High-resolution CE-MRA of Children's Hip Joint

The goal of this observational study is to learn about the feasibility of enhanced three-dimensional water-selective cartilage (3D-WATSc) sequence in displaying the vessels of children's hip by magnetic resonance. The main questions it aims to answer are: * Could the images of enhanced 3D-WATSc sequence show the healthy side hip joint vessels in children? * Could the images of enhanced 3D-WATSc sequence show the vascular disease of the suffering side hip joint in children? Participants with unilateral hip disease will undergo the magnetic resonance examination including enhanced 3D-WATSc sequence. The pelvic plain film and magnetic resonance images will be collected and analysed. Researchers will compare the images of of the normal side with the images of the abnormal side to see if the enhanced 3D-WATSc sequence images could show the vascular disease of the suffering side hip joint in children?