GFAP and Alzheimer disease: Quantitative autoradiography studies in postmortem AD brains have shown a strong regional correlation between the number of GFAP+ reactive astrocytes and the extent of in vivo 11C-PIB and in vitro 3H-PIB binding, but there appears to be no regional correlation between postmortem 3H-L-deprenyl and in vivo 11C-PIB binding [45].