肾的血氧水平依赖功能磁共振成像

肾实质不同区域解剖和生理过程之间存在明显差异,使得肾髓质在低氧环境下发挥功能,对血流的进一步降低和氧消耗的增加非常敏感[1]。以往对肾内氧分压的测量多利用微电极等有创性手段进行,但不能用于人类研究。血氧水平依赖磁共振成像(BOLD MRI)是目前唯一能无创性绘制肾内氧分布的技术,与微电极测量数据之间具有良好的一致性[2-8]。本文综述肾的BOLD MRI的理论基础、技术、临床应用以及与其他技术相比的优劣势。1肾BOLD MRI的理论基础BOLD是基于血红蛋白氧饱和水平的改变而成像的。氧合血红蛋白具有抗磁性,而脱氧血红蛋白具有顺磁…     

磁共振定量血氧水平依赖成像对大鼠脑氧代谢评估的可行性研究

目的：探讨磁共振定量血氧水平依赖(q BOLD)成像评估大鼠脑组织氧代谢的可行性。方法：利用7.0 T磁共振成像仪分别对5只健康SD大鼠以及5只C6胶质瘤大鼠麻醉后行q BOLD成像扫描,计算R2*、脑血流量(CBF)、氧饱和度(SO₂)、氧摄取分数(OEF)和脑氧代谢率(CMRO₂)。勾画荷瘤大鼠肿瘤组织、对侧脑灰质,记录正常脑组织、并比较肿瘤与对侧健康灰质氧代谢参数差异,研究BOLD成像信号影响因素。结果：健康大鼠灰质和白质的R2*值(单位：Hz)分别为37.4±1.2、36.2±1.7,SO₂值分别为66.4±3.2、53.2±2.6 (P<0.001),CBF值[单位：m L·(100 g)^-1·min^-1]分别为105.6±15.3、100.4±18.5 (P=0.03),OEF值分别为0.33±0.02、0.31±0.01,CMRO₂值[单位：m L·(100 g)^-1·min^-1]分别为3.8...     

肾脏MR血氧水平依赖成像的研究进展

MR血氧水平依赖成像主要用于中枢神经系统,近年来其在肾脏方面的研究逐渐成为热点,就血氧水平依赖在肾脏方面的应用技术、试验研究及临床应用方面的成果作一综述.     

肾脏MR血氧水平依赖成像的研究进展

MR血氧水平依赖成像主要用于中枢神经系统,近年来其在肾脏方面的研究逐渐成为热点,就血氧水平依赖在肾脏方面的应用技术、试验研究及临床应用方面的成果作一综述。     

正常前列腺组织磁共振血氧水平依赖成像的可行性研究

目的 评价正常前列腺组织吸入混合气(95%O2/5%CO2)状态下磁共振血氧水平依赖(blood oxygen level-dependent, BOLD)成像的可行性及前列腺中央腺区和外周带的磁共振信号强度-时间变化的差异性.方法 35例健康志愿者,在吸入混合气(95%O2/5%CO2)状态下行前列腺磁共振EPI成像.在吸入空气和混合气交替变化的不同时段采集图像,在工作站处理生成正常前列腺中央腺区和外周带信号强度-时间变化曲线,分别计算吸入混合气前后信号强度平均增加率,将数据进行统计学分析.结果 正常前列腺组织的中央腺区和外周带在吸入混合气状态下信号强度均增加,中央腺区信号强度的增加明显高于外周带(t=5.392, P<0.05).结论 吸入混合气状态下对正常前列腺组织行BOLD成像是可行的,且能很好地反映正常前列腺中央腺区和外周带信号强度-时间变化的差异.     

血氧水平依赖磁共振成像在肾功能不全中的应用

目的：探讨血氧水平依赖磁共振成像（BOLD MRI）在诊断肾功能不全以及鉴别不同分级肾功能不全的应用价值。方法对15名健康志愿者和55名不同分级肾功能不全患者进行BOLD MRI扫描,测量各组肾脏皮质、髓质的R2＊值并计算髓质／皮质R2＊值,对比分析各组数据。结果①正常对照组及不同分级的肾功能不全患者的皮质、髓质以及髓质／皮质R2＊值间均存在统计学差异（ P ＜0．05）;②皮质R2＊值与肾功能分级呈正相关,而髓质R2＊值及髓质／皮质R2＊比值与肾功能分级呈负相关。结论血氧水平依赖磁共振成像作为反映肾脏功能改变程度的敏感指标在肾功能不全的诊断及分级鉴别中起到重要的作用。     

血氧水平依赖MR成像对乳腺癌乏氧代谢和疗效评估的研究进展

评估乳腺癌乏氧代谢情况和微血管成熟度对临床治疗有指导作用。广泛应用于脑功能研究的血氧水平依赖功能MRI(BOLD-f MRI)可通过静息状态下基线R2*值及任务状态下△R2*值变化评估病灶内部的氧合作用及新生血管成熟度,以监测肿瘤微环境内的乏氧程度,进而制定具有针对性的个体化治疗方案,提高乳腺癌治愈率,降低病死率。就BOLD-f MRI对乳腺癌乏氧代谢、血管成熟度和疗效评估的应用现状进行综述。     

磁共振脑功能成像研究进展

血液动力学反应与神经活动间存在着密切的联系,磁共振脑功能成像是利用大脑功能区活动时,脑组织的活跃可引起局部顺磁性的脱氧血红蛋白生成减少,使局部脑组织Ｔ２及Ｔ２的弛瞎长,从而获得激活脑区的功能成像图,其突出特点是应用了平面回波（ＥＰＩ）技术,磁共振脑功能成像已用于人脑各种功能活动的研究,通过对颅内占位性病变对邻近重要功能区造成影响的研究,能够进一步指导神经外科医师合理地制定手术计划,对改善手术预后有     

血氧水平依赖磁共振成像在评估慢性肾小球肾炎患者肾脏功能及病理损伤中的应用

目的 探讨血氧水平依赖磁共振成像(BOLD-MRI)在定量评估慢性肾小球肾炎(CGN)患者肾功能及病理损伤的应用价值。方法 对19名健康志愿者和53例经肾活检确诊的CGN患者行BOLD-MRI检查,并测量肾皮髓质R₂^*值,记录临床资料及肾脏病理积分,分析R₂^*值与CGN患者肾功能及病理损伤的关系。结果 对照组与轻度损伤CGN组、中重度损伤CGN组肾皮髓质R₂^*值均有统计学意义(F=10.171,P<0.001;F=19.666,P<0.001)。皮髓质R₂^*值与肾小球滤过率估计值(eGFR)分别呈负、正相关(r=-0.570,P<0.001;r=0.357,P<0.009),肾皮髓质R₂^*值与胱抑素C、病理积分均有相关性,肾皮髓质R₂^*值鉴别对照组与轻度损伤CGN组,受试者工作特征曲线(ROC)曲线下面...     

语言的功能性磁共振成像研究进展

血氧水平依赖功能性磁共振成像（BOLD-fMRI）技术改变了传统对语言的研究方法，使人们对语言中枢的组成、分布及活动模式都有了更进一步的认识。综述了功能性磁共振成像在语言中的研究历史和现状。     

Measuring brain oxygenation in humans using a multiparametric quantitative blood oxygenation level dependent MRI approach

Quantitative blood oxygenation level dependent approaches have been designed to obtain quantitative oxygenation information using MRI. A mathematical model is usually fitted to the time signal decay of a gradient‐echo and spin‐echo measurements to derive hemodynamic parameters such as the blood oxygen saturation or the cerebral blood volume. Although the results in rats and human brain have been encouraging, recent studies have pointed out the need for independent estimation of one or more variables to increase the accuracy of the method. In this study, a multiparametric quantitative blood oxygenation level dependent approach is proposed. A combination of arterial spin labeling and dynamic susceptibility contrast methods were used to obtain quantitative estimates of cerebral blood volume and cerebral blood flow. These results were combined with T and T₂ measurements to derive maps of blood oxygen saturation or cerebral metabolic rate of oxygen. In 12 normal subjects, a mean cerebral blood volume of 4.33 ± 0.7%, cerebral blood flow of 43.8 ± 5.7 mL/min/100 g, blood oxygen saturation of 60 ± 6% and cerebral metabolic rate of oxygen 157 ± 23 μmol/100 g/min were found, which are in agreement with literature values. The results obtained in this study suggest that this methodology could be applied to study brain hypoxia in the setting of pathology. Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc.     

语言血氧水平依赖功能MR扫描在神经外科导航手术中的应用

目的 利用经皮层电刺激的方法验证血氧水平依赖(BOLD)激活信号的准确性,并探讨语言BOLD技术在神经外科导航中的应用价值.方法 选取脑肿瘤患者8例,术前行BOLD-fMRI.然后清醒麻醉状态下唤醒患者,进行经皮层电刺激过程,在神经导航的指导下与BOLD信号进行点对点对照.将皮层电刺激阳性点与BOLD激活区位置比较,分别计算刺激阳性点位于BOLD激活区(真阳性)、非激活区(假阴性)的个数及刺激阴性点位于BOLD激活区(假阳性)、非激活区(真阴性)的个数,观察BOLD的敏感度和特异度.用两种不同的方法分别统计:即刺激阳性点位于BOLD激活区上和刺激阳性点距离BOLD激活区1 cm范围内.避开语言区1.0 cm外进行病灶切除,保留阳性点0.5～1.0 cm以内的皮质.结果 8例患者仅6例顺利完成任务.6例患者中,星形胶质细胞瘤Ⅱ级3例、Ⅲ级2例,胶母细胞瘤1例.共刺激48个点,其中阳性点11个.以刺激点位于BOLD激活区为标准,结果显示BOLD敏感度72.7%(8/11),特异度81.8%(30/37);以距离BOLD激活区小于1 cm为标准,BOLD敏感度82.0%(9/11),特异度75.6%(28/37).术后随访,患者均未出现失语表现.结论 语言BOLD激活区敏感度及特异度较高.但客观上因语言脑区个体变异较大,此项技术真正应用到临床有待于样本量增加和经验总结.

Abstract：

Objective To verify the accuracy of blood oxygenation level dependent (BOLD)-based activation using electrocortical stimulation mapping (ESM) and explore the value of language fMRI in the navigating operation of neurosurgery. Methods In 8 cases with brain tumors,BOLD-fMRI examinations were done before the operations. Under the state of awake anesthesia,the patients were aroused and ESM was conducted. Point-to-point comparison between the BOLD signal activations and the ESM was carried out under the surveillance of the neuro-navigation technology. In order to observe the sensibility and specificity of BOLD activations, the location of BOLD activations and the point of ESM was compared to calculate the stimulating positive points inside the regions of BOLD signals(real positive), outside BOLD regions(pseudo-negative), the stimulating negative points inside the regions of BOLD signals(pseudo-positive), and outside BOLD region(real negative). Two kinds of criteria for assessment were used. One was that the positive stimulating points were located in BOLD regions, and the other was that the positive stimulating points were located within 1 cm around the range of BOLD regions. Removal of the lesions were conducted with the tissue 1 cm around the language region preserved, and the cortex inside 0.5-1.0 cm distance from the positive points were retained. Results Of the 8 cases, only 6 finished the tasks. Among them, 3 cases were with astrocytoma of grade 2,2 were with astrocytoma of grade 3, and one with glioblastoma. The total number of stimulating points was 48, among which the positive points were 11. When the first criteria was applied, the sensitivity was 72.7% (8/11), and the specificity was 81.8% (30/37). When the second criteria was applied, the sensitivity was 82.0% (9/11),and the specificity was 75.6% (28/37). Follow-up after operation showed no aphasia occurred. Conclusions BOLD-fMRI had a high sensitivity and specificity in displaying the language regions. But due to the great variation of brain language area among the people, we need more studies of large sample to obtain enough experience before it can be used clinically.     

Quantifying the blood oxygenation level dependent effect in cerebral blood volume-weighted functional MRI at 9.4T.

In cerebral blood volume (CBV)-weighted functional MRI (fMRI) employing superparamagnetic contrast agent, iron dose and blood oxygenation level dependent (BOLD) contamination are two important issues for experimental design and CBV quantification. Both BOLD and CBV-weighted fMRI are based upon the susceptibility effect, to which spin-echo and gradient-echo sequences have different sensitivities. In the present study, CBV-weighted fMRI was conducted using spin-echo and gradient-echo sequences at 9.4T by systematically changing the doses of contrast agent. Results suggest that BOLD contamination is a significant component in CBV-weighted fMRI at high field, particularly when relatively low dose of contrast agent is administered. A mathematical model was developed to quantify the extravascular (EV) BOLD effect. With a TE of 35 ms, the EV BOLD effect was estimated to account for 76+/-12% of the observed spin-echo fMRI signal at 9.4T. These data suggest that correcting BOLD effect may be necessary for accurately quantifying activation-induced CBV changes at high field.     

Comparison of 1H blood oxygen level–dependent (BOLD) and 19F MRI to investigate tumor oxygenation

Fluorine‐19 [¹⁹F] MRI oximetry and ¹H blood oxygen level–dependent (BOLD) MRI were used to investigate tumor oxygenation in rat breast 13762NF carcinomas, and correlations between the techniques were examined. A range of tissue oxygen partial pressure (pO₂) values was found in the nine tumors while the anesthetized rats breathed air, with individual tumor pO₂ ranging from a mean of 1 to 36 torr and hypoxic fraction (HF10) (<10 torr) ranging from 0% to 75%, indicating a large intra‐ and intertumor heterogeneity. Breathing oxygen produced significant increase in tumor pO₂ (mean ΔpO₂ = 50 torr) and decrease in HF₁₀ (P < 0.01). ¹H BOLD MRI observed using a spin echo‐planar imaging (EPI) sequence revealed a heterogeneous response and significant increase in mean tumor signal intensity (SI) (ΔSI = 7%, P < 0.01). R measured by multigradient‐echo (MGRE) MRI decreased significantly in response to oxygen (mean ΔR = ?4 s^?1; P < 0.05). A significant correlation was found between changes in mean tumor pO₂ and mean EPI BOLD ΔSI accompanying oxygen breathing (r² > 0.7, P < 0.001). Our results suggest that BOLD MRI provides information about tumor oxygenation and may be useful to predict pO₂ changes accompanying interventions. Significantly, the magnitude of the BOLD response appears to be predictive for residual tumor HFs. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.     

MRI血氧水平依赖成像评价正常大鼠肾脏氧合水平的重复性研究

目的 探讨用MR血氧水平依赖(BOLD)成像评价大鼠肾脏氧合水平的重复性和科学性.方法5只健康雄性Wistar大鼠,扫描前称量大鼠体重,在3.0 T MR扫描仪上分别在第1天(d1)、第5天(d5)、第10天(d10)、第30天(d30)和第50天(dS0)行BOLD成像,测量表观自旋-自旋弛豫率(R2*).在d30和d50扫描完成后,注射呋塞米10 min后再次扫描,计算注药前后R2*的差值(△R2*).对5次扫描的R2*进行重复测量方差分析,对d30和d50注射呋塞米前后的皮、髓质R2*和皮、髓质△R2*进行配对t检验,观察呋塞米对皮、髓质R2*的影响并评价△R2*的重复性.结果d1、d5、d10、d30和d50大鼠体重分别为(150.4±3.7)、(170.2±7.0)、(201.0±5.8)、(306.2±17.0)和(352.0±12.2)g,差异有统计学意义(F=422.103,P＜0.01);肾脏皮、髓质R2*值差异均无统计学意义(P＞0.05).d30皮、髓质R2*在注射呋塞米前分别为(25.2±1.2)和(32.8±2.2)Hz,注射后分别为(21.1±2.2)和(25.9±3.0)Hz,皮、髓质R2*在注射呋塞米后均降低(P＜0.01);d50皮、髓质R2*在注射呋塞米前分别为(25.9±0.8)和(34.3±3.9)Hz,注射后分别为(20.2±1.5)和(27.0±3.2)Hz,皮、髓质R2*在注射呋塞米后均降低(P＜0.01).d30皮、髓质△R2*值分别为(4.1±1.7)和(6.9±2.8)Hz,d50皮、髓质△R2*值分别为(5.8±1.1)和(7.3±2.8)Hz,2次检查皮、髓质的AR2*差异均无统计学意义(P＞0.05).结论 大鼠肾脏皮、髓质基础R2*值在50 d内稳定,不受体重影响;在3.0 T MR上,应用呋塞米后大鼠肾脏皮、髓质R2*值均降低.     

HIV相关脑痴呆BOLD fMRI运动功能成像

目的:应用功能磁共振成像(fMRI)研究正常健康受试者及HIV相关脑痴呆患者的右手运动功能区并且探讨其应用价值.方法:10例HIV相关脑痴呆患者和8例健康受试者,设计右手相关运动功能实验,采取右手抓握运动方法,结合患者情况分析早期认知运动功能损伤的皮质位置区域和激活情况.结果:正常健康受试者右手运动功能区多位于左侧(对...