Polymorphs of Formula I, which is 2-((E)-2-((E)-3-(2-((E)-3,3-dimethyl-5-sulfonato-1-(4-sulfonatobutyl)indolin-2-ylidene)ethylidene)-2-phenoxycyclohex-1-en-1-yl)vinyl)-3,3-dimethyl-1-(4-sulfonatobutyl)-3H-indol-1-ium-5-sulfonate and methods of making are provided.A method for organ imaging, comprising administering to a subject, a diagnostic effective amount of a composition comprising a polymorph of Formula I are also provided. In one embodiment, the organ includes one or more of kidney, bladder, ureter, urethra, bile ducts, liver, and gall bladder.