Magnetic Resonance Velocity Mapping Research Articles

Abstract 3021: An Examination Of Emerging Techniques Forquantification Of Systemic-to-pulmonary Collateral Vessel Burden Using Imaging Modalities

Introduction: The quantification of systemic-to-pulmonary collateral vessels (SPCs) and their effects on hemodynamics is a subjective standard that has been intriguing for physicians due to the implications they could have; in cases where there is significant collateral burden, occlusion of these SPCs may be desirable, though this can present with a risk of stroke due to errant embolization particles. No benchmark method of SPC flow assessment has been established. Quantitative analysis of systemic and pulmonary flow values is possible through the use of computational fluid dynamics (CFD). CFD models can provide advanced and accurate analysis of cardiovascular hemodynamics providing more information beyond routine imaging. Hypothesis: Current methods for quantifying SPC burden are inadequate and could be improved through the use of additional CFD analysis. Methods: A PubMed and Science Direct search was performed. Select inclusion and exclusion criteria were applied to search results. Results: The search resulted in a total of 155 unique articles. Of these, 94 articles were found to meet inclusion criteria, and 54 articles were settled on after reviewing articles for further exclusion criteria. Seven articles discussed the use of CT and catheterization for quantifying collateral burden while 43 described using MRI to provide flow values. Eight articles mentioned the use of CFD to quantify hemodynamics in patients with SPCs, and 25 articles provided specific formulas for collateral flow. Conclusions: Using cardiac magnetic resonance velocity mapping is currently regarded as the best method for quantifying SPC burden. The incorporation of CFD analysis with flow data acquired with CMR may be useful in simulating the effects of SPC burden prior to any intervention as well as in predicting the effects of SPC occlusion on patient hemodynamics.

Ex Vivo Pilot Study of Cardiac Magnetic Resonance Velocity Mapping for Quantification of Aortic Regurgitation in a Porcine Model in the Presence of a Transcatheter Heart Valve.

Accuracy of aortic regurgitation (AR) quantification by magnetic resonance (MR) imaging in the presence of a transcatheter heart valve (THV) remains to be established. We evaluated the accuracy of cardiac MR velocity mapping for quantification of antegrade flow (AF) and retrograde flow (RF) across a THV and the optimal slice position to use in cardiac MR imaging. In a systematic and fully controlled laboratory ex vivo setting, two THVs (Edwards SAPIEN XT, Medtronic CoreValve) were tested in a porcine model (n = 1) under steady flow conditions. Results showed a high level of accuracy and precision. For both THVs, AF was best measured at left ventricular outflow tract level, and RF at ascending aorta level. At these levels, MR had an excellent repeatability (ICC > 0.99), with a tendency to overestimate (4.6 ± 2.4% to 9.4 ± 7.0%). Quantification of AR by MR velocity mapping in the presence of a THV was accurate, precise, and repeatable in this pilot study, when corrected for the systematic error and when the best MR slice position was used. Confirmation of these results in future clinical studies would be a step forward in increasing the accuracy of the assessment of paravalvular AR severity.

Magnetic Resonance Imaging and Velocity Mapping in Chemical Engineering Applications.

This review aims to illustrate the diversity of measurements that can be made using magnetic resonance techniques, which have the potential to provide insights into chemical engineering systems that cannot readily be achieved using any other method. Perhaps the most notable advantage in using magnetic resonance methods is that both chemistry and transport can be followed in three dimensions, in optically opaque systems, and without the need for tracers to be introduced into the system. Here we focus on hydrodynamics and, in particular, applications to rheology, pipe flow, and fixed-bed and gas-solid fluidized bed reactors. With increasing development of industrially relevant sample environments and undersampling data acquisition strategies that can reduce acquisition times to <1 s, magnetic resonance is finding increasing application in chemical engineering research.

Visualization of CSF Flow with Time-resolved 3D MR Velocity Mapping in Aqueductal Stenosis Before and After Endoscopic Third Ventriculostomy : AFeasibility Study.

The aim of this study was to evaluate timed-resolved three-dimensional (3D) magnetic resonance (MR) velocity mapping as amethod for investigation of cerebrospinal fluid (CSF) flow changes in patients with aqueductal stenosis (AS) treated by endoscopic third ventriculostomy (ETV). The MR velocity mapping was performed in 12AS patients before and after ETV and in 10 healthy volunteers by using a3-Tesla MR system. Time-resolved 3D MR velocity mapping data were acquired with astandard 3D phase contrast (PC) sequence with cardiac triggering. Values of mean (vmean) and maximum (vpeak) velocity were measured at several ventricular structures using dedicated software. Of the patients 11 showed asatisfactory clinical improvement after ETV, whereas one patient needed subsequent shunt implantation. All AS patients showed significant hypomotile CSF flow dynamics in the third ventricle when compared to healthy subjects before surgery (p< 0.05). In contrast, CSF flow velocity was increased within the Foramen of Monro in AS patients. After ETV, all AS patients showed adecrease of CSF flow dynamics within the third ventricle. Mean and peak CSF flow velocities through the ventriculostomy were 1.72± 0.59cm/s (vmean) and 3.53± 0.79cm/s (vpeak), respectively after ETV. The patient who needed shunt implantation after ETV had the lowest flow velocities through the ventriculostomy. This study demonstrates that timed-resolved 3D MR velocity mapping is auseful imaging investigation for diagnostics and follow-up in patients with AS. This new technique provides an insight into the physiological CSF flow changes related with AS and its treatment.

Magnetic resonance measurement of fluid dynamics and transport in tube flow of a near-critical fluid

An ability to predict fluid dynamics and transport in supercritical fluids is essential for optimization of applications such as carbon sequestration, enhanced oil recovery, “green” solvents, and supercritical coolant systems. While much has been done to model supercritical velocity distributions, experimental characterization is sparse, owing in part to a high sensitivity to perturbation by measurement probes. Magnetic resonance (MR) techniques, however, detect signal noninvasively from the fluid molecules and thereby overcome this obstacle to measurement. MR velocity maps and propagators (i.e., probability density functions of displacement) were acquired of a flowing fluid in several regimes about the critical point, providing quantitative data on the transport and fluid dynamics in the system. Hexafluoroethane (C2F6) was pumped at 0.5 ml/min in a cylindrical tube through an MR system, and propagators as well as velocity maps were measured at temperatures and pressures below, near, and above the critical values. It was observed that flow of C2F6 with thermodynamic properties far above or below the critical point had the Poiseuille flow distribution of an incompressible Newtonian fluid. Flows with thermodynamic properties near the critical point exhibit complex flow distributions impacted by buoyancy and viscous forces. The approach to steady state was also observed and found to take the longest near the critical point, but once it was reached, the dynamics were stable and reproducible. These data provide insight into the interplay between the critical phase transition thermodynamics and the fluid dynamics, which control transport processes.

Accuracy of four-dimensional phase-contrast velocity mapping for blood flow visualizations: a phantom study

Time-resolved three-dimensional, three-directional phase-contrast magnetic resonance velocity mapping (4D PC-MRI) is a powerful technique to depict dynamic blood flow patterns in the human body. However, the impact of phase background effects on flow visualizations has not been thoroughly studied previously, and it has not yet been experimentally demonstrated to what degree phase offsets affect flow visualizations and create errors such as inaccurate particle traces. To quantify background phase offsets and their subsequent impact on particle trace visualizations in a 4D PC-MRI sequence. Additionally, we sought to investigate to what degree visualization errors are reduced by background phase correction. A rotating phantom with a known velocity field was used to quantify background phase of 4D PC-MRI sequences accelerated with SENSE as well as different k-t BLAST speed-up factors. The deviation in end positions between particle traces in the measured velocity fields were compared before and after the application of two different phase correction methods. Phantom measurements revealed background velocity offsets up to 7 cm/s (7% of velocity encoding sensitivity) in the central slice, increasing with distance from the center. Background offsets remained constant with increasing k-t BLAST speed-up factors. End deviations of up to 5.3 mm (1.8 voxels) in the direction perpendicular to the rotating disc were found between particle traces and the seeding plane of the traces. Phase correction by subtraction of the data from the stationary phantom reduced the average deviation by up to 56%, while correcting the data-set with a first-order polynomial fit to stationary regions decreased average deviation up to 78%. Pathline visualizations can be significantly affected by background phase errors, highlighting the importance of dedicated and robust phase correction methods. Our results show that pathline deviation can be substantial if adequate phase background errors are not minimized.

Editorial Comment: Correlate blood pressure, not blood flow, with atherosclerosis

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Assessment of normal flow patterns in the pulmonary circulation by using 4D magnetic resonance velocity mapping

ObjectiveThe purpose of this study was to analyze flow patterns in the pulmonary circulation of healthy volunteers by using 4D flow magnetic resonance imaging. Materials and MethodsThe study was approved by the local ethics committee and all subjects gave written informed consent. Eighteen volunteers underwent a 4D flow scan of the whole-heart. Two patients with congenital heart disease were also included to detect possible patterns of flow abnormalities (Patient 1: corrected transposition of great arteries (TGA); Patient 2: partial anomalous pulmonary venous return and atrial septal defect). To analyze flow patterns, 2D planes were placed on the main pulmonary artery (PA), left and right PA. Flow patterns were assessed manually by two independent viewers using vector fields, streamlines and particle traces, and semi-automatically by vorticity quantification. ResultsTwo counter-rotating helices were found in the main PA of volunteers. Right-handed helical flow was detected in the right PA of 15 volunteers. Analysis of the helical flow by particles traces revealed that both helices contributed mainly to the flow in the right PA. In the patient with corrected TGA helical flow was not detected. Abnormal vortical flow was visualized in the main PA of patient 2, suggesting elevated mean PA pressure. ConclusionsHelical flow is normally present in the main PA and right PA. 4D flow is an excellent tool to evaluate noninvasively complex blood flow patterns in the pulmonary circulation. Knowledge of normal and abnormal flow patterns might help to evaluate patients with congenital heart disease adding functional information undetectable with other imaging modalities.

Vortex Ring Formation in the Left Ventricle of the Heart: Analysis by 4D Flow MRI and Lagrangian Coherent Structures

Recent studies suggest that vortex ring formation during left ventricular (LV) rapid filling is an optimized mechanism for blood transport, and that the volume of the vortex ring is an important measure. However, due to lack of quantitative methods, the volume of the vortex ring has not previously been studied. Lagrangian Coherent Structures (LCS) is a new flow analysis method, which enables in vivo quantification of vortex ring volume. Therefore, we aimed to investigate if vortex ring volume in the human LV can be reliably quantified using LCS and magnetic resonance velocity mapping (4D PC-MR). Flow velocities were measured using 4D PC-MR in 9 healthy volunteers and 4 patients with dilated ischemic cardiomyopathy. LV LCS were computed from flow velocities and manually delineated in all subjects. Vortex volume in the healthy volunteers was 51±6% of the LV volume, and 21±5% in the patients. Interobserver variability was -1±13% and interstudy variability was -2±12%. Compared to idealized flow experiments, the vortex rings showed additional complexity and asymmetry, related to endocardial trabeculation and papillary muscles. In conclusion, LCS and 4D PC-MR enables measurement of vortex ring volume during rapid filling of the LV.

Three-Dimensional Blood Flow Alterations After Transcatheter Aortic Valve Implantation

We present findings in a 79-year-old man after transcatheter aortic valve implantation (TAVI) for severe symptomatic aortic stenosis using a 26-mm Edwards Lifesciences Sapien 9000TFX valve.1 His predicted risk of operative mortality (Society of Thoracic Surgery score) was 12% on the basis of the following comorbidities: 2 previous coronary artery bypass operations, New York Heart Association functional class IV, hypertension, mild lung disease, ejection fraction of 25%, creatinine of 1.2 mg/dL, atrial fibrillation, and peripheral vascular disease. He underwent transapical delivery of the valve on January 5, 2011, without complication. His initial postoperative echocardiogram showed moderate aortic regurgitation (AR), mean gradient of 49mm Hg, and ejection fraction of 25%. After discharge, the patient was reevaluated for recurrent dyspnea. To gain further insight into the systemic implications of AR on hemodynamics of the left ventricular outflow tract in relation to potential congestive heart failure after TAVI, we performed time-resolved 3-dimensional (3D) magnetic resonance velocity mapping (4-dimensional [4D] flow magnetic resonance imaging [MRI])2 6 months postoperatively. The study was approved by the institutional review board, and informed consent was obtained from the patient. Magnetic resonance imaging examination (1.5T Espree, Siemens, Germany) included 4D flow (velocity sensitivity=150 cm/s, spatial/temporal resolution=2.5×2.1×3.2 mm3/42 ms) and dynamic 2D cine imaging of the heart (steady-state free precession, spatial/temporal resolution=1.4×1.6×8 mm3/49 ms). Echocardiographic assessment of aortic insufficiency was performed using standard parasternal and apical views with …

Integrated morphologic and functional assessment of the aortic root after different tissue valve root replacement procedures

This study was undertaken to explore aspects of the hemodynamic function of different biologic tissue aortic valve root replacements. We set out to image and display the spatiotemporal distributions of axially directed blood velocity through the aortic root. The flow velocities through a plane transecting the aortic root were measured by 2-dimensional cine phase-contrast magnetic resonance velocity mapping in 44 subjects: 29 patients who had undergone aortic root replacement approximately 10 years previously (13 autografts, 10 stentless xenografts, and 6 homografts) and 15 healthy control subjects. With cine as well as velocity images, aortic sinus dimensions, effective orifice area, and several velocity parameters were measured. Color-coded plots of velocity relative to the sinus cross sections and velocity-time plots were used to compare spatiotemporal distributions of velocity. Peak flow velocity was similar between the autografts (102 ± 28.0 cm/s) and control valves (119 ± 20.0 cm/s) but was higher in xenografts (167 ± 36.0 cm/s) and homografts (206 ± 91.0 cm/s). These measurements showed an inverse relationship with the effective orifice area (7.27 ± 0.20, 4.24 ± 0.81, 3.37 ± 0.32, and 3.28 ± 0.87 cm(2), respectively). Autograft peak flow velocity showed no significant difference from control valve peak flow velocity, despite larger root dimensions (P < .001). The graphic displays provided further spatiotemporal information. Peak velocities and spatiotemporal flow patterns depend on the type of valve substitute. In the parameters measured, autograft replacements differed least from normal aortic valves.

Diastolic vortex ring formation in the human left ventricle: quantitative analysis using Lagrangian coherent structures and 4D cardiovascular magnetic resonance velocity mapping

Summary We show that 4D magnetic resonance velocity mapping and Lagrangian Coherent Structures can be used to quantify vortex ring volume in the human left ventricle. Background The vortex ring formed in the left ventricle (LV) of the human heart during early diastolic inflow (corresponding to the Doppler E-wave) contains information about the normal and pathophysiologic aspects of diastole. Previous studies suggest that the volume of the vortex ring is an important characteristic of vortex ring formation. However, due to lack of quantitative methods, vortex ring volume has not previously been studied in the human left ventricle. The study of Lagrangian Coherent Structures (LCS) is a new flow analysis method, which for the first time enables a description of vortex ring shape and the quantification of vortex ring volume. LCS have not previously been used to quantify diastolic vortex volume in humans. Therefore, the purpose of this study was to investigate if LCS and three-dimensional, time-resolved, three-directional phase contrast magnetic resonance velocity mapping (4D PC-MR) can be used to describe vortex ring shape and quantify vortex ring volume in the human LV. Methods

FourFlow - open source code software for quantification and visualization of time-resolved three-directional phase contrast magnetic resonance velocity mapping

Summary We have developed an open source software for quantification and visualization of 4D PC-MR data that enables development of new quantitative analysis tools. Background Time-resolved three-directional phase contrast magnetic resonance velocity mapping (4D PC-MR) has the potential to be a powerful modality for studying normal physiology and pathophysiology. However, a wider application of 4D PC-MR is hampered by a lack of methods for quantitative analysis. Currently available software packages for visualization of 4D PC-MR do not allow for modifications or additions by users. This limits innovation of new quantification tools, and limits the possibilities to answer specific clinical and physiological questions. Therefore, the aim of this study was to develop ac omprehensive open source software for quantification and analysis of 4D PC-MR data that includes the possibility to develop and add new quantitative analysis methods. Methods

4D cardiovascular magnetic resonance velocity mapping of alterations of right heart flow patterns and main pulmonary artery hemodynamics in tetralogy of Fallot.

BackgroundTo assess changes in right heart flow and pulmonary artery hemodynamics in patients with repaired Tetralogy of Fallot (rTOF) we used whole heart, four dimensional (4D) velocity mapping (VM) cardiovascular magnetic resonance (CMR).MethodsCMR studies were performed in 11 subjects with rTOF (5M/6F; 20.1 ± 12.4 years) and 10 normal volunteers (6M/4F; 34.2 ± 13.4 years) on clinical 1.5T and 3.0T MR scanners. 4D VM-CMR was performed using PC VIPR (Phase Contrast Vastly undersampled Isotropic Projection Reconstruction). Interactive streamline and particle trace visualizations of the superior and inferior vena cava (IVC and SVC, respectively), right atrium (RA), right ventricle (RV), and pulmonary artery (PA) were generated and reviewed by three experienced readers. Main PA net flow, retrograde flow, peak flow, time-to-peak flow, peak acceleration, resistance index and mean wall shear stress were quantified. Differences in flow patterns between the two groups were tested using Fisher's exact test. Differences in quantitative parameters were analyzed with the Kruskal-Wallis rank sum test.Results4D VM-CMR was successfully performed in all volunteers and subjects with TOF. Right heart flow patterns in rTOF subjects were characterized by (a) greater SVC/IVC flow during diastole than systole, (b) increased vortical flow patterns in the RA and in the RV during diastole, and (c) increased helical or vortical flow features in the PA's. Differences in main PA retrograde flow, resistance index, peak flow, time-to-peak flow, peak acceleration and mean wall shear stress were statistically significant.ConclusionsWhole heart 4D VM-CMR with PC VIPR enables detection of both normal and abnormal right heart flow patterns, which may allow for comprehensive studies to evaluate interdependencies of post-surgically altered geometries and hemodynamics.

Magnetic resonance velocity mapping of 3D cerebrospinal fluid flow dynamics in hydrocephalus: preliminary results

To investigate the detectability of CSF flow alterations in the ventricular system of patients with hydrocephalus using time-resolved 3D MR velocity mapping. MR velocity mapping was performed in 21 consecutive hydrocephalus patients and 21 age-matched volunteers using a 3D phase-contrast (PC) sequence. Velocity vectors and particle path lines were calculated for visualisation of flow dynamics. CSF flow was classified as "hypomotile flow" if it showed attenuated dynamics and as "hypermotile flow" if it showed increased dynamics compared with volunteers. Diagnostic efficacy was compared with routine 2D cine PC-MRI. Seven patients showed hypomotile CSF flow: six had non-communicating hydrocephalus due to aqueductal stenosis. One showed oscillating flow between the lateral ventricles after craniotomy for intracranial haemorrhage. Seven patients showed normal flow: six had hydrocephalus ex vacuo due to brain atrophy. One patient who underwent ventriculostomy 10 years ago showed a flow path through the opening. Seven patients showed hypermotile flow: three had normal pressure hydrocephalus, three had dementia, and in one the diagnosis remained unclear. The diagnostic efficacy of velocity mapping was significantly higher except for that of aqueductal stenosis. Our approach may be useful for diagnosis, therapy planning, and follow-up of different kinds of hydrocephalus.

Tridirectional phase-contrast magnetic resonance velocity mapping depicts severe hemodynamic alterations in a patient with aortic dissection type Stanford B

This report describes flow patterns derived by three-dimensional (3D) three-directional velocity-encoded cine (VEC) magnetic resonance imaging (MRI), in a patient with chronic Stanford type B aortic dissection. Acquired 3D VEC MRI data illustrated an acceleration of blood flow through the primary entry toward the vessel wall of the false lumen, leading to disturbed intraluminal flow. Furthermore, accelerated blood flow was observed in the partially compressed true lumen. 3D VEC MRI data may be helpful to guide physicians for a more comprehensive preoperative and postoperative assessment of complex aortic pathologies.

Volume Tracking: A new method for quantitative assessment and visualization of intracardiac blood flow from three-dimensional, time-resolved, three-component magnetic resonance velocity mapping

BackgroundFunctional and morphological changes of the heart influence blood flow patterns. Therefore, flow patterns may carry diagnostic and prognostic information. Three-dimensional, time-resolved, three-directional phase contrast cardiovascular magnetic resonance (4D PC-CMR) can image flow patterns with unique detail, and using new flow visualization methods may lead to new insights. The aim of this study is to present and validate a novel visualization method with a quantitative potential for blood flow from 4D PC-CMR, called Volume Tracking, and investigate if Volume Tracking complements particle tracing, the most common visualization method used today.MethodsEight healthy volunteers and one patient with a large apical left ventricular aneurysm underwent 4D PC-CMR flow imaging of the whole heart. Volume Tracking and particle tracing visualizations were compared visually side-by-side in a visualization software package. To validate Volume Tracking, the number of particle traces that agreed with the Volume Tracking visualizations was counted and expressed as a percentage of total released particles in mid-diastole and end-diastole respectively. Two independent observers described blood flow patterns in the left ventricle using Volume Tracking visualizations.ResultsVolume Tracking was feasible in all eight healthy volunteers and in the patient. Visually, Volume Tracking and particle tracing are complementary methods, showing different aspects of the flow. When validated against particle tracing, on average 90.5% and 87.8% of the particles agreed with the Volume Tracking surface in mid-diastole and end-diastole respectively. Inflow patterns in the left ventricle varied between the subjects, with excellent agreement between observers. The left ventricular inflow pattern in the patient differed from the healthy subjects.ConclusionVolume Tracking is a new visualization method for blood flow measured by 4D PC-CMR. Volume Tracking complements and provides incremental information compared to particle tracing that may lead to a better understanding of blood flow and may improve diagnosis and prognosis of cardiovascular diseases.

Time-resolved Three-dimensional Magnetic Resonance Velocity Mapping of Chronic Thoracic Aortic Dissection: A Preliminary Investigation

The blood flow patterns of chronic thoracic aortic dissection are complicated, and their clinical significance remains unknown. We evaluated the technical and clinical potentials of time-resolved 3-dimensional (3D) magnetic resonance (MR) velocity mapping for assessing these patterns. We used data collected from time-resolved 3D phase-contrast MR imaging of 16 patients with chronic thoracic aortic dissection to generate time-resolved 3D MR velocity mapping that included 3D streamline and path line. We investigated blood flow patterns of this disease in the mapping and compared them with the morphological changes of the patent false lumen. Time-resolved 3D MR velocity mapping visualized rapid flow at the entry and in the true lumen immediately distal to the entry. We observed slower helical or laminar flow in the patent false lumen. In patients with disease progression, slower helical flow following rapid entry jet collided with the outer wall of the false lumen and was also observed in a growing ulcer-like projection. We showed the potential of time-resolved 3D MR velocity mapping for visualizing pathologic flow patterns related to chronic thoracic aortic dissection.

Time-resolved three-dimensional magnetic resonance velocity mapping of cardiovascular flow paths in volunteers and patients with Fontan circulation

To apply flow-sensitive magnetic resonance imaging for the evaluation of whole-heart flow characteristics in healthy volunteers and patients with Fontan circulation. Time-resolved three-dimensional magnetic resonance velocity mapping (spatial resolution = 2.5 × 2.8 × 2.8mm(3), temporal resolution = 38.4 ms) was acquired in normal controls and in four Fontan patients with extracardiac total cavopulmonary connection. Data analysis included flow connectivity mapping and flow quantification of arterial and venous blood flow. Haemodynamics in four patients with Fontan circulation were individually evaluated in the aorta, caval veins and left and right pulmonary arteries. In four controls, nine distinct flow features were consistently identified with good feature clarity (median = 2 in 80.6% of readings) and image quality (median = 2 in 75.0% of readings). In patients, a marked variability of flow from the caval veins towards the left and right pulmonary arteries (flow ratio = 1.7 ± 0.6, range 1.2-2.6 vs 1.1 ± 0.1 in controls) was found. Increased offset of the caval venous connection resulted in enhanced pulmonary flow asymmetry. Compared with controls, reduced pulsatility in pulmonary arteries (1.4 ± 0.6 vs 4.1 ± 0.6 in controls) and caval veins (1.2 ± 0.4 vs 2.8 ± 1.1 in controls) were observed. Peak flow was reduced in both superior (22 ± 14 mls(-1) vs 76 ± 7 mls(-1) in controls) and inferior vena cava (61 ± 28 mls(-1) vs 187 ± 42 mls(-1) in controls). This feasibility study demonstrated the potential of whole-heart three-dimensional magnetic resonance velocity mapping to reveal overt haemodynamic differences in surgically palliated congenital heart with similar extracardiac cavopulmonary connection geometry. Future studies are warranted to evaluate its diagnostic impact for improved evaluation of the pre- and postoperative status in the individual patient.

Insight into the patterns of cerebrospinal fluid flow in the human ventricular system using MR velocity mapping

The patterns of cerebrospinal fluid (CSF) flow within the human ventricular system are still not fully understood in all their complexity. Knowledge is based on either the interpretation of CSF flow curves or computational simulations. Both approaches only provide an incomplete insight into the spatial and temporal dynamics of CSF flow. Time-resolved three-dimensional magnetic resonance velocity mapping has previously been used to investigate normal and pathologic blood flow patterns in the human vascular system. Here we used this technique to study the spatial and temporal dynamics of CSF flow in the ventricular system of 40 normal volunteers. Classification of the patterns of CSF flow based on calculation of three-dimensional particle path lines over the cardiac cycle revealed one uniform flow pattern for the lateral ventricles, three categories for the third and two categories for the fourth ventricle. We found no significant aging effects on either the presence of a specific CSF flow pattern or on CSF flow velocities. Our results provide the first detailed demonstration of the patterns of CSF flow within the human ventricular system.