The pathways of brain molecular clearance and potential glymphatic efflux to extracerebral cerebrospinal fluid is a matter of intense research. We investigated possible contrast enrichment in cerebrospinal fluid of the subarachnoid space following intravenous contrast injection. This approach utilizes a subtle but widespread contrast leakage across the blood-brain barrier that potentially enables the investigation of glymphatic function. Using T1-mapping as well as dynamic scanning during contrast infusion, we present data consistent with a model where molecules cleared from the brain enter subarachnoid space cerebrospinal fluid. This approach could be a clinically feasible alternative for investigating brain molecular clearance in humans.