ischaemic tissue showed a progressive normalisation in the amount of free water, whereas the inner and outer border zones of the ischaemic cortex depicted a large, monotonous increase with time. The specific lesions in brain sections were verified by H&E and immunostaining. The tissue-specific diffusion and relaxometry MRI metrics in the ischaemic cortex were significantly different compared to their conventional counterpart. CONCLUSIONS Our results demonstrate that the free water fraction in FWE MRI with echo time dependence is a valuable biomarker, sensitive to the progressive degeneration in ischaemic tissue. We showed that part of the heterogeneity previously observed in conventional parameter maps can be accounted for by a heterogeneous distribution of free water in the tissue. Our results suggest that the temporal evolution of the free fluid fraction map at the core and inner border zone can be associated with the pathological changes linked to the evolution of vasogenic oedema. Namely, the homogeneous increase in free water one day after stroke and its tendency to normalise in the core of the ischaemic cortex starting three days after stroke, followed by a progressive increase in free water at the inner border zone from three to ten days after stroke. Finally, the monotonous increase in free fluid in the outer border zone of the cortex reflects the formation of fluid-filled cysts.
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Affiliation(s)
- Ezequiel Farrher
- Institute of Neuroscience and Medicine 4, INM-4, Forschungszentrum Jülich, Germany.
| | - Chia-Wen Chiang
- Institute of Biomedical Engineering and Nanomedicine, National Health Research Institutes, Miaoli, Taiwan
| | - Kuan-Hung Cho
- Institute of Biomedical Engineering and Nanomedicine, National Health Research Institutes, Miaoli, Taiwan
| | - Farida Grinberg
- Institute of Neuroscience and Medicine 4, INM-4, Forschungszentrum Jülich, Germany
| | - Richard P Buschbeck
- Institute of Neuroscience and Medicine 4, INM-4, Forschungszentrum Jülich, Germany
| | - Ming-Jye Chen
- Institute of Biomedical Engineering and Nanomedicine, National Health Research Institutes, Miaoli, Taiwan
| | - Kuo-Jen Wu
- Center for Neuropsychiatric Research, National Health Research Institutes, Miaoli, Taiwan
| | - Yun Wang
- Center for Neuropsychiatric Research, National Health Research Institutes, Miaoli, Taiwan
| | - Sheng-Min Huang
- Institute of Biomedical Engineering and Nanomedicine, National Health Research Institutes, Miaoli, Taiwan
| | - Zaheer Abbas
- Institute of Neuroscience and Medicine 4, INM-4, Forschungszentrum Jülich, Germany
| | - Chang-Hoon Choi
- Institute of Neuroscience and Medicine 4, INM-4, Forschungszentrum Jülich, Germany
| | - N Jon Shah
- Institute of Neuroscience and Medicine 4, INM-4, Forschungszentrum Jülich, Germany; Department of Neurology, RWTH Aachen University, Aachen, Germany; JARA - BRAIN - Translational Medicine, Aachen, Germany; Institute of Neuroscience and Medicine 11, INM-11, JARA, Forschungszentrum Jülich, Germany
| | - Li-Wei Kuo
- Institute of Biomedical Engineering and Nanomedicine, National Health Research Institutes, Miaoli, Taiwan; Institute of Medical Device and Imaging, National Taiwan University College of Medicine, Taipei, Taiwan.
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Li X, Bai Y, Liao Y, Xin SX. Assessment of the effects of mimicking tissue microstructural properties on apparent diffusion coefficient and apparent exchange rate in diffusion MRI via a series of specially designed phantoms. Magn Reson Med 2021; 87:292-301. [PMID: 34435698 DOI: 10.1002/mrm.28990] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 08/04/2021] [Accepted: 08/09/2021] [Indexed: 11/11/2022]
Abstract
PURPOSE Diffusion MRI provides a valuable tool for imaging tissue microstructure. However, due to the lack of related experimental methods and specially designed phantoms, no experimental study has been conducted yet to quantitatively assess the effects of membrane permeability, intracellular volume fraction (IVF), and intracellular diffusivity on the apparent diffusion coefficient (ADC) obtained from diffusion weighted imaging (DWI), and the effects of membrane permeability on the apparent exchange rate (AXR) obtained from filter exchange imaging (FEXI). METHODS A series of phantoms with three adjustable parameters was designed to mimic tissue microstructural properties including membrane permeability, IVF, and intracellular diffusivity. Quantitative experiments were conducted to assess the effects of these properties on ADC and AXR. DWI scans were performed to obtain axial and radial ADC values. FEXI scans were performed to obtain AXR values. RESULTS Axial ADC values range from 1.148 μm2 /ms to 2.157 μm2 /ms, and radial ADC values range from 0.904 μm2 /ms to 2.067 μm2 /ms. Radial ADC decreased with a decrease in fiber permeability. Decreased axial and radial ADC values with increased intra-fiber volume fraction, and increased polyvinylpyrrolidone (PVP) concentration of the intra-fiber space were observed. AXR values range from 2.1 s-1 to 4.9 s-1 . AXR increases with fiber permeability. CONCLUSION The proposed phantoms can quantitatively evaluate the effects of mimicking tissue microstructural properties on ADC and AXR. This new phantom design provides a potential method for further understanding the biophysical mechanisms underlying the change in ADC and diffusion exchange.
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Affiliation(s)
- Xiaodong Li
- Laboratory of Biophysics, School of Medicine, South China University of Technology, Guangzhou, Guangdong, China
| | - Yafei Bai
- Laboratory of Biophysics, School of Medicine, South China University of Technology, Guangzhou, Guangdong, China
| | - Yupeng Liao
- Laboratory of Biophysics, School of Medicine, South China University of Technology, Guangzhou, Guangdong, China
| | - Sherman Xuegang Xin
- Laboratory of Biophysics, School of Medicine, South China University of Technology, Guangzhou, Guangdong, China
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Zhou IY, Guo Y, Igarashi T, Wang Y, Mandeville E, Chan ST, Wen L, Vangel M, Lo EH, Ji X, Sun PZ. Fast diffusion kurtosis imaging (DKI) with Inherent COrrelation-based Normalization (ICON) enhances automatic segmentation of heterogeneous diffusion MRI lesion in acute stroke. NMR IN BIOMEDICINE 2016; 29:1670-1677. [PMID: 27696558 PMCID: PMC5123902 DOI: 10.1002/nbm.3617] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Revised: 08/03/2016] [Accepted: 08/09/2016] [Indexed: 05/05/2023]
Affiliation(s)
- Iris Yuwen Zhou
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology; Massachusetts General Hospital and Harvard Medical School; Charlestown Massachusetts USA
| | - Yingkun Guo
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology; Massachusetts General Hospital and Harvard Medical School; Charlestown Massachusetts USA
- Department of Radiology; West China Second University Hospital, Sichuan University; Chengdu Sichuan China
| | - Takahiro Igarashi
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology; Massachusetts General Hospital and Harvard Medical School; Charlestown Massachusetts USA
| | - Yu Wang
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology; Massachusetts General Hospital and Harvard Medical School; Charlestown Massachusetts USA
- China-America Joint Neuroscience Institute, Xuanwu Hospital; Capital Medical University; Beijing China
| | - Emiri Mandeville
- Neuroprotection Research Laboratory, Department of Radiology and Neurology; Massachusetts General Hospital and Harvard Medical School; Charlestown Massachusetts USA
| | - Suk-Tak Chan
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology; Massachusetts General Hospital and Harvard Medical School; Charlestown Massachusetts USA
| | - Lingyi Wen
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology; Massachusetts General Hospital and Harvard Medical School; Charlestown Massachusetts USA
- Department of Radiology; West China Second University Hospital, Sichuan University; Chengdu Sichuan China
| | - Mark Vangel
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology; Massachusetts General Hospital and Harvard Medical School; Charlestown Massachusetts USA
| | - Eng H. Lo
- Neuroprotection Research Laboratory, Department of Radiology and Neurology; Massachusetts General Hospital and Harvard Medical School; Charlestown Massachusetts USA
| | - Xunming Ji
- China-America Joint Neuroscience Institute, Xuanwu Hospital; Capital Medical University; Beijing China
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Guo YL, Zhang ZP, Zhang GS, Kong LM, Rao HB, Chen W, Wang GW, Shen ZW, Zheng WB, Wu RH. Evaluation of mean diffusion and kurtosis MRI mismatch in subacute ischemic stroke: Comparison with NIHSS score. Brain Res 2016; 1644:231-9. [PMID: 27208488 DOI: 10.1016/j.brainres.2016.05.020] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Revised: 05/06/2016] [Accepted: 05/11/2016] [Indexed: 02/05/2023]
Abstract
Neurological deterioration (ND) is a devastating complication following ischemic stroke. This study aimed to identify the differences in lesion characteristics in subacute ischemic stroke patients with and without ND using diffusional kurtosis imaging (DKI), as well as to confirm the responsible lesions that may lead to ND, as assessed by the National Institutes of Health Stroke Scale (NIHSS) score. Seventy-nine patients with subacute cerebral infarction were allocated to the ND (-) and ND (+) groups according to the NIHSS score and lesion number. The mean diffusion (MD) lesions were significantly larger than the mean kurtosis (MK) deficits in the ND (+) group (P<0.05); however, there was no significant difference in the ND (-) group (P>0.05). The MD and MK in the lesion recovered to normal levels over time; however, the recovery trends in the ND (+) group were substantially slower than the ND (-) group. The differences between the two groups were only significant regarding the MK (p<0.05). Furthermore, multiple infarction lesions exhibited good consistency in the ND (-) group, but were non-homogeneous in the ND (+) group. To the best of our knowledge, this is the first study to demonstrate that a significant MD/MK mismatch and heterogeneity of multiple ischemic lesions on MK in subacute ischemic stroke may represent a new expansion of an ischemic lesion or acute reinfarction, which is closely related to ND.
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Affiliation(s)
- Yue-Lin Guo
- Department of Radiology, The 2nd Affiliated Hospital, Shantou University Medical College, Shantou, 515000 Guangdong, China
| | | | - Gui-Shan Zhang
- Engineering College Shantou University, Shantou, 515000 Guangdong, China
| | - Ling-Mei Kong
- Department of Radiology, The 2nd Affiliated Hospital, Shantou University Medical College, Shantou, 515000 Guangdong, China
| | - Hai-Bing Rao
- Department of Radiology, The 2nd Affiliated Hospital, Shantou University Medical College, Shantou, 515000 Guangdong, China
| | - Wei Chen
- Department of Neurology, The 2nd Affiliated Hospital, Shantou University Medical College, Shantou, 515000 Guangdong, China
| | - Guang-Wen Wang
- Department of Neurology, The 2nd Affiliated Hospital, Shantou University Medical College, Shantou, 515000 Guangdong, China
| | - Zhi-Wei Shen
- Department of Radiology, The 2nd Affiliated Hospital, Shantou University Medical College, Shantou, 515000 Guangdong, China
| | - Wen-Bin Zheng
- Department of Radiology, The 2nd Affiliated Hospital, Shantou University Medical College, Shantou, 515000 Guangdong, China
| | - Ren-Hua Wu
- Department of Radiology, The 2nd Affiliated Hospital, Shantou University Medical College, Shantou, 515000 Guangdong, China.
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Assessing the sensitivity of diffusion MRI to detect neuronal activity directly. Proc Natl Acad Sci U S A 2016; 113:E1728-37. [PMID: 26941239 DOI: 10.1073/pnas.1519890113] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Functional MRI (fMRI) is widely used to study brain function in the neurosciences. Unfortunately, conventional fMRI only indirectly assesses neuronal activity via hemodynamic coupling. Diffusion fMRI was proposed as a more direct and accurate fMRI method to detect neuronal activity, yet confirmative findings have proven difficult to obtain. Given that the underlying relation between tissue water diffusion changes and neuronal activity remains unclear, the rationale for using diffusion MRI to monitor neuronal activity has yet to be clearly established. Here, we studied the correlation between water diffusion and neuronal activity in vitro by simultaneous calcium fluorescence imaging and diffusion MR acquisition. We used organotypic cortical cultures from rat brains as a biological model system, in which spontaneous neuronal activity robustly emerges free of hemodynamic and other artifacts. Simultaneous fluorescent calcium images of neuronal activity are then directly correlated with diffusion MR signals now free of confounds typically encountered in vivo. Although a simultaneous increase of diffusion-weighted MR signals was observed together with the prolonged depolarization of neurons induced by pharmacological manipulations (in which cell swelling was demonstrated to play an important role), no evidence was found that diffusion MR signals directly correlate with normal spontaneous neuronal activity. These results suggest that, whereas current diffusion MR methods could monitor pathological conditions such as hyperexcitability, e.g., those seen in epilepsy, they do not appear to be sensitive or specific enough to detect or follow normal neuronal activity.
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Suo S, Cao M, Zhu W, Li L, Li J, Shen F, Zu J, Zhou Z, Zhuang Z, Qu J, Chen Z, Xu J. Stroke assessment with intravoxel incoherent motion diffusion-weighted MRI. NMR IN BIOMEDICINE 2016; 29:320-328. [PMID: 26748572 DOI: 10.1002/nbm.3467] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Revised: 11/19/2015] [Accepted: 11/23/2015] [Indexed: 06/05/2023]
Abstract
Intravoxel incoherent motion (IVIM) diffusion-weighted MRI can simultaneously measure diffusion and perfusion characteristics in a non-invasive way. This study aimed to determine the potential utility of IVIM in characterizing brain diffusion and perfusion properties for clinical stroke. The multi-b-value diffusion-weighted images of 101 patients diagnosed with acute/subacute ischemic stroke were retrospectively evaluated. The diffusion coefficient D, representing the water apparent diffusivity, was obtained by fitting the diffusion data with increasing high b-values to a simple mono-exponential model. The IVIM-derived perfusion parameters, pseudodiffusion coefficient D*, vascular volume fraction f and blood flow-related parameter fD*, were calculated with the bi-exponential model. Additionally, the apparent diffusion coefficient (ADC) was fitted according to the mono-exponential model using all b-values. The diffusion parameters for the ischemic lesion and normal contralateral region were measured in each patient. Statistical analysis was performed using the paired Student t-test and Pearson correlation test. Diffusion data in both the ischemic lesion and normal contralateral region followed the IVIM bi-exponential behavior, and the IVIM model showed better goodness of fit than the mono-exponential model with lower Akaike information criterion values. The paired Student t-test revealed significant differences for all diffusion parameters (all P < 0.001) except D* (P = 0.218) between ischemic and normal areas. For all patients in both ischemic and normal regions, ADC was significantly positively correlated with D (both r = 1, both P < 0.001) and f (r = 0.541, P < 0.001; r = 0.262, P = 0.008); significant correlation was also found between ADC and fD* in the ischemic region (r = 0.254, P = 0.010). For all pixels within the region of interest from a representative subject in both ischemic and normal regions, ADC was significantly positively correlated with D (both r = 1, both P < 0.001), f (r = 0.823, P < 0.001; r = 0.652, P < 0.001) and fD* (r = 0.294, P < 0.001; r = 0.340, P < 0.001). These findings may have clinical implications for the use of IVIM imaging in the assessment and management of acute/subacute stroke patients. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Shiteng Suo
- Department of Radiology, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Mengqiu Cao
- Department of Radiology, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Wanqiu Zhu
- Department of Radiology, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Lei Li
- Department of Radiology, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Jun Li
- Department of Radiology, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Fei Shen
- Department of Neurology, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Jinyan Zu
- Department of Radiology, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Zien Zhou
- Department of Radiology, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Zhiguo Zhuang
- Department of Radiology, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | | | - Zengai Chen
- Department of Radiology, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Jianrong Xu
- Department of Radiology, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
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Grinberg F, Farrher E, Ciobanu L, Geffroy F, Le Bihan D, Shah NJ. Non-Gaussian diffusion imaging for enhanced contrast of brain tissue affected by ischemic stroke. PLoS One 2014; 9:e89225. [PMID: 24586610 PMCID: PMC3937347 DOI: 10.1371/journal.pone.0089225] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Accepted: 01/16/2014] [Indexed: 12/29/2022] Open
Abstract
Recent diffusion MRI studies of stroke in humans and animals have shown that the quantitative parameters characterising the degree of non-Gaussianity of the diffusion process are much more sensitive to ischemic changes than the apparent diffusion coefficient (ADC) considered so far as the "gold standard". The observed changes exceeded that of the ADC by a remarkable factor of 2 to 3. These studies were based on the novel non-Gaussian methods, such as diffusion kurtosis imaging (DKI) and log-normal distribution function imaging (LNDFI). As shown in our previous work investigating the animal stroke model, a combined analysis using two methods, DKI and LNDFI provides valuable complimentary information. In the present work, we report the application of three non-Gaussian diffusion models to quantify the deviations from the Gaussian behaviour in stroke induced by transient middle cerebral artery occlusion in rat brains: the gamma-distribution function (GDF), the stretched exponential model (SEM), and the biexponential model. The main goal was to compare the sensitivity of various non-Gaussian metrics to ischemic changes and to investigate if a combined application of several models will provide added value in the assessment of stroke. We have shown that two models, GDF and SEM, exhibit a better performance than the conventional method and allow for a significantly enhanced visualization of lesions. Furthermore, we showed that valuable information regarding spatial properties of stroke lesions can be obtained. In particular, we observed a stratified cortex structure in the lesions that were well visible in the maps of the GDF and SEM metrics, but poorly distinguishable in the ADC-maps. Our results provided evidence that cortical layers tend to be differently affected by ischemic processes.
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Affiliation(s)
- Farida Grinberg
- Institute of Neuroscience and Medicine - 4, Forschungszentrum Juelich GmbH, Juelich, Germany
- Department of Neurology, Faculty of Medicine, JARA, RWTH Aachen University, Aachen, Germany
| | - Ezequiel Farrher
- Institute of Neuroscience and Medicine - 4, Forschungszentrum Juelich GmbH, Juelich, Germany
| | - Luisa Ciobanu
- NeuroSpin, Commissariat à l'énergie atomique et aux énergies alternatives (CEA Saclay), Gif-sur-Yvette, France
| | - Françoise Geffroy
- NeuroSpin, Commissariat à l'énergie atomique et aux énergies alternatives (CEA Saclay), Gif-sur-Yvette, France
| | - Denis Le Bihan
- NeuroSpin, Commissariat à l'énergie atomique et aux énergies alternatives (CEA Saclay), Gif-sur-Yvette, France
| | - N. Jon Shah
- Institute of Neuroscience and Medicine - 4, Forschungszentrum Juelich GmbH, Juelich, Germany
- Department of Neurology, Faculty of Medicine, JARA, RWTH Aachen University, Aachen, Germany
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Grinberg F, Ciobanu L, Farrher E, Shah NJ. Diffusion kurtosis imaging and log-normal distribution function imaging enhance the visualisation of lesions in animal stroke models. NMR IN BIOMEDICINE 2012; 25:1295-304. [PMID: 22461260 DOI: 10.1002/nbm.2802] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2011] [Revised: 02/22/2012] [Accepted: 02/29/2012] [Indexed: 05/16/2023]
Abstract
In this work, we report a case study of a stroke model in animals using two methods of quantification of the deviations from Gaussian behaviour: diffusion kurtosis imaging (DKI) and log-normal distribution function imaging (LNDFI). The affected regions were predominantly in grey rather than in white matter. The parameter maps were constructed for metrics quantifying the apparent diffusivity (evaluated from conventional diffusion tensor imaging, DKI and LNDFI) and for those quantifying the degree of deviations (mean kurtosis and a parameter σ characterising the width of the distribution). We showed that both DKI and LNDFI were able to dramatically enhance the visualisation of ischaemic lesions in comparison with conventional methods. The largest relative change in the affected versus healthy regions was observed in the mean kurtosis values. The average changes in the mean kurtosis and σ values in the lesions were a factor of two to three larger than the relative changes observed in the mean diffusivity. In conclusion, the applied methods promise valuable perspectives in the assessment of stroke.
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Affiliation(s)
- Farida Grinberg
- Institute of Neuroscience and Medicine - 4, Forschungszentrum Juelich GmbH, Juelich, Germany.
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Cheung JS, Wang E, Lo EH, Sun PZ. Stratification of heterogeneous diffusion MRI ischemic lesion with kurtosis imaging: evaluation of mean diffusion and kurtosis MRI mismatch in an animal model of transient focal ischemia. Stroke 2012; 43:2252-4. [PMID: 22773558 DOI: 10.1161/strokeaha.112.661926] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND AND PURPOSE Ischemic tissue damage is heterogeneous, resulting in complex patterns in the widely used diffusion-weighted MRI. Our study examined the spatiotemporal characteristics of diffusion kurtosis imaging in an animal model of transient middle cerebral artery occlusion. METHODS Adult male Wistar rats (N=18) were subjected to 90 minutes middle cerebral artery occlusion. Multiparametric MR images were obtained during middle cerebral artery occlusion and 20 minutes after reperfusion with diffusion-weighted MRI obtained using 8 b-values from 250 to 3000 s/mm(2) in 6 diffusion gradient directions. Diffusion and kurtosis lesions were outlined in shuffled images by 2 investigators independently. T(2) MRI was obtained 24 hours after middle cerebral artery occlusion to evaluate stroke outcome. RESULTS Mean diffusion lesion (23.5%±8.1%, percentage of the brain slice) was significantly larger than mean kurtosis lesion (13.2%±2.0%) during middle cerebral artery occlusion. Mean diffusion lesion decreased significantly after reperfusion (13.8%±4.3%), whereas mean kurtosis lesion showed little change (13.0%±2.5%) with their lesion size difference being insignificant. CONCLUSIONS We demonstrated that mean diffusion/mean kurtosis mismatch recovered reasonably well on reperfusion, whereas regions with concurrent mean diffusion and mean kurtosis deficits showed poor recovery. Diffusion kurtosis imaging may help stratify heterogeneous diffusion-weighted MRI lesions for enhanced characterization of ischemic tissue injury.
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Affiliation(s)
- Jerry S Cheung
- Athinoula A. Martinos Center, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
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11
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Motor deficits are triggered by reperfusion-reoxygenation injury as diagnosed by MRI and by a mechanism involving oxidants. J Neurosci 2012; 32:5500-9. [PMID: 22514312 DOI: 10.1523/jneurosci.5986-11.2012] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The early antecedents of cerebral palsy (CP) are unknown but are suspected to be due to hypoxia-ischemia (H-I). In our rabbit model of CP, the MRI biomarker, apparent diffusion coefficient (ADC) on diffusion-weighted imaging, predicted which fetuses will develop postnatal hypertonia. Surviving H-I fetuses experience reperfusion-reoxygenation but a subpopulation manifested a continued decline of ADC during early reperfusion-reoxygenation, which possibly represented greater brain injury (RepReOx). We hypothesized that oxidative stress in reperfusion-reoxygenation is a critical trigger for postnatal hypertonia. We investigated whether RepReOx predicted postnatal neurobehavior, indicated oxidative stress, and whether targeting antioxidants at RepReOx ameliorated motor deficits, which included testing of a new superoxide dismutase mimic (MnTnHex-2-PyP). Rabbit dams, 79% gestation (E25), were subjected to 40 min uterine ischemia. Fetal brain ADC was followed during H-I, immediate reperfusion-reoxygenation, and 4-72 h after H-I. Endpoints were postnatal neurological outcome at E32, ADC at end of H-I, ADC nadir during H-I and reperfusion-reoxygenation, and area under ADC curve during the first 20 min of reperfusion-reoxygenation. Antioxidants targeting RepReOx were administered before and/or after uterine ischemia. The new MRI-ADC biomarker for RepReOx improved prediction of postnatal hypertonia. Greater superoxide production, mitochondrial injury, and oligodendroglial loss occurred in fetal brains exhibiting RepReOx than in those without. The antioxidants, MnTnHex-2-PyP and Ascorbate and Trolox combination, significantly decreased postnatal motor deficits and extent of RepReOx. The etiological link between early injury and later motor deficits can thus be investigated by MRI, and allows us to distinguish between critical oxidative stress that causes motor deficits and noncritical oxidative stress that does not.
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12
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Mardini H, Smith FE, Record CO, Blamire AM. Magnetic resonance quantification of water and metabolites in the brain of cirrhotics following induced hyperammonaemia. J Hepatol 2011; 54:1154-60. [PMID: 21145802 DOI: 10.1016/j.jhep.2010.09.030] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/12/2010] [Revised: 09/07/2010] [Accepted: 09/15/2010] [Indexed: 12/20/2022]
Abstract
BACKGROUND & AIMS Hepatic encephalopathy (HE) is now thought to be caused by cerebral oedema although the precise pathogenesis is uncertain. We hypothesised that if ammonia is a key factor, induced hyperammonaemia would lead to transient changes in brain water distribution and metabolite concentration, detectable by diffusion tensor imaging (DTI) and magnetic resonance spectroscopy (MRS). METHODS Thirteen cirrhotic patients being evaluated for liver transplantation were challenged with 54 g of equal parts of threonine, serine, and glycine. Conventional magnetic resonance imaging was performed to exclude structural lesions and localise regions of interest. DTI was used to generate white matter apparent diffusion coefficient (ADC) maps and proton MRS to measure brain metabolite concentrations before and after the challenge. RESULTS The challenge caused a mean (±SD) rise in blood ammonia of 58 (±41) μmol/L, which was accompanied by a significant 9% increase in ADC (p=0.004). Increased ADC significantly correlated with blood ammonia (r=0.58, p=0.04). The change in ammonia levels also correlated with the increase in glutamine levels (r=0.78, p=0.002). Myo-inositol concentration decreased significantly by 0.7 (±0.7)mMol/L between scans and this correlated with the mean difference in ADC (r=0.59, p<0.04). CONCLUSIONS These results show that ammonia can directly drive changes in brain water distribution as a mechanism for cerebral oedema development. Since cerebral astrocytes contain glutamine synthetase, our MRS data suggest intracerebral formation of glutamine from ammonia. The rapid decrease in myo-inositol indicates that this organic osmolyte plays a protective role in HE by release from astrocytes in order to maintain cell volume.
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Affiliation(s)
- Hanan Mardini
- Liver Unit and Institute of Cellular Medicine, Freeman Hospital and Newcastle University, Newcastle Upon Tyne, UK
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Jensen JH, Falangola MF, Hu C, Tabesh A, Rapalino O, Lo C, Helpern JA. Preliminary observations of increased diffusional kurtosis in human brain following recent cerebral infarction. NMR IN BIOMEDICINE 2011; 24:452-7. [PMID: 20960579 PMCID: PMC3549661 DOI: 10.1002/nbm.1610] [Citation(s) in RCA: 129] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2010] [Revised: 07/18/2010] [Accepted: 07/27/2010] [Indexed: 05/06/2023]
Abstract
By application of the MRI method of diffusional kurtosis imaging, a substantially increased diffusional kurtosis was observed within the cerebral ischemic lesions of three stroke subjects, 13-26 h following the onset of symptoms. This increase is interpreted as probably reflecting a higher degree of diffusional heterogeneity in the lesions when compared with normal-appearing contralateral tissue. In addition, for two of the subjects with white matter infarcts, the increase had a strong fiber tract orientational dependence. It is proposed that this effect is consistent with a large drop in the intra-axonal diffusivity, possibly related to either axonal varicosities or alterations associated with the endoplasmic reticulum.
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Affiliation(s)
- Jens H Jensen
- Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, NY 10016-3295, USA.
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Harkins KD, Galons JP, Divijak JL, Trouard TP. Changes in intracellular water diffusion and energetic metabolism in response to ischemia in perfused C6 rat glioma cells. Magn Reson Med 2011; 66:859-67. [PMID: 21446036 DOI: 10.1002/mrm.22866] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2009] [Accepted: 01/11/2011] [Indexed: 11/09/2022]
Abstract
This work reports results of experiments in hollow-fiber bioreactor C6 glioma cell cultures where the apparent diffusion coefficient (ADC) of intracellular water (iADC) was measured at diffusion times between 0.83 and 40 ms. The experiments were carried out before and after the onset of permanent ischemia. The changes in iADC following ischemia were dependent on the diffusion time employed in the experiment. An ischemia-induced decrease in the iADC was measured at short diffusion times, while at long diffusion times the iADC increased. Decreases in the iADC measured at short diffusion times are interpreted to be a result of a decrease in the intrinsic diffusivity of intracellular water due to energy failure. Increases in iADC measured at long diffusion times, are interpreted to result from cell swelling.
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Affiliation(s)
- Kevin D Harkins
- Department of Biomedical Engineering, University of Arizona, Tucson, Arizona 85721, USA
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15
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Jensen JH, Helpern JA. MRI quantification of non-Gaussian water diffusion by kurtosis analysis. NMR IN BIOMEDICINE 2010; 23:698-710. [PMID: 20632416 PMCID: PMC2997680 DOI: 10.1002/nbm.1518] [Citation(s) in RCA: 892] [Impact Index Per Article: 63.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Quantification of non-Gaussianity for water diffusion in brain by means of diffusional kurtosis imaging (DKI) is reviewed. Diffusional non-Gaussianity is a consequence of tissue structure that creates diffusion barriers and compartments. The degree of non-Gaussianity is conveniently quantified by the diffusional kurtosis and derivative metrics, such as the mean, axial, and radial kurtoses. DKI is a diffusion-weighted MRI technique that allows the diffusional kurtosis to be estimated with clinical scanners using standard diffusion-weighted pulse sequences and relatively modest acquisition times. DKI is an extension of the widely used diffusion tensor imaging method, but requires the use of at least 3 b-values and 15 diffusion directions. This review discusses the underlying theory of DKI as well as practical considerations related to data acquisition and post-processing. It is argued that the diffusional kurtosis is sensitive to diffusional heterogeneity and suggested that DKI may be useful for investigating ischemic stroke and neuropathologies, such as Alzheimer's disease and schizophrenia.
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Affiliation(s)
- Jens H Jensen
- Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, New York 10016-3295, USA.
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Harkins KD, Galons JP, Secomb TW, Trouard TP. Assessment of the effects of cellular tissue properties on ADC measurements by numerical simulation of water diffusion. Magn Reson Med 2010; 62:1414-22. [PMID: 19785014 DOI: 10.1002/mrm.22155] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The apparent diffusion coefficient (ADC), as measured by diffusion-weighted MRI, has proven useful in the diagnosis and evaluation of ischemic stroke. The ADC of tissue water is reduced by 30-50% following ischemia and provides excellent contrast between normal and affected tissue. Despite its clinical utility, there is no consensus on the biophysical mechanism underlying the reduction in ADC. In this work, a numerical simulation of water diffusion is used to predict the effects of cellular tissue properties on experimentally measured ADC. The model indicates that the biophysical mechanisms responsible for changes in ADC postischemia depend upon the time over which diffusion is measured. At short diffusion times, the ADC is dependent upon the intrinsic intracellular diffusivity, while at longer, clinically relevant diffusion times, the ADC is highly dependent upon the cell volume fraction. The model also predicts that at clinically relevant diffusion times, the 30-50% drop in ADC after ischemia can be accounted for by cell swelling alone when intracellular T(2) is allowed to be shorter than extracellular T(2).
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Affiliation(s)
- Kevin D Harkins
- Biomedical Engineering Program, University of Arizona, Tucson, Arizona 85721, USA
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Elkin BS, Shaik MA, Morrison B. Fixed negative charge and the Donnan effect: a description of the driving forces associated with brain tissue swelling and oedema. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2010; 368:585-603. [PMID: 20047940 PMCID: PMC2944388 DOI: 10.1098/rsta.2009.0223] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Cerebral oedema or brain tissue swelling is a significant complication following traumatic brain injury or stroke that can increase the intracranial pressure (ICP) and impair blood flow. Here, we have identified a potential driver of oedema: the negatively charged molecules fixed within cells. This fixed charge density (FCD), once exposed, could increase ICP through the Donnan effect. We have shown that metabolic processes and membrane integrity are required for concealing this FCD as slices of rat cortex swelled immediately (within 30 min) following dissection if treated with 2 deoxyglucose + cyanide (2DG+CN) or Triton X-100. Slices given ample oxygen and glucose, however, did not swell significantly. We also found that dead brain tissue swells and shrinks in response to changes in ionic strength of the bathing medium, which suggests that the Donnan effect is capable of pressurizing and swelling brain tissue. As predicted, a non-ionic osmolyte, 1,2 propanediol, elicited no volume change at 2000 x 10(-3) osmoles l(-1) (Osm). Swelling data were well described by triphasic mixture theory with the calculated reference state FCD similar to that measured with a 1,9 dimethylmethylene blue assay. Taken together, these data suggest that intracellular fixed charges may contribute to the driving forces responsible for brain swelling.
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O-GlcNAc modification of proteins affects volume regulation in Jurkat cells. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2009; 39:1207-17. [PMID: 20043149 DOI: 10.1007/s00249-009-0573-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2009] [Revised: 12/07/2009] [Accepted: 12/14/2009] [Indexed: 10/20/2022]
Abstract
An increasing amount of recent research has demonstrated that the hexosamine biosynthesis pathway (HBP) plays a significant role in the modulation of intracellular signaling transduction pathways, and affects cellular processes via modification of protein by O-linked beta-N-acetylglucosamine (O-GlcNAc). Besides the many known and postulated effects of protein O-GlcNAc modifications, there is little available data on the role of O-GlcNAc in cellular volume regulation. Our objective was to test the effect of increased O-GlcNAc levels on hypotonia-induced volume changes in Jurkat cells. We pretreated Jurkat cells for 1 h with glucosamine (GlcN), PUGNAc (O-(2-acetamido-2-deoxy-D-glucopyranosylidene)-amino-N-phenylcarbamate) an inhibitor of O-GlcNAcase, or a high level of glucose to induce elevated levels of O-GlcNAc. We found that the response of Jurkat cells to hypotonic stress was significantly altered. The hypotonia induced cell-swelling was augmented in both GlcN and PUGNAc-treated cells and, to a lesser extent, in high glucose concentration-treated cells. Evaluated by NMR measurements, GlcN and PUGNAc treatment also significantly reduced intracellular water diffusion. Taken together, increased cell swelling and reduced water diffusion caused by elevated O-GlcNAc show notable analogy to the regulatory volume changes seen by magnetic resonance methods in nervous and other tissues in different pathological states. In conclusion, we demonstrate for the first time that protein O-GlcNAc could modulate cell volume regulation.
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Kotek G, Berente Z, Schwarcz A, Vajda Z, Hadjiev J, Horvath I, Repa I, Miseta A, Bogner P. Effects of intra- and extracellular space properties on diffusion and T(2) relaxation in a tissue model. Magn Reson Imaging 2008; 27:279-84. [PMID: 18768282 DOI: 10.1016/j.mri.2008.07.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2008] [Revised: 04/15/2008] [Accepted: 07/13/2008] [Indexed: 11/30/2022]
Abstract
The purpose of this study was to investigate the effects of biophysical factors on the diffusion and the relaxation time T(2) independently. Certain properties of the extracellular and the intracellular space may change radically in pathological conditions resulting in water diffusion changes. A tissue model consisting of red blood cells was studied. The extra- and intracellular spaces were modified osmotically and by suspending medium concentration. Diffusion measurements were evaluated with regard to the effective medium theory. Neither the nature of the protein in the extracellular space nor an increased level of intracellular hydration caused a significant net water diffusion change in the cell suspension. The relaxation time T(2) exhibited very little dependence on the extracellular volume fraction or the concentration or the nature of the protein in the extracellular space. An increased level of intracellular hydration resulted in systematically larger T(2) values. It seems probable that increases in extracellular protein concentrations or in the extent of intracellular hydration do not play a significant role in the diffusion changes detected in pathological conditions. T(2) appears to depend on the level of hydration or the total water content but is seemingly less dependent of the concentration and the nature of the extracellular protein in our model solutions.
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Affiliation(s)
- Gyula Kotek
- Institute of Diagnostic Imaging and Radiation Oncology, Health Science Center, University of Kaposvár, H-7400 Kaposvár, Hungary
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Lodygensky GA, Inder TE, Neil JJ. Application of magnetic resonance imaging in animal models of perinatal hypoxic-ischemic cerebral injury. Int J Dev Neurosci 2007; 26:13-25. [PMID: 17977687 DOI: 10.1016/j.ijdevneu.2007.08.018] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2007] [Revised: 08/29/2007] [Accepted: 08/29/2007] [Indexed: 11/30/2022] Open
Abstract
Brain injury occurring in the perinatal period is an important etiology of subsequent neurodevelopmental disabilities. Magnetic resonance imaging (MRI) is a tool that is used to evaluate the nature of brain injury in the human infant. MRI techniques have also been applied to various animal models of perinatal injury. The most commonly used model is the immature rat, but there have also been imaging studies in mice, rabbit kits and piglets. The studies have been carried out using MR systems of various magnetic field strengths, ranging from 1.5 to 11.7tesla (T), with applications for quantification of infarct volume, T1 measurements, T2 measurements, proton and phosphorus spectroscopy and diffusion imaging. The MR findings are then related to histopathology and, in a few cases, behavioral evaluations. There is also a growing number of studies utilizing MRI in evaluating the efficacy of neuroprotective treatments, such as hypothermia.
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Affiliation(s)
- Gregory A Lodygensky
- Departments of Pediatrics, Washington University School of Medicine, St. Louis, MO, USA.
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