The term flip-flop in radiology refers to the reversal or inversion of a normally expected phenomenon. This is not to be confused with the footwear. It may refer to the following:
flip-flop CT appearance of the liver in Budd-Chiari syndrome
flip-flop renal enhancement on CT in a renal infarct
flip-flop effect on MRI in serous atrophy of the bone marrow
flip-flop fungus sign on PET-CT of a benign pulmonary nodule