Evidence of Incoherent Cerebrospinal Fluid Flow in the Human Brain From Multidimensional MRI

ABSTRACT Purpose The human brain contains multiple fluid types, including blood, cerebrospinal fluid (CSF), and tissue water. While intravoxel incoherent motion (IVIM) imaging has been used to examine microvascular perfusion, evidence on incoherent flows of CSF is emerging. This study aims to develop in vivo multidimensional MRI methods to investigate potential contributions of CSF in the IVIM regime. Method T 1 ‐Diffusion (T 1 ‐ D ) and T 2 ‐Diffusion (T 2 ‐ D ) MRI data were acquired from 10 healthy subjects to investigate the relaxivity and diffusion signatures of incoherent fluid flows in the brain. Based on the T 1 ‐ D and T 2 ‐ D results, T 1 /T 2 selective IVIM protocols were developed to map incoherent CSF flows in the human brains. Results T 1 ‐ D and T 2 ‐ D MRI detected incoherent CSF flow in the brain subarachnoid space. Results from four different relaxation selective IVIM methods further support incoherent CSF flows in these regions. Conclusion We have shown the feasibility of using T 1 ‐ D and T 2 ‐ D MRI within the low b‐value regime to probe the heterogeneity of IVIM flow components. Designed based on the 2D MRI spectra, relaxation selective 1D IVIM acquisition can be obtained within clinically feasible time frame.