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

Abstract

Object: Cerebrospinal fluid (CSF) T2 mapping can potentially be used to investigate CSF composition. A previously proposed CSF T2–mapping method reported a T2 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 B1 and B0 inhomogeneity. Materials and methods: T2-preparation-based CSF T2-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. B1 and B0 maps were acquired. B1 and B0 dependency of the sequences was tested with a phantom. Results: T2,CSF was shorter at 7 T compared with 3 T. At 3 T, but not at 7 T, peripheral T2,CSF was significantly shorter than ventricular T2,CSF. Partial volume contributed to this T2 difference, but could not fully explain it. B1 and B0 inhomogeneity had only a very limited effect. T2,CSF did not depend on the voxel size, probably because of the used method to select of the regions of interest. Conclusion: CSF T2 mapping is feasible at 7 T. The shorter peripheral T2,CSF is likely a combined effect of partial volume and CSF composition.