The present application discloses compositions and methods of synthesis and use of 68Ga, 18F or 19F labeled molecules of use in PET or MRI imaging. Preferably, the 18F or 19F is conjugated to a targeting molecule by formation of a complex with a group IIIA metal and binding of the complex to a chelating moiety, which may be directly or indirectly attached to the targeting molecule. In other embodiments, the 68Ga, 18F or 19F labeled moiety may comprise a targetable construct used in combination with a bispecific antibody to target a disease-associated antigen. In more preferred embodiments, a chelating moiety or targetable construct may be conjugated to a targeting molecule, such as an antibody or antibody fragment.