MRI of omphalopagus conjoined twins with a Dandy-Walker malformation: prenatal true FISP and HASTE sequences.

Conjoined twins are an extremely rare congenital malformation without any known genetic predisposition. Omphalopagus twins are the second most common variety of conjoined twins and usually are joined at the umbilicus. We present omphalopagus conjoined twins demonstrated with true FISP (fast imaging with steady-state procession) and HASTE (half- Fourier acquisition single-shot turbo spin-echo) magnetic resonance imaging (MRI) sequences, which showed Dandy- Walker malformation in one of the pair. To our knowledge, this is the first case of conjoined twins with this malformation, which was diagnosed with ultrafast MRI.