The purpose of this study is to establish CSF 4D flow MRI patterns in normal individuals and to assess the effect of spine positioning on these flow patterns. Once we establish CSF flow patterns in healthy controls, we will investigate whether patients with Chiari I Malformation (CIM) exhibit similar patterns or if they are particular to CIM, which may correlate with symptom severity and/or likelihood to improve following surgery.
MR imaging protocols for CIM include sagittal images to assess the position of the cerebellar tonsils. Sometimes, 2D phase-contrast (PC) imaging is obtained to investigate whether structural abnormalities are resulting in abnormal CSF flow at the foramen magnum. Often, CSF flow improves after posterior fossa decompression when compared to a preoperative study. Unfortunately, interpretation of these studies is highly subjective and associated with poor interrater reliability.
Better, more reliable imaging techniques could improve patient selection for surgery and outcomes. Compared to 2D PC MRI, volumetric flow evaluation with ECG-triggered 3D PC MRI using 3-directional velocity encoding (4D flow MRI) is ideally suited to quantify CSF flow dynamics due to the desired extent of flow coverage. However, due to the long T1 relaxation time of CSF and the typical repetition times (TR) of 7 ms for one-directional velocity encoding and 21 ms for 3-directional velocity encoding, the flip angle (FA) of such PC MRI acquisition has to be very low (about 3-6°) for maximum signal in CSF. This results in overall low signal intensity and thus high noise. We plan to investigate a new strategy that allows longitudinal signal recovery and thus acquisition with increased  FA < 15° to achieve improved signal intensities in the CSF.

Primary contact: Susanne Schnell (PhD)
Investigators: Susanne Schnell (PhD), TBD
Collaborations: Northwestern University (Michael Markl, Tarek Hijaz, Alex Kurutz, Ali Shaibani)