▁brain ▁met abol ism , ▁which ▁in ▁turn ▁causes ▁easily ▁detect able ▁changes ▁in ▁P ET ▁sc ans . ▁P ET ▁is ▁probably ▁most ▁useful ▁in ▁early ▁cases ▁of ▁certain ▁de ment ias ▁( with ▁classic ▁examples ▁being ▁Al z heimer ' s ▁disease ▁and ▁Pick ' s ▁disease ) ▁where ▁the ▁early ▁damage ▁is ▁too ▁diff use ▁and ▁makes ▁too ▁little ▁difference ▁in ▁brain ▁volume ▁and ▁gross ▁structure ▁to ▁change ▁CT ▁and ▁standard ▁M RI ▁images ▁enough ▁to ▁be ▁able ▁to ▁reli ably ▁differenti ate ▁it ▁from ▁the ▁" normal " ▁range ▁of ▁cort ical ▁at ro phy ▁which ▁occurs ▁with ▁ag ing ▁( in ▁many ▁but ▁not ▁all ) ▁persons , ▁and ▁which ▁does ▁not ▁cause ▁clin ical ▁de ment ia . ▁ ▁P ET ▁is ▁also ▁act ively ▁used ▁for ▁multiple ▁s cl eros is ▁and ▁other ▁acquired ▁dem y elin ating ▁synd rom es , ▁but ▁mainly ▁for ▁research ▁into ▁path ogen esis ▁instead ▁of ▁diagn osis . ▁They ▁use ▁specific ▁radi ol ig ands ▁for ▁micro g li al ▁activity . ▁Currently ▁is ▁widely ▁used ▁the ▁ 1 8 - k Da ▁trans loc ator ▁protein ▁( T SP O ). ▁Also ▁combined ▁P ET - CT ▁are ▁sometimes ▁performed . ▁ ▁References ▁ ▁Category : 3 d ▁nuclear ▁medical ▁imag ing ▁Category : Ne uro im aging <0x0A> </s> ▁Pol yd rus us ▁amer ican us ▁is ▁a ▁species ▁of ▁broad - n osed ▁we ev il ▁in ▁the ▁be et le ▁family ▁Cur cul ion idae