The double panda sign refers to the combination of the face of the giant panda and face of the miniature panda (cub of the giant panda) seen on T2 weighted images of midbrain and pons respectively, most commonly seen in Wilson disease.
The midbrain face of the giant panda sign consists of normal intensity of red nuclei and lateral portions of substantia nigra pars reticulata with high signal intensity of tegmentum and hypointensity of the superior colliculus.
The pons face of the miniature panda sign consists of relative hypointensity of the central tegmental tracts (eyes of the panda) in contrast with the hyperintensity of the aqueduct opening into the fourth ventricle (nose and mouth of the panda). The superior cerebellar peduncles form the panda’s cheeks.
Although only seen in a small percentage of patients with Wilson disease, it is characteristic when present. However, the sign is not pathognomonic, and has been reported in other conditions (e.g. Leigh syndrome) 5.