Background:Recent autopsy study showed a high incidence of cerebrovascular lesions in Alzheimer's disease(AD).To assess the impact of cerebrovascular pathology in AD,we used diffusion tensor imaging(DTI) to study ...Background:Recent autopsy study showed a high incidence of cerebrovascular lesions in Alzheimer's disease(AD).To assess the impact of cerebrovascular pathology in AD,we used diffusion tensor imaging(DTI) to study AD patients with and without cerebrovascular lesions.Materials and Methods:Conventional and DTI scans were obtained from 10 patients with probable AD,10 AD/V patients(probable AD with cerebrovascular lesions) and ten normal controls.Mean diffusivity(D) and fractional anisotropy(FA) values of some structures involved with AD pathology were measured.Results:D value was higher in AD patients than in controls in hippocampus and the cingulate gyrus.In AD/V patients,increased D value was found in the same structures and also in the thalamus and basal ganglia compared to controls.There was a significant difference of D value between AD and AD/V patients.FA value reduced in the white matter of left inferior temporal gyrus and in the bilateral middle cingulate gyrus in patients with AD/V compared with controls.The MMSE(mini-mental state examination) score significantly correlated with FA value in the right hippocampus(r=0.639,P<0.019),in the right anterior cingulate gyrus(r=0.587,P<0.035) and in left parahippocampal gyrus(r=0.559,P<0.047).Conclusion:Cerebrovascular pathology had stronger impact on the D value than the AD pathology alone did.Elevated D value in thalamic and basal ganglia may contribute to cognitive decline in AD/V patients.Reduced FA values in AD/V patients may indicate that cerebrovascular pathology induced more severe white matter damage than the AD pathology alone did.展开更多
Traumatic axonal injury is a progressive process evoked by shear forces on the brain, gradually evolving from focal axonal alteration and cumulating in neural disconnection. Clinical classifiers and conventional neuro...Traumatic axonal injury is a progressive process evoked by shear forces on the brain, gradually evolving from focal axonal alteration and cumulating in neural disconnection. Clinical classifiers and conventional neuroimaging are limited in traumatic axonal injury detection, outcome prediction, and treatment guidance. Diffusion weighted imaging is an advanced magnetic resonance imaging (MRI) technique that is sensitive to the movement of water molecules, providing additional information on the micro-structural arrangement of tissue. Quantitative analysis of diffusion metrics can aid in the localization of axonal injury and/or de(dys)myelination caused by trauma. Diffusion MRI tractography is an extension of diffusion weighted imaging, and can provide additional information about white matter pathways and the integrity of brain neural networks. Both techniques are able to detect the early micro-structural changes caused by Traumatic Brain Injury (TBI), and can be used to increase understanding of the mechanisms of brain plasticity in recovery after brain injury and possibly optimize treatment planning of patients with Traumatic Brain Injury. This review focuses on the theoretical basis and applied advanced techniques of diffusion weighted imaging, their limitations and applications, and future directions in the application to TBI.展开更多
Diffusion tensor imaging(DTI)technique can detect the dispersion of water molecules in the white matter of the spinal cord,the integrity of the spinal fiber bundle,and the pathological changes after injury.Clinically,...Diffusion tensor imaging(DTI)technique can detect the dispersion of water molecules in the white matter of the spinal cord,the integrity of the spinal fiber bundle,and the pathological changes after injury.Clinically,DTI is sensitive to acute and chronic spinal cord injuries,and is most commonly used for the diagnosis of cervical spondylotic myelopathy,multiple sclerosis,secondary brain damage after spinal cord injury,and spinal nerve root damage.In animal studies involving rats,monkeys,cattle,cats,pigs,dogs,etc.,DTI could quantitatively analyze the microstructural and pathological changes of the injured spinal cord and provide a powerful auxiliary diagnosis for behavioral evaluation.展开更多
To evaluate the effect of the positive-indefinite matrix on the diffusion tensor-derived parameters, a modified algorithm is proposed for calculating these parameters. Magnetic resonance （MR） diffusion tensor images...To evaluate the effect of the positive-indefinite matrix on the diffusion tensor-derived parameters, a modified algorithm is proposed for calculating these parameters. Magnetic resonance （MR） diffusion tensor images of five healthy volunteers are collected. The diffusion sensitive gradient magnetic fields are applied along 25 directions and the diffusion weighting value is 1 000 s/mm^2. Many positive-indefinite diffusion tensors can be found in the white matter area, such as the genu and the splenium of corpus callosum. Due to the positive-indefinite matrix, the mean diffusivity （MD） and the fractional anisotropy （FA） are under-estimated and over-estimated by using the conventional algorithm. Thus, the conventional algorithm is modified by using the absolute values of all eigenvalues. Results show that both the robustness and the reliability for deriving these parameters are improved by the modified algorithm.展开更多
Purpose: The purpose of this study was to compare the deterministic and probabilistic tracking methods of diffusion tensor white matter fiber tractography in patients with brain tumors. Materials and Methods: We ident...Purpose: The purpose of this study was to compare the deterministic and probabilistic tracking methods of diffusion tensor white matter fiber tractography in patients with brain tumors. Materials and Methods: We identified 29 patients with left brain tumors ciculus was reconstructed using a deterministic Fiber Assignment by Continuous Tracking (FACT) algorithm and a probabilistic method based on an extended Monte Carlo Random Walk algorithm. Tracking was controlled using two ROIs corresponding to Broca’s and Wernicke’s areas. Tracts in tumoraffected hemispheres were examined for extension between Broca’s and Wernicke’s areas, anterior-posterior length and volume, and compared with the normal contralateral tracts. Results: Probabilistic tracts displayed more complete anterior extension to Broca’s area than did FACT tracts on the tumor-affected and normal sides (p rs.展开更多
The human brain is known to contain a maximum of eight cholinergic nuclei： the basal forebrain region： the medial septal nucleus （Ch 1）, the vertical nucleus of the diagonal band （Ch 2）, the horizontal limb of t...The human brain is known to contain a maximum of eight cholinergic nuclei： the basal forebrain region： the medial septal nucleus （Ch 1）, the vertical nucleus of the diagonal band （Ch 2）, the horizontal limb of the diago- nal band （Ch 3）, and the nucleus basalis of Meynert （Ch 4）; the brainstem： the pedunculopontine nucleus （Ch 5）, the laterodorsal tegmental nucleus （Ch 6）, and the para- bigeminal nucleus （Ch 8）; and the thalamus： the medial habenular nucleus （Ch 7） （Nieuwenhuys et al., 2008; Naidich and Duvernoy, 2009）. The cingulum is the neu- ral tract extending from the orbitofrontal cortex to the medial temporal lobe （Mufson and Pandya, 1984）. The cingulum plays an important role in memory because it is a passage of the medial cholinergic pathway, which pro- vides cholinergic innervations to the cerebral cortex after originating from Ch 1 and Ch 2 as well as Ch 4 （mainly） （Selden et al., 1998; Nieuwenhuys et al., 2008; Hong and lang, 2010）.展开更多
目的:探讨3.0 T MR扩散张量成像在颈椎病诊断中的应用效果。方法:从2013年1月开始,至2015年1月结束,一共80例颈椎病患者,采用MR诊断仪对患者进行检查,比较颈椎病患者、健康体检者不同颈髓水平ADC值、FA值、颈髓长轴、前后径、左右径。结...目的:探讨3.0 T MR扩散张量成像在颈椎病诊断中的应用效果。方法:从2013年1月开始,至2015年1月结束,一共80例颈椎病患者,采用MR诊断仪对患者进行检查,比较颈椎病患者、健康体检者不同颈髓水平ADC值、FA值、颈髓长轴、前后径、左右径。结果:(1)在健康体检者中,C2-3、C4-5、C6-7之间ADC值、FA值、颈髓长轴、前后径、左右径无明显差异,无统计学意义,P>0.05;颈髓长轴、前后径、左右径之间两两对比,颈髓长轴值高于前后径和左右径,数据比较差异具有统计学意义,P<0.05。前后径和左右径之间对比,无明显差异,无统计学意义,P>0.05。(2)和对照组对比,A组ADC、FA、a1颈髓长轴无明显差异(P>0.05);a2前后径、a3左右径明显更大(P<0.05)。B组、C组、D组ADC值、FA值、颈髓长轴、前后径、左右径明显更大,数据比较差异明显,存在统计学意义,P<0.05.结论:采用扩散张量成像技术对颈椎病患者进行诊断,能够有效地显示颈椎压迫所致的脊髓微结构变化,具有较高的敏感性,3.0 T MR扩散张量成像在颈椎病诊断中的应用效果显著,能够弥补常规MRI难以定量分析颈椎微结构受压情况的缺点。展开更多
文摘Background:Recent autopsy study showed a high incidence of cerebrovascular lesions in Alzheimer's disease(AD).To assess the impact of cerebrovascular pathology in AD,we used diffusion tensor imaging(DTI) to study AD patients with and without cerebrovascular lesions.Materials and Methods:Conventional and DTI scans were obtained from 10 patients with probable AD,10 AD/V patients(probable AD with cerebrovascular lesions) and ten normal controls.Mean diffusivity(D) and fractional anisotropy(FA) values of some structures involved with AD pathology were measured.Results:D value was higher in AD patients than in controls in hippocampus and the cingulate gyrus.In AD/V patients,increased D value was found in the same structures and also in the thalamus and basal ganglia compared to controls.There was a significant difference of D value between AD and AD/V patients.FA value reduced in the white matter of left inferior temporal gyrus and in the bilateral middle cingulate gyrus in patients with AD/V compared with controls.The MMSE(mini-mental state examination) score significantly correlated with FA value in the right hippocampus(r=0.639,P<0.019),in the right anterior cingulate gyrus(r=0.587,P<0.035) and in left parahippocampal gyrus(r=0.559,P<0.047).Conclusion:Cerebrovascular pathology had stronger impact on the D value than the AD pathology alone did.Elevated D value in thalamic and basal ganglia may contribute to cognitive decline in AD/V patients.Reduced FA values in AD/V patients may indicate that cerebrovascular pathology induced more severe white matter damage than the AD pathology alone did.
文摘Traumatic axonal injury is a progressive process evoked by shear forces on the brain, gradually evolving from focal axonal alteration and cumulating in neural disconnection. Clinical classifiers and conventional neuroimaging are limited in traumatic axonal injury detection, outcome prediction, and treatment guidance. Diffusion weighted imaging is an advanced magnetic resonance imaging (MRI) technique that is sensitive to the movement of water molecules, providing additional information on the micro-structural arrangement of tissue. Quantitative analysis of diffusion metrics can aid in the localization of axonal injury and/or de(dys)myelination caused by trauma. Diffusion MRI tractography is an extension of diffusion weighted imaging, and can provide additional information about white matter pathways and the integrity of brain neural networks. Both techniques are able to detect the early micro-structural changes caused by Traumatic Brain Injury (TBI), and can be used to increase understanding of the mechanisms of brain plasticity in recovery after brain injury and possibly optimize treatment planning of patients with Traumatic Brain Injury. This review focuses on the theoretical basis and applied advanced techniques of diffusion weighted imaging, their limitations and applications, and future directions in the application to TBI.
文摘Diffusion tensor imaging(DTI)technique can detect the dispersion of water molecules in the white matter of the spinal cord,the integrity of the spinal fiber bundle,and the pathological changes after injury.Clinically,DTI is sensitive to acute and chronic spinal cord injuries,and is most commonly used for the diagnosis of cervical spondylotic myelopathy,multiple sclerosis,secondary brain damage after spinal cord injury,and spinal nerve root damage.In animal studies involving rats,monkeys,cattle,cats,pigs,dogs,etc.,DTI could quantitatively analyze the microstructural and pathological changes of the injured spinal cord and provide a powerful auxiliary diagnosis for behavioral evaluation.
基金Supported by the Research Project of Dongguan Higher Education (200910815252)the Beijing Natural Science Foundation(7102102)the Scientific Research Key Program of Beijing Municipal Commission of Ed-ucation(KZ200810025011)~~
文摘To evaluate the effect of the positive-indefinite matrix on the diffusion tensor-derived parameters, a modified algorithm is proposed for calculating these parameters. Magnetic resonance （MR） diffusion tensor images of five healthy volunteers are collected. The diffusion sensitive gradient magnetic fields are applied along 25 directions and the diffusion weighting value is 1 000 s/mm^2. Many positive-indefinite diffusion tensors can be found in the white matter area, such as the genu and the splenium of corpus callosum. Due to the positive-indefinite matrix, the mean diffusivity （MD） and the fractional anisotropy （FA） are under-estimated and over-estimated by using the conventional algorithm. Thus, the conventional algorithm is modified by using the absolute values of all eigenvalues. Results show that both the robustness and the reliability for deriving these parameters are improved by the modified algorithm.
文摘Purpose: The purpose of this study was to compare the deterministic and probabilistic tracking methods of diffusion tensor white matter fiber tractography in patients with brain tumors. Materials and Methods: We identified 29 patients with left brain tumors ciculus was reconstructed using a deterministic Fiber Assignment by Continuous Tracking (FACT) algorithm and a probabilistic method based on an extended Monte Carlo Random Walk algorithm. Tracking was controlled using two ROIs corresponding to Broca’s and Wernicke’s areas. Tracts in tumoraffected hemispheres were examined for extension between Broca’s and Wernicke’s areas, anterior-posterior length and volume, and compared with the normal contralateral tracts. Results: Probabilistic tracts displayed more complete anterior extension to Broca’s area than did FACT tracts on the tumor-affected and normal sides (p rs.
基金supported by Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education,Science and Technology,No.2012R1A1A4A01001873
文摘The human brain is known to contain a maximum of eight cholinergic nuclei： the basal forebrain region： the medial septal nucleus （Ch 1）, the vertical nucleus of the diagonal band （Ch 2）, the horizontal limb of the diago- nal band （Ch 3）, and the nucleus basalis of Meynert （Ch 4）; the brainstem： the pedunculopontine nucleus （Ch 5）, the laterodorsal tegmental nucleus （Ch 6）, and the para- bigeminal nucleus （Ch 8）; and the thalamus： the medial habenular nucleus （Ch 7） （Nieuwenhuys et al., 2008; Naidich and Duvernoy, 2009）. The cingulum is the neu- ral tract extending from the orbitofrontal cortex to the medial temporal lobe （Mufson and Pandya, 1984）. The cingulum plays an important role in memory because it is a passage of the medial cholinergic pathway, which pro- vides cholinergic innervations to the cerebral cortex after originating from Ch 1 and Ch 2 as well as Ch 4 （mainly） （Selden et al., 1998; Nieuwenhuys et al., 2008; Hong and lang, 2010）.
文摘类淋巴系统是近年发现的中枢神经系统内通过血管周围间隙执行代谢产物运输及代谢废物清除功能的系统,类淋巴系统功能下降与多种认知障碍疾病的发病机制相关。研究证实血管周围间隙扩散张量成像技术(diffusion tensor image analysis along the perivascular space,DTI-ALPS)所计算出的DTI-ALPS指数与阿尔茨海默病、帕金森、脑小血管病等疾病的认知功能障碍及疾病进展显著相关。本文将对DTI-ALPS技术在评估认知障碍疾病的类淋巴系统功能中的研究进展进行综述。
文摘目的:探讨3.0 T MR扩散张量成像在颈椎病诊断中的应用效果。方法:从2013年1月开始,至2015年1月结束,一共80例颈椎病患者,采用MR诊断仪对患者进行检查,比较颈椎病患者、健康体检者不同颈髓水平ADC值、FA值、颈髓长轴、前后径、左右径。结果:(1)在健康体检者中,C2-3、C4-5、C6-7之间ADC值、FA值、颈髓长轴、前后径、左右径无明显差异,无统计学意义,P>0.05;颈髓长轴、前后径、左右径之间两两对比,颈髓长轴值高于前后径和左右径,数据比较差异具有统计学意义,P<0.05。前后径和左右径之间对比,无明显差异,无统计学意义,P>0.05。(2)和对照组对比,A组ADC、FA、a1颈髓长轴无明显差异(P>0.05);a2前后径、a3左右径明显更大(P<0.05)。B组、C组、D组ADC值、FA值、颈髓长轴、前后径、左右径明显更大,数据比较差异明显,存在统计学意义,P<0.05.结论:采用扩散张量成像技术对颈椎病患者进行诊断,能够有效地显示颈椎压迫所致的脊髓微结构变化,具有较高的敏感性,3.0 T MR扩散张量成像在颈椎病诊断中的应用效果显著,能够弥补常规MRI难以定量分析颈椎微结构受压情况的缺点。
