The Experts below are selected from a list of 93 Experts worldwide ranked by ideXlab platform
Bryn A Martin - One of the best experts on this subject based on the ideXlab platform.
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A numerical investigation of intrathecal isobaric drug dispersion within the cervical subarachnoid space.
PLOS ONE, 2017Co-Authors: Per Thomas Haga, Soroush Heidari Pahlavian, Bryn A Martin, Giulia Pizzichelli, Mikael Mortensen, Miroslav Kuchta, Edoardo Sinibaldi, Kent-andre MardalAbstract:Intrathecal drug and gene vector delivery is a procedure to release a solute within the cerebrospinal fluid. This procedure is currently used in clinical practice and shows promise for treatment of several central nervous system pathologies. However, intrathecal delivery protocols and systems are not yet optimized. The aim of this study was to investigate the effects of injection parameters on solute distribution within the cervical subarachnoid space using a numerical platform. We developed a numerical model based on a patient-specific three dimensional geometry of the cervical subarachnoid space with idealized dorsal and ventral nerve roots and Denticulate ligament anatomy. We considered the drug as massless particles within the flow field and with similar properties as the CSF, and we analyzed the effects of anatomy, catheter position, angle and injection flow rate on solute distribution within the cerebrospinal fluid by performing a series of numerical simulations. Results were compared quantitatively in terms of drug peak concentration, spread, accumulation rate and appearance instant over 15 seconds following the injection. Results indicated that solute distribution within the cervical spine was altered by all parameters investigated within the time range analyzed following the injection. The presence of spinal cord nerve roots and Denticulate Ligaments increased drug spread by 60% compared to simulations without these anatomical features. Catheter position and angle were both found to alter spread rate up to 86%, and catheter flow rate altered drug peak concentration up to 78%. The presented numerical platform fills a first gap towards the realization of a tool to parametrically assess and optimize intrathecal drug and gene vector delivery protocols and systems. Further investigation is needed to analyze drug spread over a longer clinically relevant time frame.
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Characterization of the discrepancies between four-dimensional phase-contrast magnetic resonance imaging and in-silico simulations of cerebrospinal fluid dynamics.
Journal of Biomechanical Engineering-transactions of The Asme, 2015Co-Authors: Soroush Heidari Pahlavian, Theresia I Yiallourou, Alexander C Bunck, Francis Loth, R. Shane Tubbs, Jan Robert Kroeger, Walter Heindel, Bryn A MartinAbstract:The purpose of the present study was to compare subject-specific magnetic resonance imaging (MRI)-based computational fluid dynamics (CFD) simulations with time-resolved three-directional (3D) velocity-encoded phase-contrast MRI (4D PCMRI) measurements of the cerebrospinal fluid (CSF) velocity field in the cervical spinal subarachnoid space (SSS). Three-dimensional models of the cervical SSS were constructed based on MRI image segmentation and anatomical measurements for a healthy subject and patient with Chiari I malformation. CFD was used to simulate the CSF motion and compared to the 4D PCMRI measurements. Four-dimensional PCMRI measurements had much greater CSF velocities compared to CFD simulations (1.4 to 5.6 x greater). Four-dimensional PCMRI and CFD both showed anterior and anterolateral dominance of CSF velocities, although this flow feature was more pronounced in 4D PCMRI measurements compared to CFD. CSF flow jets were present near the nerve rootlets and Denticulate Ligaments (NRDL) in the CFD simulation. Flow jets were visible in the 4D PCMRI measurements, although they were not clearly attributable to nerve rootlets. Inclusion of spinal cord NRDL in the cervical SSS does not fully explain the differences between velocities obtained from 4D PCMRI measurements and CFD simulations.
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the impact of spinal cord nerve roots and Denticulate Ligaments on cerebrospinal fluid dynamics in the cervical spine
PLOS ONE, 2014Co-Authors: Soroush Heidari Pahlavian, Theresia I Yiallourou, Shane R Tubbs, Alexander C Bunck, Francis Loth, Mark Goodin, Mehrdad Raisee, Bryn A MartinAbstract:Cerebrospinal fluid (CSF) dynamics in the spinal subarachnoid space (SSS) have been thought to play an important pathophysiological role in syringomyelia, Chiari I malformation (CM), and a role in intrathecal drug delivery. Yet, the impact that fine anatomical structures, including nerve roots and Denticulate Ligaments (NRDL), have on SSS CSF dynamics is not clear. In the present study we assessed the impact of NRDL on CSF dynamics in the cervical SSS. The 3D geometry of the cervical SSS was reconstructed based on manual segmentation of MRI images of a healthy volunteer and a patient with CM. Idealized NRDL were designed and added to each of the geometries based on in vivo measurments in the literature and confirmation by a neuroanatomist. CFD simulations were performed for the healthy and patient case with and without NRDL included. Our results showed that the NRDL had an important impact on CSF dynamics in terms of velocity field and flow patterns. However, pressure distribution was not altered greatly although the NRDL cases required a larger pressure gradient to maintain the same flow. Also, the NRDL did not alter CSF dynamics to a great degree in the SSS from the foramen magnum to the C1 level for the healthy subject and CM patient with mild tonsillar herniation (∼6 mm). Overall, the NRDL increased fluid mixing phenomena and resulted in a more complex flow field. Comparison of the streamlines of CSF flow revealed that the presence of NRDL lead to the formation of vortical structures and remarkably increased the local mixing of the CSF throughout the SSS.
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CEREBROSPINAL FLUID DYNAMICS IN THE CERVICAL SPINE: IMPORTANCE OF FINE ANATOMICAL STRUCTURES
Volume 1A: Abdominal Aortic Aneurysms; Active and Reactive Soft Matter; Atherosclerosis; BioFluid Mechanics; Education; Biotransport Phenomena; Bone J, 2013Co-Authors: Soroush Heidari Pahlavian, Theresia I Yiallourou, Alexander C Bunck, Francis Loth, Mark Goodin, Mehrdad Raisee, R. S. Tubbs, Bryn A MartinAbstract:Fine anatomical structures, including nerve roots and Denticulate Ligaments, can significantly influence cerebrospinal fluid (CSF) dynamics inside the spinal subarachnoid space (SSS). In this study, we completed computational fluid dynamics (CFD) simulations based on subject specific geometries of the cervical spine with and without idealized fine structures (nerve roots and Denticulate Ligaments, NRDL). The results show that NRDL had a significant impact on CSF dynamics in terms of velocity distribution, flow streamlines, bidirectional nature of the flow and the pressure drop.
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comparison of 4d phase contrast mri flow measurements to computational fluid dynamics simulations of cerebrospinal fluid motion in the cervical spine
PLOS ONE, 2012Co-Authors: Theresia I Yiallourou, Bryn A Martin, Jan Robert Kroger, Nikolaos Stergiopulos, David Maintz, Alexander C BunckAbstract:Cerebrospinal fluid (CSF) dynamics in the cervical spinal subarachnoid space (SSS) have been thought to be important to help diagnose and assess craniospinal disorders such as Chiari I malformation (CM). In this study we obtained time-resolved three directional velocity encoded phase-contrast MRI (4D PC MRI) in three healthy volunteers and four CM patients and compared the 4D PC MRI measurements to subject-specific 3D computational fluid dynamics (CFD) simulations. The CFD simulations considered the geometry to be rigid-walled and did not include small anatomical structures such as nerve roots, Denticulate Ligaments and arachnoid trabeculae. Results were compared at nine axial planes along the cervical SSS in terms of peak CSF velocities in both the cranial and caudal direction and visual interpretation of thru-plane velocity profiles. 4D PC MRI peak CSF velocities were consistently greater than the CFD peak velocities and these differences were more pronounced in CM patients than in healthy subjects. In the upper cervical SSS of CM patients the 4D PC MRI quantified stronger fluid jets than the CFD. Visual interpretation of the 4D PC MRI thru-plane velocity profiles showed greater pulsatile movement of CSF in the anterior SSS in comparison to the posterior and reduction in local CSF velocities near nerve roots. CFD velocity profiles were relatively uniform around the spinal cord for all subjects. This study represents the first comparison of 4D PC MRI measurements to CFD of CSF flow in the cervical SSS. The results highlight the utility of 4D PC MRI for evaluation of complex CSF dynamics and the need for improvement of CFD methodology. Future studies are needed to investigate whether integration of fine anatomical structures and gross motion of the brain and/or spinal cord into the computational model will lead to a better agreement between the two techniques.
Alexander C Bunck - One of the best experts on this subject based on the ideXlab platform.
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Characterization of the discrepancies between four-dimensional phase-contrast magnetic resonance imaging and in-silico simulations of cerebrospinal fluid dynamics.
Journal of Biomechanical Engineering-transactions of The Asme, 2015Co-Authors: Soroush Heidari Pahlavian, Theresia I Yiallourou, Alexander C Bunck, Francis Loth, R. Shane Tubbs, Jan Robert Kroeger, Walter Heindel, Bryn A MartinAbstract:The purpose of the present study was to compare subject-specific magnetic resonance imaging (MRI)-based computational fluid dynamics (CFD) simulations with time-resolved three-directional (3D) velocity-encoded phase-contrast MRI (4D PCMRI) measurements of the cerebrospinal fluid (CSF) velocity field in the cervical spinal subarachnoid space (SSS). Three-dimensional models of the cervical SSS were constructed based on MRI image segmentation and anatomical measurements for a healthy subject and patient with Chiari I malformation. CFD was used to simulate the CSF motion and compared to the 4D PCMRI measurements. Four-dimensional PCMRI measurements had much greater CSF velocities compared to CFD simulations (1.4 to 5.6 x greater). Four-dimensional PCMRI and CFD both showed anterior and anterolateral dominance of CSF velocities, although this flow feature was more pronounced in 4D PCMRI measurements compared to CFD. CSF flow jets were present near the nerve rootlets and Denticulate Ligaments (NRDL) in the CFD simulation. Flow jets were visible in the 4D PCMRI measurements, although they were not clearly attributable to nerve rootlets. Inclusion of spinal cord NRDL in the cervical SSS does not fully explain the differences between velocities obtained from 4D PCMRI measurements and CFD simulations.
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the impact of spinal cord nerve roots and Denticulate Ligaments on cerebrospinal fluid dynamics in the cervical spine
PLOS ONE, 2014Co-Authors: Soroush Heidari Pahlavian, Theresia I Yiallourou, Shane R Tubbs, Alexander C Bunck, Francis Loth, Mark Goodin, Mehrdad Raisee, Bryn A MartinAbstract:Cerebrospinal fluid (CSF) dynamics in the spinal subarachnoid space (SSS) have been thought to play an important pathophysiological role in syringomyelia, Chiari I malformation (CM), and a role in intrathecal drug delivery. Yet, the impact that fine anatomical structures, including nerve roots and Denticulate Ligaments (NRDL), have on SSS CSF dynamics is not clear. In the present study we assessed the impact of NRDL on CSF dynamics in the cervical SSS. The 3D geometry of the cervical SSS was reconstructed based on manual segmentation of MRI images of a healthy volunteer and a patient with CM. Idealized NRDL were designed and added to each of the geometries based on in vivo measurments in the literature and confirmation by a neuroanatomist. CFD simulations were performed for the healthy and patient case with and without NRDL included. Our results showed that the NRDL had an important impact on CSF dynamics in terms of velocity field and flow patterns. However, pressure distribution was not altered greatly although the NRDL cases required a larger pressure gradient to maintain the same flow. Also, the NRDL did not alter CSF dynamics to a great degree in the SSS from the foramen magnum to the C1 level for the healthy subject and CM patient with mild tonsillar herniation (∼6 mm). Overall, the NRDL increased fluid mixing phenomena and resulted in a more complex flow field. Comparison of the streamlines of CSF flow revealed that the presence of NRDL lead to the formation of vortical structures and remarkably increased the local mixing of the CSF throughout the SSS.
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CEREBROSPINAL FLUID DYNAMICS IN THE CERVICAL SPINE: IMPORTANCE OF FINE ANATOMICAL STRUCTURES
Volume 1A: Abdominal Aortic Aneurysms; Active and Reactive Soft Matter; Atherosclerosis; BioFluid Mechanics; Education; Biotransport Phenomena; Bone J, 2013Co-Authors: Soroush Heidari Pahlavian, Theresia I Yiallourou, Alexander C Bunck, Francis Loth, Mark Goodin, Mehrdad Raisee, R. S. Tubbs, Bryn A MartinAbstract:Fine anatomical structures, including nerve roots and Denticulate Ligaments, can significantly influence cerebrospinal fluid (CSF) dynamics inside the spinal subarachnoid space (SSS). In this study, we completed computational fluid dynamics (CFD) simulations based on subject specific geometries of the cervical spine with and without idealized fine structures (nerve roots and Denticulate Ligaments, NRDL). The results show that NRDL had a significant impact on CSF dynamics in terms of velocity distribution, flow streamlines, bidirectional nature of the flow and the pressure drop.
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comparison of 4d phase contrast mri flow measurements to computational fluid dynamics simulations of cerebrospinal fluid motion in the cervical spine
PLOS ONE, 2012Co-Authors: Theresia I Yiallourou, Bryn A Martin, Jan Robert Kroger, Nikolaos Stergiopulos, David Maintz, Alexander C BunckAbstract:Cerebrospinal fluid (CSF) dynamics in the cervical spinal subarachnoid space (SSS) have been thought to be important to help diagnose and assess craniospinal disorders such as Chiari I malformation (CM). In this study we obtained time-resolved three directional velocity encoded phase-contrast MRI (4D PC MRI) in three healthy volunteers and four CM patients and compared the 4D PC MRI measurements to subject-specific 3D computational fluid dynamics (CFD) simulations. The CFD simulations considered the geometry to be rigid-walled and did not include small anatomical structures such as nerve roots, Denticulate Ligaments and arachnoid trabeculae. Results were compared at nine axial planes along the cervical SSS in terms of peak CSF velocities in both the cranial and caudal direction and visual interpretation of thru-plane velocity profiles. 4D PC MRI peak CSF velocities were consistently greater than the CFD peak velocities and these differences were more pronounced in CM patients than in healthy subjects. In the upper cervical SSS of CM patients the 4D PC MRI quantified stronger fluid jets than the CFD. Visual interpretation of the 4D PC MRI thru-plane velocity profiles showed greater pulsatile movement of CSF in the anterior SSS in comparison to the posterior and reduction in local CSF velocities near nerve roots. CFD velocity profiles were relatively uniform around the spinal cord for all subjects. This study represents the first comparison of 4D PC MRI measurements to CFD of CSF flow in the cervical SSS. The results highlight the utility of 4D PC MRI for evaluation of complex CSF dynamics and the need for improvement of CFD methodology. Future studies are needed to investigate whether integration of fine anatomical structures and gross motion of the brain and/or spinal cord into the computational model will lead to a better agreement between the two techniques.
Theresia I Yiallourou - One of the best experts on this subject based on the ideXlab platform.
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Characterization of the discrepancies between four-dimensional phase-contrast magnetic resonance imaging and in-silico simulations of cerebrospinal fluid dynamics.
Journal of Biomechanical Engineering-transactions of The Asme, 2015Co-Authors: Soroush Heidari Pahlavian, Theresia I Yiallourou, Alexander C Bunck, Francis Loth, R. Shane Tubbs, Jan Robert Kroeger, Walter Heindel, Bryn A MartinAbstract:The purpose of the present study was to compare subject-specific magnetic resonance imaging (MRI)-based computational fluid dynamics (CFD) simulations with time-resolved three-directional (3D) velocity-encoded phase-contrast MRI (4D PCMRI) measurements of the cerebrospinal fluid (CSF) velocity field in the cervical spinal subarachnoid space (SSS). Three-dimensional models of the cervical SSS were constructed based on MRI image segmentation and anatomical measurements for a healthy subject and patient with Chiari I malformation. CFD was used to simulate the CSF motion and compared to the 4D PCMRI measurements. Four-dimensional PCMRI measurements had much greater CSF velocities compared to CFD simulations (1.4 to 5.6 x greater). Four-dimensional PCMRI and CFD both showed anterior and anterolateral dominance of CSF velocities, although this flow feature was more pronounced in 4D PCMRI measurements compared to CFD. CSF flow jets were present near the nerve rootlets and Denticulate Ligaments (NRDL) in the CFD simulation. Flow jets were visible in the 4D PCMRI measurements, although they were not clearly attributable to nerve rootlets. Inclusion of spinal cord NRDL in the cervical SSS does not fully explain the differences between velocities obtained from 4D PCMRI measurements and CFD simulations.
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the impact of spinal cord nerve roots and Denticulate Ligaments on cerebrospinal fluid dynamics in the cervical spine
PLOS ONE, 2014Co-Authors: Soroush Heidari Pahlavian, Theresia I Yiallourou, Shane R Tubbs, Alexander C Bunck, Francis Loth, Mark Goodin, Mehrdad Raisee, Bryn A MartinAbstract:Cerebrospinal fluid (CSF) dynamics in the spinal subarachnoid space (SSS) have been thought to play an important pathophysiological role in syringomyelia, Chiari I malformation (CM), and a role in intrathecal drug delivery. Yet, the impact that fine anatomical structures, including nerve roots and Denticulate Ligaments (NRDL), have on SSS CSF dynamics is not clear. In the present study we assessed the impact of NRDL on CSF dynamics in the cervical SSS. The 3D geometry of the cervical SSS was reconstructed based on manual segmentation of MRI images of a healthy volunteer and a patient with CM. Idealized NRDL were designed and added to each of the geometries based on in vivo measurments in the literature and confirmation by a neuroanatomist. CFD simulations were performed for the healthy and patient case with and without NRDL included. Our results showed that the NRDL had an important impact on CSF dynamics in terms of velocity field and flow patterns. However, pressure distribution was not altered greatly although the NRDL cases required a larger pressure gradient to maintain the same flow. Also, the NRDL did not alter CSF dynamics to a great degree in the SSS from the foramen magnum to the C1 level for the healthy subject and CM patient with mild tonsillar herniation (∼6 mm). Overall, the NRDL increased fluid mixing phenomena and resulted in a more complex flow field. Comparison of the streamlines of CSF flow revealed that the presence of NRDL lead to the formation of vortical structures and remarkably increased the local mixing of the CSF throughout the SSS.
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CEREBROSPINAL FLUID DYNAMICS IN THE CERVICAL SPINE: IMPORTANCE OF FINE ANATOMICAL STRUCTURES
Volume 1A: Abdominal Aortic Aneurysms; Active and Reactive Soft Matter; Atherosclerosis; BioFluid Mechanics; Education; Biotransport Phenomena; Bone J, 2013Co-Authors: Soroush Heidari Pahlavian, Theresia I Yiallourou, Alexander C Bunck, Francis Loth, Mark Goodin, Mehrdad Raisee, R. S. Tubbs, Bryn A MartinAbstract:Fine anatomical structures, including nerve roots and Denticulate Ligaments, can significantly influence cerebrospinal fluid (CSF) dynamics inside the spinal subarachnoid space (SSS). In this study, we completed computational fluid dynamics (CFD) simulations based on subject specific geometries of the cervical spine with and without idealized fine structures (nerve roots and Denticulate Ligaments, NRDL). The results show that NRDL had a significant impact on CSF dynamics in terms of velocity distribution, flow streamlines, bidirectional nature of the flow and the pressure drop.
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comparison of 4d phase contrast mri flow measurements to computational fluid dynamics simulations of cerebrospinal fluid motion in the cervical spine
PLOS ONE, 2012Co-Authors: Theresia I Yiallourou, Bryn A Martin, Jan Robert Kroger, Nikolaos Stergiopulos, David Maintz, Alexander C BunckAbstract:Cerebrospinal fluid (CSF) dynamics in the cervical spinal subarachnoid space (SSS) have been thought to be important to help diagnose and assess craniospinal disorders such as Chiari I malformation (CM). In this study we obtained time-resolved three directional velocity encoded phase-contrast MRI (4D PC MRI) in three healthy volunteers and four CM patients and compared the 4D PC MRI measurements to subject-specific 3D computational fluid dynamics (CFD) simulations. The CFD simulations considered the geometry to be rigid-walled and did not include small anatomical structures such as nerve roots, Denticulate Ligaments and arachnoid trabeculae. Results were compared at nine axial planes along the cervical SSS in terms of peak CSF velocities in both the cranial and caudal direction and visual interpretation of thru-plane velocity profiles. 4D PC MRI peak CSF velocities were consistently greater than the CFD peak velocities and these differences were more pronounced in CM patients than in healthy subjects. In the upper cervical SSS of CM patients the 4D PC MRI quantified stronger fluid jets than the CFD. Visual interpretation of the 4D PC MRI thru-plane velocity profiles showed greater pulsatile movement of CSF in the anterior SSS in comparison to the posterior and reduction in local CSF velocities near nerve roots. CFD velocity profiles were relatively uniform around the spinal cord for all subjects. This study represents the first comparison of 4D PC MRI measurements to CFD of CSF flow in the cervical SSS. The results highlight the utility of 4D PC MRI for evaluation of complex CSF dynamics and the need for improvement of CFD methodology. Future studies are needed to investigate whether integration of fine anatomical structures and gross motion of the brain and/or spinal cord into the computational model will lead to a better agreement between the two techniques.
Soroush Heidari Pahlavian - One of the best experts on this subject based on the ideXlab platform.
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A numerical investigation of intrathecal isobaric drug dispersion within the cervical subarachnoid space.
PLOS ONE, 2017Co-Authors: Per Thomas Haga, Soroush Heidari Pahlavian, Bryn A Martin, Giulia Pizzichelli, Mikael Mortensen, Miroslav Kuchta, Edoardo Sinibaldi, Kent-andre MardalAbstract:Intrathecal drug and gene vector delivery is a procedure to release a solute within the cerebrospinal fluid. This procedure is currently used in clinical practice and shows promise for treatment of several central nervous system pathologies. However, intrathecal delivery protocols and systems are not yet optimized. The aim of this study was to investigate the effects of injection parameters on solute distribution within the cervical subarachnoid space using a numerical platform. We developed a numerical model based on a patient-specific three dimensional geometry of the cervical subarachnoid space with idealized dorsal and ventral nerve roots and Denticulate ligament anatomy. We considered the drug as massless particles within the flow field and with similar properties as the CSF, and we analyzed the effects of anatomy, catheter position, angle and injection flow rate on solute distribution within the cerebrospinal fluid by performing a series of numerical simulations. Results were compared quantitatively in terms of drug peak concentration, spread, accumulation rate and appearance instant over 15 seconds following the injection. Results indicated that solute distribution within the cervical spine was altered by all parameters investigated within the time range analyzed following the injection. The presence of spinal cord nerve roots and Denticulate Ligaments increased drug spread by 60% compared to simulations without these anatomical features. Catheter position and angle were both found to alter spread rate up to 86%, and catheter flow rate altered drug peak concentration up to 78%. The presented numerical platform fills a first gap towards the realization of a tool to parametrically assess and optimize intrathecal drug and gene vector delivery protocols and systems. Further investigation is needed to analyze drug spread over a longer clinically relevant time frame.
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Characterization of the discrepancies between four-dimensional phase-contrast magnetic resonance imaging and in-silico simulations of cerebrospinal fluid dynamics.
Journal of Biomechanical Engineering-transactions of The Asme, 2015Co-Authors: Soroush Heidari Pahlavian, Theresia I Yiallourou, Alexander C Bunck, Francis Loth, R. Shane Tubbs, Jan Robert Kroeger, Walter Heindel, Bryn A MartinAbstract:The purpose of the present study was to compare subject-specific magnetic resonance imaging (MRI)-based computational fluid dynamics (CFD) simulations with time-resolved three-directional (3D) velocity-encoded phase-contrast MRI (4D PCMRI) measurements of the cerebrospinal fluid (CSF) velocity field in the cervical spinal subarachnoid space (SSS). Three-dimensional models of the cervical SSS were constructed based on MRI image segmentation and anatomical measurements for a healthy subject and patient with Chiari I malformation. CFD was used to simulate the CSF motion and compared to the 4D PCMRI measurements. Four-dimensional PCMRI measurements had much greater CSF velocities compared to CFD simulations (1.4 to 5.6 x greater). Four-dimensional PCMRI and CFD both showed anterior and anterolateral dominance of CSF velocities, although this flow feature was more pronounced in 4D PCMRI measurements compared to CFD. CSF flow jets were present near the nerve rootlets and Denticulate Ligaments (NRDL) in the CFD simulation. Flow jets were visible in the 4D PCMRI measurements, although they were not clearly attributable to nerve rootlets. Inclusion of spinal cord NRDL in the cervical SSS does not fully explain the differences between velocities obtained from 4D PCMRI measurements and CFD simulations.
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the impact of spinal cord nerve roots and Denticulate Ligaments on cerebrospinal fluid dynamics in the cervical spine
PLOS ONE, 2014Co-Authors: Soroush Heidari Pahlavian, Theresia I Yiallourou, Shane R Tubbs, Alexander C Bunck, Francis Loth, Mark Goodin, Mehrdad Raisee, Bryn A MartinAbstract:Cerebrospinal fluid (CSF) dynamics in the spinal subarachnoid space (SSS) have been thought to play an important pathophysiological role in syringomyelia, Chiari I malformation (CM), and a role in intrathecal drug delivery. Yet, the impact that fine anatomical structures, including nerve roots and Denticulate Ligaments (NRDL), have on SSS CSF dynamics is not clear. In the present study we assessed the impact of NRDL on CSF dynamics in the cervical SSS. The 3D geometry of the cervical SSS was reconstructed based on manual segmentation of MRI images of a healthy volunteer and a patient with CM. Idealized NRDL were designed and added to each of the geometries based on in vivo measurments in the literature and confirmation by a neuroanatomist. CFD simulations were performed for the healthy and patient case with and without NRDL included. Our results showed that the NRDL had an important impact on CSF dynamics in terms of velocity field and flow patterns. However, pressure distribution was not altered greatly although the NRDL cases required a larger pressure gradient to maintain the same flow. Also, the NRDL did not alter CSF dynamics to a great degree in the SSS from the foramen magnum to the C1 level for the healthy subject and CM patient with mild tonsillar herniation (∼6 mm). Overall, the NRDL increased fluid mixing phenomena and resulted in a more complex flow field. Comparison of the streamlines of CSF flow revealed that the presence of NRDL lead to the formation of vortical structures and remarkably increased the local mixing of the CSF throughout the SSS.
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CEREBROSPINAL FLUID DYNAMICS IN THE CERVICAL SPINE: IMPORTANCE OF FINE ANATOMICAL STRUCTURES
Volume 1A: Abdominal Aortic Aneurysms; Active and Reactive Soft Matter; Atherosclerosis; BioFluid Mechanics; Education; Biotransport Phenomena; Bone J, 2013Co-Authors: Soroush Heidari Pahlavian, Theresia I Yiallourou, Alexander C Bunck, Francis Loth, Mark Goodin, Mehrdad Raisee, R. S. Tubbs, Bryn A MartinAbstract:Fine anatomical structures, including nerve roots and Denticulate Ligaments, can significantly influence cerebrospinal fluid (CSF) dynamics inside the spinal subarachnoid space (SSS). In this study, we completed computational fluid dynamics (CFD) simulations based on subject specific geometries of the cervical spine with and without idealized fine structures (nerve roots and Denticulate Ligaments, NRDL). The results show that NRDL had a significant impact on CSF dynamics in terms of velocity distribution, flow streamlines, bidirectional nature of the flow and the pressure drop.
Francis Loth - One of the best experts on this subject based on the ideXlab platform.
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Characterization of the discrepancies between four-dimensional phase-contrast magnetic resonance imaging and in-silico simulations of cerebrospinal fluid dynamics.
Journal of Biomechanical Engineering-transactions of The Asme, 2015Co-Authors: Soroush Heidari Pahlavian, Theresia I Yiallourou, Alexander C Bunck, Francis Loth, R. Shane Tubbs, Jan Robert Kroeger, Walter Heindel, Bryn A MartinAbstract:The purpose of the present study was to compare subject-specific magnetic resonance imaging (MRI)-based computational fluid dynamics (CFD) simulations with time-resolved three-directional (3D) velocity-encoded phase-contrast MRI (4D PCMRI) measurements of the cerebrospinal fluid (CSF) velocity field in the cervical spinal subarachnoid space (SSS). Three-dimensional models of the cervical SSS were constructed based on MRI image segmentation and anatomical measurements for a healthy subject and patient with Chiari I malformation. CFD was used to simulate the CSF motion and compared to the 4D PCMRI measurements. Four-dimensional PCMRI measurements had much greater CSF velocities compared to CFD simulations (1.4 to 5.6 x greater). Four-dimensional PCMRI and CFD both showed anterior and anterolateral dominance of CSF velocities, although this flow feature was more pronounced in 4D PCMRI measurements compared to CFD. CSF flow jets were present near the nerve rootlets and Denticulate Ligaments (NRDL) in the CFD simulation. Flow jets were visible in the 4D PCMRI measurements, although they were not clearly attributable to nerve rootlets. Inclusion of spinal cord NRDL in the cervical SSS does not fully explain the differences between velocities obtained from 4D PCMRI measurements and CFD simulations.
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the impact of spinal cord nerve roots and Denticulate Ligaments on cerebrospinal fluid dynamics in the cervical spine
PLOS ONE, 2014Co-Authors: Soroush Heidari Pahlavian, Theresia I Yiallourou, Shane R Tubbs, Alexander C Bunck, Francis Loth, Mark Goodin, Mehrdad Raisee, Bryn A MartinAbstract:Cerebrospinal fluid (CSF) dynamics in the spinal subarachnoid space (SSS) have been thought to play an important pathophysiological role in syringomyelia, Chiari I malformation (CM), and a role in intrathecal drug delivery. Yet, the impact that fine anatomical structures, including nerve roots and Denticulate Ligaments (NRDL), have on SSS CSF dynamics is not clear. In the present study we assessed the impact of NRDL on CSF dynamics in the cervical SSS. The 3D geometry of the cervical SSS was reconstructed based on manual segmentation of MRI images of a healthy volunteer and a patient with CM. Idealized NRDL were designed and added to each of the geometries based on in vivo measurments in the literature and confirmation by a neuroanatomist. CFD simulations were performed for the healthy and patient case with and without NRDL included. Our results showed that the NRDL had an important impact on CSF dynamics in terms of velocity field and flow patterns. However, pressure distribution was not altered greatly although the NRDL cases required a larger pressure gradient to maintain the same flow. Also, the NRDL did not alter CSF dynamics to a great degree in the SSS from the foramen magnum to the C1 level for the healthy subject and CM patient with mild tonsillar herniation (∼6 mm). Overall, the NRDL increased fluid mixing phenomena and resulted in a more complex flow field. Comparison of the streamlines of CSF flow revealed that the presence of NRDL lead to the formation of vortical structures and remarkably increased the local mixing of the CSF throughout the SSS.
-
CEREBROSPINAL FLUID DYNAMICS IN THE CERVICAL SPINE: IMPORTANCE OF FINE ANATOMICAL STRUCTURES
Volume 1A: Abdominal Aortic Aneurysms; Active and Reactive Soft Matter; Atherosclerosis; BioFluid Mechanics; Education; Biotransport Phenomena; Bone J, 2013Co-Authors: Soroush Heidari Pahlavian, Theresia I Yiallourou, Alexander C Bunck, Francis Loth, Mark Goodin, Mehrdad Raisee, R. S. Tubbs, Bryn A MartinAbstract:Fine anatomical structures, including nerve roots and Denticulate Ligaments, can significantly influence cerebrospinal fluid (CSF) dynamics inside the spinal subarachnoid space (SSS). In this study, we completed computational fluid dynamics (CFD) simulations based on subject specific geometries of the cervical spine with and without idealized fine structures (nerve roots and Denticulate Ligaments, NRDL). The results show that NRDL had a significant impact on CSF dynamics in terms of velocity distribution, flow streamlines, bidirectional nature of the flow and the pressure drop.