highly significantP < 0.001
Association between PSD volume and enrichment and clearance of CSF tracer CSF tracer in PSD There was a strong and highly significant association between tracer enrichment in PSD and tracer enrichment in nearby subarachnoid CSF space at 3 hours ( R = 0.79, P < 0.001), 6 hours ( R = 0.93, P < 0.001), 24 hours ( R = 0.84, P < 0.001) and 48 hours ( R = 0.73, P < 0.001).