MR扩散加权成像在慢性肾病肾功能损害方面的价值研究

目的探讨MR扩散加权成像(DWI)在评价慢性肾病(CKD)肾功能损害方面的价值。资料与方法 CKD患者及正常对照组各57例,采用b值500 s/mm2在屏气情况下进行肾脏冠状面DWI。所有患者及正常对照组均收集血清肌酐水平(SCr)等实验室检查结果。比较病例组与正常对照组肾脏表观扩散系数(ADC)值,并分析患者肾脏ADC值与SCr、肾小球滤过率(GFR)间的相关性。结果 CKD组肾脏ADC值显著低于正常对照组(t=4.466,P<0.01)。病例组双肾间无显著统计学差异。正常对照组与CKD1期患者肾脏ADC值间无显著统计学差异,但与CKD2～5期间具有显著差异(P<0.05)。病例组肾脏ADC值与SCr间呈显著负相关关系(r=-0.449,P=0.001)。病例组肾脏ADC值与肾脏核医学GFR间存在正相关关系(r=0.426,P=0.011)。结论 DWI不但有助于CKD早期肾功能损害的诊断,对于CKD的分期也有一定的价值。     

磁共振扩散成像在慢性肾病中的初步研究

目的探讨磁共振扩散加权成像在慢性肾病中的应用价值。方法将10例健康志愿者和45例不同分期的慢性肾病患者(包括慢性肾病肌酐正常者10例,慢性肾衰肾功能代偿者9例,慢性肾衰肾功能失代偿者9例,慢性肾功能衰竭者8例及慢性肾衰尿毒症者9例)进行常规肾脏磁共振检查和扩散加权成像检查。观察分析其扩散成像的影像学表现,使用系统软件包在ADC图上直接测量肾脏的ADC值。结果慢性肾病肾脏的ADC值(×10-3mm2/s)在b值为300、500、800s/mm2时分别为2.29±0.27、2.07±0.21、1.91±0.22,均明显低于正常对照组肾脏ADC值;慢性肾病不同分期患者肾脏ADC值之间可能有差异。结论DWI可以作为临床评价肾脏功能的一种无创检查手段。     

Preliminary Study of Biexponential Model of Diffusion Weighted Imaging in Evaluation of Chronic Kidney Disease

目的 应用扩散加权成像(DWI)双指数模型计算肾脏皮髓质的纯扩散系数(ADCd)及灌注分数(Fp),并分析其在慢性肾脏病(CKD)患者评价中的应用价值.方法 搜集临床确诊的52例CKD患者和27名健康志愿者,分别行0、50,0、100,0、500,0、1000( s/mm2)四组b值的DWI检查,根据体素内不相干运动(IVIM)的双指数模型计算肾脏皮髓质的ADCd和Fp值,分析CKD患者皮髓质ADCd、Fp值的变化规律及其与肾小球滤过率估算值(eG-FR)之间的相关性.结果 正常对照组肾脏皮质ADCd值显著大于髓质(P＜0.05).正常对照组、CKD轻度损害组和中重度损害组之间的肾脏皮髓质ADCd值均存在显著性差异(正常对照组＞CKD轻度损害组＞CKD中重度损害组)(P＜0.001),三组之间的肾脏皮髓质Fp值均存在显著性差异(正常对照组＞CKD轻度损害组＞CKD中重度损害组)(P＜0.001).CKD患者的皮髓质ADCd值、髓质Fp值与eGFR均呈正相关(P＜0.05).结论 DWI双指数模型能够得到反映肾脏真实水分子扩散运动及微循环灌注的指标,肾脏皮髓质ADCd值及髓质Fp值可以在一定程度上反映CKD患者的肾脏功能改变.     

应用扩散加权成像双指数模型评价慢性肾脏病的初步研究

目的应用扩散加权成像(DWI)双指数模型计算肾脏皮髓质的纯扩散系数(ADCd)及灌注分数(Fp),并分析其在慢性肾脏病(CKD)患者评价中的应用价值。方法搜集临床确诊的52例CKD患者和27名健康志愿者,分别行0、50,0、100,0、500,0、1000(s/mm2)四组b值的DWI检查,根据体素内不相干运动(IVIM)的双指数模型计算肾脏皮髓质的ADCd和Fp值,分析CKD患者皮髓质ADCd、Fp值的变化规律及其与肾小球滤过率估算值(eG-FR)之间的相关性。结果正常对照组肾脏皮质ADCd值显著大于髓质(P<0.05)。正常对照组、CKD轻度损害组和中重度损害组之间的肾脏皮髓质ADCd值均存在显著性差异(正常对照组>CKD轻度损害组>CKD中重度损害组)(P<0.001),三组之间的肾脏皮髓质Fp值均存在显著性差异(正常对照组>CKD轻度损害组>CKD中重度损害组)(P<0.001)。CKD患者的皮髓质ADCd值、髓质Fp值与eGFR均呈正相关(P<0.05)。结论 DWI双指数模型能够得到反映肾脏真实水分子扩散运动及微循环灌注的指标,肾脏皮髓质ADCd值及髓质Fp值可以在一定程度上反映CKD患者的肾脏功能改变。     

MR扩散加权成像在慢性肾病诊断中的价值分析

目的 探讨MR扩散加权成像(DWI)在慢性肾病(CKD)诊断中的价值. 资料与方法 对25例CKD患者25例正常人行肾脏DWI,比较分析肾脏表观扩散系数(ADC)值间的差异,分析肾脏ADC值与血清肌酐水平的关系. 结果 正常组双肾ADC值差异无统计学意义;正常组男女志愿者肾脏的ADC值差异无统计学意义.病例组双肾ADC值差异无统计学意义;病例组男女患者肾脏ADC值差异无统计学意义.正常组肾脏ADC值为(2.53±0.24)×10-3 mm2/s,病例组肾脏ADC值为(2.40±0.31)×10-3 mm2/s,两组间肾脏ADC值差异有统计学意义.早期肾功能损害组与正常组肾脏ADC值差异无统计学意义;中晚期肾功能损害组与正常组肾脏ADC值间差异有统计学意义.CKD患者肾脏ADC值与血清肌酐水平呈轻度负相关. 结论 肾脏DWI可用于慢性肾病的诊断,在中期肾功能损害诊断方面具有一定价值.     

磁共振肾灌注成像技术

目的　探讨磁共振肾灌注成像 (PWI)技术的价值。资料与方法　在应用平面回波成像 (EPI)技术的基础上 ,采用PWI技术 ,对 12例单侧上尿路梗阻患者进行肾功能损害的测定。结果　肾灌注成像曲线呈反抛物线形 ,正常两侧的肾灌注曲线几乎是重叠的 ,病肾与正常肾灌注曲线相比 ,波始时间、达波谷时间均延长 ,经t检验 ,有显著差异 (P <0 .0 0 1) ,并且病肾的波幅小于正常肾。结论　在应用EPI基础上 ,采用PWI技术 ,可进一步评价肾功能     

慢性肾病肾脏皮髓质分界的MRI研究

目的观察慢性肾病患者肾脏皮髓质分界（CMD）在MRI中的变化规律。资料与方法选择21名正常志愿者,以及23例慢性肾病患者,记录血清肌酐（sCr）值,并将患者按sCr水平分为未升高组（12例）和升高组（11例）,分别行MRT1脂肪抑制（T1FS）扫描和梯度回波增强（CE-GRE）扫描,观察其CMD,并测量T1FS序列图像上皮质信号强度及髓质信号强度,计算皮髓质对比度（CMC）。结果对照组21名双侧42个肾脏CMD清晰,CMC为0.161±0.044;慢性肾病患者中,sCr水平未升高组（sCr值61～135μmol/L）12例,T1FS序列图像上,16个肾脏（66.7%）CMD清晰,2个（8.3%）模糊,6个（25%）CMD消失,CMC为0.105±0.057;CE-GRE序列图像上,22个（91.7%）CMD清晰,2个（8.3%）模糊;sCr水平升高组（sCr值164～753μmol/L）11例,T1FS序列图像上,6个（27.3%）CMD清晰,4个（18.2%）模糊,12个（54.5%）CMD消失,CMC为0.061±0.054;CE-GRE序列图像上,14个（63.6%）CMD清晰,3个（13.6%）模糊,5个（22.7%）CMD消失。两组患者CMC与对照组比较均明显降低（P〈0.01）,且随sCr水平升高,CMC降低更为显著,CMC与sCr水平呈负相关（r=-0.501,P〈0.05）。结论慢性肾病肾脏CMD改变与sCr水平具有相关关系,它能早期反映肾脏的功能状态。     

慢性阻塞性肺部病变患者肺部CT灌注成像特征

目的探讨慢性阻塞性肺疾病(COPD)患者肺部CT灌注成像的时间密度曲线(TDC)和灌注参数特征。方法共44例,分为COPD组25例及对照组19例。均行肺部多层螺旋CT(MSCT)动态增强扫描。图像经后处理,设定感兴趣区(右腹肺、右背肺和左腹肺、左背肺),得到各处肺组织TDC和灌注参数,包括灌注值(P),强化峰值增量(PEI),达峰值时间(TTP)和血容量(BV)。比较分析COPD组和对照组的TDC特征,以及各灌注参数的差异性。结果COPD组较对照组TDC波峰延后。各灌注参数腹背肺比率在2组无显著性差异(P>0.05)。COPD组TTP较对照组明显延长(P=0.010)。P、PEI和BV在2组无显著性差异(P>0.05)。结论CT灌注成像显示COPD患者肺部血流灌注异常主要表现为TDC波峰延后,TTP延长。     

应变率成像评价慢性肾脏病患者左心室收缩及舒张功能的研究

目的 探讨应变率成像用于评价慢性肾脏病(CKD)患者左室收缩及舒张功能的价值.资料与方法 选取71例CKD患者(CKD3期23例,CKD4期22例,CKD5期26例),同时选取20例正常人作为对照组,利用常规超声心动图及应变率成像观察心脏结构及基底部各节段收缩、舒张早期及舒张晚期应变率指标.结果CKD患者左房内径、左室...     

正常兔脑多层螺旋CT灌注及MR灌注成像

目的：探讨多层螺旋CT及MR在正常兔脑血流动力学测量中的应用。材料和方法：健康新西兰种大白兔15只，行CT平扫后，选择基底节层面及相邻层面，经耳缘静脉途径以0．5ml／s速率注入CT造影剂，同时开始连续50s多层动态扫描；CT造影剂排空后，经耳缘静脉途径快速团注MR造影剂，同时开始连续43s多层动态扫描，经后处理获得CT及MR灌注图像。对感兴趣区测量血流量、血容量及平均通过时间等血流动力学参数，并与小脑的相应值相比进行分析。结果：应用CT灌注可以获得较好图像质量，MR灌注可反映出全兔脑组织的血流动力学状态，CT灌注及MR灌注获得的血流动力学参数相对值之间比较无显著性差异（P〉0．05）。结论：多层螺旋CT灌注及MR灌注成像为兔脑血流动力学研究提供了新的无创性手段。     

正常肾脏MSCT灌注成像的研究

目的: 探讨MSCT灌注成像在肾脏检查的初步临床应用.材料和方法: 采用16 排螺旋CT及灌注软件对32例双侧肾脏和12例单侧肾脏进行灌注扫描,对比剂为优维显(300mgI/ml)50ml,注射速度4ml/s.结果: 32例双侧肾脏皮质或髓质的同一灌注指标无明显差异,但同侧肾脏皮质和髓质的同一灌注指标明显不同.一侧肾脏切除后,对侧肾脏的灌注指标变化明显.结论: MSCT灌注成像实现了肾脏血流的定量研究,可直观评价肾组织微循环的血液动力学变化.     

肾脏功能磁共振成像的研究进展

功能磁共振成像(functional magnetic resonance imaging, fMRI)是指从微观水平对机体各组织器官生理状态和病理改变进行评价的磁共振检查技术和方法的总称.fMRI最早应用于中枢神经系统,是一种极具潜力的无创性功能成像技术.随着快速成像序列及相关应用分析软件的开发应用,fMRI在体部的应用日益广泛.本文对近年来有关肾脏的fMRI研究进行回顾,包括在评价肾脏血流灌注及氧合状态,肾小球滤过率,尿液浓缩功能及肾内水质子的弥散等中的应用.     

中枢神经细胞瘤的常规磁共振和灌注成像

目的　探讨中枢神经细胞瘤(CNC)的常规MRI和灌注成像(PWI)表现,评价两者对CNC的诊断价值。方法　收集3例经手术和病理证实的CNC患者,并以4例室管膜瘤作对照,行常规MRI和PWI检查,观察两者的MRI表现,计算并比较2种肿瘤的相对局部脑血流容积(rrCBV)。结果　CNC在T1WI上呈等信号,T2WI呈高信号,轻度强化。室管膜瘤在T1WI上为低或等信号,T2WI为高或稍高信号,轻度强化。PWI上CNC为明显高灌注,rrCBV平均11. 2;而室管膜瘤的rrCBV平均为2. 1; 2组间有显著性差异(P<0. 001)。结论　CNC的常规MRI表现不具特征性,但PWI在CNC的诊断中具有重要作用。     

Functional Imaging of the Foot with Perfusion Angiography in Critical Limb Ischemia

Purpose

To report on the first clinical experience with perfusion angiography (PA) of the foot in patients with chronic critical limb ischemia.

Materials and Methods

PA is a post-processing software algorithm and no extra digital subtraction angiography (DSA) has to be performed for this analysis. The data used to test the feasibility of PA were obtained from a consecutive group of 89 patients with CLI who were treated with standard below the knee angioplasty and 12 separate patients who were not suitable for endovascular revascularization.

Results

Motion artifacts in the dataset of the DSA made post-procedural analysis impossible in 10 % intervention. In the majority of patients (59/68) PA showed an increase in volume flow in the foot after successful angioplasty of the crural vessels. However, in 9/68 patients no increase was seen after successful angioplasty. With the use of a local administered competitive α-adrenergic receptor antagonist, it is also possible to test and quantify the capillary resistance index which is a parameter for the remaining functionality of the microcirculation in CLI patients.

Conclusion

PA might be used as a new endpoint for lower limb revascularization and can also be used to test the functionality the microcirculation to identify sub-types of patients with CLI. Clinical evaluation and standardization of PA is mandatory before introduction in daily practice.

     

Clinical Application of 3D Arterial Spin-Labeled Brain Perfusion Imaging for Alzheimer Disease: Comparison with Brain Perfusion SPECT

BACKGROUND AND PURPOSE:Alzheimer disease is the most common neurodegenerative disorder with dementia, and a practical and economic biomarker for diagnosis of Alzheimer disease is needed. Three-dimensional arterial spin-labeling, with its high signal-to-noise ratio, enables measurement of cerebral blood flow precisely without any extrinsic tracers. We evaluated the performance of 3D arterial spin-labeling compared with SPECT, and demonstrated the 3D arterial spin-labeled imaging characteristics in the diagnosis of Alzheimer disease.MATERIALS AND METHODS:This study included 68 patients with clinically suspected Alzheimer disease who underwent both 3D arterial spin-labeling and SPECT imaging. Two readers independently assessed both images. Kendall W coefficients of concordance (K) were computed, and receiver operating characteristic analyses were performed for each reader. The differences between the images in regional perfusion distribution were evaluated by means of statistical parametric mapping, and the incidence of hypoperfusion of the cerebral watershed area, referred to as “borderzone sign” in the 3D arterial spin-labeled images, was determined.RESULTS:Readers showed K = 0.82/0.73 for SPECT/3D arterial spin-labeled imaging, and the respective areas under the receiver operating characteristic curve were 0.82/0.69 for reader 1 and 0.80/0.69 for reader 2. Statistical parametric mapping showed that the perisylvian and medial parieto-occipital perfusion in the arterial spin-labeled images was significantly higher than that in the SPECT images. Borderzone sign was observed on 3D arterial spin-labeling in 70% of patients misdiagnosed with Alzheimer disease.CONCLUSIONS:The diagnostic performance of 3D arterial spin-labeling and SPECT for Alzheimer disease was almost equivalent. Three-dimensional arterial spin-labeled imaging was more influenced by hemodynamic factors than was SPECT imaging.

Alzheimer disease (AD) is the most common neurodegenerative disorder with dementia and is becoming a social problem in most developed countries. A practical and economic biomarker for diagnosis of AD is needed. CBF is commonly accepted as a physiologic correlate of brain function.¹ AD is associated with regional decreases in CBF, so the ability of CBF to differentiate between individuals affected by AD and healthy individuals has been evaluated with the use of SPECT.²Arterial spin-labeling (ASL) enables measurement of CBF without any extrinsic tracers by use of magnetically labeled arterial blood water as a diffusible tracer. ASL MR imaging has 2 major modalities: pulsed ASL³ and continuous ASL.⁴ The continuous ASL technique uses continuous adiabatic inversion, whereas pulsed ASL uses a single inversion pulse. The recently developed pulsed-continuous ASL imaging protocol based on 3D stack-of-spirals readouts⁵ is an intermediate method between the conventional pulsed ASL and continuous ASL methods, in that pulsed-continuous offers a longer tag bolus than does pulsed ASL and a higher labeling efficiency than does the amplitude-modulated continuous ASL.^6,7 Each section acquired with 2D ASL experiences a slightly different inflow time; thus, it is difficult to estimate a precise transit time when multiple sections are acquired. The use of 3D acquisition techniques overcomes many of these limitations, allowing both whole-brain coverage and simultaneous acquisition to ensure a unified mean transit time. The SNR of 3D acquisitions can be greater than that of 2D multisection methods. Although ASL has inherently low SNR, mainly because of the relatively small amount of labeled spins in the tissue, pulsed-continuous can provide a better balance between labeling efficiency and SNR than conventional ASL methods. This can improve the accuracy of quantified CBF estimates. Many AD studies by use of ASL have been reported, which indicates that ASL MR imaging is an indispensable technique for studying AD.^8–12 CBF measured with ASL MR imaging can detect regional hypoperfusion in the AD precuneus and bilateral parietal cortex and discriminate individuals with AD from normal subjects. Recent research with the use of pulsed-continuous reported that 3D ASL can evaluate the severity of cognitive impairment as measured by the correlation of CBF with cognition.¹³SPECT is now commonly used for CBF assessment in the diagnosis of AD, so we considered that it was important to evaluate the differences in CBF distribution in perfusion images obtained with both SPECT and ASL by use of similarly behaved diffusible tracers and to demonstrate the characteristics of ASL in comparison with SPECT. To the best of our knowledge, the evaluation of brain perfusion imaging by use of both ASL and SPECT in the same subjects with clinically suspected AD to discriminate the AD group from the non-AD group has not been reported. We used whole-brain 3D ASL MR imaging with pulsed-continuous labeling for CBF measurement in the diagnosis of AD because of its high SNR and the possibilities for improving image quality.In this study, we evaluated the detectability of reduced regional cerebral perfusion in AD by use of 3D ASL compared with brain perfusion SPECT and demonstrated the characteristics of perfusion images obtained by means of 3D ASL.     

Prenatal MRI Findings of Polycystic Kidney Disease Associated with Holoprosencephaly

Holoprosencephaly (HPE) and polycystic kidney disease (PKD) are genetically heterogeneous anomalies which can make up part of various syndromes or chromosomal anomalies. Due to the rapid lethality prognosis, early and precise prenatal diagnosis would be of great value. This case report describes extensive PKD involvement, already present in utero, in a patient with HPE and subdural effusion visible by MR imaging. The detailed anatomic information obtained by the MR imaging can guide the surgical planning and can aid antenatal counseling.     

多层螺旋CT灌注成像在肾脏的应用

CT灌注成像是利用CT的同层动态增强扫描了解组织及病变的血流灌注特点及血管特性,并可通过色阶赋值获得灌注伪彩色图像,达到功能性诊断的目的.目前颅脑和肝脏灌注成像比较成熟,但肾脏灌注研究较少,现就灌注成像在肾脏的应用做一综述.