In-vivo diagnostic method by means of NIR radiation

A process for in vivo diagnosis using near infra red (NIR) irradiation is claimed. The process uses dyestuffs or their derivs. of formula Bl-(F-Wn)m (I) or their physiologically acceptable salts. l = 0-6; n = 0-10; m = 1-100; B = a biological diagnostic unit of mol. wt. up to 30000 which binds on certain cell populations or which binds specifically to receptors or which enriches in tissues or tumours or which remains largely in the blood; or B = a non-specifically binding macromolecule; F = a dyestuff which has an absorption maximum 650-1200 nm; W = a hydrophilic gp. which improves water solubility. (I; l = 0) has an n-octanol-water partition coefficient less than or equal to 2.0. Also claimed are cyanine dyestuffs of formula (V) and their salts. Q = =CH-C(R30)=CH-, =CH-CH=C(R30)-CH=CH-, or a gp. of formula (a) or (b); R30 = H, OH, COOH, 1-4C alkoxy or Cl; b=2-3; R31 = H or 1-4C alkyl; X, Y = O, S, CH=CH or C(CH2R32)(CH2R33); R, R1-R9, R32, R33 = R' or R"; or adjacent pairs of R-R7 may combine to form a 5-6 membered aromatic or saturated annelated ring; R' = H, OH, COOH, SO3H, up to 10C carboxyalkyl, up to 10C alkoxycarbonyl, up to 10 C alkoxyoxoalkyl or 1-4C sulphoalkyl; R" = a non-specific macromolecule or (O)v-(CH2)o-CONR34-(CH2)s-(NHCO)q-R35; o, s = 0; or o, s = 1-6; q and v = 0-1; R34 = H or Me; R35 = 1-6C alkyl (substd. with 1-3 carboxy), 6-9C aryl, 7-15C aralkyl, nC alkyl contg. 2 to (n-1) OH gps., or CH2(N(CH2COOH)CH2CH2)yN(CH2COOH)2; n = 3-6; y = 1 or 2; provided that if X and Y = O, S, CH=CH or CMe2, then at least one of R-R9 = R" and q = 1.