This　study　further　investigates　the　influence　of　temporarily　disrupting　the　blood-brain　barrier　(BBB)　on　the　level　of　manganese　used　in　AIM　fMRI　other　than　the　recognized　function　of　allowing　that　substance　to　enter　into　the　activated　brain　regions　more　effectively　during　the　BBB　opening.　We　injected　manganese　into　Wistar　rats　through　ICA　following　the　disruption　of　BBB　with　mannitol　in　a　functional　MRI　test　of　the　visual　cortex.　Through　comparing　MRI　signal　intensity　and　manganese　contents　in　the　visual　cortex　of　rats　received　visual　stimuli　of　unequal　degree　after　the　restoration　of　BBB,　we　found　that　the　signal　in　the　visual　cortex　could　be　further　enhanced　on　T1WI　given　visual　stimulation　after　the　restoration　of　BBB.　Temporary　BBB　disruption　has　an　additional　advantage　in　allowing　Mn2+　to　enter　the　CSF　or　brain　for　later　transference　to　the　activated　brain　area.　So　the　dosage　of　manganese　in　AIM　fMRI　could　be　minimized　by　extending　the　stimulus.