共查询到18条相似文献,搜索用时 78 毫秒
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扩散峰度成像(DKI)是一项新兴磁共振成像技术,它是在扩散张量成像(diffusion tensor imaging,DTI)技术上的扩展,通过探测生物组织内水分子的非高斯分布扩散运动的特性,来更加敏感地反映组织微观结构的复杂程度[1],是目前能通过非侵袭性手段探测活体组织微观信息的磁共振技术之一。因此,DKI可以为某些疾病的早期组织微结构的变化提供更为准确的评价,尤其是在显示精细的中枢神经系统的微 相似文献
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扩散峰度成像(DKI)是近年发展起来的一项新的MR扩散加权成像(DWI)技术,不同于传统的DWI及扩散张量成像(DTI),DKI主要是通过描述组织内水分子扩散运动偏离正态分布的程度,评价组织的微结构,间接反映组织生理、病理情况。DKI目前已广泛应用于中枢神经系统的临床研究,尤其在脑肿瘤方面。对DKI的基本原理及其在脑肿瘤中的临床应用予以综述。 相似文献
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MR扩散峰度成像(DKI)基于多项式模型,能够量化组织中水分子的扩散运动与自由高斯运动的偏差。DKI技术可以定量评价组织微环境的复杂性和异质性,近年来已用于评价肾脏功能及相关疾病,在肾脏肿瘤的分级,以及在梗阻性肾病、糖尿病肾病、高尿酸血症肾病等常见疾病的早期诊断中具有一定的应用价值。就DKI成像原理及在正常肾脏和肾脏常见疾病中的研究进展予以综述。 相似文献
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在磁共振成像领域中,扩散张量成像(diffusion tensor imaging,DTI)作为一项磁共振功能成像技术,可以从微观领域评估组织结构的完整性,目前最主要应用于脑组织各方向白质纤维及纤维束的评价。扩散加权成像(DWI)及DTI的理论前提为水分子扩散呈正态分布[2];而扩散峰度成像(diffusion kurtosis imaging,DKI)是基于DTI技术上的延伸,为描绘组织内非正态分布水分子扩散的一种新的磁共振成像方法,较传统的DTI技术,DKI更适合把握组织微观结构的变化[3]。笔者旨在简要综述DKI在中枢神经系统的有关应用及DKI与DTI在相关方面作一定的比较。 相似文献
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磁共振扩散峰度成像(DKI)是一种反映体内水分子非高斯分布扩散运动状态的MR成像新技术。近年来DKI已广泛应用于神经系统,并取得良好的效果。目前也逐步被应用于前列腺、肾脏、肝脏等体部脏器成像,其中在前列腺的应用最为广泛,通过应用DKI可提高对前列腺肿瘤诊断与分级的能力。就DKI技术在腹部的应用研究现状予以综述。 相似文献
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MR扩散加权成像和扩散张量成像能够发现癫痫发作期脑内部分区域的ADC值短暂下降,可提供新近癫痫活动的定位信息。发作间期ADC值的升高和FA值的下降反映了慢性癫痫病灶特征性的病理改变。综述MR扩散成像对癫痫病人的功能应用研究。 相似文献
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系统性红斑狼疮(SLE)累及神经系统而出现各种神经精神症状时称为精神神经性狼疮(NPSLE),NPSLE是SLE的主要死亡原因之一。早期诊断并治疗NPSLE对病人的预后有重要的意义。扩散张量成像及扩散峰度成像能够实现对早期NPSLE脑部损伤的可视化,其特征参数的变化能够反映NPSLE的病理过程,具有一定的判断病情活跃性和预后的价值。就扩散张量成像及扩散峰度成像对NPSLE的相关研究及进展进行综述。 相似文献
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Xu Yan Minxiong Zhou Lingfang Ying Dazhi Yin Mingxia Fan Guang Yang Yongdi Zhou Fan Song Dongrong Xu 《Computerized medical imaging and graphics》2013,37(4):272-280
Diffusion kurtosis imaging (DKI) is a new method of magnetic resonance imaging (MRI) that provides non-Gaussian information that is not available in conventional diffusion tensor imaging (DTI). DKI requires data acquisition at multiple b-values for parameter estimation; this process is usually time-consuming. Therefore, fewer b-values are preferable to expedite acquisition. In this study, we carefully evaluated various acquisition schemas using different numbers and combinations of b-values. Acquisition schemas that sampled b-values that were distributed to two ends were optimized. Compared to conventional schemas using equally spaced b-values (ESB), optimized schemas require fewer b-values to minimize fitting errors in parameter estimation and may thus significantly reduce scanning time. Following a ranked list of optimized schemas resulted from the evaluation, we recommend the 3b schema based on its estimation accuracy and time efficiency, which needs data from only 3 b-values at 0, around 800 and around 2600 s/mm2, respectively. Analyses using voxel-based analysis (VBA) and region-of-interest (ROI) analysis with human DKI datasets support the use of the optimized 3b (0, 1000, 2500 s/mm2) DKI schema in practical clinical applications. 相似文献
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神经突方向离散度和密度成像(NODDI)是一种新型的多隔室扩散成像模型,该模型能够定量分析神经突密度和纤维方向离散度,这两种因素均可影响扩散张量成像(DTI)的参数各向异性分数(FA),能够比DTI更特异性地评估组织微观结构的变化。目前该技术已在生长发育和老化、神经退行性疾病、多发性硬化症、精神类疾病和脑卒中等方面展开研究。就NODDI的原理及其在中枢神经系统的研究进展进行综述。 相似文献
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目的评价磁共振扩散张量成像(DTI)在诊断中枢系统疾病中的用途。方法 86例临床证实的中枢神经系统疾病患者包括超急性及急性期脑梗死40例,脑肿瘤32例,脑白质疏松7例,多发性硬化4例,脑中毒3例以及作为正常对照的健康志愿者9例均经常规磁共振序列和DWI、DTI检查,对患侧和健侧大脑白质纤维束感兴趣区各向异性分数(FA)值进行定量分析,获得方向编码彩色(DEC)图和黑白各向异性(FA)图,扩散张量纤维束成像(DTI)显示脑白质纤维束走形方向、损伤、受压、移位等情况。结果健康组不同部位的脑白质的FA值不同,但大脑半球两侧的FA值差异无统计学意义。超急性(发病后小于6 h)脑梗死区白质FA值与对侧相比轻度增高或降低,急性期(发病后6~72 h)脑梗死区白质FA值显著减低,FA图为低信号,健侧脑白质为高信号,均有明显差别。良恶性脑肿瘤FA值仅在瘤周水肿区的比较中有统计学差异,FA图肿瘤实质为稍低信号,中心坏死及周围水肿表现为低信号。脑白质病变和正常对照组感兴趣区测量FA值,病变区FA值降低,两组差异有统计学意义。结论 DTI可无创且清晰地显示白质纤维束走行方向及分布情况,对诊断中枢神经系统病变有重要用途。 相似文献
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《Computerized medical imaging and graphics》2014,38(6):469-480
Diffusion kurtosis imaging (DKI) is a new model in magnetic resonance imaging (MRI) characterizing restricted diffusion of water molecules in living tissues. We propose a method for fast estimation of the DKI parameters. These parameters – apparent diffusion coefficient (ADC) and apparent kurtosis coefficient (AKC) – are evaluated using an alternative iteration schema (AIS). This schema first roughly estimates a pair of ADC and AKC values from a subset of the DKI data acquired at 3 b-values. It then iteratively and alternately updates the ADC and AKC until they are converged. This approach employs the technique of linear least square fitting to minimize estimation error in each iteration. In addition to the common physical and biological constrains that set the upper and lower boundaries of the ADC and AKC values, we use a smoothing procedure to ensure that estimation is robust. Quantitative comparisons between our AIS methods and the conventional methods of unconstrained nonlinear least square (UNLS) using both synthetic and real data showed that our unconstrained AIS method can significantly accelerate the estimation procedure without compromising its accuracy, with the computational time for a DKI dataset successfully reduced to only 1 or 2 min. Moreover, the incorporation of the smoothing procedure using one of our AIS methods can significantly enhance the contrast of AKC maps and greatly improve the visibility of details in fine structures. 相似文献
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Diffusional kurtosis imaging for differentiating between high‐grade glioma and primary central nervous system lymphoma
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Xuefei Dang MD Xiaoyuan Feng PhD Zhenwei Yao PhD Jingsong Wu PhD Chengjun Yao PhD Ning DI PhD Diana Cristina Ghinda MD Yong Zhang PhD 《Journal of magnetic resonance imaging : JMRI》2016,44(1):30-40
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目的探讨儿童抽动秽语综合征(tourette syndrome,TS)患者中枢神经系统弥散张量成像特点。方法选取17例右利手TS患儿(TS组)和17例右利手健康(对照组)儿童进行头颅MR弥散张量成像(diffusion tensor imaging,DTI)。使用手工画感兴趣区(ROI)法,在DTI图像的基底节最大层面,分别测量双侧壳核,尾状核,丘脑,部分额叶白质等兴趣区的分数各向异性(fractional anisotropy,FA)值和表观弥散系数(apparent diffusion coefficient,ADC)。使用独立样本t检验,比较分析TS组与对照组相对应脑结构的FA值及ADC值的差异。使用Pearson相关性分析TS组测量的FA值ADC值分别与病程的相关性。结果组间比较,TS组右侧壳状核FA较对照组右侧壳状核FA值下降(t=2.362,P=0.024<0.05),TS组右侧尾状核FA值较对照组右侧尾状核FA值下降(t=2.046,P=0.049<0.05);TS组右侧尾状核ADC值较对照组右侧尾状核ADC值上升(t=2.908,P=0.007<0.01)。与病程相关性,TS组右壳核FA值降低程度与病程呈正相关P=0.008<0.01,r=0.48。结论 TS中枢神经系统的DTI定量分析表明,壳核,尾状核部位弥散参数异常,可能提示TS患儿脑组织的病理改变。 相似文献
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Meng-Yue Tang Xiao-Ming Zhang Tian-Wu Chen Xiao-Hua Huang 《World journal of radiology》2015,7(12):424-437
Pancreatic cancer is one of the most common malignant tumors and remains a treatment-refractory cancer with a poor prognosis. Currently, the diagnosis of pancreatic neoplasm depends mainly on imaging and which methods are conducive to detecting small lesions. Compared to the other techniques, magnetic resonance imaging (MRI) has irreplaceable advantages and can provide valuable information unattainable with other noninvasive or minimally invasive imaging techniques. Advances in MR hardware and pulse sequence design have particularly improved the quality and robustness of MRI of the pancreas. Diffusion MR imaging serves as one of the common functional MRI techniques and is the only technique that can be used to reflect the diffusion movement of water molecules in vivo. It is generally known that diffusion properties depend on the characterization of intrinsic features of tissue microdynamics and microstructure. With the improvement of the diffusion models, diffusion MR imaging techniques are increasingly varied, from the simplest and most commonly used technique to the more complex. In this review, the various diffusion MRI techniques for pancreatic cancer are discussed, including conventional diffusion weighted imaging (DWI), multi-b DWI based on intra-voxel incoherent motion theory, diffusion tensor imaging and diffusion kurtosis imaging. The principles, main parameters, advantages and limitations of these techniques, as well as future directions for pancreatic diffusion imaging are also discussed. 相似文献