磁共振相位对比电影对蛛网膜囊肿与蛛网膜下腔扩大的鉴别诊断

目的：应用磁共振相位对比法,揭示脑与脑脊液运动的相互关系,以评价此方法对鉴别蛛网膜囊肿与蛛网膜下腔扩大的诊断价值。材料与方法：运用磁共振相位对比电影和流动分析软件,对１０例健康人脑与脑脊液运动规律相关性进行研究和１０例影像学疑蛛网膜囊肿或蛛网膜下腔扩大患者的脑脊液运动进行最化分析,绘出一个心动周期不同时相脑脊液流量贡线和时间、信号强度曲线,并进行分析比较。结果：脑脊液流动是由脑运动驱动引起,而脑运     

磁共振相位对比法对脑与脑脊液运动的相关性研究

目的 应用磁共振相位对比法,揭示脑与脑脊液（ＣＳＦ）运动的相互关系,测定脑运动位移和脑脊液流量率。方法 运用磁共振相位对比电影和流动分析软件,对一组１０例健康人脑与脑脊液运动规律相关性进行研究。并测定在１个心动周期内脑实质各解剖区域的运动位移量和脑脊液流量率,绘制出动－静脉流量差,导水管、Ｃ２,３蛛网膜下腔、幕切迹区的脑脊液流量率、脑实质位移的时间－信号强度曲线,并进行分析。结果 脑运动大１个心动     

MR相位对比电影法在蛛网膜囊肿诊断中应用价值初探

目的：评价磁共振相位对比电影法在蛛网膜囊肿与蛛网膜下腔扩大及囊肿与邻近脑池是否相通的诊断价值。材料和方法：运用磁共振相位对比电影法和流动分析软件对21例影像学疑为蛛网膜囊肿或蛛网膜下腔扩大患者进行检查，并分析其相位幅度图像形态及博动情况,测定相应病变区在相位速度图上的搏动强度。结果：蛛网膜囊肿在相位幅度图上可不清楚显示囊肿与邻近脑池相分隔：同时可显示囊肿内搏动幅度。囊肿内反向流动信号及喷射信号改变，提示与邻近蛛网膜腔相通。而在四脑室扩大者，相位幅度图未见明显囊腔，可见与导水管相通。结论：磁共振相位对比电影法对显示不同部位颅内蛛网膜囊肿的形态、与邻近蛛网膜下腔结构鉴别及了解囊肿内搏动情况判断与邻近脑池是否交通有重要价值。     

正常脑脊液流动的磁共振定性研究

目的探讨MRI 相位对比电影序列 （cine PC） 定性分析脑脊液流动的可能性,并运用该技术对正常志愿者进行分析.方法采用MRI cine PC序列对15名正常志愿者的脑室、脑池和颈椎管内蛛网膜下腔的脑脊液流动进行定性观察,并对心脏周期不同时段脑脊液流动方向的变化进行分析.结果 MRI cine PC序列可清楚地显示心脏周期各个时段各个脑室、脑池和脊髓蛛网膜下腔中脑脊液运动方向的变化.结论 MRI cine PC法是一种新型的无创性的检查手段,对脑脊液的流动有很强的敏感性,是一种很有前途的研究手段.     

磁共振相位对比电影成像在脑积水诊断中的临床应用

目的评价磁共振相位对比电影成像（PC-MRI）技术在脑积水诊断中的临床应用价值。方法使用GE3.0 T磁共振扫描仪,采用PC-MRI程序检查,对我院收治的20例交通性脑积水及25例梗阻性脑积水患者及48名同期在我院体检的志愿者的中脑导水管水平脑脊液流速、流量进行检测,比较2组脑脊液相关力学数据基本情况。结果 交通性脑积水中脑导水管水平脑脊液在不同阶段所引起的反应存在着一定的差异,其中在收缩期与舒张期分别表现为向下、向上峰速,而且均大幅增加了其流量;梗阻性脑积水中脑导水管水平脑脊液在不同阶段所引起的反应也存在一定的差异,其中在收缩期与舒张期分别表现为向下、向上峰速,而且在流量方面都出现大幅降低的现象。相较于健康人进行统计有明显差异（P<0.05）,健康人（对照组）脑脊液流动曲线呈U形、倒U形,正弦波形,曲线光滑,而脑积水组脑脊液流动曲线呈锯齿状,无规则,或呈直线。结论 磁共振相位对比电影成像能无创检测脑脊液流速、流量和方向,可鉴别脑积水类型,为临床治疗提供方向。     

低磁场MR CBASS在颈椎椎间盘病变中的应用价值

目的：探讨CBASS序列在低磁场MR颈椎椎间盘病变诊断中的应用价值。方法：在低磁场MR上对39例颈椎分别行普通FE(GRE)T2*加权序列、普通FSE T1加权序列及CBASS序列的3mm薄层横断扫描，重建图像请有经验的放射科医生采用双盲法进行评价，评价内容包括椎间盘、蛛网膜下腔、椎间盘与蛛网膜下腔脑脊液之间界限显示情况，评价标准分三个等级。另外，对图像显示的椎间盘与蛛网膜下腔脑脊液的组织对比噪声比进行定性测量。结果：CBASS序列无论在显示椎间盘、蛛网膜下腔、椎间盘与蛛网膜下腔脑脊液之间界限都明显好于普通SE、FE(GRE)T1或T2、T2*加权序列。CBASS序列不仅信噪比极高，对流动不敏感，而且扫描时间大大缩短。结论：CBASS序列在颈椎椎间盘横断薄层扫描中具有重要的应用价值，在低磁场MR上值得推广。     

MRI监测脑脊液动力学在外伤性脑静脉窦血栓形成临床诊治中的应用

目的探讨运用MRI监测脑脊液循环动力学异常在外伤性脑静脉窦血栓形成临床诊治中的价值。方法对75例脑外伤后临床颅脑血流动力学异常患者及健康志愿者40例,采用MRI 2D-PC cine法序列,以编码流速20cm/s,于颈1～2椎间隙水平测量患者的脑脊液流速、流量,在其接受尿激酶治疗过程中进行随访复查,并与腰穿脑脊液压力进行对照分析。结果颈1～2椎间隙水平脑脊液流动在一个心动周期内均表现为近似于正弦曲线的双向流动,脑外伤组治疗前收缩期、舒张期脑脊液峰值流速、流量均高于正常人群(P<0.05)。经尿激酶治疗后68例患者脑脊液压力恢复正常,其脑脊液收缩期、舒张期脑脊液峰值流速、流量均较治疗前降低(P<0.05)。脑脊液流速与脑脊液压力呈正相关(r=0.805,P<0.05),脑脊液向下净流量与脑脊液压力呈正相关(r=0.794,P<0.05)。结论静脉窦血栓形成前患者脑脊液循环动力学会发生相应改变,磁共振PC-cine法可以早期检测出其循环动力学改变,对脑外伤后患者颅内压改变的监测及预后评价有重要指导意义。     

脊髓病变病人的脑脊液流动MRI研究

目的：利用相位对比动力学MRI研究脊髓病变病人的脑脊液动力学。材料和方法：对脊椎侧凸病人20例，脊髓空洞症病人20例，Chiari畸形病人20例，脊髓肿瘤20例和无脊椎脊髓病变50例，采用Philips 1．5T超导型磁共振常规MRI检查后，行磁共振Qflow序列检查。测量部位选择C2—3椎间盘横断面，将检测数据传到Easyvison后处理工作站计算出流速和流量，并通过软件模拟出脑脊液流动的波形。结果：以50例无脊椎脊髓病变的脑脊液动力学为等动力学参照，发现脊椎侧凸病人和脊髓肿瘤的脑脊液动力学为高动力学，脊髓空洞症病人和Chiari畸形病人的脑脊液动力学为低动力学。结论：①无创伤性相位对比动力学MRI为研究脊髓病变病人的脑脊液流动提供可靠、稳定的技术方法；②脊髓空洞症脑脊液低动力学为临床脊髓空洞症做出定量的诊断，有进一步研究和推广应用的价值。     

MR流体定量技术在脑脊液循环障碍疾病诊断中的应用

目的:无创性定量研究脑脊液循环改变及其临床意义。材料和方法:应用MR相位对比电影法,测定了15例正常志愿者,67例脑脊液循环障碍患者(交通性脑积水32例、阻塞性脑积水31例、Chiaril畸形4例)以及15例脑萎缩患者的中脑导水管、C2水平及部分第三脑室底部造瘘口水平的脑脊液动力学指标(峰值流速、流量及CSF流动波型)。结果:(1)正常志愿组中脑导水管脑脊液流动在一个心动周期内均表现为双向流动,即收缩期向下流动和舒张期向上流动,向下及向上峰速分别为12.60±4.42mm/s和10.10±3.58mm/s;(2)交通性脑积水组脑脊液循环表现为高动力学改变,向下及向上峰速分别为26.60±9.06mm/s和22.61±7.92mm/s,与正常志愿组比较有显著差异(P<0.05)。脑积水分流前后比较导水管循环减慢者提示有效;阻塞性脑积水组表现为低动力学或流动波消失,2例行第三脑室造瘘者导水管流动不规则,造瘘口出现上下流动现象;Chiaril畸形组C2水平脊髓后间隙缩小,流动减慢,脊髓前间隙增宽,1例合并空洞者囊腔内出现高动力学改变;(3)脑萎缩组表现为低动力学改变,向下及向上峰速分别为11.71±4.75mm/s和8.54±3.08mm/s,与正常志愿组、交通性脑积水组比较均有显著差异(P<0.05)。结论:MR相位对比电影法可有效评价脑脊液循环动力学改变,可丰富脑脊液循环     

SEO序列T_2WI脑脊液信号反常增高的意

目的：探讨ＳＥＯ 序列Ｔ２ ＷＩ 上脑脊液信号反常增高的意义。材料和方法：我们回顾分析了１２２５ 例作椎管ＭＲ 检查的病人,使用ＡＳＭ － ０６０ 超导ＭＲ 成像系统,全部病例均采用ＳＥＯ 序列,重点观察矢状面Ｔ２ ＷＩ 上蛛网膜下腔的信号改变。结果： 大部分病例Ｔ２ ＷＩ 上蛛网膜下腔呈低信号, 有５２ 例病变下方的蛛网膜下腔信号由低变高。结论：ＳＥＯ 序列Ｔ２ ＷＩ 上脑脊液信号的反常增高意味着脑脊液循环的梗阻, 提示有椎管内占位病变或椎管狭窄的存在。     

Plow quantitation with echo-planar phase-contrast velocity mapping: In vitro and in vivo evaluation

We present a multishot echo-planar imaging (EPI) phase-contrast implementation for flow quantitation. The measurement accuracy of this technique was evaluated in vitro and in vivo. A gated eight-shot EPI phase-contrast sequence (TR/TE = 16/7.4, 45° flip angle), with a flow-phase interval of 32 msec and an in-plane resolution of 2× 2 mm was initially evaluated in a pulsatile flow phantom. Subsequently, EPI phase-contrast flow measurements of the ascending and descending aorta, obtained in 10 volunteers, were compared with flow volume data acquired with a conventional cine phase-contrast sequence (TR/TE = 24/7, 45° flip angle, 48-msec flow-phase interval, 2 × 1 mm in-plane resolution). Comparisons between flow measurements were made using data obtained with the flow probe and cine phase contrast as the standard of reference for in vitro and in vivo measurements, respectively. EPI phase-contrast sequences reduced data acquisition times tenfold compared with cine phase-contrast sequences. EPI phase-contrast flow measurements correlated were with phantom flow (r = 0.98, slope = 1.1) as well as with aortic cine phase-contrast flow volume determinations (r = 0.98). A 95% confidence interval of measurement differences between echo-planar and cine phase-contrast imaging, ranging from 2.0 to - 1058 mL/min was computed. Ultrafast phase-contrast flow measurements are possible. Multishot EPI phase-contrast imaging provides high measurement accuracy in pulsatile vessels while keeping the image acquisition interval short enough to be accomplished in a comfortable breath-hold.     

Blood flow volume quantification of cerebral ischemia: comparison of three noninvasive imaging techniques of carotid and vertebral arteries

OBJECTIVE: Determination of blood flow volume is useful in assessing ischemic cerebrovascular disease. We compared the blood flow volume measurement of three noninvasive imaging techniques, namely color velocity imaging quantification, spectral Doppler imaging quantification, and MR phase-contrast flow quantification, to see how well the flow values determined by each technique agreed with one another. SUBJECTS AND METHODS: Flow volume quantification was tested experimentally using a flow simulator and by the three techniques in the vertebral and internal carotid arteries of 40 patients with histories of cerebral ischemia. In the flow simulation study, the flow values in each technique were compared with the phantom flow by the Wilcoxon's signed rank test. In the patient study, the flow values between each paired technique were compared by paired t test. The significance level was taken at p less than 0.05. RESULTS: Flow volumes were measured by color velocity imaging quantification. MR phase-contrast flow quantification agreed with the phantom flow simulation within the tested range, and spectral Doppler imaging quantification values were significantly overestimated. In patients, a large variation of the blood flow volume was obtained between each technique (p < 0.05). Among them, spectral Doppler imaging quantification showed the highest flow values in the vessels (internal carotid arteries, 312.6 mL/min; vertebral arteries, 112.0 mL/min), followed by color velocity imaging quantification (internal carotid arteries, 216.8 mL/min; vertebral arteries, 58.1 mL/min) and MR phase-contrast flow quantification (internal carotid arteries, 169.1 mL/min; vertebral arteries, 66.5 mL/min). CONCLUSION: Blood flow volume measurements determined by the three noninvasive imaging techniques on the same vessel can differ widely, and spectral Doppler imaging quantification consistently overestimated the flow volume. It is, therefore, essential that the same technique, preferably color velocity imaging quantification or MR phase-contrast flow quantification, be used for clinical follow-up investigations in the future.     

Blood flow in major cerebral arteries measured by phase-contrast cine MR.

PURPOSETo measure mean blood flow in individual cerebral arteries (carotid, basilar, anterior cerebral, middle cerebral, and posterior cerebral) using a cine phase contrast MR pulse sequence.METHODSTen healthy volunteers (22 to 38 years of age) were studied. The cine phase-contrast section was positioned perpendicular to the vessel of interest using oblique scanning planes. This pulse sequence used a velocity encoding range of 60 to 250 cm/sec. From the velocity and area measurements on the cine images, mean blood flow was calculated in milliliters per minute and milliliters per cardiac cycle. In the same subjects, transcranial Doppler measurements of blood velocity in these same vessels were also obtained.RESULTSThere was no difference in blood flow in the paired cerebral arteries. Carotid arteries had mean blood flow in the range of 4.8 +/- 0.4 ml/cycle, the basilar artery 2.4 +/- 0.2 ml/cycle, the middle cerebral artery 1.8 +/- 0.2 ml/cycle, the distal anterior cerebral artery 0.6 +/- 0.1 ml/cycle, and the posterior cerebral artery 0.8 +/- 0.1 ml/cycle. Overall, there was poor correlation between MR-measured and transcranial Doppler-measured peak velocity.CONCLUSIONAlthough careful attention to technical detail is required, mean blood flow measurements in individual cerebral vessels is feasible using a cine phase-contrast MR pulse sequence.     

Blood-flow volume quantification in internal carotid and vertebral arteries: comparison of 3 different ultrasound techniques with phase-contrast MR imaging

BACKGROUND AND PURPOSE: Optimal estimation of cerebral blood-flow volume (BFV) may be an important indicator for better evaluation of the patients with cerebrovascular disorders. In this study, we compared the BFV values at bilateral internal carotid and vertebral arteries of healthy volunteers obtained with color Doppler, power Doppler, and B-flow ultrasound (US) studies and tried to determine which examination is more correlated with MR phase-contrast quantification. METHODS: BFVs of the internal carotid and vertebral arteries of 40 healthy volunteers (19 men and 21 women; age range, 20-47 years) were measured by using color Doppler, power Doppler, B-flow US and MR phase-contrast imaging. The flow measurements obtained with the sonographic techniques were compared with MR phase contrast, which is accepted as the most reliable method for the estimation of cerebral BFV. RESULTS: Quantification with power Doppler imaging showed the highest values among sonography techniques, followed by color Doppler imaging, B-flow imaging (BFI), and MR phase-contrast flow quantification. There was a statistically significant difference between the flow-volume values obtained with these 4 different techniques (P < .05). BFI yielded the closest values (internal carotid arteries, 238.84 mL/min; vertebral arteries, 51.16 mL/min) to MR phase-contrast flow quantification study with higher correlation rates. CONCLUSION: Flow volumes obtained with BFI showed the highest correlation with MR phase-contrast imaging among 3 different sonography techniques. B-flow sonography may be a very effective and cost-efficient alternative for MR phase-contrast studies for the calculation of cerebral BFV.     

Quantifying the effect of posture on intracranial physiology in humans by MRI flow studies

PURPOSE: To quantify the effect of posture on intracranial physiology in humans by MRI, and demonstrate the relationship between intracranial compliance (ICC) and pressure (ICP), and the pulsatility of blood and CSF flows. MATERIALS AND METHODS: Ten healthy volunteers (29+/-7 years old) were scanned in the supine and sitting positions using a vertical gap MRI scanner. Pulsatile blood and CSF flows into and out from the brain were visualized and quantified using time-of-flight (TOF) and cine phase-contrast techniques, respectively. The total cerebral blood flow (tCBF), venous outflow, ICC, and ICP for the two postures were then calculated from the arterial, venous, and CSF volumetric flow rate waveforms using a previously described method. RESULTS: In the upright posture, venous outflow is considerably less pulsatile (57%) and occurs predominantly through the vertebral plexus, while in the supine posture venous outflow occurs predominantly through the internal jugular veins. A slightly lower tCBF (12%), a considerably smaller CSF volume oscillating between the cranium and the spinal canal (48%), and a much larger ICC (2.8-fold) with a corresponding decrease in the MRI-derived ICP values were measured in the sitting position. CONCLUSION: The effect of posture on intracranial physiology can be quantified by MRI because posture-related changes in ICC and ICP strongly affect the dynamics of cerebral blood and CSF flows. This study provides important insight into the coupling that exists between arterial, venous, and CSF flow dynamics, and how it is affected by posture.     

Velocity and flow quantitation in the superior sagittal sinus with ungated and cine (gated) phase-contrast MR imaging

Normal blood flow and velocity in the superior sagittal sinus were measured in 30 patients. A fast two-dimensional ungated phase-contrast (PC) pulse sequence was compared with a peripherally gated cine PC technique for velocity and flow quantitation. The same imaging parameters were used for both methods. Measured values for mean velocity and flow obtained with the two methods were compared by using regression analysis and t testing. For blood flow, the correlation coefficient was 0.976. For velocity measurements, r was 0.950. Mean flow was 285 mL/min ± 19 with the ungated PC method and 281 mL/min ± 19 with the cine PC method. The mean velocities measured with the two methods were 12.94 cm/sec ± 1.1 and 13.59 cm/sec ± 1.1, respectively. There was no significant difference (paired t test) between the methods for mean flow or velocity data. This was true even though flow in the superior sagittal sinus is moderately pulsatile, as shown with the cine PC technique. The ungated PC method provided these data in 13 seconds versus 3.5 minutes for the cine PC method.     

Normal flow patterns of intracranial and spinal cerebrospinal fluid defined with phase-contrast cine MR imaging

A phase-contrast cine magnetic resonance (MR) imaging technique was used to study normal dynamics of cerebrospinal fluid (CSF) in 10 healthy volunteers and four patients with normal MR images. This pulse sequence yielded 16 quantitative flow-encoded images per cardiac cycle (peripheral gating). Flow encoding depicted craniocaudal flow as high signal intensity and caudo-cranial flow as low signal intensity. Sagittal and axial images of the head, cervical spine, and lumbar spine were obtained, and strategic sites were analyzed for quantitative CSF flow. The onset of CSF systole in the subarachnoid space was synchronous with the onset of systole in the carotid artery. CSF systole and diastole at the foramen of Monro and aqueduct were essentially simultaneous. The systolic and diastolic components were different in the subarachnoid space, where systole occupied approximately 40% and diastole 60% of the cardiac cycle, compared with the ventricular system, where they were equal. This difference results in systole in the intracranial and spinal subarachnoid spaces preceding that in the ventricular system; the same is true for diastole. The fourth ventricle and cisterna magna serve as mixing chambers. The high-velocity flow in the cervical spine and essentially no flow in the distal lumbar sac indicate that a portion of the capacitance necessary in this essentially closed system resides in the distal spinal canal.     

Evaluation of CSF flow patterns of posterior fossa cystic malformations using CSF flow MR imaging

Introduction Differential radiologic diagnosis of cystic malformations of the posterior fossa is often difficult with conventional imaging techniques because of overlapping features of these entities. Posterior fossa cystic malformations occupy the cerebrospinal fluid (CSF) spaces. They may create secondary dynamic effects on the movements of CSF. The aim of this study was to investigate CSF flow alterations in posterior fossa cystic malformations with CSF flow MR imaging.Methods The study included 40 patients with cystic malformations of the posterior fossa. The patients underwent cardiac-gated phase-contrast cine MR imaging. CSF flow was qualitatively evaluated using an in-plane phase-contrast sequence in the midsagittal plane. The MR images were displayed in a closed-loop cine format.Results Twelve of the patients had communicating arachnoid cyst, seven had non-communicating arachnoid cyst, ten had mega cisterna magna, six had Dandy-Walker malformation, two had Dandy-Walker variant, and three had Blake’s pouch cyst. CSF flow MR imaging indicated the regions of no, slow or higher flow, direction of flow, and abnormal cystic fluid motion. Each malformation displayed a distinct CSF flow pattern.Conclusion Phase-contrast cine MR imaging for CSF flow evaluation may be a useful adjunct to routine MR imaging in the evaluation of the cystic malformations of the posterior fossa because it can improve the specificity in differentiating such malformations.Electronic Supplementary Material Supplementary material is available in the online version of this article at Part of this article was presented as a poster exhibition at the ESNR 28th Annual Congress and 12th Advanced Course, 11–14 September 2003, Istanbul.     

MR评估在体血管壁切应力的方法探讨

目的 研究一种临床适用的MR技术在体无创性评估颈总动脉血管壁切应力(WSS)的方法.方法 选取1名健康志愿者,对其右侧颈总动脉行相位对比法MR血流定量扫描,应用三维抛物面(3DP)模型函数拟合方法,结合图像后处理技术,计算局部WSS,获取颈总动脉的血管横截面积、平均血流速度、最大速度及瞬时血流率等血流动力学参数,综合评估颈总动脉的血流动力学状态.结果 颈总动脉局部WSS值范围为(0.75±0.41)N/m2;平均血流速度为(23.4±12.0)cm/s,血管横截面积为(32.2±2.9)mm2;血流率为(7.8±4.6)ml/s.结论 MR血流定量技术结合3DP模型方法可以对颈动脉局部WSS大小、分布和变化进行评估.     

Characterization of interpolation effects in cine anatomic and phase-velocity images

PURPOSE: To compare actual and predicted frequency response of reconstruction algorithms applied to anatomic and phase-contrast velocity cine images. MATERIALS AND METHODS: Anatomic and phase-contrast velocity segmented cine gradient echo images were collected from a stationary, doped-agarose phantom, using non-phase-contrast cine and phase-contrast cine with one to three directional encodings, one to 16 views per segment, and nearest-neighbor or linear interpolation. Temporal power spectra from object pixels were fit to linear transfer function models; nearest-neighbor interpolation by a sinc function and linear interpolation by a sinc(2) function. RESULTS: Simple linear transfer function models predicted >98% of the observed power spectral variation. Finite word effects produced small systematic differences at high temporal frequency. CONCLUSION: Temporal power spectra of cine images collected from stationary objects completely characterizes low pass filtration effects of interpolation.