New Insights into MR Safety for Implantable Medical Devices.

Over the last two decades, the status of MR safety has dramatically changed. In particular, ever since the MR-conditional cardiac device was approved by the Food and Drug Administration (FDA) in 2008 and by the Pharmaceuticals and Medical Devices Agency (PMDA) in 2012, the safety of patients with an implantable medical device (IMD) has been one of the most important issues in terms of MR use. In conjunction with the regulatory approvals for various IMDs, standards, technical specifications, and guidelines have also been rapidly created and developed. Many invaluable papers investigating and reviewing the history and status of MR use in the presence of IMDs already exist. As such, this review paper seeks to bridge the gap between clinical practice and the information that is obtained by standard-based tests and provided by an IMD's package insert or instructions for use. Interpretation of the gradient of the magnetic flux density intensity of the static magnetic field with respect to the magnetic displacement force is discussed, along with the physical background of RF field. The relationship between specific absorption rate (SAR) and B1+RMS, and their effects on image quality are described. In addition, insofar as providing new directions for future research and practice, the feasibility of safety test methods for RF-induced heating of IMDs using MR thermometry, evaluation of tissue heat damage, and challenges in cardiac IMDs will be discussed.

Evaluation of Cardiac- and Respiratory-driven Cerebrospinal Fluid Motions by Applying the S-transform to Steady-state Free Precession Phase Contrast Imaging.

PURPOSE: To extract the status of hydrocephalus and other cerebrospinal fluid (CSF)-related diseases, a technique to characterize the cardiac- and respiratory-driven CSF motions separately under free breathing was developed. This technique is based on steady-state free precession phase contrast (SSFP-PC) imaging in combination with a Stockwell transform (S-transform). METHODS: 2D SSFP-PC at 3 T was applied to measure the CSF velocity in the caudal-cranial direction within a sagittal slice at the midline (N = 3) under 6-, 10-, and 16-s respiratory cycles and free breathing. The frequency-dependent window width of the S-transform was controlled by a particular scaling factor, which then converted the CSF velocity waveform into a spectrogram. Based on the frequency bands of the cardiac pulsation and respiration, as determined by the electrocardiogram (ECG) and respirator pressure sensors, Gaussian bandpass filters were applied to the CSF spectrogram to extract the time-domain cardiac- and respiratory-driven waveforms. RESULTS: The cardiac-driven CSF velocity component appeared in the spectrogram clearly under all respiratory conditions. The respiratory-driven velocity under the controlled respiratory cycles was observed as constant frequency signals, compared to a time-varying frequency signal under free breathing. When the widow width was optimized using the scale factor, the temporal change in the respiratory-driven CSF component was even more apparent under free breathing. CONCLUSION: Velocity amplitude variations and transient frequency changes of both cardiac- and respiratory-driven components were successfully characterized. These findings indicated that the proposed technique is useful for evaluating CSF motions driven by different cyclic forces.

Differentiation between ICA and ECA Feeder Distributions in Meningioma Using MR Perfusion Original Image.

OBJECTIVE: Preoperative information regarding tumor feeder distribution is important in meningioma surgery. We aimed to examine the relationship between the contrast-enhancement pattern in meningioma on magnetic resonance (MR) perfusion images and the feeder pattern. METHODS: The subjects were 21 patients diagnosed with meningioma who underwent MR perfusion imaging between 2017 and 2020. RESULTS: The distribution of feeders from the internal carotid artery (ICA) system or external carotid artery (ECA) system within the tumor based on angiograms was compared with that in areas of enhancement on original MR perfusion images in seven of 21 patients who underwent cerebral angiography. The aspect ratios of tumors, which was defined as the ratio of the area of contrast enhancement to the length of the enhanced area in contact with the tumor margin on the early-phase MR perfusion images, supplied by the ICA (pial feeder pattern) and ECA (dural feeder pattern) systems were 0.12 ± 0.11 and 7.21 ± 4.99 (mean ± standard deviation), respectively (p < 0.0001). MR perfusion imaging in all 21 patients revealed higher frequency of the pial feeder pattern in patients with peritumoral edema (p = 0.0009). CONCLUSION: The distribution of pial and dural feeders within a meningioma could be distinguished by the aspect ratio based on original MR perfusion images.

Respiratory-driven Cyclic Cerebrospinal Fluid Motion in the Intracranial Cavity on Magnetic Resonance Imaging: Insights into the Pathophysiology of Neurofluid Dysfunction.

Neurofluids, a recently developed term that refers to interstitial fluids in the parenchyma and cerebrospinal fluid (CSF) in the ventricle and subarachnoid space, play a role in draining waste products from the brain. Neurofluids have been implicated in pathological conditions such as Alzheimer's disease and normal pressure hydrocephalus. Given that CSF moves faster in the CSF cavity than in the brain parenchyma, CSF motion can be detected by magnetic resonance imaging. CSF motion is synchronized to the heartbeat and respiratory cycle, but respiratory cycle-induced CSF motion has yet to be investigated in detail. Therefore, we analyzed CSF motion using dynamic improved motion-sensitized driven-equilibrium steady-state free precession-based analysis. We analyzed CSF motion linked to the respiratory cycle in four women and six men volunteers aged 23 to 38 years. We identified differences between free respiration and tasked respiratory cycle-associated CSF motion in the ventricles and subarachnoid space. Our results indicate that semi-quantitative analysis can be performed using the cranial site at which CSF motion is most prominent as a standard. Our findings may serve as a reference for elucidating the pathophysiology of diseases caused by abnormalities in neurofluids.

Characterization of Cardiac- and Respiratory-driven Cerebrospinal Fluid Motions Using a Correlation Mapping Technique Based on Asynchronous Two-dimensional Phase Contrast MR Imaging.

PURPOSE: The cardiac- and respiratory-driven components of cerebrospinal fluid (CSF) motion characteristics and bulk flow are not yet completely understood. Therefore, the present study aimed to characterize cardiac- and respiratory-driven CSF motions in the intracranial space using delay time, CSF velocity waveform correlation, and displacement. METHODS: Asynchronous two-dimensional phase-contrast at 3T was applied to measure the CSF velocity in the inferior-superior direction in a sagittal slice at the midline (N = 12) and an axial slice at the foramen magnum (N = 8). Volunteers were instructed to engage in six-second respiratory cycles. The calculated delay time and correlation coefficients of the cardiac- and respiratory-driven velocity waveforms, separated in the frequency domain, were applied to evaluate the propagation of the CSF motion. The cardiac- and respiratory-driven components of the CSF displacement and motion volume were calculated during diastole and systole, and during inhalation and exhalation, respectively. The cardiac- and respiratory-driven components of the velocity, correlation, displacement, and motion volume were compared using an independent two-sample t-test. RESULTS: The ratio of the cardiac-driven CSF velocity to the sum of the cardiac- and respiratory-driven CSF velocities was higher than the equivalent respiratory-driven ratio for all cases (P < 0.01). Delay time and correlation maps demonstrated that the cardiac-driven CSF motion propagated more extensively than the respiratory-driven CSF motion. The correlation coefficient of the cardiac-driven motion was significantly higher in the prepontine (P < 0.01), the aqueduct, and the fourth ventricle (P < 0.05). The respiratory-driven displacement and motion volume were significantly greater than the cardiac-driven equivalents for all observations (P < 0.01). CONCLUSION: The correlation mapping technique characterized the cardiac- and respiratory-driven CSF velocities and their propagation properties in the intracranial space. Based on these findings, cardiac-driven CSF velocity is greater than respiratory-induced velocity, but the respiratory-driven velocity might displace farther.

Changing the Currently Held Concept of Cerebrospinal Fluid Dynamics Based on Shared Findings of Cerebrospinal Fluid Motion in the Cranial Cavity Using Various Types of Magnetic Resonance Imaging Techniques.

The "cerebrospinal fluid (CSF) circulation theory" of CSF flowing unidirectionally and circulating through the ventricles and subarachnoid space in a downward or upward fashion has been widely recognized. In this review, observations of CSF motion using different magnetic resonance imaging (MRI) techniques are described, findings that are shared among these techniques are extracted, and CSF motion, as we currently understand it based on the results from the quantitative analysis of CSF motion, is discussed, along with a discussion of slower water molecule motion in the perivascular, paravascular, and brain parenchyma. Today, a shared consensus regarding CSF motion is being formed, as follows: CSF motion is not a circulatory flow, but a combination of various directions of flow in the ventricles and subarachnoid space, and the acceleration of CSF motion differs depending on the CSF space. It is now necessary to revise the currently held concept that CSF flows unidirectionally. Currently, water molecule motion in the order of centimeters per second can be detected with various MRI techniques. Thus, we need new MRI techniques with high-velocity sensitivity, such as in the order of 10 µm/s, to determine water molecule movement in the vessel wall, paravascular space, and brain parenchyma. In this paper, the authors review the previous and current concepts of CSF motion in the central nervous system using various MRI techniques.

Cardiac-driven Pulsatile Motion of Intracranial Cerebrospinal Fluid Visualized Based on a Correlation Mapping Technique.

PURPOSE: A correlation mapping technique delineating delay time and maximum correlation for characterizing pulsatile cerebrospinal fluid (CSF) propagation was proposed. After proofing its technical concept, this technique was applied to healthy volunteers and idiopathic normal pressure hydrocephalus (iNPH) patients. METHODS: A time-resolved three dimensional-phase contrast (3D-PC) sampled the cardiac-driven CSF velocity at 32 temporal points per cardiac period at each spatial location using retrospective cardiac gating. The proposed technique visualized distributions of propagation delay and correlation coefficient of the PC-based CSF velocity waveform with reference to a waveform at a particular point in the CSF space. The delay time was obtained as the amount of time-shift, giving the maximum correlation for the velocity waveform at an arbitrary location with that at the reference location. The validity and accuracy of the technique were confirmed in a flow phantom equipped with a cardiovascular pump. The technique was then applied to evaluate the intracranial CSF motions in young, healthy (N = 13), and elderly, healthy (N = 13) volunteers and iNPH patients (N = 13). RESULTS: The phantom study demonstrated that root mean square error of the delay time was 2.27%, which was less than the temporal resolution of PC measurement used in this study (3.13% of a cardiac cycle). The human studies showed a significant difference (P < 0.01) in the mean correlation coefficient between the young, healthy group and the other two groups. A significant difference (P < 0.05) was also recognized in standard deviation of the correlation coefficients in intracranial CSF space among all groups. The result suggests that the CSF space compliance of iNPH patients was lower than that of healthy volunteers. CONCLUSION: The correlation mapping technique allowed us to visualize pulsatile CSF velocity wave propagations as still images. The technique may help to classify diseases related to CSF dynamics, such as iNPH.

The Choroid Plexus of the Lateral Ventricle As the Origin of CSF Pulsation Is Questionable.

The advent of magnetic resonance imaging (MRI) enables noninvasive measurement of cerebrospinal fluid (CSF) motion, and new information about CSF motion has now been acquired. The driving force of the CSF has long been thought to be choroid plexus (CP) pulsation, but to investigate whether this phenomenon actually occurs, CSF motion was observed in the ventricular system and subarachnoid space using MRI. Eleven healthy volunteers, ranging in age from 23 to 58 years, participated in this study. The MRI sequences used were four-dimensional phase-contrast (4D-PC) and time-spatial labeling inversion pulse (t-SLIP). The 4D-PC images included sagittal images in the cranial midline, coronal images focusing on the foramen of Monro (FOM), and oblique coronal images of the trigone to quantify CSF velocity and acceleration. These values were compared and analyzed as non-parametric data using the Kolmogorov-Smirnov test and the Mann-Whitney U test. 4D-PC showed that the median CSF velocity was significantly lower in the posterior part of the lateral ventricle than in other regions. The quantitative analysis of velocity and acceleration showed that they were decreased around the CP in the trigone. Image analysis of both velocity mapping and t-SLIP showed suppressed CSF motion around the CP in the trigone. These findings cast doubt on CP pulsation being the driving force for CSF motion.

Hyperdynamic CSF motion profiles found in idiopathic normal pressure hydrocephalus and Alzheimer's disease assessed by fluid mechanics derived from magnetic resonance images.

BACKGROUND: Magnetic resonance imaging (MRI) does not only ascertain morphological features, but also measures physiological properties such as fluid velocity or pressure gradient. The purpose of this study was to investigate cerebrospinal fluid (CSF) dynamics in patients with morphological abnormalities such as enlarged brain ventricles and subarachnoid spaces. We used a time-resolved three dimensional phase contrast (3D-PC) MRI technique to quantitatively evaluate CSF dynamics in the Sylvian aqueduct of healthy elderly individuals and patients with either idiopathic normal pressure hydrocephalus (iNPH) or Alzheimer's disease (AD) presenting with ventricular enlargement. METHODS: Nineteen healthy elderly individuals, ten iNPH patients, and seven AD patients (all subjects ≥ 60 years old) were retrospectively evaluated 3D-PC MRI. The CSF velocity, pressure gradient, and rotation in the Sylvian aqueduct were quantified and compared between the three groups using Kolmogorov-Smirnov and Mann-Whitney U tests. RESULTS: There was no statistically significant difference in velocity among the three groups. The pressure gradient was not significantly different between the iNPH and AD groups, but was significantly different between the iNPH group and the healthy controls (p < 0.001), and similarly, between the AD group and the healthy controls (p < 0.001). Rotation was not significantly different between the iNPH and AD groups, but was significantly different between the iNPH group and healthy controls (p < 0.001), and similarly, between the AD group and the healthy controls (p < 0.001). CONCLUSIONS: Quantitative analysis of CSF dynamics with time resolved 3D-PC MRI revealed differences and similarities in the Sylvian aqueduct between healthy elderly individuals, iNPH patients, and AD patients. The results showed that CSF motion is in a hyperdynamic state in both iNPH and AD patient groups compared to healthy elderly individuals, and that iNPH patients and AD patients display similar CSF motion profiles.

Characterization of cardiac- and respiratory-driven cerebrospinal fluid motion based on asynchronous phase-contrast magnetic resonance imaging in volunteers.

BACKGROUND: A classification of cardiac- and respiratory-driven components of cerebrospinal fluid (CSF) motion has been demonstrated using echo planar imaging and time-spatial labeling inversion pulse techniques of magnetic resonance imaging (MRI). However, quantitative characterization of the two motion components has not been performed to date. Thus, in this study, the velocities and displacements of the waveforms of the two motions were quantitatively evaluated based on an asynchronous two-dimensional (2D) phase-contrast (PC) method followed by frequency component analysis. METHODS: The effects of respiration and cardiac pulsation on CSF motion were investigated in 7 healthy subjects under guided respiration using asynchronous 2D-PC 3-T MRI. The respiratory and cardiac components in the foramen magnum and aqueduct were separated, and their respective fractions of velocity and amount of displacement were compared. RESULTS: For velocity in the Sylvian aqueduct and foramen magnum, the fraction attributable to the cardiac component was significantly greater than that of the respiratory component throughout the respiratory cycle. As for displacement, the fraction of the respiratory component was significantly greater than that of the cardiac component in the aqueduct regardless of the respiratory cycle and in the foramen magnum in the 6- and 10-s respiratory cycles. There was no significant difference between the fractions in the 16-s respiratory cycle in the foramen magnum. CONCLUSIONS: To separate cardiac- and respiratory-driven CSF motions, asynchronous 2D-PC MRI was performed under respiratory guidance. For velocity, the cardiac component was greater than the respiratory component. In contrast, for the amount of displacement, the respiratory component was greater.

Magnetic Resonance Imaging Technique for Visualization of Irregular Cerebrospinal Fluid Motion in the Ventricular System and Subarachnoid Space.

BACKGROUND: Many studies have shown that cerebrospinal fluid (CSF) behaves irregularly, rather than with laminar flow, in the various CSF spaces. We adapted a modified previously known magnetic resonance imaging technique to visualize irregular CSF motion. Subsequently, we assessed the usefulness and clinical significance of the present method. MATERIALS AND METHODS: Normal CSF motion in 10 healthy volunteers was visualized with the dynamic improved, motion-sensitized, driven-equilibrium steady-state free precession technique. Subsequently, CSF motion visualization with a modified sequence was applied to 3 patients. RESULTS: In healthy volunteers, we achieved visualization of the irregularity of CSF flow in the ventricles and spinal canal, whereas CSF motion was diminished in the peripheral part of the intracranial subarachnoid space. In one case, we confirmed the patency of the patient's third ventriculostomy fenestration site. In the other, we verified the usefulness of the proposed sequence for determining the communication between the ventricle or subarachnoid space and the cyst. CONCLUSIONS: Using the present sequence, we obtained images that accentuated CSF motion, which is largely composed of irregular motion. This method does not require pulse triggering or complex post-processing of images and allows visualization of CSF motion in a short period of time in selected whole imaging planes. It can therefore be applied clinically to diagnose various diseases that cause abnormalities in the CSF space.

Investigation of driving forces of cerebrospinal fluid motion by power and frequency mapping based on asynchronous phase contrast technique.

To classify the cardiac- and respiratory-driven cerebrospinal fluid (CSF) motions, asynchronous 2D phase contrast (PC) of magnetic resonance imaging (MRI) with 217 ms time resolution in conjunction with power and frequency mapping was performed for 7 healthy subjects under respiration guidance. In the frequency domain, the cardiac-driven motion was at around 1.29±0.21 Hz and respiratory-driven motion was at 0.16±0.01 Hz under 6 sec respiratory cycle. Two different techniques were proposed for characterizing the motions; one was power-map (P-map) depicting integrated power spectrum in a selected band, and the other was frequency-map (F-map) delineating the frequency of maximum peak in power spectral density (PSD). These maps visualized the anatomical distributions of the two motions. Portions of the cardiac- and respiratory-driven CSF motions in the spinal subarachnoid space were 58.1±22.2 and 9.50±3.83 %, respectively. Power and frequency mapping clearly classified the cardiac-driven and respiratory-driven CSF motions.

Characterization of cardiac- and respiratory-driven cerebrospinal fluid motions using correlation mapping with asynchronous 2-dimensional phase contrast technique.

To investigate spatial distribution properties of the cardiac- and respiratory-driven cerebrospinal fluid (CSF) motions in the intracranial space, correlation mapping technique was conducted. Time series of CSF velocity were acquired in 7 healthy subjects of 26±5 years old under by asynchronous 2-dimensional phase contrast (2D-PC) method with 217-msec temporal resolution. The delay time and maximum correlation maps of the cardiac- and respiratory-driven CSF motions demonstrated clear differences in the propagation properties. When the reference region was set at anterior spinal subarachnoid space, the maximum correlation coefficients in the case of 6-sec respiratory period were 0.91±0.05 for cardiac-driven and 0.78±0.08 for respiratory-driven. They were 0.90±0.06 and 0.81±0.06 in the case of 10-sec period. The cardiac- and respiratory CSF motions differently distributed in intracranial space.

Quantitative Analysis of Cerebrospinal Fluid Pressure Gradients in Healthy Volunteers and Patients with Normal Pressure Hydrocephalus.

Magnetic resonance imaging (MRI) can depict not only anatomical information, but also physiological factors such as velocity and pressure gradient. Measurement of these physiological factors is necessary to understand the cerebrospinal fluid (CSF) environment. In this study we quantified CSF motion in various parts of the CSF space, determined changes in the CSF environment with aging, and compared CSF pressure gradient between patients with idiopathic normal pressure hydrocephalus (iNPH) and healthy elderly volunteers. Fifty-seven healthy volunteers and six iNPH patients underwent four-dimensional (4D) phase-contrast (PC) MRI. CSF motion was observed and the pressure gradient of CSF was quantified in the CSF space. In healthy volunteers, inhomogeneous CSF motion was observed whereby the pressure gradient markedly increased in the center of the skull and gradually decreased in the periphery of the skull. For example, the pressure gradient at the ventral surface of the brainstem was 6.6 times greater than that at the convexity of the cerebrum. The pressure gradient was statistically unchanged with aging. The pressure gradient of patients with iNPH was 3.2 times greater than that of healthy volunteers. The quantitative analysis of 4D-PC MRI data revealed that the pressure gradient of CSF can be used to understand the CSF environment, which is not sufficiently given by subjective impression of the anatomical image.

Visualization of Pulsatile CSF Motion Around Membrane-like Structures with both 4D Velocity Mapping and Time-SLIP Technique.

PURPOSE: We compared the depiction of pulsatile CSF motion obtained by 4-dimensional phase-contrast velocity mapping (4D-VM) with that by time-spatial labeling inversion pulse (time-SLIP) technique in the presence of membrane structures. MATERIALS AND METHODS: We compared the 2 techniques using a flow phantom comprising tubes with and without a thin rubber membrane and applied the techniques to 6 healthy volunteers and 2 patients to analyze CSF dynamics surrounding thin membrane structures, such as the Liliequist membrane (LM), or the wall of an arachnoid cyst. RESULTS: Phantom images exhibited propagation of the flow and pressure gradient beyond the membrane in the tube. In contrast, fluid labeled by the time-SLIP technique showed little displacement from the blockage of spin travelling by the membrane. A similar phenomenon was observed around the LM in healthy volunteers and the arachnoid cyst wall in a patient. CONCLUSION: Four-dimensional phase-contrast velocity mapping permitted visualization of the propagation of CSF pulsation through the intracranial membranous structures. This suggests that 4D-VM and the time-SLIP technique provide different information on flow and that both techniques are useful for classifying the pathophysiological status of CSF and elucidating the propagation pathway of CSF pulsation in the cranium.

Correlation mapping for visualizing propagation of pulsatile CSF motion in intracranial space based on magnetic resonance phase contrast velocity images: preliminary results.

Correlation time mapping based on magnetic resonance (MR) velocimetry has been applied to pulsatile cerebrospinal fluid (CSF) motion to visualize the pressure transmission between CSF at different locations and/or between CSF and arterial blood flow. Healthy volunteer experiments demonstrated that the technique exhibited transmitting pulsatile CSF motion from CSF space in the vicinity of blood vessels with short delay and relatively high correlation coefficients. Patient and healthy volunteer experiments indicated that the properties of CSF motion were different from the healthy volunteers. Resultant images in healthy volunteers implied that there were slight individual difference in the CSF driving source locations. Clinical interpretation for these preliminary results is required to apply the present technique for classifying status of hydrocephalus.

Velocity and pressure gradients of cerebrospinal fluid assessed with magnetic resonance imaging.

OBJECT: New approaches for understanding CSF motion in healthy individuals and patients with hydrocephalus and Chiari malformation are presented. The velocity and the pressure gradient of CSF motion were determined using phase contrast (PC) MRI. METHODS: The authors examined 11 healthy control subjects and 2 patients (1 with hydrocephalus and 1 with Chiari malformation), using 4-dimensional PC (4D-PC) MRI and a newly developed computer analysis method that includes calculation of the pressure gradient from the velocity field. Sagittal slices including the center of the skull and coronal slices of the foramen of Monro and the third ventricle were used. RESULTS: In the ventricular system, mixing and swirling of the CSF was observed in the third ventricle. The velocity images showed that the CSF was pushed up and back down to the adjacent ventricle and then returned again to the third ventricle. The CSF traveled bidirectionally in the foramen of Monro and sylvian aqueduct. Around the choroid plexus in the lateral ventricle, the CSF motion was stagnant and the CSF pressure gradient was lower than at the other locations. An elevated pressure gradient was observed in the basal cistern of the subarachnoid space. Sagittal imaging showed that the more prominent pressure gradients originated around the cisterna magna and were transmitted in an upward direction. The coronal image showed a pressure gradient traveling from the central to the peripheral subarachnoid spaces that diminished markedly in the convexity of the cerebrum. The 2 patients, 1 with secondary hydrocephalus and 1 with Chiari malformation, were also examined. CONCLUSIONS: The observed velocity and pressure gradient fields delineated the characteristics of the CSF motion and its similarities and differences among the healthy individuals and between them and the 2 patients. Although the present results did not provide general knowledge of CSF motion, the authors' method more comprehensively described the physiological properties of the CSF in the skull than conventional approaches that do not include measurements of pressure gradient fields.

Visualization of pulsatile CSF motion separated by membrane-like structure based on four-dimensional phase-contrast (4D-PC) velocity mapping.

This work was performed to indicate the usefulness of magnetic resonance (MR) 4-dimentional phase contrast (4D-PC) technique in assessing CerebroSpinal Fluid (CSF) motion in comparison with the time-Spatial Labeling Inversion Pulse (Time-SLIP) technique. 4D-velocity vector, their curl, and, pressure gradient were evaluated in both flow phantom, and normal volunteers and a patient with hydrocepharus. The velocity and pressure gradient fields obtained by the 4D-PC technique were useful to visualize the CSF dynamics under the presence of a membrane-like structure, unlike the Time-SLIP in which the spin travel was visualized. Quantitative property was another advantage of the 4D-PC. The curl and the pressure gradient fields obtained with actual units should help clinicians to classify the conditions of the patients with CSF disorders.

Cerebrospinal fluid image segmentation using spatial fuzzy clustering method with improved evolutionary Expectation Maximization.

Visualization of cerebrospinal fluid (CSF), that flow in the brain and spinal cord, plays an important role to detect neurodegenerative diseases such as Alzheimer's disease. This is performed by measuring the substantial changes in the CSF flow dynamics, volume and/or pressure gradient. Magnetic resonance imaging (MRI) technique has become a prominent tool to quantitatively measure these changes and image segmentation method has been widely used to distinguish the CSF flows from the brain tissues. However, this is often hampered by the presence of partial volume effect in the images. In this paper, a new hybrid evolutionary spatial fuzzy clustering method is introduced to overcome the partial volume effect in the MRI images. The proposed method incorporates Expectation Maximization (EM) method, which is improved by the evolutionary operations of the Genetic Algorithm (GA) to differentiate the CSF from the brain tissues. The proposed improvement is incorporated into a spatial-based fuzzy clustering (SFCM) method to improve segmentation of the boundary curve of the CSF and the brain tissues. The proposed method was validated using MRI images of Alzheimer's disease patient. The results presented that the proposed method is capable to filter the CSF regions from the brain tissues more effectively compared to the standard EM, FCM, and SFCM methods.