Abstract
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.
Highlights
Cerebrospinal fluid (CSF) dynamics have been examined in craniospinal disorders because analysis of brain and spinal cord morphology alone has been insufficient to explain patient symptoms and surgical outcome [1,2]
In the present study we focus on analysis of CSF dynamics present in the cervical spinal subarachnoid space (SSS) by comparing 4D PC MRI measurements to subject-specific rigid wall and anatomically simplified computational fluid dynamics (CFD) simulations
CSF dynamics were found to be considerably different in 4D PC MRI versus CFD simulations
Summary
Cerebrospinal fluid (CSF) dynamics have been examined in craniospinal disorders because analysis of brain and spinal cord morphology alone has been insufficient to explain patient symptoms and surgical outcome [1,2]. Time-resolved three-directional velocity encoded phase contrast MR imaging (4D PC MRI) has been increasingly appreciated for its potential to quantitatively and qualitatively assess CSF flow dynamics and provide insight into complex flow phenomena such as secondary flow and vortex strength that can occur in craniospinal disorders [1,10]. The CSF flow field obtained by 4D PC MRI has not been compared to 3D computational fluid dynamics (CFD) simulations; a helpful tool to quantify the CSF movement within the SSS and intracranial space [14,15,16,17,18,19]. CFD simulations are uniquely suited for variational analysis; a technique that can be used to help assess the importance of individual anatomical aspects of the CSF system such as the spinal cord nerve roots or PLOS ONE | www.plosone.org
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