Aqueductal Cerebrospinal Fluid Flow Research Articles

Cerebrospinal Fluid Flow in Patients with Huntington's Disease.

Investigations of cerebrospinal fluid (CSF) flow aberrations in Huntington's disease (HD) are of growing interest, as impaired CSF flow may contribute to mutant Huntington retention and observed heterogeneous responsiveness to intrathecally administered therapies. We assessed net cerebral aqueduct CSF flow and velocity in 29 HD participants (17 premanifest and 12 manifest) and 51 age- and sex matched non-HD control participants using 3-Tesla magnetic resonance imaging methods. Regression models were applied to test hypotheses regarding: (i) net CSF flow and cohort, (ii) net CSF flow and disease severity (CAP-score), and (iii) CSF volume after correcting for age and sex. Group-wise analyses support a decrease in net CSF flow in HD (mean 0.14 ± 0.27 mL/min) relative to control (mean 0.32 ± 0.20 mL/min) participants (p = 0.02), with lowest flow in the manifest HD cohort (mean 0.04 ± 0.25 mL/min). This finding was explained by hyperdynamic CSF movement, manifesting as higher caudal systolic CSF flow velocity and higher diastolic cranial CSF flow velocity across the cardiac cycle, in HD (caudal flow: 0.17 ± 0.07 mL/s, cranial flow: 0.14 ± 0.08 mL/s) compared to control (caudal flow: 0.13 ± 0.06 mL/s, cranial flow: 0.11 ± 0.04 mL/s) participants. A positive correlation between cranial diastolic flow and disease severity was observed (p = 0.02). Findings support aqueductal CSF flow dynamics changing with disease severity in HD. These accelerated changes are consistent with changes observed over the typical adult lifespan, and may have relevance to mutant Huntington retention and intrathecally administered therapeutics responsiveness. ANN NEUROL 2023;94:885-894.

Choroid plexus perfusion and bulk cerebrospinal fluid flow across the adult lifespan

The choroid plexus (ChP) comprises a collection of modified ependymal cells that play an important role in the production of brain cerebrospinal fluid (CSF), and ChP perfusion aberrations have been implicated in a range of cerebrovascular and neurodegenerative disorders. To provide an exemplar for the growing interest in ChP activity, we evaluated ChP perfusion and bulk CSF flow cross-sectionally across the healthy adult lifespan. Participants (n = 77; age range = 21–86 years) were scanned at 3T using T1-weighted, T2-weighted-FLAIR, perfusion-weighted pCASL, and phase contrast MRI to calculate ChP anatomy, perfusion, and aqueductal CSF flow, respectively. Regression models were applied to evaluate aging effects on ChP volume and ChP perfusion in the lateral ventricles, as well as CSF flow. ChP volume (mean ± std = 2.81 ± 1.1 cm3) increased (p < 0.001), ChP perfusion (36.3 ± 8.6 mL/100 g/min) decreased (p = 0.0078), and ChP total blood flow (1.13 ± 0.34 mL/min) increased (p < 0.001) with age. Cranial-to-caudal net CSF flow (0.245 ± 0.20 mL/min) decreased, absolute CSF flow (4.86 ± 2.96 mL/min) increased, and CSF regurgitant fraction (0.87 ± 0.126) increased with age (all: p < 0.001). ChP perfusion was directly related to net cranial-to-caudal CSF flow through the aqueduct (p = 0.033). The implications of these findings are discussed in the context of the growing literature on CSF circulatory dysfunction in neurodegeneration and cerebrovascular disease.

Influence of the area of the aqueduct and region of interest on quantification of stroke volume in healthy volunteers using phase-contrast cine magnetic resonance imaging.

Phase-contrast cine magnetic resonance imaging (PC-MRI) has been used to measure cerebrospinal fluid (CSF) flow dynamics, but the influence of the area of the aqueduct and region of interest (ROI) on quantification of stroke volume (SV) has not been assessed. To assess the influence of the area of the ROI in quantifying the aqueductal SV measured with PC-MRI within the cerebral aqueduct. Nine healthy volunteers (mean age = 29.6 years) were enrolled in the study, and brain MRI examinations were performed on a 3.0-T system. Quantitative analysis of the aqueductal CSF flow was performed using manual ROI placement. ROIs were separately drawn for each of the 12 phases of the cardiac cycle, and changes in aqueduct size during the cardiac cycle were determined. The SV was calculated using 12 different aqueductal ROIs and compared with the SV calculated using a fixed ROI size. There was variation in the size of the aqueduct during the cardiac cycle. In addition, the measured SV increased with a greater area of the ROI. A significant difference in the calculated SVs with the 12 variable ROIs was observed compared with that using a fixed ROI throughout the cardiac cycle. To establish reliable reference values for the SV in future studies, a variable ROI should be considered.

Tetraventricular hydrocephalus with aqueductal flow void: an overlooked entity having consistent improvement following endoscopic third ventriculostomy

Background Tetraventricular Hydrocephalus (TetHCP) is a heterogeneous group of cerebrospinal fluid (CSF) flow disorders having varying success rates with Endoscopic third ventriculostomy (ETV). This is report on the efficacy and rationale of ETV in a specific subset of primary TetHCP with aqueductal CSF flow voids. Methods Patients of primary acquired TetHCP presenting with increasing head size and/or headache having aqueductal CSF flow void on sagittal Magnetic Resonance Imaging (MRI) were included in this study. All of them underwent ETV. All patients were evaluated for clinical improvement & MRI at 3 months, and need for any additional procedure, in contrast to those without CSF flow void. The pathophysiology of hyperdynamic CSF circulation and its correlation to ETV was further reviewed. Results Eleven patients had tetraventricular hydrocephalus and aqueductal flow void, with age ranging from 10 months to 59 years. Two patients who could undergo quantitative flow study confirmed the hyperdynamic flow across the aqueduct. Following ETV, all showed clinical improvement. MRI at 3 months showed CSF flow void across the third ventricular stoma in addition to across the aqueduct. None of these patients required any redo procedures for a mean follow-up of 39.2 months. In contrast, there was 30% failure rate after ETV among 10 patients of tetraventricular hydrocephalus without aqueductal flow void. Conclusion Tetraventricular hydrocephalus with aqueductal CSF flow void may be a unique entity with hyperdynamic CSF circulation and relative resistance at fourth ventricular outlets. ETV is highly efficacious in these patients, resulting in consistent clinico-radiological improvement.

Using deep learning convolutional neural networks to automatically perform cerebral aqueduct CSF flow analysis

Since the development of phase-contrast magnetic resonance imaging (PC-MRI), quantification of cerebrospinal fluid (CSF) flow across the cerebral aqueduct has been utilized for diagnosis of conditions such as normal pressure hydrocephalus (NPH). This study aims to develop an automated method of aqueduct CSF flow analysis using convolution neural networks (CNNs), which can replace the current standard involving manual segmentation of aqueduct region of interest (ROI). Retrospective analysis was performed on 333 patients who underwent PC-MRI, totaling 353 imaging studies. Aqueduct flow measurements using manual ROI placement was performed independently by two radiologists. Two types of CNNs, MultiResUNet and UNet, were trained using ROI data from the senior radiologist, with PC-MRI studies being randomly divided into training (80%) and validation (20%) datasets. Segmentation performance was assessed using Dice similarity coefficient (DSC), and CSF flow parameters were calculated from both manual and CNN-derived ROIs. MultiResUNet, UNet and second radiologist (Rater 2) had DSCs of 0.933, 0.928, and 0.867, respectively, with p < 0.001 between CNNs and Rater 2. Comparison of CSF flow parameters showed excellent intraclass correlation coefficients (ICCs) for MultiResUNet, with lowest correlation being 0.67. For UNet, lower ICCs of −0.01 to 0.56 were observed. Only 3/353 (0.8%) studies failed to have appropriate ROIs placed by MultiResUNet, compared to 12/353 (3.4%) failed cases for UNet. In conclusion, CNNs were able to measure aqueductal CSF flow with similar performance to a senior neuroradiologist. MultiResUNet demonstrated fewer cases of segmentation failure and more consistent flow measurements compared to the widely adopted UNet.

Direction and magnitude of cerebrospinal fluid flow vary substantially across central nervous system diseases

BackgroundSeveral central nervous system diseases are associated with disturbed cerebrospinal fluid (CSF) flow patterns and have typically been characterized in vivo by phase-contrast magnetic resonance imaging (MRI). This technique is, however, limited by its applicability in space and time. Phase-contrast MRI has yet to be compared directly with CSF tracer enhanced imaging, which can be considered gold standard for assessing long-term CSF flow dynamics within the intracranial compartment.MethodsHere, we studied patients with various CSF disorders and compared MRI biomarkers of CSF space anatomy and phase-contrast MRI at level of the aqueduct and cranio-cervical junction with dynamic intrathecal contrast-enhanced MRI using the contrast agent gadobutrol as CSF tracer. Tracer enrichment of cerebral ventricles was graded 0–4 by visual assessment. An intracranial pressure (ICP) score was used as surrogate marker of intracranial compliance.ResultsThe study included 94 patients and disclosed marked variation of CSF flow measures across disease categories. The grade of supra-aqueductal reflux of tracer varied, with strong reflux (grades 3–4) in half of patients. Ventricular tracer reflux correlated with stroke volume and aqueductal CSF pressure gradient. CSF flow in the cerebral aqueduct was retrograde (from 4th to 3rd ventricle) in one third of patients, with estimated CSF net flow volume about 1.0 L/24 h. In the cranio-cervical junction, net flow was cranially directed in 78% patients, with estimated CSF net flow volume about 4.7 L/24 h.ConclusionsThe present observations provide in vivo quantitative evidence for substantial variation in direction and magnitude of CSF flow, with re-direction of aqueductal flow in communicating hydrocephalus, and significant extra-cranial CSF production. The grading of ventricular reflux of tracer shows promise as a clinical useful method to assess CSF flow pattern disturbances in patients.Graphic abstract

Microstructural Predictors of Cognitive Impairment in Cerebral Small Vessel Disease and the Conditions of Their Formation.

Introduction: Cerebral small vessel disease (CSVD) is the leading cause of vascular and mixed degenerative cognitive impairment (CI). The variability in the rate of progression of CSVD justifies the search for sensitive predictors of CI. Materials: A total of 74 patients (48 women, average age 60.6 ± 6.9 years) with CSVD and CI of varying severity were examined using 3T MRI. The results of diffusion tensor imaging with a region of interest (ROI) analysis were used to construct a predictive model of CI using binary logistic regression, while phase-contrast magnetic resonance imaging and voxel-based morphometry were used to clarify the conditions for the formation of CI predictors. Results: According to the constructed model, the predictors of CI are axial diffusivity (AD) of the posterior frontal periventricular normal-appearing white matter (pvNAWM), right middle cingulum bundle (CB), and mid-posterior corpus callosum (CC). These predictors showed a significant correlation with the volume of white matter hyperintensity; arterial and venous blood flow, pulsatility index, and aqueduct cerebrospinal fluid (CSF) flow; and surface area of the aqueduct, volume of the lateral ventricles and CSF, and gray matter volume. Conclusion: Disturbances in the AD of pvNAWM, CB, and CC, associated with axonal damage, are a predominant factor in the development of CI in CSVD. The relationship between AD predictors and both blood flow and CSF flow indicates a disturbance in their relationship, while their location near the floor of the lateral ventricle and their link with indicators of internal atrophy, CSF volume, and aqueduct CSF flow suggest the importance of transependymal CSF transudation when these regions are damaged.

Respiratory influence on cerebrospinal fluid flow \u2013 a computational study based on long-term intracranial pressure measurements

Current theories suggest that waste solutes are cleared from the brain via cerebrospinal fluid (CSF) flow, driven by pressure pulsations of possibly both cardiac and respiratory origin. In this study, we explored the importance of respiratory versus cardiac pressure gradients for CSF flow within one of the main conduits of the brain, the cerebral aqueduct. We obtained overnight intracranial pressure measurements from two different locations in 10 idiopathic normal pressure hydrocephalus (iNPH) patients. The resulting pressure gradients were analyzed with respect to cardiac and respiratory frequencies and amplitudes (182,000 cardiac and 48,000 respiratory cycles). Pressure gradients were used to compute CSF flow in simplified and patient-specific models of the aqueduct. The average ratio between cardiac over respiratory flow volume was 0.21 ± 0.09, even though the corresponding ratio between the pressure gradient amplitudes was 2.85 ± 1.06. The cardiac cycle was 0.25 ± 0.04 times the length of the respiratory cycle, allowing the respiratory pressure gradient to build considerable momentum despite its small magnitude. No significant differences in pressure gradient pulsations were found in the sleeping versus awake state. Pressure gradients underlying CSF flow in the cerebral aqueduct are dominated by cardiac pulsations, but induce CSF flow volumes dominated by respiration.

The role of arterial and venous blood flow and cerebrospinal fluid flow disturbances in the development of cognitive impairments in cerebral microangiopathy

Cerebral microangiopathy (CMA) is the main cause of vascular cognitive disorders, the leading cause of mixed dementia, and the main modifiable risk factor in Alzheimer’s disease. Study objective. To investigate the role of arterial and venous blood flow and cerebrospinal fluid flow, as well as their interrelation in the development of cognitive disorders in patients with CMA. Materials and methods. Ninety-six patients (32 men and 64 women, mean age 60.6±6.3 years) with cognitive complaints and CMA, diagnosed according to the STRIVE international MRI criteria, were examined. The severity of cognitive disturbance was assessed based on the overall cognitive level (MoCA scale and independence in daily life), the results of memory tests (10 words memory test) and executive brain function tests (TMT B-A). Phase contrast MRI was used to measure blood flow in the internal carotid and vertebral arteries (total arterial blood flow), the internal jugular veins and the straight and superior sagittal sinuses, as well as the aqueductal cerebrospinal fluid flow. Arterial pulsation and intracranial compliance indices were calculated. Results. Dementia and severe memory impairment were statistically significantly associated with an increase in the arterial pulsation index, intracranial compliance index and the aqueductal CSF stroke volume. Significant disturbances in brain executive function were also associated with a decrease in the total arterial blood flow, as well as the venous blood flow in the straight and superior sagittal sinuses. The characteristics of blood flow and cerebrospinal fluid are closely related, and the arterial pulsation index affects all the studied parameters. Conclusion. The severity of cognitive disturbance in CMA is determined by an increase in the arterial pulsation index, the intracranial compliance index and the aqueductal CSF stroke volume, while the severity of dysregulation disorders is determined by a concurrent decrease in the total arterial blood flow and venous blood flow in the straight and superior sagittal sinuses. The specific changes in blood flow and CSF flow and their interrelation in patients with cognitive impairment due to CMA suggest the pathogenetic importance of cerebral hydrodynamic disturbances in the aetiology of brain damage and the development of cognitive impairment in CMA.

Aqueductal Cerebrospinal Fluid Stroke Volume Flow in a Rodent Model of Chronic Communicating Hydrocephalus: Establishing a Homogeneous Study Population for Cerebrospinal Fluid Dynamics Exploration

Idiopathic normal pressure hydrocephalus (iNPH) is a cause of dementia that can be reversed when treated timely with cerebrospinal fluid (CSF) diversion. Understanding CSF dynamics throughout the development of hydrocephalus is crucial to identify prognostic markers to estimate benefit/risk to shunts. To explore the cerebral aqueduct CSF flow dynamics with phase-contrast magnetic resonance imaging (MRI) in a novel rodent model of adult chronic communicating hydrocephalus. Kaolin was injected into the subarachnoid space at the convexities in Sprague-Dawley adult rats. 11.7-T Bruker MRI was used to acquire T2-weighted images for anatomic identification and phase-contrast MRI at the cerebral aqueduct. Aqueductal stroke volume (ASV) results were compared with the ventricular volume (VV) at 15, 60, 90, and 120 days. Significant ventricular enlargement was found in kaolin-injected animals at all times (P < 0.001). ASV differed between cases and controls/shams at every time point (P= 0.004, 0.001, 0.001, and <0.001 at 15, 60, 90, and 120 days, respectively). After correlation between the ASV and the VV, there was a significant correlation at 15 (P= 0.015), 60 (P= 0.001), 90 (P < 0.001), and 120 days. Moreover, there was a significant positive correlation between the VV expansion and the aqueductal CSF stroke between 15 and 60 days. An initial active phase of rapid ventricular enlargement shows a strong correlation between the expansion of the VV and the increment in the ASV during the first 60 days, followed by a second phase with less ventricular enlargement and heterogeneous behavior in the ASV. Further correlation with complementary data from intracranial pressure and histologic/microstructural brain parenchyma assessments are needed to better understand the ASV variations after 60 days.

Magnitude and direction of aqueductal cerebrospinal fluid flow: large variations in patients with intracranial aneurysms with or without a previous subarachnoid hemorrhage.

Net cerebrospinal fluid (CSF) flow within the cerebral aqueduct is usually considered to be antegrade, i.e., from the third to the fourth ventricle with volumes ranging between 500 and 600ml over 24h. Knowledge of individual CSF flow dynamics, however, is hitherto scarcely investigated. In order to explore individual CSF flow rate and direction, we assessed net aqueductal CSF flow in individuals with intracranial aneurysms with or without a previous subarachnoid hemorrhage (SAH). A prospective observational study was performed utilizing phase-contrast magnetic resonance imaging (PC-MRI) to determine the magnitude and direction of aqueductal CSF flow with an in-depth, pixel-by-pixel approach. Estimation of net flow was used to calculate CSF flow volumes over 24h. PC-MRI provides positive values when flow is retrograde. The study included eight patients with intracranial aneurysms. Four were examined within days after their SAH; three were studied in the chronic stage after SAH while one patient had an unruptured intracranial aneurysm. There was a vast variation in magnitude and direction of aqueductal CSF flow between individuals. Net aqueductal CSF flow was retrograde, i.e., directed towards the third ventricle in 5/8 individuals. For the entire patient cohort, the estimated net aqueductal CSF volumetric flow rate (independent of direction) was median 898ml/24h (ranges 69ml/24h to 12.9l/24h). One of the two individuals who had a very high estimated net aqueductal CSF volumetric flow rate, 8.7l/24h retrograde, later needed a permanent CSF shunt. The magnitude and direction of net aqueductal CSF flow vary extensively in patients with intracranial aneurysms. Following SAH, PC-MRI may offer the possibility to perform individualized assessments of the CSF circulation.

Cerebrospinal fluid flowmetry using phase-contrast MRI technique and its clinical applications

Background and aim and aim Cine phase-contrast (PC) MRI is a useful noninvasive imaging technique in evaluating the dynamics of cerebrospinal fluid (CSF) in the evaluation, follow-up, surgical decision, and postoperative survey of certain disease processes, such as normal pressure hydrocephalus, aqueduct stenosis (AS), postendoscopic third ventriculostomy, and arachnoid cysts cases. The aim of this study was to determine the value of cardiac-gated cine-PC-MRI in characterizing CSF flow in patients with CSF flow disorders. Patients and methods The study included 30 patients with 10 persons as the control group and 20 patients who were suspected to have CSF flow abnormalities. Two imaging techniques were applied: the axial plane for flow quantification and the sagittal plane for a qualitative assessment. Results Among the 30 patients, quantitative analysis revealed the mean value to be 22 μl as the average aqueductal stroke volume in the control group. In the normal pressure hydrocephalus group, systolic velocities as well as stroke volume values were higher than those of the controls. In the AS group, lack of significant aqueductal CSF flow was noticeable. Both peak systolic and diastolic velocities were found to be statistically significantly lower in patients with AS than in the control group. In arachnoid cyst cases, CSF flow study with cine PC-MRI enables visualization of flow communication between cysts and neighboring CSF compartments. Two cases were assigned as communicating cysts and four cases were noncommunicating. Conclusion Assessment of CSF flow indicates the potentials of using PC-MRI adjunct to routine MR for the clinical study of CSF-related diseases.

The Predictor Role of the Aqueduct Cerebrospinal Fluid Flow on Endoscopic Third Ventriculostomy: Explication on Assumption Physical Model.

To evaluate the cerebrospinal fluid (CSF) flow dynamics in the aqueductus sylvii of patients with obstructive hydrocephalus who underwent endoscopic third ventriculostomy (ETV) and to predict ventriculostomy patency via aqueduct flow measurements. Twenty-four patients with obstructive hydrocephalus caused by primary aqueduct stenosis who underwent ETV were included in the study. All the patients underwent conventional and cine magnetic resonance imaging before and after treatment. The flow of CSF in the aqueduct of Sylvius and prepontine cistern was assessed, and the diameter of the third ventricle was also measured. Increase in the aqueduct flow velocity after a successful ETV was supported by the assumption physical model that highlights a possible mechanism that explains the clinical findings. The flow pattern and velocity in the prepontine cistern and aqueduct were normal in 17 out of 24 patients who responded to ETV clinically. However, seven patients who did not respond to ETV had an abnormal flow pattern in both the prepontine cistern and aqueduct. The flow pattern in the aqueduct was normalised and velocity was increased compared with those of preoperative values after a successful ETV. The flow of CSF in the prepontine cistern is routinely used for ventriculostomy patency assessment. In addition, aqueduct measurements may be useful in predicting ventriculostomy patency. The physical model provides valuable insights on a possible mechanism that affected the experimental data.

Investigation of cerebrospinal fluid flow in the cerebral aqueduct using high-resolution phase contrast measurements at 7T MRI.

Background The cerebral aqueduct is a central conduit for cerebrospinal fluid (CSF), and non-invasive quantification of CSF flow in the aqueduct may be an important tool for diagnosis and follow-up of treatment. Magnetic resonance (MR) methods at clinical field strengths are limited by low spatial resolution. Purpose To investigate the feasibility of high-resolution through-plane MR flow measurements (2D-PC) in the cerebral aqueduct at high field strength (7T). Material and Methods 2D-PC measurements in the aqueduct were performed in nine healthy individuals at 7T. Measurement accuracy was determined using a phantom. Aqueduct area, mean velocity, maximum velocity, minimum velocity, net flow, and mean flow were determined using in-plane resolutions 0.8 × 0.8, 0.5 × 0.5, 0.3 × 0.3, and 0.2 × 0.2 mm2. Feasibility criteria were defined based on scan time and spatial and temporal resolution. Results Phantom validation of 2D-PC MR showed good accuracy. Invivo, stroke volume was -8.2 ± 4.4, -4.7 ± 2.8, -6.0 ± 3.8, and -3.7 ± 2.1 µL for 0.8 × 0.8, 0.5 × 0.5, 0.3 × 0.3, and 0.2 × 0.2 mm2, respectively. The scan with 0.3 × 0.3 mm2 resolution fulfilled the feasibility criteria for a wide range of heart rates and aqueduct diameters. Conclusion 7T MR enables non-invasive quantification of CSF flow and velocity in the cerebral aqueduct with high spatial resolution.

Radiofrequency saturation induced bias in aqueductal cerebrospinal fluid flow quantification obtained using two-dimensional cine phase contrast magnetic resonance imaging.

To explore the extent of bias in cerebrospinal fluid flow estimates due to radiofrequency saturation, and its possible impact on the use of two-dimensional cine phase contrast magnetic resonance imaging in the diagnosis and characterization of normal pressure hydrocephalus in patients. Theoretical signal equations were generated to describe saturation dependence on velocity. An experimental set of phase contrast magnetic resonance imaging scans with two different flip angles was used to show bias in flow estimates in a flow phantom, and in six different healthy volunteers. The cerebral aqueduct was targeted as the flow region of interest. Data from a constant flow phantom showed a spatial distribution of voxels with significant bias in flow at the periphery of the flow region. The velocity difference (bias) maps of the cerebral aqueduct correlated with the spatial velocity gradients around peak systole and peak diastole, and high correlation with temporal velocity gradients during transition between systole and diastole. The aqueductal stroke volume for θ = 30° were found to be significantly higher than for θ = 10° using a Wilcoxon signed rank test. This work shows the extent of bias in cerebrospinal fluid flow quantification due to radiofrequency saturation effects. This clinical relevance of this error was presented with respect to shunt responsiveness among normal pressure hydrocephalus patients. Magn Reson Med 79:2067-2076, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Quantitative Evaluation of Normal Aqueductal Cerebrospinal Fluid Flow Using Phase-Contrast Cine MRI According to Age and Sex.

The aim of this study was cerebrospinal fluid (CSF) flow quantification in the cerebral aqueduct using phase-contrast cine magnetic resonance ımaging (PCC-MRI) according to both sexes and three different age groups to obtain normative data. Seventy two volunteers with no cerebral pathology were included in this study. Subjects were divided into three age groups: 20-34 years, 35-49 years, and 50-65 years including equal gender groups. CSF flow's quantitatively evaluation was performed with images that were obtained by 1.5 T Magnetic Resonance (MR) unit from cerebral aqueduct level on the semi-axial plan. Between groups, peak velocity (cmsec-1 ), average velocity (cm/s), forward volume (mL), reverse volume (mL), net forward volume (mL), and average flow over range (ml/min) values of current flowing through aqueduct and average aqueductal areas were compared. There were no statistically significant differences in CSF flow parameters among different age groups and between sexes (P > 0.05). There was a statistically significant difference in average cerebral aqueduct area between the age group of 50-65 years and the other age groups (P = 0.002). The average aqueductal area was higher in the age group of 50-65 years. Normal aqueductal CSF flow parameters evaluated with PCC-MRI don't show a significant difference by age and sex. We have achieved the lower and upper values of these parameters would be useful in future clinical studies. The size of aqueductal area may also be explained by atrophy-dependent ventricular system dilatation in the elderly. Anat Rec, 300:549-555, 2017. © 2016 Wiley Periodicals, Inc.

Evaluation of aqueductal cerebrospinal fluid flow dynamics with phase-contrast cine magnetic resonance imaging in normal pediatric cases

PurposeThis study aimed to determine differences according to age groups and gender in the parameters of aqueductal cerebrospinal fluid (CSF) flow in childhood using phase-contrast cine magnetic resonance imaging (MRI) method. Materials and methodsThis prospective study included 47 boys and 36 girls for a total of 83 healthy children. The cases were divided into three groups depending on age as infants (1–12 months), children (12–120 months), and adolescents (120–204 months). To quantitatively evaluate CSF flow, images in the transverse plane were taken at the cerebral aqueduct level using the phase-contrast MR angiography technique in a 1.5-T MR unit. Peak and average velocity (cm/s), cranial direction, caudal direction and net volume (ml), and aqueduct area (mm2) were calculated. To assess differences between the groups, a one-way analysis of variance and least significant difference tests were used. ResultsA statistically significant difference was determined between children and adolescents in peak velocity and caudal direction volume (P=.012 and P=.039, respectively) and between infants and children in cranial direction volume (P=.036). Peak velocity, cranial direction, and net volume were higher in boys (P=.050, P=.016, and P=.029, respectively). There were no differences by age and gender in the aqueduct area. ConclusionIn conclusion, this study determined the normal values for the CSF flow parameters of velocity, volume, and aqueduct area using phase-contrast MRI in healthy children. Velocity and volume parameters varied according to age and sex and were not affected in the aqueductal area.

Cerebrospinal fluid and blood flow patterns in idiopathic normal pressure hydrocephalus.

Increased aqueduct cerebrospinal fluid (CSF) flow pulsatility and, recently, a reversed CSF flow in the aqueduct have been suggested as hallmarks of idiopathic normal pressure hydrocephalus (INPH). However, these findings have not been adequately confirmed. Our objective was to investigate the flow of blood and CSF in INPH, as compared to healthy elderly, in order to clarify which flow parameters are related to the INPH pathophysiology. Sixteen INPH patients (73years) and 35 healthy subjects (72years) underwent phase-contrast magnetic resonance imaging (MRI). Measurements included aqueduct and cervical CSF flow, total arterial inflow (tCBF; i.e. carotid + vertebral arteries), and internal jugular vein flow. Flow pulsatility, net flow, and flow delays were compared (multiple linear regression, correcting for sex and age). Aqueduct stroke volume was higher in INPH than healthy (148±95 vs 90±50mL, P<.05). Net aqueduct CSF flow was similar in magnitude and direction. The cervical CSF stroke volume was lower (P<.05). The internal carotid artery net flow was lower in INPH (P<.05), although tCBF was not. No differences were found in internal jugular vein flow or flow delays. The typical flow of blood and CSF in INPH was mainly characterized by increased CSF pulsatility in the aqueduct and reduced cervical CSF pulsatility. The direction of mean net aqueduct CSF flow was from the third to the fourth ventricle. Our findings may reflect the altered distribution of intracranial CSF volume in INPH, although the causality of these relationships is unclear.

Chapter 28 - Cerebrospinal fluid flow in adults

This chapter uses magnetic resonance imaging phase-contrast cerebrospinal fluid (CSF) flow measurements to predict which clinical normal-pressure hydrocephalus (NPH) patients will respond to shunting as well as which patients with Chiari I are likely to develop symptoms of syringomyelia. Symptomatic NPH patients with CSF flow (measured as the aqueductal CSF stroke volume) which is shown to be hyperdynamic (defined as twice normal) are quite likely to respond to ventriculoperitoneal shunting. The hyperdynamic CSF flow results from normal systolic brain expansion compressing the enlarged ventricles. When atrophy occurs, there is less brain expansion, decreased aqueductal CSF flow, and less likelihood of responding to shunting. It appears that NPH is a "two-hit" disease, starting as benign external hydrocephalus in infancy, followed by deep white-matter ischemia in late adulthood, which causes increased resistance to CSF outflow through the extracellular space of the brain. Using computational flow dynamics (CFD), CSF flow can be modeled at the foramen magnum and in the upper cervical spine. As in the case of NPH, hyperdynamic CSF flow appears to cause the signs and symptoms in Chiari I and can provide an additional indication for surgical decompression. CFD can also predict CSF pressures over the cardiac cycle. It has been hypothesized that elevated pressure pulses may be a significant etiologic factor in some cases of syringomyelia.

Analysis of cerebrospinal fluid flow dynamics and morphology in Chiari I malformation with cine phase-contrast magnetic resonance imaging

To determine cerebrospinal fluid (CSF) dynamics and morphology in Chiari I malformation (CMI) and assess the response to surgery of the posterior cranial fossa, we examined midsagittal imaging along with anterior cervical 2-3 (AC2-3), posterior cervical 2-3 (PC2-3), and aqueduct CSF flow hydrodynamics in axial imaging by using cine phase-contrast magnetic resonance imaging (PCMR). We examined 52 patients with CMI, both with and without syringomyelia (SM), pre-/post-surgery, and compared them to 17 healthy volunteers. Statistical analyses included paired t-tests, independent-samples t-tests, binary logistic regression, and crosstab with MedCalc software. Patients with CMI had significantly shorter clivus length and larger tentorial angle than the healthy controls (P = 0.004, P = 0.019, respectively). The AC2-3 cranial/caudal peak velocity (PV), PC2-3 cranial/caudal PV and aqueduct cranial peak PV of patients with CMI were significantly lower than healthy volunteers pre-surgery (P = 0.034 AC2-3 cranial PV, P = 0.000002 AC2-3 caudal PV; P = 0.046 PC2-3 cranial PV, P = 0.015 PC2-3 caudal PV; P = 0.022 aqueduct cranial PV) and increased after surgery (P = 0.024 AC2-3 cranial PV, P = 0.002 AC2-3 caudal PV; P = 0.001 PC2-3 cranial PV, P = 0.032 PC2-3 caudal PV; P = 0.003 aqueduct cranial PV). The aqueduct caudal PV of patients with CMI was higher than that of healthy controls (P = 0.004) and decreased post-surgery (P = 0.012). Patients with pre-surgery PC2-3 cranial PV >2.63 cm/s and aqueduct cranial PV >2.13 cm/s, respectively, experienced primary symptom improvement after surgery. The innate bony dysontogenesis in patients with CMI contributes to tonsilar ectopia and exacerbates CSF flow obstruction. A pressure gradient that existed between SM and SAS supports the perivascular space theory that is used to explain SM formation. Our findings demonstrate that PCMR maybe a useful tool for predicting patient prognosis.