Evaluation of optimized b-value sampling schemas for diffusion kurtosis imaging with an application to stroke patient data

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.     

扩散峰度成像与扩散加权成像在诊断宫颈鳞癌分级中的价值

目的对比分析扩散峰度成像(DKI)与扩散加权成像(DWI)诊断宫颈鳞癌分级的价值。方法回顾性纳入经术后病理证实的宫颈鳞癌病人42例,年龄39~69岁,平均(54.9±7.9)岁。以病理结果为金标准,分为高中分化组(27例)和低分化组(15例),分别测量2组肿瘤实质区平均扩散峰度(MK)值、平均扩散系数(MD)值及平均表观扩散系数(ADC)值、最小ADC值,采用独立样本t检验比较2组间各参数值的差异,采用受试者操作特征(ROC)曲线评价各参数值的诊断效能及最佳诊断阈值,并根据约登指数确定各参数相应的敏感度和特异度。结果2名观察者测得各参数的一致性均良好(均ICC>0.60,P<0.05)。低分化组的MK值高于高中分化组,而MD、平均ADC、最小ADC值均低于高中分化组(均P<0.05)。采用单一参数鉴别低分化与高中分化宫颈鳞癌时,MK为0.88时,AUC最大(0.877)、敏感度(92.6%)最高;MD为1.04×10^-3mm^2/s时,特异度(86.7%)最高。联合MK、MD和最小ADC值诊断时,AUC最大(0.937),敏感度最高(96.3%)。结论与传统DWI相比,DKI可更有效地鉴别低分化与高中分化宫颈鳞癌,联合应用DKI和DWI参数可有效提高诊断效能。     

同时多层采集技术在乳腺MR高清扩散峰度成像中的可行性研究

目的:探讨同时多层采集技术在乳腺高清扩散峰度成像(RESOLVE DKI)中的应用价值.方法:回顾性分析行乳腺MRI检查并经病理学证实的46例女性患者(48个病变,其中恶性病变41个,良性病变7个)的临床及影像资料,分别采集常规RESOLVE DKI和采用同时多层采集技术RE-SOLVE DKI序列(SMS RESOL...     

扩散加权成像在卵巢肿瘤中的应用

扩散加权成像(DWI)是目前唯一能够检测生物组织内水分子扩散运动的无创方法 ,该种扩散运动可以通过表观扩散系数(ADC)来量化分析。扩散峰度成像(DKI)、体素内不相干运动(IVIM)成像、背景抑制扩散加权全身成像(DWIBS)等DWI新技术用于卵巢肿瘤的评估提高了卵巢肿瘤影像诊断的准确性。综述DWI及其新技术在卵巢肿瘤定性诊断、分期、疗效评估、预后判断中的作用及其潜在缺陷。     

Updates in advanced diffusion-weighted magnetic resonance imaging techniques in the evaluation of prostate cancer

Diffusion-weighted magnetic resonance imaging (DW-MRI) is considered part of the standard imaging protocol for the evaluation of patients with prostate cancer. It has been proven valuable as a functional tool for qualitative and quantitative analysis of prostate cancer beyond anatomical MRI sequences such as T2-weighted imaging. This review discusses ongoing controversies in DW-MRI acquisition, including the optimal number of b-values to be used for prostate DWI, and summarizes the current literature on the use of advanced DW-MRI techniques. These include intravoxel incoherent motion imaging, which better accounts for the non-mono-exponential behavior of the apparent diffusion coefficient as a function of b-value and the influence of perfusion at low b-values. Another technique is diffusion kurtosis imaging (DKI). Metrics from DKI reflect excess kurtosis of tissues, representing its deviation from Gaussian diffusion behavior. Preliminary results suggest that DKI findings may have more value than findings from conventional DW-MRI for the assessment of prostate cancer.     

扩散峰度成像直方图在脑胶质瘤分级中的应用

目的探讨MRI扩散峰度成像(diffusion kurtosis imaging,DKI)直方图分析在脑胶质瘤术前分级诊断中的价值。方法通过对经手术及病理证实的45例脑胶质瘤患者的DKI图像资料的回顾性分析。选取整个肿瘤的实质区作为感兴趣容积(volume of interest,VOI)进行直方图分析,获得表观扩散系数(apparent diffusion for gaussian distribution,Dapp)及表观扩散峰度(apparent kurtosis coefficient,Kapp)的直方图参数。使用独立样本t检验及Mann-Whitney U检验评估高级别和低级别神经胶质瘤各直方图参数间的差异。受试者工作特征曲线(receiver operating characteristic,ROC)用于分析各直方图参数对胶质瘤分级的诊断效能。应用组内相关系数(intra-class correlation coefficient,ICC)分析数据测量的可重复性。结果DKI直方图参数在高低级别胶质瘤中有显著性差异(P<0.05)。Dapp直方图参数中Dapp-10th的诊断效能最高,曲线下面积(area under the curve,AUC)、敏感性和特异性分别为0.856、74.1%、83.3%。Kapp直方图参数中Kapp-30th的诊断能力最高,AUC、敏感性和特异性分别为0.905、81.5%、94.4%。每个参数具有良好的观察者间信度,ICC范围为0.861~0.964。结论DKI直方图分析有助于提高低级别胶质瘤与高级别胶质瘤之间的鉴别诊断能力。     

扩散峰度成像与DWI在卵巢实性病灶良恶性鉴别诊断中的应用

目的:探讨扩散峰度成像(DKI)与DWI在卵巢实性病灶良恶性鉴别诊断中的应用价值.方法:回顾性分析87例卵巢实性病灶的临床及影像资料,患者均行卵巢MRI常规平扫、DWI、DKI检查,分别获取ADC值、平均扩散峰度(MK)和平均扩散率(MD),评估DWI、DKI对卵巢良恶性病变的鉴别诊断价值.结果:与卵巢恶性病变相比,卵...     

新生猪缺氧缺血性脑病扩散峰度成像的时间进程变化

目的分析新生猪缺氧缺血性脑病扩散峰度成像(DKI)相关参数随时间变化规律,并与扩散张量成像(DTI)相关参数对比。材料与方法选取出生3~5 d内的健康约克种猪20只,分为实验组15只和对照组5只。实验组结扎双侧颈总动脉后放入氧浓度为4%的乏氧箱内,乏氧30 min。对照组仅行分离双侧颈总动脉的假手术。实验组和对照组在模型建立后3、6、9、12、16、24 h分别进行DKI扫描,扫描完成后,实验组和对照组各选3只猪取脑行病理学检查。结果实验组猪缺氧缺血发生后,病变处DKI相关参数平均扩散峰度(MK)、径向扩散峰度(Kr)、轴向扩散峰度(Ka)较对照组逐渐升高,差异有统计学意义(P<0.05);DTI相关参数平均扩散系数(MD)、垂直扩散张量(Dr)、轴向扩散张量(Da)逐渐降低,差异有统计学意义(P<0.05)。DKI相关参数值变化率大于DTI相关参数值变化率,且平行于轴突方向的变化率均大于垂直于轴突方向的变化率(Ka、Da、Kr及Dr的平均变化率分别为119.75%、55.54%、93.32%、50.51%)。实验组病理结果显示神经元水肿,大量炎症细胞浸润,局部可见坏死。结论与DTI相关参数相比,DKI能够更敏感地评价缺氧缺血性脑病脑组织微结构的变化。     

扩散峰度成像的基本原理及其在脑肿瘤中的应用

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。     

MR扩散峰度成像原理及其在中枢神经系统的初步应用

通过对水分子扩散运动的测量,扩散张量成像（ＤＴＩ）可以无创地对组织结构进行评价,而扩散峰度成像（ＤＫＩ）是以DTI为基础,对生物组织内水分子扩散的非高斯分布特征进行定量分析,揭示组织结构细微改变。DKI较DTI能提供更多关于组织微观结构的信息。综述DKI的原理及其在中枢神经系统的应用,包括神经退行性疾病、创伤性脑损伤、缺血性脑卒中、胶质瘤、多发性硬化、脑发育等。     

MR扩散峰度成像在腹部的研究现状

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。     

体素内不相干运动联合扩散峰度成像对乳腺癌HER-2表达的判断价值

目的探讨体素内不相干运动成像(IVIM)联合扩散峰度成像(DKI)对乳腺癌HER-2表达状态的诊断价值。方法选取本院经病理证实的乳腺癌患者201例,HER-2阳性组106例,HER-2阴性组95例,所有病例均行IVIM及DKI检查。分析两组间的临床病例资料和表观扩散系数(ADC)、真实扩散系数(D)、灌注相关扩散系数(D^*)、灌注分数(f)、平均扩散峰度值(MK)和平均扩散率(MD);运用2检验分析临床病理资料的差异性;采用两独立样本t检验比较IVIM、DKI诸参数的差异,绘制ROC比较其诊断效能。结果 HER-2阳性组乳腺癌形态多为不规则形,淋巴结转移亦多见,两组间差异有统计学差异(P<0.05)。HER-2阳性组的D和MK值小于阴性组,而D^*和f值高于阴性组,差异有统计学意义(P<0.05)。D值、MK与HER-2表达呈负相关,而D^*和f值与HER-2表达呈正相关(|r|为0.149～0.362)。当D≤0.69×10^-3mm²/s、D^*≥...     

Diffusional kurtosis imaging in the lung using hyperpolarized 3He.

Diseases of the small airspaces represent an increasingly important health problem. Asthma is primarily a disease of airway dysfunction, while chronic obstructive pulmonary disease (COPD) is associated with abnormalities in both the small airways and the alveoli. Conventional diffusion magnetic resonance imaging (MRI) of hyperpolarized noble gases, because of the short T(2)* of the gas, is only capable of monitoring diffusion over short times and hence only short distances. Diffusion imaging is therefore only sensitive to changes in small structures of the lung (primarily the alveoli), and will not adequately interrogate diffusion along the longitudinal axes of bronchi and bronchioles. In this communication we present a new method, termed diffusional kurtosis imaging (DKI), that is particularly sensitive to diffusion over longer distances. DKI may therefore be more sensitive to abnormalities in the bronchioles and bronchi than conventional diffusion imaging. Preliminary DKI measurements on healthy human subjects and one patient with symptoms suggestive of small airway disease are presented. Although the apparent diffusion coefficient (ADC) in the patient was similar to that in the normal controls, diffusional kurtosis was markedly reduced. This suggests that DKI measurements may be useful for assessing diseases of the small airways.     

肾脏MR扩散峰度成像研究进展

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。     

MR diffusion kurtosis imaging predicts malignant potential and the histological type of meningioma

PurposeTo explore the value of Diffusion kurtosis imaging (DKI) metrics in the differential diagnosis of meningioma.MethodsFor this study, we retrospectively enrolled 35 patients of cerebral meningioma with DKI which included axial diffusion coefficient (AD), radial diffusion coefficient (RD), mean diffusion coefficient (MD), fractional anisotropy (FA), axial kurtosis (AK), radial kurtosis (RK) and mean kurtosis (MK). All of these metrics were normalized according to contralateral normal-appearing white matter (NAWMc). Patients were divided into two groups (benign and malignant meningioma) and were further analyzed using the independent sample t-test and receiver operating characteristic (ROC) curve. A one-way ANOVA analysis was used to analyze four groups divided according to pathological subtypes.ResultsThe metrics of AD, normalized AD, normalized MD, MK and normalized MK showed a significant difference between benign and malignant group, and MK showed relatively higher diagnostic ability with its cut-off value, area under the curve (AUC), sensitivity and specificity of 0.875, 0.780, 70% and 89%, respectively. The metrics of normalized MD, RD and normalized RD, FA and normalized FA, AK and normalized AK, and RK showed significant difference among four subtypes. MK and RK in meningioma were found to correlate positively with the Ki-67 labeling index (Ki-67 LI).ConclusionsDKI metrics may be used to differentiate benign from malignant meningioma, and also to distinguish some histological subtypes of meningioma. Moreover, DKI metrics may potentially reflect cellular proliferation.     

MRI在肝外胆管癌诊断中的应用

胆管癌是一种少见的恶性肿瘤,预后不良,大多数发生于肝外胆管。肝外胆管癌（EHCC）的定位诊断常依赖于影像检查,MRI为目前诊断EHCC常用的影像检查方法之一。随着MR技术的发展,越来越多的序列如扩散加权成像（DWI）、体素内不相干运动（IVIM）、扩散峰度成像（DKI）等应用于EHCC的诊断,并且可以对肿瘤的病理级别进行预测和评估,对判断病人的预后及肿瘤的复发具有重要意义。就不同MR成像序列在EHCC诊断中的应用予以综述。     

大脑中动脉不同部位急性脑梗死的DKI表现特点

目的 比较DKI各峰度参数与扩散参数早期诊断急性脑梗死的能力,评估大脑中动脉供血区不同部位急性脑梗死后DKI峰度参数的变化特点,探究早期诊断不同部位脑梗死的优势参数图。 方法 回顾性收集单侧大脑中动脉供血区的急性脑梗死病人62例（共84个病灶）,男37例,女25例,年龄43~71岁,平均（57.26±6.27）岁。行DKI扫描并获得轴向扩散率（AD）、平均扩散率（MD）、径向扩散率（RD）、轴向扩散峰度（AK）、平均扩散峰度（MK）、径向扩散峰度（RK）图。按梗死部位将所有病灶分为3组,包括皮质（28个）、皮质下白质（25个）和基底节区（31个）组。采用配对t检验比较各参数值患侧与健侧的差异,采用秩和检验比较各峰度参数变化率（Δ参数值%）的差异,采用单因素方差分析比较3组间各峰度参数健侧绝对值的差异。 结果 与健侧对照区相比,所有梗死灶的扩散参数（AD、MD、RD）值均减低,而峰度参数（AK、MK、RK）值均增高（均P<0.05）。其中,扩散参数的变化率均小于其对应峰度参数的（均P<0.05）。健侧对照区中,皮质下白质区和基底节区的MK、RK值均高于皮质区,而基底节区的RK值也高于皮质下白质区（均P<0.05）。皮质、皮质下白质、基底节区病灶的ΔAK%依次增大（P<0.05）。皮质组的ΔAK%、ΔMK%、ΔRK%的差异无统计学意义（P>0.05）;皮质下白质组的ΔAK%与ΔMK%均大于ΔRK%（均P<0.05）;基底节区组的ΔAK%、ΔMK%、ΔRK%数值呈降序分布（均P<0.05）。 结论 DKI峰度参数较扩散参数更易检出梗死病灶。缺血状态下,皮质下白质及基底节区的组织微结构改变较皮质更为复杂,且AK、MK较RK更有评估不同部位缺血损伤的潜力。对位于皮质、皮质下白质的脑梗死评估,MK图具有优势,而对基底节区的脑梗死早期评估,AK图更具优势。     

扩散峰度成像在脑电图表现正常儿童特发性全面性癫痫的研究

目的:分析脑电图(EEG)结果正常的特发性全面性癫痫(IGE)患儿扩散峰度成像(DKI)的各向特征值。方法:将头皮EEG结果正常的9例IGE患儿与18例年龄、性别匹配的正常对照(NC)组儿童的头部DKI影像,通过基于体素分析方法估计,DKI参数各向异性分数(FA)、平均扩散吸系数(MD,)及平均峰度值(MK),MD包括MD⊥和MD∥,MK包括MK⊥和MK∥,比较病例组与NC组间DKI参数的差异。结果:在病例与NC组比较中,病例组FA减低区域为体素簇391左侧半球额叶白质、114下额叶皮层灰质、100脑回下区域等区域。病例组MD增高区域为体素簇362左侧大脑半球颞叶白质及240颞中回。病例组MK∥异常区域为体素簇66的左侧大脑半球叶下区域。结论:DKI各特征值可检出EEG正常IGE患儿脑白质、灰质异常,可为临床抗癫痫药物治疗及随访提供影像信息支持。     

DKI推算序列优化直肠癌术前分期的应用研究

目的 探索基于扩散峰度成像(DKI)扫描参数的推算序列代替常规扩散加权成像(DWI)序列扫描的应用价值.方法 回顾性分析2019年11月至2020年10月瑞金医院确诊的直肠癌患者62例,其手术前2周内均行MR扫描,将DKI图像经后处理推算出b=1000 s/mm2扩散图像,两名医师分别对推算序列与常规DWI序列的b=1...     

DKI对动态增强时间-信号曲线呈平台型乳腺纤维腺瘤及乳腺癌的诊断价值

目的探讨扩散峰度成像(DKI)对动态增强时间-信号曲线呈平台型的乳腺纤维腺瘤和乳腺癌的鉴别诊断价值。方法选取DCE-TIC为平台型的20例(20个病灶)乳腺纤维腺瘤患者和61例(64个病灶)乳腺癌患者。测得病变的平均扩散峰度系数(MK)和平均扩散系数(MD)以及ADC值,观察病变形态和强化特征。以病理结果为金标准,采用X²检验比较两类病变间形状、边缘、背景实质强化、内部强化特征、早期强化率的差异;采用两独立样本t检验比较DKI、DWI参数的差异,绘制ROC比较其诊断效能。结果DCE-TIC呈平台型的乳腺纤维腺瘤及乳腺癌,形状、边缘、内部强化特征以及早期强化率差异均有统计学意义(P<0.05),背景实质强化差异无统计学意义(P>0.05);MK、MD、ADC值的差异均有统计学意义(P<0.05),联合MK、MD和ADC,ROC下面积为0.991,敏感度、特异度和准确度分别达0.922、1.000和0.922。结论DKI对DCE-TIC呈平台型乳腺纤维腺瘤及乳腺癌具有良好的鉴别诊断意义,将DKI和DWI联合应用可获得更高的诊断效能。