A simple approach for three-dimensional mapping of baseline cerebrospinal fluid volume fraction

A simple method of measuring baseline cerebrospinal fluid volume fraction (V_CSF) in three-dimensional is proposed that used the characteristic of cerebrospinal fluid with very long T₂. It is based on the fitting of monoexponential decay of only cerebrospinal fluid signal, using a nonselective T₂ preparation scheme. Three-dimensional gradient- and spin-echo acquisition also improves signal-to-noise ratio efficiency and brain coverage. Both V_CSF and T_2,CSF are fitted voxel by voxel and analyzed in different cortical areas across subjects. V_CSF is largely regionally dependent (occipital: 8.9 ± 1.7%, temporal: 11.4 ± 2.4%, and frontal: 21.4 ± 6.9%). Measured T_2,CSF was 1573 ± 146 msec within cortical lobes as compared with 2062 ± 37 msec from ventricle regions. Different parameter set were compared, and the robustness of the new method is demonstrated. Conversely, when comparing with the proposed approach, large overestimation of segmentation based method using T₁-weighted images is found, and the underlying causes are suggested.