We measured the ctDNA level among 27 CSF samples and found the ctDNA level showed significant differences across age (p = 0.025, Figure 1A), Ki-67 index (p = 0.013, Figure 1B), MRI signal (p = 0.004, Figure 1C), and tumor subtypes (p = 0.001, Figure 1D). Here, MKI67 is linked to neoplasm.