T 2 mapping of cerebrospinal fluid: 3 T versus 7 T

Cerebrospinal fluid (CSF) T (2) mapping can potentially be used to investigate CSF composition. A previously proposed CSF T (2)-mapping method reported a T (2) difference between peripheral and ventricular CSF, and suggested that this reflected different CSF compositions. We studied the performance of this method at 7 T and evaluated the influence of partial volume and B (1) and B (0) inhomogeneity. T (2)-preparation-based CSF T (2)-mapping was performed in seven healthy volunteers at 7 and 3 T, and was compared with a single echo spin-echo sequence with various echo times. The influence of partial volume was assessed by our analyzing the longest echo times only. B (1) and B (0) maps were acquired. B (1) and B (0) dependency of the sequences was tested with a phantom. T (2,CSF) was shorter at 7 T compared with 3 T. At 3 T, but not at 7 T, peripheral T (2,CSF) was significantly shorter than ventricular T (2,CSF). Partial volume contributed to this T (2) difference, but could not fully explain it. B (1) and B (0) inhomogeneity had only a very limited effect. T (2,CSF) did not depend on the voxel size, probably because of the used method to select of the regions of interest. CSF T (2) mapping is feasible at 7 T. The shorter peripheral T (2,CSF) is likely a combined effect of partial volume and CSF composition.