Intracranial fluid dynamics in normal and hydrocephalic states: systems analysis with phase-contrast magnetic resonance imaging

OBJECTIVE: To present a novel magnetic resonance (MR) method of analysis of cerebrospinal fluid (CSF) flow dynamics. METHODS: Fifty-one subjects were explored with phase-contrast cine MR imaging. There were 36 volunteers, 9 patients with normal pressure hydrocephalus (NPH), and 6 patients with asymptomatic ventricular dilation (VD). The transfer function XFRA/CSF from the arterial pulse waves (APWs) and the CSF pulse waves (CSFPWs) and the transfer function XFRCSF/SS from the CSF pulse waves (CSFPWs) and the sagittal sinus pulse waves (SSPWs) were studied separately. RESULTS: There was a significant difference in the amplitude spectrum of the XFRA/CSF of patients with VD and volunteers (P < 0.05) and in that of patients with NPH and volunteers (P = 0.005). The amplitude of the fundamental frequency was higher in the NPH group than in the VD group (P = 0.02). In patients with NPH, the amplitude spectrum of XFRCSF/SS showed an attenuation of the pulse wave components that significantly differed from the observed amplification in healthy subjects (P = 0.009) and patients with VD (P = 0.012). CONCLUSION: This systems analysis method could help to detect increased venous compliance in VD and decreased venous compliance in NPH.     

MRI-intracranial compliance analysis in patients with NPH

We devised a method for non-invasively assessing intracranial compliance with retrospective ECG-triggered phase contrast cine MRI. This method was examined in patients with normal pressure hydrocephalus (NPH) group and those with asymptomatic ventricular dilation or brain atrophy (VD group), and in healthy volunteers (control group). Intracranial volume change (DeltaV(max)) was calculated from arterial inflow, venous outflow, cerebrospinal fluid (CSF) flow, and spinal cord motion at the C2 level during a cardiac cycle. Next, craniospinal CSF pressure gradient change (DeltaPG(max)) was calculated from measured CSF flow velocity using a simplified Navier-Stokes equation. Finally, Ci was obtained by dividing Delta V(max) into DeltaPG(max). Ci in the NPH group was significantly smaller and could be differentiated from other groups. This method makes it possible to non-invasively obtain a more detailed determination of the intracranial state and dynamics in NPH and to assist in its diagnosis.     

Cerebrospinal fluid flow in patients with dilated ventricles studied with MR imaging

The purpose of this study was to measure the cerebrospinal fluid (CSF) velocity and flow in the aqueduct in patients with wide ventricles with or without signs of normal pressure hydrocephalus (NPH) before and after shunt surgery. We studied 18 patients with wide ventricles with MRI and measured the CSF velocity values in the aqueducts. Twelve patients with the clinical triad of NPH were examined. Six patients were studied only before shunt surgery and 6 patients were studied both before and after shunt surgery. Three patients with wide ventricles without clinical triad of NPH, and 3 patients with hydrocephalus following subarachnoid hemorrhage were also examined. Seven NPH patients with hyperdynamic CSF flow and three NPH patients with normal CSF velocity and flow values showed a positive clinical response to shunt surgery. Two of the three patients with hydrocephalus and hyperdynamic CSF flow values in the aqueduct secondary to subarachnoid bleeding responded to shunt surgery. One patient with same disease and low CSF velocity and flow values did not respond. No change was detected in the CSF flow values of the aqueduct when measurements before and after shunt surgery were compared. Ventriculoperitoneal shunting does not change the CSF dynamics in the aqueduct. Received: 8 March 1999; Revised: 30 November 1999; Accepted: 23 February 2000     

Noninvasive MRI assessment of intracranial compliance in idiopathic normal pressure hydrocephalus

PURPOSE: To assess the state and dynamics of the intracranial system in idiopathic normal-pressure hydrocephalus (I-NPH), we determined intracranial compliance using magnetic resonance imaging (MRI). MATERIALS AND METHODS: The intracranial compliance index (ICCI), which was defined as the ratio of the peak-to-peak intracranial volume change (ICVC(p-p)) to the peak-to-peak cerebrospinal fluid (CSF) pressure gradient (PG(p-p)) during the cardiac cycle, was obtained from the net transcranial blood and CSF flow measured with phase-contrast (PC) cine MRI. ICCI was determined in patients with I-NPH (N = 7), brain atrophy, or asymptomatic ventricular dilation (VD) (N = 6), and in healthy volunteers (control group; N = 11). The changes in ICCI indices were also analyzed after a CSF tap test (N = 2). RESULTS: The ICCI in the I-NPH group was significantly lower than in the control and VD groups, whereas no difference was found between the control and VD groups. The ICVC(p-p) was also lower than in the control and VD groups. However, no significant difference was found in the PG(p-p) between groups. The ICCI increased after the tap test. CONCLUSION: Intracranial compliance analysis with MRI makes it possible to noninvasively obtain more detailed information of intracranial biomechanics in the I-NPH and to assist in the diagnosis of I-NPH.     

Cerebrospinal fluid flow and production in patients with normal pressure hydrocephalus studied by MRI

An interleaved velocity-sensitised fast low-angle shot pulse sequence was used to study cerebrospinal fluid (CSF) flow in the cerebral aqueduct, and supratentorial CSF production in 9 patients with normal pressure hydrocephalus (NPH) and 9 healthy volunteers. The peak aqueduct CSF flow, both caudal and rostral, was significantly increased in patients with NPH. No significant difference in the supratentorial CSF production rate was found between patients (mean 0.60+/–0.59 ml/min) and healthy volunteers (mean 0.68+/–0.31 ml/min). Our method may be useful for investigation and monitoring of patients with NPH before and after ventriculoperitoneal shunt operations.     

Cerebrospinal fluid flow

Summary Cardiac- and respiration-related movements of the cerebrospinal fluid (CSF) were investigated by MRI in 71 patients. In most patients with arteriosclerotic occlusive vascular disease CSF pulsations are normal. Decreased pulsatile flow is detectable in those with arteriovenous malformations, intracranial air and following lumbar puncture and withdrawal of CSF. Increased pulsatile flow in the cerebral aqueduct was found in 2 patients with large aneurysms, idiopathic communicating syringomyelia and in most cases of normal pressure hydrocephalus (NPH). CSF flow in the cervical spinal canal is, however, reduced or normal in NPH, indicating reduction of the unfolding ability of the surface of the brain and/or inhibition of rapid CSF movements in the subarachnoid space over its convexity.     

颅内疾病对导水管脑脊液流量的影响

目的：探讨用磁共振相位对比电影(PC cine)对导水管脑脊液定量测量的临床应用价值。方法：将35例中枢神经系统不同疾病分三组，用PC cine方法进行导水管脑脊液流量测量。结果：在脑血管病组伴白质改变时导水管流量增加；梗阻性脑积水导水管流量减少，流动波形异常；交通性脑积水导水管流量增加，波形圆钝。结论：磁共振PC cine方法测量导水管脑脊液流量简单易行，可为临床提供更多的影像信息。     

Cerebrospinal fluid pulsation amplitude and its quantitative relationship to cerebral blood flow pulsations: a phase-contrast MR flow imaging study

Our purpose in this investigation was to explain the heterogeneity in the cerebrospinal fluid (CSF) flow pulsation amplitudes. To this end, we determined the contributions of the cerebral arterial and jugular venous flow pulsations to the amplitude of the CSF pulsation. We examined 21 healthy subjects by cine phase-contrast MRI at the C2–3 disc level to demonstrate the CSF and vascular flows as waveforms. Multiple regression analysis was performed to calculate the contributions of (a) the arterial and venous waveform amplitudes and (b) the delay between the maximum systolic slopes of the arterial and venous waveforms (AV delay), in order to predict the amplitude of the CSF waveform. The contribution of the arterial waveform amplitude was positive (r = 0.61; p = 0.003) to the CSF waveform amplitude and that of the venous waveform amplitude was negative (r = −0.50; p = 0.006). Both in combination accounted for 56 % of the variance in predicting the CSF waveform amplitude (p < 0.0006). The contribution of AV delay was not significant. The results show that the variance in the CSF flow pulsation amplitudes can be explained by concurrent evaluation of the CSF and vascular flows. Improvement in the techniques, and controlled experiments, may allow use of CSF flow pulsation amplitudes for clinical applications in the non-invasive assessment of intracranial dynamics by MRI. Received: 3 January 1996 Accepted: 5 June 1996     

Assessment of CSF dynamics and venous flow in the superior sagittal sinus by MRI in idiopathic intracranial hypertension: a preliminary study

A velocity-sensitive magnetic resonance imaging (MRI) phase-mapping method was used for noninvasive study of cerebrospinal fluid (CSF) flow in the cerebral aqueduct, for indirect calculation of supra-tentorial CSF production, and for measurement of blood flow in the superoor sagittal sinus (SSS). We examined 12 patients with idiopathic intracranial hypertension (HH; pseudotumour cerebri), and 10 healthy volunteers. The peak caudal and rostal CSF flow in the aqueduct during the cardiac cycle did not differ significantly between the patients and the volunteers. A significant correlation was found between the CSF volume flow amplitude and the resistance to cerebrospinal fluid out-flow in the patients (p<0.05). The calculated mean supratentorial CSF production rate was 0.79 ml/min in the patients and 0.70 ml/min in the controls, but this difference was not statistically significant. However, the MRI measurements suggested CSF hypersecretion in three patients, whereas increased transependymal passage of CSF could have been the cause of negative calculated CSF production rates in two others. A tendency towards lower mean blood flow in the SSS (mean 345 ml/min) in the patients than in the controls (mean 457 ml/min) was found, and in two patients showed very low values. We showed that MRI phase-mapping may be used to study the relative importance of the pathophysiological factors thought to play a role in the development of IIH.     

SPAMM, cine phase contrast imaging and fast spin-echo T2-weighted imaging in the study of intracranial cerebrospinal fluid (CSF) flow

AIM: To compare the qualitative assessment of cerebrospinal fluid (CSF) flow using a SPAMM (spatial modulation of magnetization) technique with cine phase contrast images (cine PC) and fast spin echo (FSE) T2-weighted images. MATERIALS AND METHODS: SPAMM, PC and T2-weighted sequences were performed on 22 occasions in 19 patients. Eleven of the studies were performed following a neuroendoscopic third ventriculostomy (NTV), and in these cases, the success of the NTV was determined by clinical follow-up. Two observers used consensus to grade the presence of CSF flow at nine different sites for each study. RESULTS: At 14 of the 178 matched sites, which could be assessed by both SPAMM and cine PC, SPAMM CSF flow grade was higher than that of cine PC. At a further 14/178 matched sites, the cine PC grade was higher than that of SPAMM. There was definite CSF flow at 113/182 (62%) of all the cine PC sites assessed, and 110/181 (61%) of all SPAMM sites assessed whilst 108/198 (54%) of FSE T2-weighted image sites demonstrated flow voids. Cine PC grades were higher than SPAMM at the cerebral aqueduct (P < 0.05, Wilcoxon sign rank test). Definite CSF flow within the anterior third ventricle was present in 4/5 (SPAMM) and 3/5 (cine PC) successful NTVs, 0/2 (SPAMM and cine PC) unsuccessful NTVs and 1/10 (SPAMM and cine PC) patients without NTV. CONCLUSION: SPAMM provides a comparable assessment of intracranial CSF flow to that of cine phase contrast imaging at all CSF sites except the cerebral aqueduct.     

The pathophysiology of the aqueduct stroke volume in normal pressure hydrocephalus: can co-morbidity with other forms of dementia be excluded?

Variable results are obtained from the treatment of normal pressure hydrocephalus (NPH) by shunt insertion. There is a high correlation between NPH and the pathology of Alzheimers disease (AD) on brain biopsy. There is an overlap between AD and vascular dementia (VaD), suggesting that a correlation exists between NPH and other forms of dementia. This study seeks to (1) understand the physiological factors behind, and (2) define the ability of, the aqueduct stroke volume to exclude dementia co-morbidity. Twenty-four patients from a dementia clinic were classified as having either early AD or VaD on the basis of clinical features, Hachinski score and neuropsychological testing. They were compared with 16 subjects with classical clinical findings of NPH and 12 aged-matched non-cognitively impaired subjects. MRI flow quantification was used to measure aqueduct stroke volume and arterial pulse volume. An arterio-cerebral compliance ratio was calculated from the two volumes in each patient. The aqueduct stroke volume was elevated in all three forms of dementia, with no significant difference noted between the groups. The arterial pulse volume was elevated by 24% in VaD and reduced by 35% in NPH, compared to normal (P=0.05 and P=0.002, respectively), and was normal in AD. There was a spectrum of relative compliance with normal compliance in VaD and reduced compliance in AD and NPH. The aqueduct stroke volume depends on the arterial pulse volume and the relative compliance between the arterial tree and brain. The aqueduct stroke volume cannot exclude significant co-morbidity in NPH.     

Flowing cerebrospinal fluid in normal and hydrocephalic states: appearance on MR images

The signal intensity of the cerebrospinal fluid (CSF) in the cerebral aqueduct and lateral ventricles on magnetic resonance (MR) images was evaluated in 16 healthy individuals and in 32 patients with various forms of hydrocephalus (20 with chronic normal pressure hydrocephalus [NPH], seven with acute communicating hydrocephalus, and five with hydrocephalus ex vacuo [atrophy]). The low signal intensity frequently observed in the cerebral aqueduct is believed to reflect the pulsatile motion of CSF, which is related to the cardiac cycle. While this "aqueductal flow void phenomenon" can be observed in healthy individuals, it is most pronounced in patients with chronic, communicating NPH; is less evident in patients with acute, communicating hydrocephalus; and is least evident in patients with atrophy. Ventricular compliance is known to be essentially normal in atrophy; mildly decreased in acute, communicating hydrocephalus; and severely decreased in NPH. The degree of aqueductal signal loss is believed to reflect the velocity of the pulsatile CSF motion, which in turn depends on the relative ventricular compliance and surface area.     

CSF pulsation patterns in occlusive hydrocephalus

Fifteen patients with solid and cystic occlusions of the cerebrospinal fluid (CSF) circulation pathways were examined with MRI using an ECG retrogated two-dimensional FISP sequence to determine whether there are certain defined pathological CSF flow patterns in these patients. All patients were clinically still compensated. The results of the measurements of CSF flow velocities at different locations in the CSF system were compared with the results from 8 healthy volunteers. In all patients with occlusive processes of the intraventricular CSF pathways (4 aqueduct stenoses, 1 membranous occlusion of the fourth ventricular outlets, 1 solid tumour at the foramen of Monro and 1 solid fourth ventricular tumour) we observed hyperdynamic CSF pulsation above the lesion. This was transmitted into the spinal canal. Close by a solid occlusion within the aqueduct the flow velocity curve over the RR cycle was typically shifted, resulting in a mirroring of the flow velocity curve compared with normals. In cystic lesions (n = 4) there was transmission of the pulsation wave through the lesion and therefore no mirroring of the flow velocity curve. This technique allows very good delineation of cystic structures in the peripineal region (n = 4), also due to the opposite direction of flow within the cyst compared with the surrounding CSF spaces, depending on the extent of communication. Correspondence to: U. Kunz     

Cine cerebrospinal fluid imaging in multiple sclerosis

Purpose:

To investigate cerebrospinal fluid (CSF) dynamics in the aqueduct of Sylvius in multiple sclerosis (MS) patients and healthy controls (HC) using cine phase contrast imaging.

Materials and Methods:

In all, 67 MS patients (48 relapsing‐remitting [RR] and 19 secondary‐progressive [SP]), nine patients with clinically isolated syndrome (CIS), and 35 age‐ and sex‐matched HC were examined. CSF flow and velocity measures were quantified using a semiautomated method and compared with clinical and magnetic resonance imaging (MRI) disease outcomes.

Results:

Significantly decreased CSF net flow was detected in MS patients compared to HC (?3.7 vs. ?7.1 μL/beat, P = 0.005). There was a trend for increased net positive flow between SP, RR, and CIS patients. Altered CSF flow and velocity measures were associated with more severe T1 and T2 lesion volumes, lateral and fourth ventricular volumes, and third ventricular width in MS and CIS patients (P < 0.01 for all). In CIS patients, conversion to clinically definite MS in the following year was related to decreased CSF net flow (P = 0.007). There was a trend between increased annual relapse rate and altered CSF flow/velocity measures in RRMS patients (P < 0.05).

Conclusion:

CSF flow dynamics are altered in MS patients. More severe clinical and MRI outcomes in RRMS and CIS patients relate to altered CSF flow and velocity measures. J. Magn. Reson. Imaging 2012;36:825–834. © 2012 Wiley Periodicals, Inc.

     

Functional analysis of third ventriculostomy patency by quantification of CSF stroke volume by using cine phase-contrast MR imaging

OBJECTIVE: Endoscopic third ventriculostomy (ETV) is increasingly used as alternative treatment for obstructive hydrocephalus. The aim of this study was to determine the utility of quantitative and qualitative examinations with cine phase-contrast MR imaging to determine the efficacy of ventriculostomy across time and whether CSF pulsation is restored after ETV. METHODS: Thirty-eight patients treated with ETV were evaluated with cine phase-contrast MR within 1 month after surgery. Follow-up studies were performed after 1 year in 25 patients and after 2 years in 12. We evaluated flow void changes in the floor of the third ventricle and quantified the stroke volume at the site of the ventriculostomy. We also recorded changes in ventricular size and clinical outcome. To determine the restoration of CSF pulsation, we compared the CSF waveform at the ventriculostomy with the CSF waveform at the aqueduct in a healthy control group. RESULTS: After ventriculostomy, restoration of pulsate motion characteristics of CSF circulation was observed. The stroke volume registered at ventriculostomy was maintained with time. There was a statistically significant relationship between clinical outcome and stroke volume. Overall flow magnitude was the most effective variable to determine which patients would improve after surgery. Values >75 mm3 showed a sensitivity of 76.7% and a specificity of 87.5% There was no relationship between ventricular size changes and clinical outcome. Patients with primary aqueduct stenosis had the best response to surgery, whereas patients with Arnold Chiari malformation or communicating hydrocephalus had the worst response. CONCLUSION: Quantitative analysis with phase-contrast MR imaging indicates that ETV is an efficient technique for restoring CSF pulsation, with efficacy being maintained during the follow-up controls. Quantification of stroke volume at ventriculostomy is a good indicator of the functional status of ETV, and a high stroke volume in the ventriculostomy appears to be a positive predictor of favorable clinical outcome.     

Dynamic visualization of arachnoid adhesions in a patient with idiopathic syringomyelia using high‐resolution cine magnetic resonance imaging at 3T

A 39‐year‐old female patient with thoracic syringomyelia underwent routine magnetic resonance imaging (MRI) and 3 T MRI to investigate the value of retrospectively cardiac‐gated cine steady‐state free precession (SSFP) MRI in the preoperative and postoperative diagnosis of arachnoid membranes in the spinal subarachnoid space. Therefore, 3T MRI included sagittal and transverse retrospectively cardiac‐gated cine balanced fast‐field echo (balanced‐FFE) sequences both preoperatively and after microsurgical lysis of arachnoid adhesions and expansive duraplasty. Arachnoid membranes were detected and this result was correlated with intraoperative findings and the results of routine cardiac‐gated phase‐contrast cerebrospinal fluid (CSF) flow MRI. Retrospectively cardiac‐gated cine SSFP MRI enabled imaging of arachnoid membranes with high spatial resolution and sufficient contrast to delineate them from hyperintense CSF preoperatively and postoperatively. The images were largely unaffected by artifacts. Surgery confirmed the presence of arachnoid adhesions in the upper thoracic spine. Not all arachnoid membranes that were seen on cine balanced‐FFE sequences caused significant spinal CSF flow blockages in cardiac‐gated phase‐contrast CSF flow studies. In conclusion, retrospectively cardiac‐gated cine SSFP MRI may become a valuable tool for the preoperative detection of arachnoid adhesions and the postoperative evaluation of microsurgical adhesiolysis in patients with idiopathic syringomyelia. J. Magn. Reson. Imaging 2010. © 2010 Wiley‐Liss, Inc.     

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     

磁共振脑脊液电影对四脑室囊虫病诊断意义的研究

目的：探讨磁共振脑脊液电影对四脑室囊虫病的诊断意义。材料与方法：经手术病理证实的四脑室囊虫病９例，回顾性分析其磁共振脑脊液电影表现。脑脊液电影采用头部正中矢状面，手指门控扫描技术。结果：（１）直接显示脑脊液（ＣＳＦ）循环通路及分布情况，四脑室内病灶均表现为ＣＳＦ的充盈缺损区。囊虫均为囊性，信号均、壁光整，壁可薄可厚。（２）ＣＳＦ流动为搏动性往复运动，以导水管区最明显。在心脏收缩期，导水管内的ＣＳＦ由三脑室流向四脑室，囊虫上方残余的四脑室腔扩张增大，舒张期缩小，顺应性良好。（３）四脑室囊虫存活期，边缘光整，ＣＳＦ于其上方前后分流呈杯口状，囊虫游离于四脑室内，并可滚动，其形态在一个心动周期内可有轻微变化；退变死亡期囊虫，周围室管膜出现炎性反应，并与囊虫壁粘连，ＣＳＦ循环受阻更明显。结论：磁共振不但能对四脑室囊虫病做出准确的定位、定性诊断，而且可通过脑脊液电影了解囊虫灶对ＣＳＦ循环的阻塞程度和方式，以及观察囊虫与室管膜是否有粘连，从而为选择治疗方案提供指导意义。     

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.