Methods of imaging distribution of myeloperoxidase activity in a subject are disclosed. These methods include the use of bioluminescent substrates, including luminol and wavelength-shifted analogues of luminol. Bioluminescent myeloperoxidase substrates that emit light at longer wavelengths compared to luminol are shown to be useful for imaging myeloperoxidase activity in vivo. The disclosed methods can be used for imaging sites of inflammation and other pathological conditions associated with abnormal levels of MPO activity in vivo. Methods of synthesis of luminol analogues are also disclosed.