Fluorine (19F) magneticresonance imaging (MRI) is severelylimited by a low signal-to noise ratio (SNR), and tapping it for 19F drug detection in vivo still poses a significant challenge.However, it bears the potential for label-free theranostic imaging.Recently, we detected the fluorinated dihydroorotate dehydrogenase(DHODH) inhibitor teriflunomide (TF) noninvasively in an animal modelof multiple sclerosis (MS) using 19F MR spectroscopy (MRS).In the present study, we probed distinct modifications to the CF3 group of TF to improve its SNR. The gene discussed is DHODH; the disease is myeloid sarcoma.