A compound represented by Formula I: or a pharmaceutically acceptable salt or solvate thereof; for use in a method for measuring amyloid deposits in a patient comprising the steps of administering to the patient a detectable quantity of said compound of formula I or salt or solvate thereof, and detecting the binding of the compound to amyloid deposits in the patient; wherein: Z is selected from the group consisting of phenyl, benzothiazolyl, indolyl, pyridyl, pyrazolopyridinyl, benzodioxolyl, and pyrrolopyridinyl all optionally substituted with 1 to 3 groups of R2, R3 or R4; R represents hydrogen, or -C 1-6 alkyl; R 1 represents hydrogen, -cos_10 heterocyclyl, -N(R 2) 2, CN, -(CH 2) n halo, CF 3,-O(CH 2) n R, -O(CH 2) n C 5-10 heterocyclyl, -C 1-6 alkyl, -OCF 3, -O(CH 2) n F,-(O(CH 2) s)phalo, -(O(CH 2) s)pOR, -C OR, or hetero-spirocycle said alkyl, and heterocyclyl optionally substituted with 1 to 3 groups of R a, with the proviso that R 1, R 2, R 3 and R 4 are not hydrogen at the same time, or when R 1 is hydrogen, Z is phenyl and two of R 2, R 3 and R 4 are hydrogen, then the other of R 2, R 3 and R 4 is not methyl, furyl, halo, hydroxyl, ethoxy, dimethoxy, isopropyloxy, amino, methylamino, dimethylamino or methoxy; R 2, R 3 and R 4 independently represent hydrogen, -(CH 2) n halo, -C 1-6 alkyl, -CF 3,- n OR, (CH 2) n C 5-10 heterocyclyl, -N 2, said alkyl, and heterocyclyl optionally substituted with 1 to 3 groups of R a; R a represents -CN, NO 2, halo, CF 3, -C 1-6 alkyl, -C 1-6 alkenyl, -C 1-6 alkynyl,-(CH 2) n halo, -OR, -NRR 1, -C(=NR 1)NR 2 R 3, -N(=NR 1)NR 2 R 3, - NR 1 COR 2, -NR 1 CO 2 R 2, -NR 1 SO 2 R 4, -NR 1 CONR 2 R 3,-SR 4, -SOR 4, -SO 2 R 4, - SO 2 NR 1 R 2, -COR 1, -CO 2 R 1, -CONR 1 R 2, -C(=NR 1)R 2, or-C(=NOR 1)R 2; n represents 0-6; s represents 2-4; and p represents 1-3. Z is selected from the group consisting of phenyl, benzothiazolyl, indolyl, pyridyl, pyrazolopyridinyl, benzodioxolyl, and pyrrolopyridinyl all optionally substituted with 1 to 3 groups of R2, R3 or R4; R represents hydrogen, or -C 1-6 alkyl; R 1 represents hydrogen, -cos_10 heterocyclyl, -N(R 2) 2, CN, -(CH 2) n halo, CF 3,-O(CH 2) n R, -O(CH 2) n C 5-10 heterocyclyl, -C 1-6 alkyl, -OCF 3, -O(CH 2) n F,-(O(CH 2) s)phalo, -(O(CH 2) s)pOR, -C OR, or hetero-spirocycle said alkyl, and heterocyclyl optionally substituted with 1 to 3 groups of R a, with the proviso that R 1, R 2, R 3 and R 4 are not hydrogen at the same time, or when R 1 is hydrogen, Z is phenyl and two of R 2, R 3 and R 4 are hydrogen, then the other of R 2, R 3 and R 4 is not methyl, furyl, halo, hydroxyl, ethoxy, dimethoxy, isopropyloxy, amino, methylamino, dimethylamino or methoxy; R 2, R 3 and R 4 independently represent hydrogen, -(CH 2) n halo, -C 1-6 alkyl, -CF 3,- n OR, (CH 2) n C 5-10 heterocyclyl, -N 2, said alkyl, and heterocyclyl optionally substituted with 1 to 3 groups of R a; R a represents -CN, NO 2, halo, CF 3, -C 1-6 alkyl, -C 1-6 alkenyl, -C 1-6 alkynyl,-(CH 2) n halo, -OR, -NRR 1, -C(=NR 1)NR 2 R 3, -N(=NR 1)NR 2 R 3, - NR 1 COR 2, -NR 1 CO 2 R 2, -NR 1 SO 2 R 4, -NR 1 CONR 2 R 3,-SR 4, -SOR 4, -SO 2 R 4, - SO 2 NR 1 R 2, -COR 1, -CO 2 R 1, -CONR 1 R 2, -C(=NR 1)R 2, or-C(=NOR 1)R 2; n represents 0-6; s represents 2-4; and p represents 1-3.