Panda Signs and Wilson Disease

The "face of the giant panda" sign refers to the characteristic appearance of Wilson disease on T2-weighted MRI of the midbrain:

• High signal intensity in the tegmentum sparing the red nucleus. The relatively hypointense red nucleus makes up the eyes.
• Preservation of signal intensity of the lateral portion of the pars reticulata of the substantia nigra makes up the ears.
• Low signal intensity of the superior colliculus makes up the chin.

Panels B and C of this figure give a good demonstration.

Some people also see the "face of the miniature panda" or "face of the panda cub" more inferiorly in the pontine tegmentum. To me this looks more like a mustachioed man wearing a turban, but people like consistency.

• The relative hypointensity of the medial longitudinal fasciculi and central tegmental tracts give the eyes of the panda.
• The hyperintensity of the aqueduct opening into the fourth ventricle results in the nose and mouth of the panda
• The normal superior cerebellar peduncles form the panda's cheeks.

An image of the baby panda can be found here.

References

• Hitoshi S, Iwata M, Yoshikawa K. Mid-brain pathology of Wilson's disease: MRI analysis of three cases. J Neurol Neurosurg Psychiatry. 1991 Jul;54(7):624-6.
• Jacobs DA, Markowitz CE, Liebeskind DS, Galetta SL. The "double panda sign" in Wilson's disease. Neurology. 2003 Oct 14;61(7):969.
• Shivakumar R, Thomas SV. Teaching NeuroImages: face of the giant panda and her cub: MRI correlates of Wilson disease. Neurology. 2009 Mar 17;72(11):e50.